Category Archives: Spray Foam Insulation

Pt1 Spray Foam Insulation StLouis Brick Building

 To help educate the people of StLouis against future problems in regard to: Air Quality, Durability, and Creature Comforts I put together: Part One-Basement, Crawl Space, Stone Foundation Insulation Series on: Cost Effective:Energy Conservation for StLouis Brick Buildings [ where, how and why with suggested solutions in regard to spray foam insulation.]

Recently I’ve had a couple of requests to “Spray Foam” Insulate a StLouis Brick Home with Spray Foam Insulation-I don’t know who has been telling people its ok to do ‘this or that’ but I want to show all the readers the basic principles behind the Actual Building Science behind Spray Foam Insulation and the best practices for using this product.

Many times the shows on TV and supposed building professionals performing similar home improvement services [in some instances these shows are correct;many times they are not.]  So before you start spraying foam insulation on the walls of your building there are a few areas that need to be considered before starting on a project such as this-follow the suggested Building Science Principles for



See, Review and Comment on the Google Cloud Document: Spray Foam Insulation St Louis Brick Buildings

Thank you for stopping by St Louis Renewable Energy. Feel free to comment in the section below or contact Scotts Contracting- St Louis Home Improvement Projects and Energy Reducing Needs Get Your Green Building Tips and Resources at St Louis Renewable Energy Green Blog


Part 2 on Home Weatherization Series, by Scotts Contracting-St Louis Renewable Energy

Example of How a Box Sill is Constructed using Standard Building Techniques

Box Sill-What is it? And How to Insulate the Area 

In this Article I’m going to explain how to Seal and Insulate the Box Sill of your home and why it is important to add Insulation in this area of your Building. Adding Insulation will: Reduce the Energy Needs of your Property, while Increasing Your Personal Comfort level. 
Its a Win-Win option for any Home-Owner

Spray Foam: Open Cell VS Closed Cell

Scotty writes: In response to a prior questions:

Q:Which Spray Foam Insulation is Best, Open Cell or Closed Cell?

Open-Cell Vs. Closed-Cell

The real distinction between types of foam insulation focuses on whether they are open- or closed-cell. In general, both are made from the same materials and work in the same way, trapping air or gas in a plastic matrix. The differences start with the “blowing agents” used to create bubbles and end with both varied performance and cost.

Open-cell foam costs slightly less for the same thickness, but offers lower per-inch R-values than closed-cell products. In some instances, this is a disadvantage, but where thickness is less relevant, or where higher R-values are not needed, then open-cell can provide the better choice. It also has some green advantages over closed-cell: The blowing agent used to install open-cell insulation is water, which reacts with air to become CO2—while closed-cell products use HFCs.

Because CO2 expands quickly, the bubbles tend to burst before the plastic sets, and hence the “open cells,” which produce a spongy, lightweight foam. The industry describes the foam as “half-pound” material, which simply means the foam has a mass that weighs 0.5 pounds per cubic foot. This density yields an R-value of approximately 3.6 per inch, equivalent to most traditional insulations. Because of the open cell structure, open-cell foam allows some vapor to pass through, making it a good choice in hot, humid climates, and under roof sheathing, such as in conditioned attics, where water vapor caught between insulation and sheathing could promote wood rot.

In short, open-cell foam, tested in accordance with ASTM E 283, provides an air barrier with vapor breathability. Water-blown solutions have less environmental impact than the current HFCs used for most closed-cell spray-foam insulation. And open-cell has about twice the noise reduction coefficient in normal frequency ranges as closed-cell foam. Because the blowing agent in open-cell insulation dissipates as it sets, instead of slowly over time, there is no degeneration of the R-value—a minor point given aged closed-cell R-values still trump open-cell R-values by a magnitude of nearly 100%.

Unlike open-cell foam, closed-cell foam uses chemical blowing agents that come in liquid form and become gasses as they are applied. These gasses expand, but not as quickly as CO2, allowing the polyurethane plastic to set before the bubbles burst. This yields dense foam weighing nearly 2 pounds per cubic foot, and without the capillary characteristics of open-cell, it remains impermeable. The blowing agents used perform like the inert gasses between the panes of high-performance windows, adding to the insulating qualities of the foam. Unlike open-cell foam, closed-cell foam rarely requires any trimming, with little or no jobsite waste.

Closed-cell has more obvious advantages over open-cell, and a slightly higher price tag (20% to 30% for the same thickness). It provides both a vapor and air barrier and offers an aged R-value of a whopping 6.5 per inch. Because of its density and glue-like consistency, it remains very strong, providing both compressive and tensile strength to structure comparable to added sheathing, increasing the racking strength of walls by as much as 300%, according to the NAHB Research Center. Because water does not penetrate or degrade the product, FEMA recommends closed-cell foam as a suitable insulation material for flood regions.

The principle disadvantage of closed-cell foam comes with overkill. If you do not require the extra vapor barrier, structural strength, and R-value per inch, then you may be wasting money. As for the added wall strength, while real and substantial, it’s not acknowledged by building codes currently, so you can’t reduce the structural bracing as a tradeoff.
Information found at:

Spray Foam: Toxic Blowing Agents and Fire Proofing

Scott’s Contracting


Which Kind Of Insulation Is Best?

Email: Scotts Contracting to Schedule a Green Proposal

for Your Next Project 

Scotts Contracting Offers Green Insulation Installs for the St Louis Area



  • Why Insulate Your House?
  • How Insulation Works

Which Kind of Insulation is Best?

  • What Is an R-Value?
  • Reading the Label
  • Insulation Product Types

Insulating a New House

  • Where and How Much
  • Air Sealing
  • Moisture Control and Ventilation
  • Installation Issues
    • Precautions
    • Attics
    • Walls
  • Design Options
    • Crawlspaces and Slabs
    • Advanced Wall Framing
    • Metal Framing
    • Insulating Concrete Forms
    • Massive Walls
    • Structural Insulated Panels
    • External Insulation Finish System
    • Attic Ventilation or a Cathedralized Attic

Adding Insulation to an Existing House

  • Where and How Much
  • How Much Insulation Do I Already Have?
  • Air Sealing
  • Moisture Control and Ventilation
  • Insulation Installation, the Retrofit Challenge
    • Precautions
    • Attics
    • Walls
    • Basement Walls
    • Floors and Crawlspaces

Resources and Links
About This Fact Sheet

Which Kind Of Insulation Is Best?

Based on our email, this is one of the most popular questions homeowners ask before buying insulation. The answer is that the ‘best’ type of insulation depends on:

  • how much insulation is needed,
  • the accessibility of the insulation location,
  • the space available for the insulation,
  • local availability and price of insulation, and
  • other considerations unique to each purchaser.

Whenever you compare insulation products, it is critical that you base your comparison on equal R-values.

What Is an R-Value?
Insulation is rated in terms of thermal resistance, called R-value, which indicates the resistance to heat flow. The higher the R-value, the greater the insulating effectiveness. The R-value of thermal insulation depends on the type of material, its thickness, and its density. In calculating the R-value of a multi-layered installation, the R-values of the individual layers are added.

The effectiveness of an insulated ceiling, wall or floor depends on how and where the insulation is installed.

  • Insulation which is compressed will not give you its full rated R-value. This can happen if you add denser insulation on top of lighter insulation in an attic. It also happens if you place batts rated for one thickness into a thinner cavity, such as placing R-19 insulation rated for 6 1/4 inches into a 5 1/2 inch wall cavity.
  • Insulation placed between joists, rafters, and studs does not retard heat flow through those joists or studs. This heat flow is called thermal bridging. So, the overall R-value of a wall or ceiling will be somewhat different from the R-value of the insulation itself. That is why it is important that attic insulation cover the tops of the joists and that is also why we often recommend the use of insulative sheathing on walls. The short-circuiting through metal framing is much greater than that through wood-framed walls; sometimes the insulated metal wall’s overall R-value can be as low as half the insulation’s R-value.

Reading the Label
No matter what kind of insulation you buy, check the information on the product label to make sure that the product is suitable for the intended application. To protect consumers, the Federal Trade Commission has very clear rules about the R-value label that must be placed on all residential insulation products, whether they are installed by professionals, or whether they are purchased at a local supply store. These labels include a clearly stated R-value and information about health, safety, and fire-hazard issues. Take time to read the label BEFORE installing the insulation. Insist that any contractor installing insulation provide the product labels from EACH package (which will also tell you how many packages were used). Many special products have been developed to give higher R-values with less thickness. On the other hand, some materials require a greater initial thickness to offset eventual settling or to ensure that you get the rated R-value under a range of temperature conditions.

Insulation Product Types
Some types of insulation require professional installation, and others you can install yourself. You should consider the several forms of insulation available, their R-values, and the thickness needed. The type of insulation you use will be determined by the nature of the spaces in the house that you plan to insulate. For example, since you cannot conveniently “pour” insulation into an overhead space, blankets, spray-foam, board products, or reflective systems are used between the joists of an unfinished basement ceiling. The most economical way to fill closed cavities in finished walls is with blown-in insulation applied with pneumatic equipment or with sprayed-in-place foam insulation.
The different forms of insulation can be used together. For example, you can add batt or roll insulation over loose-fill insulation, or vice-versa. Usually, material of higher density (weight per unit volume) should not be placed on top of lower density insulation that is easily compressed. Doing so will reduce the thickness of the material underneath and thereby lower its R-value. There is one exception to this general rule: When attic temperatures drop below 0°F, some low-density, fiberglass, loose-fill insulation installations may allow air to circulate between the top of your ceiling and the attic, decreasing the effectiveness of the insulation. You can eliminate this air circulation by covering the low-density, loose-fill insulation with a blanket insulation product or with a higher density loose-fill insulation.

Blankets, in the form of batts or rolls, are flexible products made from mineral fibers, including fiberglass or rock wool. They are available in widths suited to standard spacings of wall studs and attic or floor joists. They must be hand-cut and trimmed to fit wherever the joist spacing is non-standard (such as near windows, doors, or corners), or where there are obstructions in the walls (such as wires, electrical outlet boxes, or pipes). Batts can be installed by homeowners or professionals. They are available with or without vapor-retarder facings. Batts with a special flame-resistant facing are available in various widths for basement walls where the insulation will be left exposed.
Blown-in loose-fill insulation includes cellulose, fiberglass, or rock wool in the form of loose fibers or fiber pellets that are blown using pneumatic equipment, usually by professional installers. This form of insulation can be used in wall cavities. It is also appropriate for unfinished attic floors, for irregularly shaped areas, and for filling in around obstructions.
In the open wall cavities of a new house, cellulose and fiberglass fibers can also be sprayed after mixing the fibers with an adhesive or foam to make them resistant to settling.
Foam insulation can be applied by a professional using special equipment to meter, mix, and spray the foam into place. Polyisocyanurate and polyurethane foam insulation can be produced in two forms: open-cell and closed-cell. In general, open-celled foam allows water vapor to move through the material more easily than closed-cell foam. However, open-celled foams usually have a lower R-value for a given thickness compared to closed-cell foams. So, some of the closed-cell foams are able to provide a greater R-value where space is limited.
Rigid insulation is made from fibrous materials or plastic foams and is produced in board-like forms and molded pipe coverings. These provide full coverage with few heat loss paths and are often able to provide a greater R-value where space is limited. Such boards may be faced with a reflective foil that reduces heat flow when next to an air space. Rigid insulation is often used for foundations and as an insulative wall sheathing.
Reflective insulation systems are fabricated from aluminum foils with a variety of backings such as kraft paper, plastic film, polyethylene bubbles, or cardboard. The resistance to heat flow depends on the heat flow direction, and this type of insulation is most effective in reducing downward heat flow. Reflective systems are typically located between roof rafters, floor joists, or wall studs. If a single reflective surface is used alone and faces an open space, such as an attic, it is called a radiant barrier.
Radiant barriers are installed in buildings to reduce summer heat gain and winter heat loss. In new buildings, you can select foil-faced wood products for your roof sheathing (installed with the foil facing down into the attic) or other locations to provide the radiant barrier as an integral part of the structure. For existing buildings, the radiant barrier is typically fastened across the bottom of joists, as shown in this drawing. All radiant barriers must have a low emittance (0.1 or less) and high reflectance (0.9 or more).

Adding Insulation to an Existing House (Smart Approaches)

[Where and How Much] [How Much Insulation Do I Already Have?] [Air Sealing] [Moisture Control and Ventilation] [Insulation Installation, the Retrofit Challenge]
Does your home need more insulation? Unless your home was constructed with special attention to energy efficiency, adding insulation will probably reduce your utility bills. Much of the existing housing stock in the United States was not insulated to the levels used today. Older homes are likely to use more energy than newer homes, leading to higher heating and air-conditioning bills.

Where and How Much
Adding more insulation where you already have some, such as in an attic, will save energy. You can save even greater amounts of energy if you install insulation into places in your home that have never been insulated. Figure 1 shows which building spaces should be insulated. These might include an uninsulated floor over a garage or crawlspace, or a wall that separates a room from the attic. Figure 3 can give you general guidance regarding the appropriate amount of insulation you should add to your home, and the rest of this page will provide more specific information.

A qualified home energy auditor will include an insulation check as a routine part of an energy audit. For information about home energy audits, call your local utility company. State energy offices are another valuable resource for information. An energy audit of your house will identify the amount of insulation you have and need, and will likely recommend other improvements as well. If you don’t have someone inspect your home, you’ll need to find out how much insulation you already have.

After you find out how much you have, you can use the ZipCode tool to find out how much you should add. This recommendation balances future utility bill savings against the current cost of installing insulation. So the amount of insulation you need depends on your climate and heating fuel(gas, oil, electricity), and whether or not you have an air conditioner. The program is called the ZipCode because it includes weather and cost information for local regions defined by the first three digits of each postal service zip code. The program also allows you to define your own local costs and to input certain facts about your house to improve the accuracy of the recommendations. However, some personal computer security systems won’t allow Java programs to run properly. The recommended R-values table can be helpful in those cases, because it will provide recommendations based on insulation and energy costs for your local area.

Look into your attic. We start with the attic because it is usually easy to add insulation to an attic. This table will help you figure out what kind of insulation you have and what its R-value is.

Look into your walls. It is difficult to add insulation to existing walls unless:

  • You are planning to add new siding to your house, or
  • You plan to finish unfinished space (like a basement or bonus room).

If so, you need to know whether the exterior walls are already insulated or not. One method is to use an electrical outlet on the wall, but first be sure to turn off the power to the outlet. Then remove the cover plate and shine a flashlight into the crack around the outlet box. You should be able to see whether or not insulation is in the wall. Also, you should check separate outlets on the first and second floor, and in old and new parts of the house, because wall insulation in one wall doesn’t necessarily mean that it’s everywhere in the house. An alternative to checking through electrical outlets is to remove and then replace a small section of the exterior siding.

Look under your floors. Look at the underside of any floor over an unheated space like a garage, basement, or crawlspace. Inspect and measure the thickness of any insulation you find there. It will most likely be a fiberglass batt, so multiply the thickness in inches by 3.2 to find out the R-value (or the R-value might be visible on a product label). If the insulation is a foam board or sprayed-on foam, use any visible label information or multiply the thickness in inches by 5 to estimate the R-value.

Look at your ductwork. Don’t overlook another area in your home where energy can be saved – the ductwork of the heating and air- conditioning system. If the ducts of your heating or air-conditioning system run through unheated or uncooled spaces in your home, such as attic or crawlspaces, then the ducts should be insulated. First check the ductwork for air leaks. Repair leaking joints first with mechanical fasteners, then seal any remaining leaks with water-soluble mastic and embedded fiber glass mesh. Never use gray cloth duct tape because it degrades, cracks, and loses its bond with age. If a joint has to be accessible for future maintenance, use pressure- or heat-sensitive aluminum foil tape. Then wrap the ducts with duct wrap insulation of R-6 with a vapor retarder facing on the outer side. All joints where sections of insulation meet should have overlapped facings and be tightly sealed with fiber glass tape; but avoid compressing the insulation, thus reducing its thickness and R-value.

Return air ducts are often located inside the heated portion of the house where they don’t need to be insulated, but they should still be sealed off from air passageways that connect to unheated areas. Drywall- to-ductwork connections should be inspected because they are often poor (or nonexistent) and lead to unwanted air flows through wall cavities. If the return air ducts are located in an unconditioned part of the building, they should be insulated.

Look at your pipes. If water pipes run through unheated or uncooled spaces in your home, such as attic or crawlspaces, then the pipes should be insulated.

Air sealing is important, not only because drafts are uncomfortable, but also because air leaks carry both moisture and energy, usually in the direction you don’t want. For example, air leaks can carry hot humid outdoor air into your house in the summer, or can carry warm moist air from a bathroom into the attic in the winter.

Most homeowners are aware that air leaks into and out of their houses through small openings around doors and window frames and through fireplaces and chimneys. Air also enters the living space from other unheated parts of the house, such as attics, basements, or crawlspaces. The air travels through:

  • any openings or cracks where two walls meet, where the wall meets the ceiling, or near interior door frames;
  • gaps around electrical outlets, switch boxes, and recessed fixtures;
  • gaps behind recessed cabinets, and furred or false ceilings such as kitchen or bathroom soffits;
  • gaps around attic access hatches and pull-down stairs;
  • behind bath tubs and shower stall units;
  • through floor cavities of finished attics adjacent to unconditioned attic spaces;
  • utiltity chaseways for ducts, etc., and
  • plumbing and electrical wiring penetrations.

These leaks between the living space and other parts of the house are often much greater than the obvious leaks around windows and doors. Since many of these leakage paths are driven by the tendency for warm air to rise and cool air to fall, the attic is often the best place to stop them. It’s important to stop these leaks before adding attic insulation because the insulation may hide them and make them less accessible. Usually, the attic insulation itself will not stop these leaks and you won’t save as much as you expect because of the air flowing through or around the insulation. There are many fact sheets that will help you stop these air leaks:

Moisture Control and Ventilation
We talk about moisture control in an insulation fact sheet because wet insulation doesn’t work well. Also, insulation is an important part of your building envelope system, and all parts of that system must work together to keep moisture from causing damage to the structure or being health hazards to the occupants. For example, mold and mildew grow in moist areas, causing allergic reactions and damaging buildings.
When Is Moisture a Problem?

When moist air touches a cold surface, some of the moisture may leave the air and condense, or become liquid. If moisture condenses inside a wall, or in your attic, you will not be able to see the water, but it can cause a number of problems. Adding insulation can either cause or cure a moisture problem. When you insulate a wall, you change the temperature inside the wall. That can mean that a surface inside the wall, such as the sheathing behind your siding, will be much colder in the winter than it was before you insulated. This cold surface could become a place where water vapor traveling through the wall condenses and leads to trouble. The same thing can happen within your attic or under your house. On the other hand, the new temperature profile could prevent condensation and help keep your walls or attic drier than they would have been.

Four Things You Can Do to Avoid Moisture Problems:

1. Control liquid water. Rain coming through a wall, especially a basement or crawlspace wall, may be less apparent than a roof leak, especially if it is a relatively small leak and the water remains inside the wall cavity. Stop all rain-water paths into your home by:

  • making sure your roof is in good condition,
  • caulking around all your windows and doors, and
  • keeping your gutters clean – and be sure the gutter drainage flows away from your house.
  • If you replace your gutters, choose larger gutters and gutter guards to help keep rain from dripping onto the ground near the house.

Be sure that the condensate from your air conditioner is properly drained away from your house. You should also be careful that watering systems for your lawn or flower beds do not spray water on the side of your house or saturate the ground near the house. It is also a good idea to check the caulking around your tub or shower to make sure that water is not leaking into your walls or floors. You can place thick plastic sheets on the floor of your crawlspace to keep any moisture in the ground from getting into the crawlspace air, and then into your house.

2. Ventilate. You need to ventilate your home because you and your family generate moisture when you cook, shower, do laundry, and even when you breathe. More than 99% of the water used to water plants eventually enters the air. If you use an unvented natural gas, propane, or kerosene space heater, all the products of combustion, including water vapor, are exhausted directly into your living space. This water vapor can add 5 to 15 gallons of water per day to the air inside your home. If your clothes dryer is not vented to the outside, or if the outdoor vent is closed off or clogged, all that moisture will enter your living space. Just by breathing and perspiring, a typical family adds about 3 gallons of water per day to their indoor air. You especially need to vent your kitchen and bathrooms. Be sure that these vents go directly outside, and not to your attic, where the moisture can cause problems. Remember that a vent does not work unless you turn it on; so if you have a vent you are not using because it is too noisy, replace it with a quieter model. If your attic is ventilated, it is important that you never cover or block attic vents with insulation. Take care to prevent loose-fill insulation from clogging attic vents by using baffles or rafter vents. When you think about venting to remove moisture, you should also think about where the replacement air will come from, and how it will get into your house. When natural ventilation has been sharply reduced with extra air-sealing efforts, it may be necessary to provide fresh air ventilation to avoid build-up of stale air and indoor air pollutants. Special air-to-air heat exchangers, or heat- recovery ventilators, are available for this purpose. For more information about controlled ventilation, see the Whole-House Ventilation Systems Technology Fact Sheet.

3. Stop Air Leaks. It is very important to seal up all air-leakage paths between your living spaces and other parts of your building structure. Measurements have shown that air leaking into walls and attics carries significant amounts of moisture. Remember that if any air is leaking through electrical outlets or around plumbing connections into your wall cavities, moisture is carried along the same path. The same holds true for air moving through any leaks between your home and the attic, crawlspace, or garage. Even very small leaks in duct work can carry large amounts of moisture, because the airflow in your ducts is much greater than other airflows in your home. This is especially a problem if your ducts travel through a crawlspace or attic, so be sure to seal these ducts properly (and keep them sealed!). Return ducts are even more likely to be leaky, because they often involve joints between drywall and ductwork that may be poorly sealed, or even not sealed at all.

4. Plan a moisture escape path. Typical attic ventilation arrangements are one example of a planned escape path for moisture that has traveled from your home’s interior into the attic space. Cold air almost always contains less water than hot air, so diffusion usually carries moisture from a warm place to a cold place. You can let moisture escape from a wall cavity to the dry outdoors during the winter, or to the dry indoors during the summer, by avoiding the use of vinyl wall coverings or low-perm paint. You can also use a dehumidifier to reduce moisture levels in your home, but it will increase your energy use and you must be sure to keep it clean to avoid mold growth. If you use a humidifier for comfort during the winter months, be sure that there are no closed-off rooms where the humidity level is too high.
Insulation Installation, the Retrofit Challenges

Whether you install the insulation yourself or have it done by a contractor, it is a good idea to educate yourself about proper installation methods because an improper installation can reduce your energy savings.
Also, if your house is very old, you may want to have an electrician check to see if:

  • the electrical insulation on your wiring is degraded,
  • the wires are overloaded, or
  • knob and tube wiring was used (often found in homes built before 1940).

If any of these wiring situations exists in your house, it may be hazardous to add thermal insulation within a closed cavity around the wires because that could cause the wires to overheat. THIS IS FOR FIRE SAFETY. The National Electric Code forbids the installation of loose, rolled, or foam-in-place insulation around knob and tube wiring. Adding thermal insulation to the ceiling or walls of a mobile home is complex and usually requires installation by specialists.

If adding insulation over existing insulation, do NOT use a vapor barrier between the two layers!

On unfinished attic floors, work from the perimeter toward the attic door. Be careful about where you step in the attic. Walk only on the joists so that you won’t fall through the drywall ceiling. You may need to place walking boards across the tops of the joists to make the job easier. Remember that it is important to seal up air leaks between your living space and the attic before adding insulation in your attic.
Installing batts and rolls in attics is fairly easy, but doing it right is very important. Use unfaced batts, especially if reinsulating over existing insulation. If there is not any insulation in your attic, fit the insulation between the joists. If the existing insulation is near or above the top of the joists, it is a good idea to place the new batts perpendicular to the old ones because that will help to cover the tops of the joists themselves and reduce thermal bridging through the frame. Also, be sure to insulate the trap or access door. Although the area of the door is small, an uninsulated attic door will reduce energy savings substantially.

In some houses, it is easier to get complete coverage of the attic floor with blown-in loose-fill insulation. It is best to hire an insulation contractor for this job. Loose-fill insulation must be prevented from shifting into vents or from contacting heat-producing equipment (such as recessed lighting fixtures). Block off those areas with baffles or retainers to hold the loose-fill insulation in place.
When you stack new insulation on top of existing attic insulation, the existing insulation is compressed a small amount. This will slightly decrease the R-value of the existing insulation. This effect is most important if the new insulation is more dense than the old insulation. You can compensate for this stacking effect and achieve the desired total R-value by adding about one extra inch of insulation if the old insulation is fiber glass, or about 1/2 inch if the old insulation is rock wool or cellulose.

Reflective Systems are installed in a manner similar to placing batts and blankets. Proper installation is very important if the insulation is to be effective. Study and follow the manufacturer’s instructions. Often, reflective insulation materials have flanges that are to be stapled to joists. Since reflective foil will conduct electricity, avoid making contact with any bare electrical wiring.

Radiant barriers may be installed in attics in several configurations. The radiant barrier is most often attached near the roof, to the bottom surface of the attic truss chords or to the rafter framing. Do not lay a radiant barrier on top of your insulation or on the attic floor because it will soon be covered with dust and will not work. A separate DOE fact sheet is available for radiant barriers to show which parts of the country are most likely to benefit from this type of system.

If your attic has NO insulation, you may decide to insulate the underside of the roof instead of the attic floor. (This option is more often used in new houses and is described in Design Option: ATTIC VENTILATION OR A CATHEDRALIZED ATTIC). If you choose the cathedralized attic approach, all attic vents must be sealed. Spray-foam is then often used to insulate the underside of the roof sheathing. If batts are used for this purpose, they must be secured in a manner similar to that described below for insulating under floors. It is best to hire an insulation contractor with experience in this type of installation for this job.


Installing insulation in the cavity of exterior walls is difficult. However, when new siding is to be installed, it is a good idea to consider adding thermal insulation under the new siding. The Retrofit Best Practices Guide provides useful information about adding insulation when you remodel the outside of your house. It usually requires the services of a contractor who has special equipment for blowing loose-fill insulation into the cavity through small holes cut through the sidewall, which later are closed. It is sometimes feasible to install rigid insulation on the outdoor side of masonry sidewalls such as concrete block or poured concrete. However, if that is not an option, you can use rigid insulation boards or batts to insulate the interior of masonry walls. To install boards, wood furring strips should be fastened to the wall first. These strips provide a nailing base for attaching interior finishes over the insulation. Fire safety codes require that a gypsum board finish, at least 1/2 inch thick, be placed over plastic foam insulation. The gypsum board must be attached to the wood furring strips or underlying masonry using nails or screws.
The first-floor band joist may be accessible from the basement or crawlspace. Make sure it is properly insulated as shown in Figure 1. More detailed drawings and insulation techniques for the band joist are shown in the Wall Insulation Technology Fact Sheet.

Basement Walls
When using batt or rigid insulation to insulate the inside of concrete basement walls, it is necessary to attach wood furring strips to the walls by nailing or bonding, or to build an interior stud-wall assembly on which the interior finish can be attached after the insulation is installed. The cavity created by the added framing should be thick enough for the desired insulation R-value.

The kraft paper or standard foil vapor retarder facings on many blanket insulation products must be covered with gypsum or interior paneling because of fire considerations. Some blanket products are available without these facings or with a special flame resistant facing (labeled FS25 – or flame spread index 25) for places where the facing would not be covered. Sometimes the flame-resistant cover can be purchased separately from the insulation. Also, there are special fiber glass blanket products available for basement walls that require less framing and can be left exposed. These blankets have a flame-resistant facing and are labeled to show that they comply with ASTM C 665, Type II, Class A.

Floors and Crawlspaces
If you have a floor over a crawlspace, you can EITHER:

  • Insulate the underside of the floor and ventilate the crawlspace, OR
  • Leave the floor uninsulated and insulate the walls of an unventilated crawlspace.

When batts or rolls are used on the underside of a floor above an unheated crawlspace or basement, fit the insulation between the beams or joists and push it up against the floor overhead as securely as possible without excessive compaction of the insulation. The insulation can be held in place, either by tacking chicken wire (poultry netting) to the edges of the joist, or with snap-in wire holders. Batts and rolls must be cut and fit around cross-bracing between floor joists or any other obstructions. Strips of insulation may be cut off and stuffed into tight spaces by hand. Don’t forget to place insulation against the perimeter that rests on the sill plate. If you insulate above an unheated crawlspace or basement, you will also need to insulate any ducts or pipes running through this space. Otherwise, pipes could freeze and burst during cold weather.

Reflective Systems are installed in a manner similar to placing batts. Proper installation is very important if the insulation is to be effective. Study and follow the manufacturer’s instructions. Often, reflective insulation materials have flanges that are to be stapled to floor joists. Since reflective foil will conduct electricity, one must avoid making contact with any bare electrical wiring.

Spray-foam can be used to insulate the underside of a floor. The spray foam can do a good job of filling in the space around wires and other obstructions and in filling any oddly-shaped areas. It is best to hire an insulation contractor with experience in this type of installation.

When a fiberglass blanket is used to insulate the walls of an unventilated crawlspace, it is sometimes necessary to attach wood furring strips to the walls by nailing or bonding. The insulation can then be stapled or tacked into place. Alternatively, the insulation can be fastened to the sill plate and draped down the wall. You should continue the insulation over the floor of the crawl space for about two feet on top of the required ground vapor retarder. Because the insulation will be exposed, be sure to use either an unfaced product or one with the appropriate flame spread rating. When rigid foam insulation boards are used to insulate the walls of an unventilated crawlspace, they can be bonded to the wall using recommended adhesives. Because the insulation will be exposed, be sure to check the local fire codes and the flame-spread rating of the insulation product. If you live in an area prone to termite damage, check with a pest control professional to see if you need to provide for termite inspections.

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Scott’s Contracting

Wall RValue, Configuring Wall RValues, Wall RValue Testing

Wall R-Values that Tell It Like It Is

by Jeffrey E. Christian and Jan Kosny
Jeffrey E. Christian is the manager of the DOE Building Envelope Systems and Materials Program at the Oak Ridge National Laboratory, Oak Ridge, Tennessee, and Jan Kosny is a research engineer at the University of Tennessee in Knoxville.

There’s a lot more to most walls than meets the eye, and the R-value of a whole wall can be considerably lower than the R-value of the insulation that fills it. At DOE’s Buildings Technology Center, scientists have developed a system for measuring whole-wall R-value, and have already tested several types of wall system.

DOE’s rotatable guarded hot box is the workhorse behind the whole-wall rating label system. Sample wall sections are placed in the box, where their thermal properties can be tested in a controlled environment.

Several new wall systems are gaining popularity, due to increasing interest in energy efficiency, alternatives to dimensional wood framing, and building sustainable structures. Steel framing, insulating concrete forms, autoclave cellular concretes, structural insulated core panels, engineered wood wall framing, and a variety of hybrid wall systems are a few of the new types. But accurately comparing the thermal performance of these systems has been difficult.

How Wall R-Value Is Usually Calculated

Currently, most wall R-value calculation procedures are based on calculations developed for conventional wood frame construction, and they don’t factor in all of the effects of additional structural members at windows, doors, and exterior wall corners. Thus they tend to overestimate the actual field thermal performance of the whole wall system.
In these common procedures, the user enters a framing factor (ratio of stud area to whole opaque exterior wall area). The framing factor is usually estimated, is seldom verified against actual site construction, and is frequently underestimated (see “Is an R-19 Wall Really R-19?HE Mar/Apr ’95, p. 5). Framing factors range from 15% to 40% of the opaque exterior wall area, yet lower values are commonly used. Unfortunately, the wall’s energy efficiency is usually marketed solely by the misleading clear-wall R-value (Rcw).

Clear-wall R-value accounts for the exterior wall area that contains only insulation and necessary framing materials for a clear section. This means a section with no windows, doors, corners, or connections with roofs and foundations. Even worse is the center-of-cavity R-value, an R-value estimation at the point in the wall containing the most insulation. This converts to a 0% framing factor and does not account for any of the thermal short circuits through the framing.

The consequences of poorly selected connections between envelope components are severe. These interface details can affect more than half of the overall opaque wall area (see Figure 1). For some conventional wall systems, the whole-wall R-value (Rww) is as much as 40% less than the clear-wall value. Poor interface details may also cause excessive moisture condensation and lead to stains and dust markings on the interior finish, which reveal envelope thermal shorts in an unsightly manner. This moist surface area can encourage the growth of molds and mildews, leading to poor indoor air quality.

Metal-framed walls are particularly vulnerable to thermal shorts. Unfortunately, builders often attempt to solve metal wall problems by making thicker walls and adding more insulation in the cavity between the metal studs. In fact, the thicker walls have an even higher percentage difference between clear-wall and whole-wall R-value.

Figure 1. Interface details for metal and wood framing.

Measuring Whole-Wall R-values

To compare wall systems more accurately, we have developed a procedure for estimating the Rww for various system types and construction materials (see “Wall R-Value Terms”). The methodology is based on laboratory measurements and simulations of heat flow in a variety of wood, metal, and masonry systems (see “How We Evaluate Wall Performance”). The whole-wall R-value includes the thermal performance not only of the clear-wall area, with its insulation and structural elements, but also of typical envelope interface details. These details include wall/wall (corner), wall/roof, wall/floor, wall/door, and wall/window connections.

Table 1. Clear-Wall and Whole-Wall R-Values for Tested Wall Systems
No. System Description Clear Wall R-Value (Rcw) Whole Wall R-Value (Rww) (Rww/Rcw) x 100%
1. 12-in two-core insulating units concrete 120lb/ft3, EPS inserts 1 7/8-in thick, grout fillings 24 in o.c. 3.7 3.6 97%
2. 12-in two-core insulating units wood concrete 40lb/ft3, EPS inserts 1 7/8-in thick, grout fillings 24 in o.c. 9.4 8.6 92%
3. 12-in cut-web insulating units concrete 120lb/ft3, EPS inserts 2 1/2 in thick, grout fillings 16 in o.c. 4.7 4.1 88%
4. 12-in cut-web insulating units wood concrete 40lb/ft3, EPS inserts 2 1/2 in thick, grout fillings 16 in o.c. 10.7 9.2 86%
5. 12-in multicore insulating units polystyrene beads concrete 30lb/ft3, EPS inserts in all cores 19.2 14.7 77%
6. EPS block forms poured in place with concrete, block walls 1 7/8 in thick 15.2 15.7 103%
7. 2 x 4 wood stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior, 1/2-in gypsum board interior 10.6 9.6 91%
8. 2 x 4 wood stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior, 1/2-in gypsum board interior 10.8 9.9 91%
9. 2 x 6 wood stud wall 24 in o.c., R-19 batts, 1/2-in plywood exterior, 1/2-in gypsum board interior 16.4 13.7 84%
10. Larsen truss walls 2 x 4 wood stud wall 16 in o.c., R-11 batts + 8-in-thick Larsen trusses insulated by 8-in-thick batts, 1/2-in plywood exterior, 1/2-in gypsum board interior 40.4 38.5 95%
11. Stressed-skin panel wall, 6-in-thick foam core + 1/2-in oriented strand board (OSB) boards, 1/2-in plywood exterior, 1/2-in gypsum board interior 24.7 21.6 88%
12. 4-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. NAHB Energy Conservation House Details. 14.8 10.9 74%
13. 3 1/2-in metal stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in wood siding, 1/2-in gypsum board interior 7.4 6.1 83%
14. 3 1/2-in metal stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details 9.9 8.0 81%
15. 3 1/2-in metal stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior + 1-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details 11.8 9.5 81%
16. 3 1/2-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details 9.4 7.1 75%
17. 3 1/2-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details 11.8 8.9 76%
18. 3 1/2-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details 13.3 10.2 77%

We estimated whole-wall R-values for 18 wall systems, using a computer model. We validated the accuracy of the modeling using the results of 28 experimental tests on masonry, wood frame, and metal stud walls. The model was sufficiently accurate at reproducing the experimental data.
The whole-wall R-values estimated for the 18 wall systems are shown in Table 1 along with the clear-wall R-values. A reference building was used to establish the location and area weighing of all the interface details. The comparison of these two values gives a good overall perspective of the importance of wall interface details for conventional wood, metal, masonry, and several high-performance wall systems.
In general, construction details for the wall systems chosen come from the ASHRAE Handbook and from the respective manufacturers. In the case of the metal frame systems, the details come from the American Iron and Steel Institute and other common sources.
A wall’s thermal performance is often simply described at the point of sale as the clear-wall value. The results shown in Table 1 indicate that the whole-wall value could be overstated by up to 26% for these systems. These differences can be even greater with interface details that are easier to construct but that may have more thermal shorts.

Whole-Wall versus Clear-Wall
Interesting comparisons can be made using the data in Table 1 to illustrate the importance of using a whole-wall value to select the most energy-efficient wall system. It could be argued that the difference between the clear wall and whole-wall R-value represents the energy savings potential of adopting the rating procedure proposed in this paper. Most building owners assume that they have the higher clear-wall value, rather than the more realistic whole-wall value.

An insulating concrete form with metal ties is prepared for testing at the Buildings Technology Center. Its whole-wall R-value and thermal mass will be measured.

Knowing whole-wall R-value could affect consumer choices. Systems 5 and 6 in Table 1 show two different high-performance masonry units. If one used the clear-wall data to choose the unit with the highest R-value, one would pick System 5, the low-density concrete multicore insulation unit, because its clear-wall value is 19.2 compared to 15.2 for System 6, expanded polystyrene (EPS) block forms. However, if one used the whole-wall data, one would choose just the opposite, because System 6 has the higher value–15.7 compared to 14.7 for System 5. Also, the whole-wall value of the foam form system is actually higher than the clear-wall value by more than 3%. This illustrates the effect of the high thermal resistance of the interface details.
Systems 7, 8, and 9 are all conventional wood frame systems. Note that the details affect the whole-wall R-value more for 2 x 6 walls than for 2 x 4 walls. The ratio of Rww to Rcw is about 90% for the 2 x 4 walls and 84% for the 2 x 6 wall.

Comparing System 11, the 6-inch stressed-skin panel wall, to System 9, the conventional 2 x 6 wood frame wall, shows that the Rcw for the former (R-24.7) is 51% higher than that for the latter (R-16.4). However, the figures for the Rww are R-21.6 to R-13.7 respectively, an improvement of 58%. As this example shows, advanced systems will generally benefit from a performance criterion that reflects whole-wall rather than clear-wall values.

How We Evaluate Wall Performance

To determine whole-wall R-value, we test a clear-wall section, 8 ft x 8 ft, in a guarded hot box. We compare experimental results with sophisticated heat conduction model predictions to get a calibrated model. Next, we make simulations of the clear-wall area with insulation, structural elements, and eight interface details–corner, wall/roof, wall/foundation, window header, windowsill, doorjamb, door header, and window jamb–that make up a representative residential whole-wall elevation. Results from these detailed computer simulations are combined into a single whole-wall steady-state R-value estimation. This estimation is compared with simplified calculation procedures and results from other wall systems. The user defines a reference wall elevation to weigh the impact of each interface detail.

For each wall system for which the whole-wall R-value is to be determined, all details commonly used and recommended (outside corner, wall/floor, wall/flat ceiling, wall/cathedral ceiling, doorjamb, window jamb, windowsill, and door header) must be included. The detail descriptions include drawings, with all physical dimensions, and thermal property data for all material components contained in the details.

Beyond R-Value

The R-value is only the first of five elements that are needed to compare whole-wall performance. The other four elements are thermal mass, airtightness, moisture tolerance, and sustainability. We are working on standard ways to measure thermal mass, airtightness, and moisture tolerance. For some systems all five factors are important; for others, only whole-wall R-value is relevant.

Thermal Mass Benefit

Wall systems with significant thermal mass have the potential–depending on the climate–to reduce annual heating and cooling energy requirements below those required by standard wood frame construction with similar steady-state R-value. The thermal mass benefit is a function of climate.
Effective R-values for massive walls are obtained by comparing the massive wall to light-weight wood frame walls. However this effective R-value is only a way to determine the link between the thermal mass of the wall and annual space heating and cooling loads, or a way to answer the question “what R-value would an identical house with wood frame walls need to obtain the same space heating and cooling loads as the massive walled house?” The term cannot be generally applied to a given wall type.

A procedure to account for thermal mass was used to create the generic tables found in the Model Energy Code (MEC) for all thermal mass walls with more than 6.0 Btu/ft2 of wall thermal capacitance. The tables have been in use since 1988. Customized tables can be used to show code compliance with the prescriptive Uw requirements in the MEC that are based on wood frame construction.


Users of the DOE Buildings Technology Center follow a combination of ASTM Standards C236 or C976 (ASTM 1989) or E1424 and E283 (ASTM 1995) to measure air leakage and heat loss through clear-wall assemblies under simulated wind conditions ranging from 0 to 15 mph. Varying the differential pressures from 0 to 25-50 Pascals (Pa) simulates the extremes to which a wall is exposed in a real building. The test specimens contain one light switch and one duplex outlet connected with 14-gauge wiring that spans the width of the wall.

Because heat loss in a building can be as high as 40% due to infiltration, it is important to include this performance parameter, but the quality of workmanship on the construction site, as compared to a laboratory specimen, must be considered. A second complicating factor is that materials may shrink or crack over time, and this will change the leakage. We will never completely predict the impact of workmanship on energy loss in buildings. What is important is to establish a uniform baseline for all wall systems.

Moisture Tolerance

The wall’s moisture behavior, like the benefit of thermal mass, is a function of climate and building operation. Annual moisture accumulation due to vapor diffusion of a particular wall system can be estimated by computer simulation. It is harder to estimate moisture accumulation due to air flow into the wall. It is important, in a long-lasting wall assembly, that the wall have the ability to dry itself out if it is built wet or picks up moisture due to a leak. The drying rate can be modeled and measured in the laboratory. The potential for moisture accumulation over specific full annual climatic cycles can also be modeled by heat and mass transfer codes such as MOIST (available from the National Institute of Standards and Technology, Special Publications 853, Release 2.1) and MATCH (available from Carston Rode, Technical University of Denmark, Department of Buildings and Energy, Building 188, DK-2800, Lyngby).

Systems 12 through 18 are all metal-framed. On average, the whole-wall value for these seven systems is 22% less than the clear-wall value. Metal can be used to build energy-efficient envelopes, but not by using techniques common to wood frame construction. The conventional metal residential systems reflected in Table 1 do not fare as well, compared to the other systems, when the whole-wall value is used as the reference. For example, if one is considering either System 6 (EPS block forms) or System 12 (a 4-inch metal stud wall), the clear-wall R-value is about the same–R-15. However, if the comparison is made using the whole-wall R-value, the EPS block form system has a 45% higher value–R-15.7 compared to R-10.9.

A standard metal frame wall section before insulation and drywall is installed.

Whole-Wall versus Center-of-Cavity
We also compared whole-wall R-values to center-of-cavity R-values. When a real estate agent or contractor states the R-value of insulation across the cavity to a potential home buyer, the implied whole-wall R-value is often overstated by 27% to 58%. If one compared metal (System 13) and wood (System 7) frames using center-of-cavity R-values, one would conclude that there was no difference, since both have center-of-cavity values of about R-14. However, the whole-wall value of the 2 x 4 wood wall system is 56% better than the whole-wall value for the metal system — R-9.6 compared to R-6.1.

These comparisons are not meant to imply that one type of construction is always better than another. They are all based on representative details. Whole-wall R-values could change if certain key interface details were changed. The purpose of making these sample comparisons is simply to show the importance of having the whole-wall value available in the marketplace, to guide designers, manufacturers, and buyers to more energy-efficient systems.

An autoclave concrete wall is stuccoed in preparation for the hot box test.

Coming Soon: A Wall Rating Label?

A number of innovative wall systems offer advantages that will continue to gain acceptance as the cost of dimensional lumber rises, the quality of framing lumber declines, availability fluctuates, and consumers remain concerned about the environmental impact of the nonsustainable harvesting of wood. For instance, while common dimensional lumber systems historically represent about 90% of the market, metal framing manufacturers anticipate attaining 25% of the residential wall market by the year 2000. This projection may be a bit optimistic, but it is clear that cold form steel is set to make major inroads into the residential market.
Now that a growing wall database and an evaluation procedure are available, the building industry can develop a national whole-wall thermal performance rating label. This would establish in the marketplace a more realistic energy savings indicator for builders and homeowners faced with selecting a wall system for their buildings.

Labels could also help specific systems to gain the acceptance of code officials, building designers, builders, and building energy-rating programs such as Home Energy Rating Systems (HERS) and EPA Energy Star Buildings. The whole-wall R-value procedure has been proposed for adoption in the ASHRAE Standard 90.2, the Council of American Building Officials Model Energy Code, and U.S. Department of Energy’s national voluntary guidelines for HERS. Many of the documents that are available to show builders how to comply with applicable codes, standards, and energy efficiency incentive programs would benefit by using the whole-wall R-value comparison procedure.
Ultimately, wall comparisons should include five elements: whole-wall R-value, thermal mass benefits, airtightness, moisture tolerance, and sustainability (see “Beyond R-Value”). Publication of this article was supported by the U.S. Department of Energy’s Office of State and Community Programs, Energy Efficiency and Renewable Energy.

Wall R-Value Terms

Center-of-cavity R-value: R-value estimation at the point in the wall that contains the most insulation.
Clear-wall R-value (Rcw): R-value estimation for the exterior wall area that contains only insulation and necessary framing materials for a clear section, with no windows, doors, corners, or connections between other envelope elements, such as roofs and foundations.
Interface details: A set of common structural connections between the exterior wall and other envelope components–such as wall/wall (corners), wall/roof, wall/floor, window header, windowsill, doorjamb, door header, and window jamb–that make up a representative residential whole-wall elevation.
Whole-wall R-value (Rww): R-value estimation for the whole opaque wall, including the thermal performance of both the “clear wall” area and typical interface details.
Opaque wall area: The total wall area, not including windows and doors.

Continuing research is being cofunded by DOE’s Office of Buildings Technology and Community Programs and by private industry to add more advanced wall systems to the database, and to address not only thermal shorts, but thermal mass benefits, airtightness, and moisture tolerance. Industry participants so far include American Polysteel, Integrated Building and Construction Solutions (IBACOS), Icynene Incorporated, Society for the Plastics Industry Spray Foam Contractors, Hebel USA L.P., Composite Technologies, Structural Insulated Panel Systems Association, LeRoy Landers Incorporated, Florida Solar Energy Center, American Society of Heating, Refrigerating and Air-Conditioning Engineers and Enermodal.

The database of advanced wall systems is available on the Internet ( For more information, contact Jeffrey E. Christian at Oak Ridge National Laboratory, P. O. Box 2008, MS 6070 Oak Ridge, TN 37831-6070. Tel:(423) 574-4345; Fax:(423)574-9338; E-mail:

Further Reading

Kosny, J., and A. O. Desjarlais. “Influence of Architectural Details on the Overall Thermal Performance of Residential Wall Systems.” Journal of Thermal Insulation and Building Envelopes Vol. 18 (July 1994) pp. 53-69.
Kosny, J., and J. E. Christian. “Thermal Evaluation of Several Configurations of Insulation and Structural Materials for Some Metal Stud Walls.” Energy and Buildings, Summer 1995, pp. 157-163.
Christian, J. E. “Thermal Mass Credits Relating to Building Envelope Energy Standards.” ASHRAE Transactions 1991, Vol. 97, pt. 2.
Kosny, Jan and Jeffrey E. Christian. “Reducing the Uncertainties Associated with Using the ASHRAE ZONE Method for R-Value Calculations of Metal Frame Walls.” ASHRAE Transactions 1995, Vol. 101, pt. 2.
Christian, J.E., and J. Kosny. “Toward a National Opaque Wall Rating Label.” Proceedings from Thermal Performance of the Exterior Envelopes VI conference, December 1995.

Publication of this article was supported by the U.S. Department of Energy’s Office of State and Community Programs, Energy Efficiency and Renewable Energy.

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Insulating Roofs, Walls, and Floors


Its not unusual for a house to have three or four types of insulation: spray foam, loose fill, rigid foam, and/or batts. Each type has multiple uses, but most also have limitations on where they can be used.

The best insulation for each location depends on a number of factors, including cost, ease of installation, available space, and the material’s resistance to moisture.
All insulation types perform best when they’re installed well. Some (like batts and blankets) can lose significant R-valuewith even a slightly sloppy installation.

Grading installation quality

The Residential Energy Services Network (RESNET), a national association of home-energy raters, long struggled with the question of how to estimate the R-value of walls that vary widely in performance depending on the skill of the insulation installer. Eventually, RESNET developed a useful rating system for insulation installation quality. The system is described in an article published in the January/February 2005 issue of Home Energy magazine, “Insulation Inspections for Home Energy Ratings,” by Bruce Harley. The RESNET rating system recognizes three levels of insulation installation quality: Grade I, Grade II, and Grade III.

Grade I is the best installation

“In order to qualify for a Grade I rating, insulation must … fill each cavity side to side and top to bottom, with no substantial gaps or voids around obstructions (that is, blocking or bridging—as seen in the grade II photo below), and it must be split, or fitted tightly, around wiring and other services in the cavity. In general, no exterior sheathing should be visible through gaps in the material,” Harley wrote. “Compression or incomplete fill amounting to 2% or less of the surface area of insulation is acceptable for Grade 1, if the compression or missing fill spaces are less than 30% of the intended fill thickness (that is, 70% or more of the intended insulation thickness is present).”

The standard for a Grade II installation is somewhat lower

“A Grade II rating represents moderate to frequent defects: gaps around wiring, electrical outlets, plumbing, other intrusions; rounded edges or ‘shoulders,’ larger gaps, or more significant compression. No more than 2% of the surface area of insulation missing is acceptable for Grade II.”

Grade III installations are the worst
“A Grade III rating applies to any installation that is worse than Grade II.” For further information on the RESNET grading system—including illustrations of good jobs and sloppy jobs—see “Assessing the Quality of Insulation Installed in New York Energy Star Labeled Homes.”



Because foundations aren’t really exposed to vast temperature swings, less insulation is needed there. Insulation in a basement should be chosen to do more than slow the flow of heat through these relatively stable environments; the best choices of basement insulation stop air and water, too. Basement walls and floors can be insulated on the inside or the outside, inside being the easier method for retrofits and outside being easier (in general) for new construction.

Exterior insulation choices should be moisture tolerant

Below-grade walls and floors should be insulated on the outside with, spray foam, or rigid mineral wool. Because polyisocyanurate can absorb water, it should not be used under a slab or on the outside of a foundation. Polyisocyanurate performs well, however, when used on the inside wall of a basement or crawlspace.

The most common insulation under slabs is XPS, although EPS also works if its density is adequate and if it is rated for ground contact. If the insulated slab must bear heavy loads, XPS is usually a better choice than EPS.

Closed-cell spray polyurethane foam can also be used under a slab.
Basement walls can be insulated on the exterior or interior with EPS, XPS, spray polyurethane foam, or rigid mineral wool (for example, Roxul drainboard).

To insulate a basement wall from the inside, the foam should be applied directly to the concrete, in order to keep moist interior air away from the cool, damp surface and lower the risk of condensation. To allow any accumulated moisture to dry to the inside, a semipermeable foam (EPS or XPS) is the best choice. To meet code requirements for a thermal barrier, the foam will probably need to be protected with a layer of gypsum drywall; fiberglass-faced drywall is more moisture resistant than paper-faced drywall.

Under no circumstances should fiberglass batts be used to insulate basement walls. Because fiberglass batts are air-permeable, they are unable to prevent moist interior air from contacting colder basement walls. That’s why fiberglass-insulated basement walls can easily become damp and moldy.


Although some builders insulate the floor above a crawlspace (the crawlspace ceiling), most building scientists recommend building a sealed, insulated crawlspace that includes wall insulation. It usually requires less insulation (and involves fewer tricky details) to cover a short wall around the perimeter than the whole floor.

Sealed crawlspaces should be built and insulated exactly like basements.

Of course, a well-detailed insulated crawlspace needs more than just insulation. Among the other critical details are careful air-sealing of the rim-joist area and (if the crawlspace has a dirt floor) installation of a ground cover.

Slabs on grade

Some builders insulate slab perimeters without insulating under the slab. In all but the warmest climates, however, it’s better to install a continuous layer of EPS, XPS, or spray polyuyrethane foam under the entire slab. Some builders modify an ICF  for use as a form for the slab that includes insulation.

If the home has in-floor radiant heat, it’s especially important to include a thick layer of foam directly under the entire slab. Experts disagree on exactly how much foam to add, but they all agree that at least some is a good idea. Engineer John Straube of Building Science Corp. says that after about 4 in.—perhaps 6 in. if the slab includes radiant heat—the money is better spent elsewhere. However, Passivhaus builders sometimes install up to 14 in. of sub-slab insulation.

Soil has a measurable R-value, so it can insulate the bottom of the slab from the exterior air to some extent. But soil is also a nearly infinite heat sink. The average soil temperature varies depending on the climate and the soil depth; however, if the soil has an average temperature of 55°F and the interior of a house has an average temperature of 72°F, heat will always want to flow from the warm side of the slab toward the soil. That’s why it’s important to insulate under a slab.


The strategy adopted for insulating a home’s above-grade walls depends on the wall construction used.

  • Walls built from SIPs or ICFs already include insulation.
  • Concrete-block  walls are best insulated from the exterior with rigid foam or spray polyurethane foam.
  • Wood-framed walls can be insulated with cavity insulation (fiberglass batts, sprayed-in-place fiberglass, cellulose, or spray polyurethane foam), on the interior (with rigid foam board), on the exterior (with rigid foam board or spray polyurethane foam), or with a combination of approaches (for example, some cavity insulation and exterior foam sheathing).

Thermal bridging
The effective R-value of a framed wall assembly with cavity insulation is always less than the R-value of the insulation alone, as thermal bridging through the studs degrades the performance of the wall. Thermal bridging can be reduced, and the thickness of the wall increased, by:

  • adding foam sheathing to the exterior of the wall;
  • adding a layer of rigid foam under the interior drywall; or
  • building a double-stud wall with staggered studs.

Foam sheathing

The performance of any wood-framed wall will be improved by installing exterior rigid foam sheathing; the usual choices are XPS or polyisocyanurate. Although EPS can be used, it is more fragile than the other two options.
Adding foam insulation to the outside of a wall affects the wall’s ability to dry out when it gets wet. Different types of foam insulation have different permeance ratings, but after a few inches they’re all pretty impermeable to moisture. Most foam-sheathed walls are designed to dry to the inside. This means that interior plastic vapor barriers should never be used on foam-sheathed walls.

According to Joseph Lstiburek and Peter Baker of Building Science Corp. (see link below), adding 1 in. of R-5 insulation to a 2×6 wall insulated with fiberglass batts increases the effective R-value of the wall from 14.4 to 19.4, a 35% gain with only a 15% increase in wall thickness.

Adding 2 in. of foam raises the R-value from 14.4 to 23.8, an improvement of 65%. A layer of insulating foam on the outside of walls also reduces the risk of condensation by raising the dew point of the surface where water vapor is likely to collect.

Thick foam sheathing is safer than thin foam sheathing. To learn more about determining a safe thickness for exterior foam, see “Calculating the Minimum Thickness of Rigid Foam Sheathing.”


Flat ceilings under unconditioned attics can be insulated with fiberglass batts, blown fiberglass, or blown cellulose, but cellulose works best—especially in very cold temperatures when convective loops can degrade the performance of fiberglass. Regardless of the type of insulation used, more is always better, and it’s usually an inexpensive upgrade as space is less of a limiting factor than it would be for walls.

Spray polyurethane foam can also be used to insulate a flat ceiling, although at a much higher cost than cellulose. An advantage of spray foam is that it air-seals as it insulates. With all types of attic insulation, air-sealing before insulating is almost more important than type and depth of insulation.

Attic-floor insulation should extend over the top plates of perimeter walls. To provide enough room for the necessary depth of attic insulation, be sure to specify raised-heel roof trusses.

Locating insulation at the attic floor has several advantages over locating insulation along the slope of the roof:

  • It’s cheaper, easier, and faster to install thick insulation at the attic floor.
  • Unconditioned attics are easier to vent than insulated rafter bays.
  • It’s easier to detect and pinpoint roof leaks when the attic is unconditioned.


Sloped ceilings and roofs can be insulated from above (by installing rigid foam on top of the roof sheathing), by installing insulation between the rafters, from below (by installing rigid foam under the rafters), or by a combination of some or all three of these insulation methods. Any of these methods will work. Although installing insulation on top of the roof sheathing is more foolproof, it’s also less common.
,or polyisocyanurate foam can be installed above roof sheathing. Two or more layers of rigid foam with staggered seams can be topped with eave-to-ridge 2x4s to create vent channels, followed by a second layer of roof sheathing. Exterior insulation like this with staggered seams disrupts conductive heat flow through the framing assembly.

Installing insulation in rafter bays is risky, as interior moisture can migrate through the insulation (either by diffusion or by piggybacking with exfiltrating air) and contact the cold roof sheathing, leading to condensation. This problem can be prevented by using closed-cell spray polyurethane foam, with or without a ventilation channel under the roof sheathing.


Although adding insulation to an existing home is always more challenging than insulating a new home, weatherization contractors have developed many cost-effective methods of improving existing insulation levels.

It’s important to manage any moisture problems in a home before engaging in air-tightening measures or insulation improvements. Inspect the home to identify any leaks or high-moisture areas, and be sure that the home is equipped with adequate mechanical ventilation.

Among the tried-and-true methods used by experienced weatherization workers:

  • To insulate a basement floor, install a continuous layer of XPS foam on top of the concrete. Top the foam with 2×4 sleepers and a plywood subfloor. If a low ceiling makes every inch critical, the sleepers can be omitted; in that case the plywood subfloor should be mechanically fastened through the foam to the concrete.
  • Basement or crawlspace walls can be insulated with interior XPS, EPS, or closed-cell spray polyurethane foam. The foam should be protected with a thermal barrier (for example, 1/2-in. drywall).
  • Above-grade frame walls can be insulated by blowing dense-packed cellulose into stud cavities through holes drilled through the siding. When insulation is complete, the holes are plugged.
  • If siding is being replaced, rigid foam or spray polyurethane foam can be installed on top of the exterior sheathing. Exterior foam retrofit jobs require considerable trim work around windows and doors, however.
  • Flat ceilings under unconditioned attics are usually easy to insulate with blown-in cellulose.
  • Improving the insulation over a sloped ceiling is often easier from the exterior than the interior. Rigid foam insulation can be added above the roof sheathing in conjunction with new roofing.

After air-sealing and insulation work is complete, the renovated home should be tested for radon. Radon levels often increase after a home has been weatherized.
If a house is undergoing extensive remodeling, it’s worth considering a deep energy retrofit.

Scott’s Contracting

Insulation and Thermal Performance

Thermal Performance is Just the Beginning

InsulSafe ® 4, made by CertainTeed Corporation, is a formaldehyde-free, loose-fill, fiberglass insulation suitable for open-blow attic applications. The product contains recycled glass cullet and carries Greenguard™ certification for low emissions.

We last took a broad look at insulation materials exactly ten years ago: in the January/February 1995 issue. A lot has happened since then—manufacturers have introduced new insulation materials, new product formulations have eliminated problem materials such as HCFCs, and improved understanding of performance and health risks has informed our building practices. But the fundamental issues have not changed over ten years. Insulation remains a critically important component of any green building—whether residential or commercial. No matter the type of insulation used, if it is used appropriately, its environmental benefits over a building’s life will almost certainly far outweigh any negatives—and dwarf any environmental differences among the alternative materials.

This article provides a survey of insulation materials, beginning with an examination of what insulation is and how it works. Much of the article focuses on life-cycle considerations for different insulation materials: environmental and health issues associated with resource extraction, manufacture, use, and disposal.

Understanding Insulation

To really understand insulation materials, you have to understand the basics of heat flow. There are three primary mechanisms of heat flow: conduction, convection, and radiation. Thermal conduction is the movement of heat from direct contact: one molecule is activated (excited) by heat and transfers that kinetic energy to an adjacent molecule. We generally think of conduction occurring between solid materials—the handle of a hot skillet conducting its heat to your hand, for example—but thermal conduction also occurs with liquids and gases.

Convection is the transfer of heat in liquids and gases by the movement of those molecules from one place to another. As air is warmed, it expands, becomes more buoyant, and rises—a process called natural convection. Forced convection is the distribution of warm air by use of a fan or air handler.

Finally, radiation is the transfer of heat from one body to another via the propagation of electromagnetic waves. A warmer body will radiate heat to a cooler body. When you sit in front of a fireplace and look into the fire, your face is warmed by the radiant transfer of energy from that heat source to your face. That radiant energy is not affected by air currents and occurs even across a vacuum—as we know from lying in the sun!

Most insulation materials function by slowing the conductive flow of heat. Materials with low thermal conductivity more effectively block heat flow than materials with high thermal conductivity. The R-value of an insulation material measures its resistance to heat flow. R-value is the inverse of U-factor, which is a measure of heat transfer, usually measured in Btu/hr·ft 2·°F or W/m 2·°C. Most insulation materials work by trapping tiny pockets of air (or some other gas). The performance of that insulation material is determined primarily by the conductivity of the air, or other gas, in those spaces. If convection is prevented, a 1″ (25 mm) air space has a conductivity of about 0.18 Btu/hr·ft 2·°F (1.02 W/m 2·°C). Its resistance to conductive heat loss, the inverse of that value, is R-5.5 per inch (RSI-38/m). With fiber insulation materials, such as fiberglass, cellulose, and cotton, pockets of air are trapped between the fibers. With cellular insulation materials, such as polystyrene, polyisocyanurate (polyiso), and polyurethane, the air—or other gas—is trapped within the plastic cells comprising the foam.

While resistance to conductive heat flow is the primary operative property of insulation materials, convection and radiation can come into play as well. With polyiso insulation, for example, according to Richard Roe of the Atlas Roofing Corporation in an August 2002 article in Interface magazine, 60–65% of the heat transfer is attributed to the conductivity of the blowing agent gases trapped in the cells, while 20–25% is attributed to the thermal conductivity of the solid polymer matrix, and 10–15% is attributed to radiation. One key design features of an insulation material is keeping the air pockets small enough to limit convection within those spaces and radiation across those spaces. With fiber insulation materials, the fibers have to be packed densely enough to effectively stop airflow through the material. (Air blowing through the insulation would carry heat by convection.)

With insulation materials that incorporate radiant barriers (foil-faced batt insulation, radiant-barrier bubble-pack insulation, and reflective barriers on rigid foam sheathing), the reflective surface functions by reducing radiant heat transfer. To function in this capacity, the reflective surface has to be next to an air space. The surface may function by reflecting heat radiation or (more commonly) by emitting less radiant energy from it. This is why a radiant barrier can reduce heat loss even when the reflective (low-emissivity) surface is facing the cold side.

Note that air leakage is a type of convection. Air leakage allows conditioned air to leak out of a building and unconditioned air to leak in—bypassing the insulated portions of the envelope. In older homes air leakage around windows, through poorly fitting doors, and across poorly detailed walls can sometimes account for over half of the total wintertime heat loss! Air leakage can also occur through an insulation material, which can reduce that material’s effective R-value. Loose-fill fiberglass, for example, usually allows more airflow than does cellulose insulation.

Life-Cycle Considerations with Insulation Materials

In this portion of the article, we examine the four primary life-cycle stages of any building material: raw material acquisition; manufacturing; the use phase, including indoor air quality concerns; and end-of-life disposal and recyclability. In each of these life-cycle stages we highlight key differences among insulation materials and discuss recent developments. Summaries of the key life-cycle considerations are presented by insulation material in the accompanying table.

Raw material acquisition

All Johns Manville fiberglass insulation is now produced with formaldehyde-free binders.

Fiberglass. The most prevalent type of insulation in North America, fiberglass is produced from silica sand with various additives, including boron. Most fiberglass also contains a fairly high percentage of recycled glass. The recycled content can be pre-consumer (post-industrial) glass cullet from float-glass manufacture or post-consumer glass collected through bottle recycling programs. In 2003 the fiberglass insulation industry used 1.1 billion pounds (500 million kg) of recycled glass, according to the North American Insulation Manufacturers Association (NAIMA), though the industry-wide split between pre-consumer and post-consumer recycled glass is not available. According to Robin Bectel of NAIMA, fiberglass insulation represents the second-largest market for recycled bottle glass (after the packaging industry).

Most U.S. fiberglass insulation has a minimum 20–30% recycled content. Owens Corning, for example, has been third-party certified by Scientific Certification Systems (SCS) to contain at least 30% recycled content—4% post-consumer and 26% pre-consumer, according to Jim Worden of the company. Johns Manville has an SCS-certified minimum recycled content of 25%; CertainTeed claims a minimum recycled content of 20–25% to meet U.S. Environmental Protection Agency (EPA) requirements under the Comprehensive Procurement Guidelines (CPG); and Knauf Fiberglass claims a minimum 20% recycled content, all of it post-consumer. Recycled-content information for Guardian Fiberglass was not available.

Mineral wool. Mineral wool is made from both iron ore blast-furnace slag (an industrial waste product from steel production) and rock such as basalt. In 2003 the mineral-slag wool industry used 514 million pounds (233 million kg) of slag. This is down 45% from the slag use in 1992. Mineral-slag wool production is down in part because building codes are shifting away from the passive fire resistance that mineral wool provides toward active sprinklering of buildings.

Cellulose. Cellulose insulation is made primarily from post-consumer recycled newspaper, with up to 20% ammonium sulfate and/or borate flame retardants. While cellulose insulation used to be one of the highest-value uses of old newspaper, today dozens of de-inking plants in North America turn old newspaper into new newsprint. Producing cellulose insulation from old newspaper can be referred to as downcycling; from an environmental standpoint, turning a waste product back into a new form of the same material is preferable to turning it into a lower-grade material. (Note that producing fiberglass insulation from beverage bottles or glass cullet is also downcycling.)

Plastic foam insulation. Plastic foam insulation materials, including extruded polystyrene (XPS), expanded polystyrene (EPS), polyisocyanurate, and the various types of spray polyurethane insulation, are all produced primarily from petrochemicals. Both natural gas and petroleum are common feedstocks, and both have significant environmental impacts associated with their extraction, refining, and transport.

At least two open-cell, spray polyurethane insulation products are manufactured in part from soybeans. Two-component BioBase 501 (see EBN Vol. 12, No. 9) and HealthySeal 500 are produced with soy oil comprising approximately 40% of the polyol component. (Polyurethanes are produced by reacting an isocyanate with a polyol, which is a type of alcohol.) The resultant polyurethane foam ends up being about 25% soy-derived and 75% petrochemical-derived.

Polystyrene. Recycled polystyrene can be incorporated into polystyrene foam insulation fairly easily, since polystyrene is a thermoplastic. At least one EPS insulation product contains recycled polystyrene: Polar 10 from Polar Industries is made with up to 40–60% post-industrial recycled content (see EBN Vol. 10, No. 2). The only XPS product that includes recycled content today is Owens Corning Foamular®, which is SCS-certified to contain a minimum of 15% pre-consumer recycled polystyrene.

Polyisocyanurate. Polyiso insulation incorporates a relatively small amount (9–10%) of recycled content to comply with CPG minimums. A portion of the polyol used in polyiso is produced from recycled PET bottles. The polyiso industry is one of the largest users of recycled, mixed-color PET bottles, according to the Polyisocyanurate Insulation Manufacturers Association (PIMA). The foil facings on many polyiso boardstock products may also contain some recycled content.

Bonded Logic’s cotton insulation is manufactured from pre-consumer recycled denim waste.

Cotton insulation. Cotton insulation is made today by two manufacturers. Bonded Logic, Inc. and Inno-Therm, Inc. make batt insulation products from pre-consumer recycled denim scrap. The cotton or cotton-polyester fibers are treated with a nonhalogenated flame retardant. UltraTouch, produced by Bonded Logic, contains approximately 85% pre-consumer recycled fiber saturated with borate flame retardants to provide fire resistance. Inno-Therm is believed to be using a mix of borate and ammonium sulfate flame retardants. In addition to its use in batt insulation products, cotton insulation is used by Payless Insulation, Inc. in insulated flexible duct products; Bonded Logic supplies the cotton insulation for these products.

Cementitious foam insulation. The totally inorganic, cementitious Air Krete ® is produced from magnesium oxide, derived from seawater, and from a ceramic talc mined in Governor, New York. While essentially the same material as it was when last covered in EBN ( Vol. 6, No. 7), Air Krete has undergone some modest refinements, according to vice-president Bruce Christopher. “We have continued to improve both the product and the equipment for installation,” he told EBN. But he noted that friability—the fragility of the cured foam—remains their biggest challenge. “If there is a downside to Air Krete, it’s its friability.” Despite its resistance to the idea, the company may decide to add a little plastic to make it less friable, said Christopher. The challenge in adding plastic would be maintaining the superb fire resistance of the insulation material. While cost is highly variable, depending on location, size of the job, and other factors, it averages 30–50¢ per board foot, according to Christopher.

Air Krete remains a very good alternative to another foamed-in-place insulation material used primarily for insulating masonry block, Tripolymer ® foam, produced by the C. P. Chemical Company. Tripolymer foam is a foamed phenol-formaldehyde insulation—a material that some manufacturers of urea-formaldehyde foam insulation (UFFI) switched to after formaldehyde emissions from UFFI led to its discontinuance in the 1970s.

Radiant barriers. Radiant barriers could be produced with recycled aluminum, but this is rarely if ever done, because very pure aluminum is needed to achieve the thin foils. Recycled polyethylene, however, can be used for the foam that is sometimes used with radiant barriers. Low-E ® Insulation, produced by Environmentally Safe Products, Inc., uses polyethylene foam with 40% post-consumer recycled content. In its TempShield™ radiant insulation product, Sealed Air Corporation uses 20% recycled-content cellular polyethylene for the insulation laminated between layers of reflective foil. A number of manufactured panel products have reflective facings glued to one side.

Manufacturing and transport

Fiberglass. Fiberglass insulation is manufactured with binders (typically phenol-formaldehyde) that hold the glass fibers together. The only fiberglass insulation material that did not contain a binder, Owens Corning’s Miraflex™ (see EBN Vol. 4, No. 1) was pulled off the market late in 2004. Manufacture of Miraflex was actually discontinued at the beginning of 2003, according to Gale Tedhams, Owens Corning’s product manager for residential insulation, but enough material had been stockpiled to sell it through 2004—mostly through Lowe’s stores. “It just had a very limited market,” Tedhams told EBN. Owens Corning did not promote the health benefits of not having a binder but focused on the packaging benefits—rolls of the insulation take up half the space of standard fiberglass. While the product carried a “slight price premium,” according to Tedhams, it was “very expensive to manufacture.” See additional discussion of binders used in fiberglass insulation under “Use phase and IAQ concerns.”

Cellulose. Because cellulose is inherently combustible, flame retardants are required to make it an acceptable material for building insulation. As has been the case for the past ten years, the primary flame retardants used in cellulose insulation are ammonium sulfate, borax, and boric acid. According to Daniel Lea, executive director of the Cellulose Insulation Manufacturers Association (CIMA), these additives are typically used in combination, though a few manufacturers offer products that use all-borate retardants.

Polyisocyanurate. The biggest environmental news in foam boardstock insulation has been the elimination of HCFC-141b in polyiso. The industry completed the transition from that ozone-depleting compound to the blowing agent pentane at the end of 2002. (Some manufacturers continued using stockpiled HCFC-141b in early 2003 while plant modifications were completed.) The transition to an ozone-safe formulation was a big step for polyiso, and it renders the product significantly better environmentally than extruded polystyrene (XPS), which in North America is still made with an HCFC blowing agent.

In an industry that is generally slow to change, these changes in polyiso have been dramatic. In 1992 polyiso was all produced with CFC-11. By mid-1993 the polyiso industry had shifted completely to HCFC-141b, which has only about 10% the ozone depletion potential of CFC-11. Atlas Industries then led the transition away from HCFCs, introducing its ozone-friendly AC-Ultra™ in February 1998 (see EBN Vol. 7, No. 5). By May 2001 the company had fully converted three of its plants to pentane (see EBN Vol. 10, No. 5), with others converted early in 2002.

Polystyrene. Polystyrene has some fairly troubling chemical precursors in its production. The polystyrene used in both XPS and EPS is made by reacting ethylene (from natural gas or crude oil) with benzene (from crude oil, via naphtha catalytic reforming) to produce ethyl-benzene. The ethyl-benzene is converted into vinyl-benzene or styrene monomer, which is then polymerized into polystyrene. Benzene is listed in the 10th Report on Carcinogens, put out by the National Toxicology Program of the U.S. Department of Health and Human Services, as a “known carcinogen.” The International Agency for Research on Cancer (IARC) of the World Health Organization lists benzene as a “confirmed human carcinogen” and styrene monomer as a “possible human carcinogen.” Some material safety data sheets (MSDS) for polystyrene list residual styrene monomer as a constituent of the foam at levels up to 0.2%. While benzene is also used in polyiso and polyurethane production, these insulation materials are less likely than polystyrene to contain residual toxic chemicals.

Extruded polystyrene. XPS and EPS differ in how the foam is expanded—and they use quite different blowing agents. EPS has long been made with non-ozone-depleting pentane, but XPS still relies on HCFCs. Though the XPS industry led the charge in replacing CFCs with far-less-damaging HCFCs, it is today the only type of boardstock insulation that remains harmful to stratospheric ozone. Amofoam (now Pactiv) was the first company to switch from CFC-12 to HCFC-142b, in 1990, and the entire XPS industry completed that transition in 1992. The transition away from HCFC-142b is not likely in the U.S. until close to the 2010 EPA deadline for doing so (see EBN Vol. 11, No. 7), according to Worden at Owens Corning. While European manufacturers of XPS shifted to either HFC-134A or carbon dioxide in 2002, more stringent energy standards and different construction systems in North America make the same sort of conversion more difficult here, says Worden. European XPS is a higher-density product with a lower R-value.

Expanded polystyrene. Expanded polystyrene (EPS) continues to be made with non-ozone-depleting pentane as the expanding agent. Some manufacturers are using a low-pentane formulation that results in lower pentane emissions. (While not an ozone-depleting compound, pentane can generate ground-level smog.) The more distributed production of EPS, compared with XPS, may reduce shipping energy consumption to some extent.

Flame retardants and polystyrene. All foam plastic insulation materials rely on flame retardants to meet fire-resistance standards. EPS and XPS are produced using the brominated flame retardant HBCD (hexabromocyclododecane) at concentrations of 0.5–2.0% by weight. HBCD is not the focus of as much attention as another class of brominated flame retardants (PBDEs), but some evidence indicates that it is more bioaccumulative than PBDEs and just as likely to be toxic to humans (see EBN Vol. 13, No. 6).

Flame retardants and polyisocyanurate. Ironically, until recently flame retardants were not used in most polyiso insulation. With HCFC blowing agents, this thermoset plastic foam was able to achieve the required Class I fire ratings without any added flame retardant. But with the substitution of pentane blowing agents for HCFC-141b, manufacturers now must add flame retardants. Although manufacturers rarely divulge their formulations (and can apparently get around the requirement to list the flame retardant in the MSDS because it is part of one component or the other (the polyol or isocyanate), the most common flame retardant used in polyiso today is believed to be TCPP (tris(chloropropyl) phosphate), a compound that relies on both phosphorous and chlorine as the fire-retarding components. The typical concentration in the foam insulation is 5–14% by weight. While a halogenated compound, TCPP is much less likely to be a persistent bioaccumulative toxin than HBCD, according to the PBT Profiler software from EPA.

Spray polyurethane. While polyiso manufacturers had to eliminate their use of HCFC-141b by January 1, 2003, manufacturers of closed-cell (high-density) spray polyurethane were given an extension for the transition to non-ozone-depleting blowing agents. HCFC-141b for spray polyurethane cannot be sold after December 31, 2004, though polyurethane installers can use inventoried HCFC-based chemicals until July 1, 2005, according to Ken Gayer, the global business manager for foam blowing agents at Honeywell Specialty Materials, which produces the non-ozone-depleting blowing agent HFC-245fa under the tradename Enovate 3000.

Most spray polyurethane companies are converting to Honeywell’s HFC-245fa. While significantly more expensive than HCFC-141b, the resultant foam achieves similar energy performance. The ozone depletion potential of HFC-245fa is zero, but the global warming potential is similar to that of HCFC-141b. Hydrocarbon blowing agents are avoided with spray polyurethane because of flammability concerns and difficulties with the vapor pressure, according to Gayer.

Low-density, open-cell polyurethane produced by Icynene is material-
efficient and uses water as the blowing agent.

Open-cell polyurethane, including the products made by Icynene, Inc. and Demilec, Inc. as well as the newer soy-based foams, are produced with water as the blowing agent. They do not achieve R-values as high as those of closed-cell polyurethane, but they are more resource-efficient, using just one-fourth to one-third the material used for a comparable volume of closed-cell polyurethane.

Flame retardants and spray polyurethane. Both closed-cell (high-density) and open-cell (low-density) polyurethane insulation contain flame retardants, but these are non-brominated flame retardants. While manufacturers are reluctant to share this information, the best available information indicates that the two flame retardants most commonly used in spray polyurethane are TCPP, which contains chlorine but not bromine, and RDP (resorcinol-bis-diphenylphosphate), which is totally halogen-free.

Use phase and IAQ concerns

Fiberglass and mineral wool. Concerns about mineral and glass fibers possibly being carcinogenic have been widely publicized over the past ten years—especially by competing industries. These concerns resulted in cancer warning labels being required for most products, but more recently these concerns are waning. In October 2001, IARC changed its classification for fiberglass and mineral wool from “possible human carcinogen” to “not a known human carcinogen.” This change has allowed mineral wool (slag wool and rock wool) manufacturers to drop the warning labels.

Fiberglass insulation continues to carry the cancer warnings because, in addition to the IARC listing, the National Toxicology Program added glass fibers to its Report on Carcinogens in 1990. According to Angus Crane, the vice president and general council for NAIMA, glass fibers were added to the NTP possible-carcinogen list because of the IARC-reported studies. Now that IARC has dropped the possible-carcinogen listing for glass fibers, the material is likely to be dropped from the NTP list. NAIMA has petitioned NTP to delist glass fibers, but that process typically takes several years. Crane hopes to see the listing removed in late 2005 or early 2006. If and when that happens, the industry will petition the State of California to remove the requirement under Proposition 65 that fiberglass insulation products include a warning about cancer.

Meanwhile, the carcinogenicity of formaldehyde, which could be released in very small quantities from the phenol-formaldehyde binder used in most fiberglass insulation, has recently been upgraded. In June 2004, IARC changed its classification of formaldehyde from a “probable human carcinogen” to a “confirmed human carcinogen.” Most of this binder is volatized and dissipated during a baking stage of the manufacturing process, but residual formaldehyde may remain in the product. Johns Manville, one of the five major producers of fiberglass insulation in North America, switched to 100% acrylic binder for its fiberglass insulation product line in 2002 (see EBN Vol. 11, No. 3). The other major fiberglass insulation manufacturers have all had their products certified as low-emitting by Greenguard™.

Mineral wool. For cavity-fill and attic applications, rock wool and slag wool are similar to fiberglass in look and feel, though the density is greater and the sound control better. The fire resistance of mineral wool is also significantly better than that of fiberglass, because of both the higher density and the significantly higher temperatures required for melting. While these fire-resistance properties used to be a major selling point, greater reliance on sprinklers in buildings, rather than passive fire resistance, is resulting in decreased use of mineral wool, according to Crane of NAIMA.

For below-grade applications, one rigid mineral-wool product, Roxul drainboard, offers superb performance, owing to its hydrophobic properties and its excellent drainage characteristics (see EBN Vol. 4, No. 6). This material has never been actively marketed in the U.S., but Roxul products in general are becoming more widely available here.

Cellulose. Cellulose insulation has never been required to carry indoor air quality warnings, and the fiberglass and mineral wool industries remain upset that their products have come under greater scrutiny than cellulose. “Our competitors have not gone through the testing,” said Angus Crane of NAIMA. “It is dangerous to assume that an untested material is safe,” he told EBN. The editors at EBN continue to take the position that all fiber insulation products (fiberglass, mineral wool, and cellulose) are safe if properly installed, and we would much prefer to see insulation manufacturers focus on the positive benefits of all insulation, rather than potential risks of their competitors’ products. The health concerns with cellulose range from inhalation of dust during installation to VOC emissions from printing inks (which are now almost entirely vegetable-based) and limited evidence of toxicity of boric acid flame retardants. For more on health issues with cellulose insulation see EBN Vol. 2, No. 5.

As for installation and performance, cellulose insulation has evolved considerably over the past 20 years. According to Daniel Lea of CIMA, the average installed density of cellulose insulation has dropped from 2.6 pounds per cubic foot (42 kg/m 3) in 1984 to 1.6 pcf (26 kg/m 3) today. “R for R, today’s cellulose insulation products are almost 40% lighter than those of 1984,” said Lea. Most cellulose insulation today is being installed as “cellulose wall-cavity spray,” a process that has sometimes been referred to as “wet-spray” cellulose. CIMA is trying to discourage the use of the term wet-spray because it implies a process that is far wetter than is the case. “I think there is a perception that the material is applied almost as a fibrous papier-mâché,” said Lea. “That is far from the case; if you were to touch wall spray seconds after it’s applied, you probably couldn’t tell that water was added during the installation process,” he said. The typical installed moisture content today is 30–35%, according to Lea, while a moisture content as high as 60% was not uncommon 15 years ago.

Fiber insulation installation. Quality dust masks or respirators should be used while installing fiberglass, mineral wool, and cellulose. (Cotton insulation is the only fiber insulation material that can be installed safely without protective measures.) Building design and detailing should ensure that fibers cannot enter forced-air distribution or ventilation systems. Airtight construction practices should be used to ensure that fiber insulation stays where it was installed.

Polystyrene. Indoor air quality concerns with XPS and EPS are similar to concerns addressed previously relating to manufacturing: the potential release of residual styrene monomer and flame retardants. The brominated flame retardants used in polystyrene present a greater health concern than the nonbrominated flame retardants used in polyisocyanurate, spray polyurethane, and cellulose insulation.

Polyisocyanurate. Now that polyiso is no longer produced with HCFCs, it is the environmentally preferred rigid boardstock insulation for above-grade applications. (Polyiso is not recommended for below-grade applications because it can absorb moisture.) Polyiso manufacturers disagree as to whether rigid foam produced today with hydrocarbon blowing agents achieves an R-value comparable to that of the older material made with HCFC-141b. The conductivity of the hydrocarbon blowing agent is higher than that of HCFC-141b, and this has led Dow Chemical to downgrade the rated R-values for all of its polyiso insulation, including Thermax ®. However, Richard Roe of Atlas Roofing argues that the smaller cell size of foam produced with hydrocarbon blowing agents, the slower diffusion rate of the hydrocarbon out of the polymer cells, and the lower absorption of the hydrocarbon blowing agent by the polymer collectively result in better long-term R-value stability.

Most polyiso manufacturers are now using new long-term thermal resistance (LTTR) values for reporting aged R-values. This method was adopted in Canada in mid-2002 and in the U.S. in January 2003. This method produces 5-year aged R-values that are lower than the 6-month aged R-values that had previously been reported. The bottom line is that the rated long-term stabilized R-value of polyiso is now between R-6 and 6.5 per inch (RSI-42 to 45 per meter), depending on thickness and facings.

Closed-cell polyurethane. Closed-cell, high-density polyurethane is a very good performer owing to the low-conductivity gas in the cellular structure. It is used both for cavity installation and as an insulating roofing material, which is typically referred to as spray polyurethane foam or SPF. The closed-cell structure gives SPF structural properties. There should be no significant impact on R-value with the shift to non-ozone-depleting HFC-245fa blowing agent, which is becoming the industry standard. Polyurethane also exhibits superb adhesive properties and good compressive strength.

Open-cell polyurethane. Open-cell polyurethane is most commonly installed into open cavities, though formulations are available for filling closed cavities from holes at the top. This is a nonstructural foam, though these materials seal very well, and their flexibility allows for some movement of the framing materials as shrinkage and expansion occur. These properties make them very effective insulation materials for older buildings.

Both closed-cell and open-cell polyurethane must be installed by trained professionals. Special care is required to ensure the safety of insulation installers working with these materials; other people should not be in the space while polyurethane insulation is being installed. Once cured, polyurethane insulation is considered by most IAQ experts to be quite inert.

End-of-life reuse and recyclability

Loose-fill and batt insulation. It is difficult to salvage loose-fill or batt insulation and reuse it, though this can be done. Virtually no fiber insulation is recycled after use in buildings—due to contamination with dust and other materials. Scrap insulation generated during installation can be collected and reused quite easily.

Insulation Materials – Summary of Environmental and Health Considerations

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Rigid boardstock insulation. Rigid insulation can be salvaged and reused if it is protected during removal. For roof insulation applications, reuse is most feasible when protected-membrane or inverted roof configurations are used (see EBN Vol. 7, No. 10). In this system, a non-water-absorbing rigid insulation, such as XPS, is laid on top of the roof membrane, and ballast is installed on top of the insulation. When re-roofing is required, the insulation can be removed and stored for safekeeping, then reinstalled after the new roof membrane is laid down.

Of the rigid insulation materials, only polystyrene can be recycled. This thermoplastic can be melted and re-expanded into either polystyrene insulation or packaging. Unfortunately, very little polystyrene is being recycled currently. Polyiso and polyurethane cannot be recycled because these foams are thermoset plastics.

Final Thoughts and Recommendations

Insulation is a key component of any green building. More important than the decision of what type of insulation to install is the decision of how much insulation should be installed. From an environmental standpoint, a thicker layer of a relatively nongreen insulation material is almost always better than an inadequate thickness of the greenest insulation material available. This point cannot be over-emphasized.

However, assuming that adequate R-values can be achieved, choosing a green insulation material over a nongreen one can be a very good decision. The accompanying table should help to identify materials that meet your needs and satisfy the environmental priorities of your project.

Summary recommendations:

• Provide the highest feasible insulation levels.

• With lower R-value materials, increase insulation thickness.

• Avoid extruded polystyrene due to the ozone-depletion potential of blowing agent.

• Except where moisture may be an issue, use polyiso instead of either XPS or EPS.

• Rigid mineral wool, such as that made by Roxul, is a very good foundation insulation material due to its superb drainage properties.

• With highly conductive framing systems, especially steel, minimize thermal bridging by wrapping the frame with a layer of rigid board insulation.

• Choose high-recycled-content insulation materials when doing so will not result in significant loss of R-value compared with other materials.

• With roof insulation, consider a protected-membrane roof so that insulation can be reused.

• Address air leakage and moisture resistance in insulation detailing. A good source of information on building science issues is

• For chemically sensitive individuals, test potential insulation materials for reaction before installation.

• Choose an insulation contractor who recycles scrap insulation.

Insulation: Guidelines, Facts, Applications,


Thicker is better
In cold weather, a puffy parka holds in your body heat. Insulation does the same thing for a house. The thicker the insulation, the better it works to reduce heat flow from the inside of a home to the outside during winter, and from outside to inside during summer.
The thermal barrier of a home should consist of a continuous layer of insulation on all sides—including the lowest floor, the exterior walls, and the ceiling or roof.

Doubling the thickness of insulation will double the insulation’s R-value, cutting heat loss in half. Each time the insulation layer is doubled in thickness, this rule applies. The energy saved per year by doubling insulation from R-10 to R-20, however, will be considerably more than the energy saved by doubling insulation from R-20 to R-40, because of the law of diminishing returns. In some cases, like an attic, it’s worth piling on more insulation because there is plenty of room. It’s much more expensive to add that much insulation to exterior walls.

It takes more than just insulation to slow heat
Stopping air leaks is just as important—maybe more important—than adding insulation. Unless builders prevent air from leaking through walls and ceilings, insulation alone won’t do much good. Not only are drafts uncomfortable, but air moving through insulated cavities can cut the efficiency of the insulation by as much as 50%.
Some insulation types make good air barriers, and some don’t. In all cases, it’s best to keep the insulation tight to the air barrier.


When there is no insulation in a roof or wall, the framing is the most insulated part of the assembly. It has the highest R-value. Softwood lumber has an R-value of 1.25 per inch, so a 2×6 stud has an R-value of almost 7. As soon as you put insulation between the studs or rafters above R-7, however, the framing becomes the weak thermal link. If the framing cavities are filled with closed-cell spray foam insulation, the insulation has an R-value of about 36. At that point, the studs or rafters become a glaring weakness in the design.

Building scientists call this phenomenon “thermal bridging” because the studs or rafters bridge the space between inside and outside the thermal envelope.

If you look for it, thermal bridging can sometimes be seen from either inside or outside. Inside, it can cause a problem called ghosting, or cold stripes behind the drywall during winter. These cold stripes can encourage condensation that leads to the accumulation of dust particles on the drywall; eventually, visible vertical stripes may form. Outside, you can see the effect of thermal bridging in snow-melt patterns on roofs and drying patterns on walls.

A continuous layer of rigid foam installed on the inside or outside of a wall or roof drastically reduces thermal bridging through the framing.


Heat flows from hot to cold; it can’t be stopped, but it can be slowed
If we measure the rate at which heat flows through a building material or building assembly—for example, a wall or a roof—we can calculate a number (the R-value) to indicate its insulating ability. The higher a material’s R-value, the better the material is at resisting heat flow through conduction, convection, and radiation (outlined above). Insulation manufacturers report R-values determined by tests following ASTMstandards (for example, ASTM C518).

Common insulation types and their R-values
Residential insulation materials have R-values that range from about 3 to 7 per inch. The amount of insulation installed in any given building assembly depends on the climate, the part of the house being insulated, the project budget, and local code requirements.

  • Batts and blankets: R-3.1 to R-4.1 per in.
  • Blown-in and loose-fill insulation: R-2.6 to R-4.2 per in.
  • Rigid foam: R-3.6 to R-6.8 per in.
  • Closed-cell spray foam: R-6 to R-6.8 per in.
  • Open-cell spray foam: R-3.5 to R-3.6 per in.

Green homes go beyond code minimum

The U.S. Department of Energy has developed a list of recommended insulation levels for different climate zones. The climate zones are represented on the map (click to enlarge). Houses heated by natural gas, fuel oil, or an electric heat pump should use the R-values set out by the DOE and listed below as a base. Because electric heat is relatively expensive, houses with electric resistance heat need more insulation than shown in the table below.

In some parts of the country, minimum code requirements for insulation already (or may soon) exceed these DOE recommendations. For example, the 2009 International Residential Code requires cold-climate builders to include a minimum of R-20 wall insulation and R-15 basement wall insulation.

DOE-Department of Energy-recommended R-values for various parts of a house

Zone Attic Wall Floor Slab edge Basement wall (framing cavity insulation) Basement wall (continuous rigid insulation)
1 R-30 to R-49 R-13 to R-15 R-13 R-4 R-11 R-10
2-3 R-30 to R-60 R-13 to R-15 R-13 to R-25 R-8 R-11 R-10
4 R-38 to R-60 R-16 to R-21 R-25 to R-30 R-8 R-11 R-4
5 R-38 to R-60 R-16 to R-27 R-25 to R-30 R-8 R-11 to R-19 R-10 to R-15
6-8 R-49 to R-60 R-18 to R-27 R-25 to R-30 R-8 R-11 to R-19 R-10 to R-15

In any case, green builders almost always exceed minimum code requirements for insulation thickness. Many energy consultants, including Betsy Pettit and Joseph Lstiburek, now recommend that cold-climate homes include R-60 ceilings, R-40 above-grade walls, R-20 basement walls, and R-10 basement slabs.

Some builders go further; for example, an Illinois home designed to meet the rigorous German Passivhaus standard is insulated to nearly R-60 on every side—even under the slab.


Insulation can’t work in a wind tunnel
No matter what type of insulation you choose, it will perform poorly if installed in a house that is riddled with air leaks. Because many types of insulation (like loose fill and batts) work by trapping air, leaky walls, roofs, and floors mean poor thermal performance. For this reason, building scientists are fanatical about air-sealing. To get the most out of batts and blown insulation, every house needs an air barrier adjacent to or contiguous with the insulation layer.
Some types of insulation are fairly effective at stopping air infiltration. For example, when rigid foam is used as wall sheathing, it can be an effective barrier, as long as the seams are taped. Spray polyurethane foam creates a very effective air barrier.

But neither rigid foam nor spray foam addresses air leaks at the seams where different components meet, such as under the bottom plates of walls. An air barrier is only effective if all of these seams and intersections are addressed with gaskets, glues, or sealants.

Of all available insulation materials, fiberglass batts are the most permeable to air leakage—so permeable that fiberglass is used to make furnace air filters. Because it doesn’t restrict air flow, fiberglass is often singled out and derided for its poor performance.

In fact, much of the criticism of fiberglass insulation is unwarranted. As long as fiberglass is installed in a house with an adequate air barrier, it will perform well. Fiberglass performs best when installed in a framing cavity (for example, a stud bay or joist bay) with an air barrier on all six sides.
Installation details for high-quality fiberglass batts have been incorporated into the insulation installation guidelines established by the home raters from the Residential Energy Services Network (RESNET).

For every location in a house, there are always several ways to create an effective air barrier. However, not all methods are equally easy to achieve. In many locations, including rim-joist areas, spray polyurethane foam is so much faster than alternative methods that its use has become almost universal among builders of high-performance homes.

Moisture can piggyback on air
There’s another benefit to stopping air: less moisture in roofs and walls. That’s because most moisture problems in walls and roofs are caused by moisture transported by air. Vapor diffusionis a much smaller problem.

Moisture can accumulate in a wall or ceiling when warm, humid interior air leaks through cracks in the shell. When this exfiltrating air encounters a cold surface—for example, OSB wall sheathing—the moisture in the air can condense into liquid and puddle in the wall cavity. The same thing can happen in summer, when warm, humid outdoor air leaks through cracks in the wall. If the home is air-conditioned, the moisture in this infiltrating air can condense when it reaches any cool surface—drywall, ductwork, etc. The best way to limit this type of moisture migration is to install an effective air barrier. If air isn’t leaking through cracks in a home’s walls and ceilings, the problem is nipped in the bud.

Insulation can stop air
Some insulation types act as air barriers, while others act like air filters. If you choose an insulation that doesn’t stop air flow, it’s important to install an adjacent air barrier material.

Best to worst at stopping airflow:
Spray foam
Rigid foam
Blown-in fiberglass
Fiberglass batts


Vapor permeability can be a good thing or a bad thing — vapor retarders slow wetting, but they also slow drying, which may be more important. As long as you design a roof, wall, or floor assembly with these concepts in mind, then almost any type of insulation can work.

Least to most vapor permeable:
Foil-faced polyisocyanurate
Closed-cell spray foam
Open-cell spray foam
Blown-in fiberglass
Fiberglass batts

More on the vapor permance of insulation materials at


Although residential wall insulation is traditionally installed in stud cavities, the best place to locate wall insulation is outside the frame. This exterior insulation reduces the thermal-bridging effect that studs have in a wall, because each piece of framing can act as a thermal bridge through the cavity insulation. These thermal bridges seriously degrade the performance of the wall.

The thermal-bridging effect can be partially addressed by using rigid foam sheathing—usually 1 in. or 2 in. of XPS or polyisocyanurate. Even better are wall designs that place all the insulation—6 in. to 10 in. of rigid foam—outside the framing.

When insulation is outside the frame, framing materials stay warm and dry. When stud bays are not filled with insulation, the work of electricians and plumbers is greatly simplified.
Houses with foam sheathing should not include an interior polyethylene vapor retarder.


Insulation can stop air
Some insulation types act as air barriers, while others act like air filters. If you choose an insulation that doesn’t stop air flow, it’s important to install an adjacent air barrier material.

Best to worst at stopping airflow:
Spray foam
Rigid foam
Blown-in fiberglass
Fiberglass batts


Vapor permeability can be a good thing or a bad thing — vapor retarders slow wetting, but they also slow drying, which may be more important. As long as you design a roof, wall, or floor assembly with these concepts in mind, then almost any type of insulation can work.

Least to most vapor permeable:
Foil-faced polyisocyanurate
Closed-cell spray foam
Open-cell spray foam
Blown-in fiberglass
Fiberglass batts

More on the vapor permance of insulation materials at


Although residential wall insulation is traditionally installed in stud cavities, the best place to locate wall insulation is outside the frame. This exterior insulation reduces the thermal-bridging effect that studs have in a wall, because each piece of framing can act as a thermal bridge through the cavity insulation. These thermal bridges seriously degrade the performance of the wall.

The thermal-bridging effect can be partially addressed by using rigid foam sheathing—usually 1 in. or 2 in. of XPS or polyisocyanurate. Even better are wall designs that place all the insulation—6 in. to 10 in. of rigid foam—outside the framing.

When insulation is outside the frame, framing materials stay warm and dry. When stud bays are not filled with insulation, the work of electricians and plumbers is greatly simplified.
Houses with foam sheathing should not include an interior polyethylene vapor retarder.


Uninsulated slab edges
Window frames
Wall and roof penetrations

–contact for additional details Scott’s Contracting

Spray Foam-Eco Conscious

Spray foam for the eco-conscious

  June 17th, 2009 in Blogs         

RYagid Rob Yagid , associate editor

Hardworking crops. The oil from soybeans, which is also being considered to create alternative forms of energy, is replacing the petroleum in some spray foams.
Hardworking crops. The oil from soybeans, which is also being considered to create alternative forms of energy, is replacing the petroleum in some spray foams.
Photo: BioBased Insulation

I’ve gotten a lot of good feedback on an article I wrote for FHB#204 on spray foam. Many folks were concerned about the environmental impact of the foam itself and its toxicity to the resources we’re ultimately trying to conserve. Below, I’ll share a little bit about the make-up of the foam and also describe what makes some foam “green”. For those of you interested in learning more about the various players in the spray-foam market right now, see the source list from my article toward the bottom of my post. And, of course, feel free to comment if you have opinions on the performance of spray-foam or its greater environmental impact.

Spray foam is made of a two-part mixture. The A part is isocyanate, a petroleum-based chemical made by only a handful of companies in the world. The B part contains a catalyst, polyol resin, a surfactant, and a blowing agent.

Consuming fossil fuels to make products intended to conserve fossil fuels makes little sense to a lot of people. All spray foams contain a certain level of petroleum in their A component and in their B component. Manufacturers such as BioBased Insulation, Demilec, and Icynene have created more environmentally benign spray-foam products by reducing the amount of petroleum used in their B component. They replace a portion of the polyol resin, which makes up 20% to 30% of the B component, with a renewable resource such as soybean or castor-bean oil. Apex even has a sucrose-based polyol. Manufacturers say that the transition to bean oil or sucrose doesn’t alter the look or the performance of open- or closed-cell foam in any way.
The amount of soybean, castor bean, or sucrose found in foam varies by manufacturer, so identifying the “greenest” foam might not be so easy. 
According to the U.S. Department of Agriculture, only 7% of a spray-foam product needs to be made of a renewable resource to be labeled as a bio-based foam. This, of course, doesn’t factor in the petroleum fueling the crop-cultivation process. I wonder how “green” these foams really are? Sure, they may be a bit more healthful than strictly petroleum based foams, but can manufacturers be doing more to produce a better spray foam product?

Although this is not a complete list of spray-foam manufacturers, it is representative of the larger national companies. For assistance in finding a spray-foam insulation contractor, visit the Spray Polyurethane Foam Alliance.

Apex Foam Industries     Fomo Products
                              Great Stuff
BioBased                        Icynene
CertainTeed                   NCFI
Chemical Design            Tiger Foam
Corbond                         Touch n’ Seal
Demilec                          Urethane Soy Systems 
Foametix                        Versi-Foam Systems
Read the complete article…
Spray Foam: What Do You Really Know?
To get the full benefit of this superinsulation, you must understand the difference between open- and closed-cell foams, how they perform, and how they’re installed
by Rob Yagid
Get   the PDF

Scott’s Contracting

Re: Guest Post: Touch n Seal, Insulation- Local Manufacturer

Weatherize Your Home with Touch ‘n Seal Insulating Foam Sealants

Air Sealing Your Home with Insulating Foam Saves Money and Energy

Hi Scotty – I just discovered your website and blog – love it!!  I work in public relations for Fenton-based Touch ‘n Seal and wanted to submit this press release to you for publication consideration.

Carolyn Schinsky
Ryan Public Relations
(314) 822-9784 Office
(314) 308-1682 Cell
Media Contacts:
Carolyn Schinsky / Ryan PR / 314-822-9784/
  Weatherize Your Home with Touch ‘n Seal Insulating Foam Sealants
Air Sealing Your Home with Insulating Foam Saves Money and Energy
ST. LOUIS—Sept. 13, 2010—It’s common knowledge that air leaks from drafty windows and gaps and cracks around the house can cause even a well-insulated home’s energy bills to soar.  All year long, a leaky house wastes energy and creates an often uncomfortable living environment.  However, weatherizing a home by sealing air leaks, gaps and cracks with Touch ‘n Seal insulating foam sealants and products can reduce energy loss by up to 38 percent.
“The first step in weatherizing a home is to determine where air leakage is occurring,” says Michael Sites, Product Specialist at Touch ‘n Seal.   “Some leaks around windows and doors may be obvious, but be sure to also inspect for cracks and gaps around places like electrical outlets, plumbing pipes, dryer vents and phone jacks.” 
Touch 'n Seal No-Warp FoamNo Warp Window & Door Foam Stops Drafts to Minimize Energy Loss
One of the most common sources of air leaks are drafty windows and doors.  However, Touch ‘n Seal’s gun-applied No-Warp Window & Door Insulating Sealant provides a quick and easy solution to this age-old problem.   No-Warp is a bright white expanding one-component polyurethane foam that is specially formulated for use around window and door frames – providing airtight insulation that blocks drafts, moisture and insects without bowing the frame.
“NoWarp is a great fenestration foam sealant because it expands fully to seal gaps and cracks, but won’t put undue pressure on window and door frames,” says Sites. “Most foams are inappropriate for use in these areas, because the excessive pressure can warp frames and jambs, rendering the window or door inoperable.”
 Constant Pressure Dispensing System Delivers More Spray Foam, Twice as Fast 

Air sealing with spray foam insulation creates a barrier that holds in heat in the winter months and keeps home cooler in the summer. Commonly used for weatherproofing attics, walls, ceilings and crawl spaces, spray foam provides CPDS 1000superior efficiency because it expands to fit the applied area, completely preventing drafts and air infiltration that can let dust, pollen and allergens into the structure.

Contractors can cut costs when applying spray foam insulation and enhance service offerings with Touch ‘n Seal’s new CPDS 1000 Constant Pressure Dispensing System.  The CPDS 1000 is a self-contained, portable, constant pressure spray foam system that dispenses Class I fire retardant, thermal insulating and sound dampening 2-component polyurethane spray foam – twice as fast as foam kits. As contractors around the country are discovering, the CPDS 1000 is an affordable alternative to buying or hiring a foam dispensing truck, saving both time and money.

With an internal air compressor, the CPDS 1000 operates on a standard 120V power supply.  “Efficiency, energy savings and environmental awareness are key factors when weatherizing a home or building,” states Sites. “The CPDS 1000 is the culmination of all these things – it provides reduced chemical waste, reduced fossil fuel consumption, reduced overall energy consumption and no ozone depleting chemicals.” 

Air-Seal & Resist Flames with Gun Foam II Sealant
Most homes have a multitude of unnoticed sources of energy loss.  Some leaks that often get overlooked are cracks and gaps in basement and foundation walls, Gun Foam II Polyurethane foam sealantdropped ceilings over cabinets and attic chases – small enclosures around ducts and plumbing – all which lead to skyrocketing energy bills.   “Air-sealing floor penetrations and air leaks in walls with Touch ‘n Seal’s Gun Foam II Insulating Sealant is a quick and easy way to prevent energy loss,” says Sites. “It provides weatherization in a variety of areas common in most residential construction.”
Gun Foam II is ideal for use at the juncture of the sill and the slab or foundation, and any penetration through floors or ceilings such as electrical lines, HVAC ducting or pipes. It fills cracks and holes in the exterior sheeting (due to poor application or penetrations made for utility services), at the corner and tee joints in framing, and any other place where air might penetrate the exterior envelope.
Touch ‘n Seal Gun Foam II Insulating Sealant is a gun-applied, bright orange one-component polyurethane foam that is more cost effective and easier to install than traditional fire blocking methods such a s gypsum, cement or fiberglass.  Though not a firestop, Gun Foam II withstands flaming over twice as long as the leading competitor, lending crucial seconds to dangerous situations.
“Weatherizing a home not only makes it more comfortable, the long term financial rewards are significant. In addition to saving money on energy bills, when Congress passed the stimulus bill earlier this year, it tripled the tax credit for weatherization home improvements through 2010,” concludes Site. 
# # #
About Touch ‘n Seal:
Convenience Products, the manufacturer of Touch ‘n Seal products, is headquartered in St. Louis, Missouri.   Touch ‘n Seal insulating foams and sealants are the benchmark for performance in commercial and industrial building and maintenance, OEM manufacturing and specialty applications. A full line of one and two-component spray foams, caulks and adhesives are available, including fire blocking foam  (ICC-ES: ESR-1926), Low Pressure Window & Door Foam, Drywall Panel Adhesives, Two-Component, Disposable Units, Mining Specialty Units, One-Component Disposable Cylinders and Fire Break Caulks.  The company also manufactures Touch ‘n Foam one-component foams for the do-it-yourself market.  For more information, visit

Carolyn Schinsky
Ryan Public Relations
(314) 822-9784 Office
(314) 308-1682 Cell

Scott’s Contracting