Division 7 Thermal & Moisture Protection

07200 Insulation


There are several types of insulation addressed in this section that can be used in walls, floors, and ceilings.

Cellulose insulation is made from recycled newspaper and treated with fire retardants and insect protection. Borates, derived from the mineral Boron, are natural materials that can be used as fire retardants and insect repellents in cellulose insulation.

CFC and HCFC insulation refers to the blowing agents that contain chlorofluorocarbons used in making many rigid insulating sheathing products. Extruded polystyrene and polyisocyanurate foam insulation boards are currently made with CFC or HCFC blowing agents.

Agricultural fiber insulation is available in the form of cotton insulation made with mill waste, low grade, and recycled cotton. It is treated with a non-toxic fire retardant and comes in batts comparable to fiberglass insulation batts.

Cementitious foam insulation is made from magnesium from sea water and blown in place with air.

Perlite insulation is made from a natural occurring volcanic mineral and is often used as loose fill insulation in concrete block cavities.


Insulation materials play a primary role in achieving high energy efficiencies in buildings. There has been concern over the health impacts of the material constituents of insulation ever since the problems associated with asbestos became apparent, followed by the banning of urea formaldehyde based insulation. Some health concerns have spread to potential inhalation of fiberglass and cellulose insulation fibers and dust. Always wear a proper dust mask when working with these materials.

Cellulose insulation uses recycled newsprint that contains printers inks which can possibly outgas formaldehyde into a home. If there is any outgassing from inks, it should fall well below levels irritating most persons. However, an environmentally-sensitive person should be careful in selecting cellulose and install a vapor retarder between the insulation and the living space. (Note that the vapor retarder can exacerbate mildew problems if humidity levels in the house are high.)

There are also chemical additives often added to treat cellulose that are not thoroughly understood from an indoor air quality standpoint. Cellulose insulation that is treated with borates is preferred. Cellulose insulation can be bound together as a wet spray and installed in open wall cavities where it effectively seals the entire wall.

Rigid board insulations employed as sheathing on homes have played an important role in achieving high R-values. The use of CFCs in many of these materials has caused increased release of chlorine molecules into the atmosphere contributing to ozone depletion. HCFCs outgas a lesser amount of chlorine molecules. However, the severity of the ozone depletion situation has led to the recommendation to avoid both types of insulation blowing agent. Alternatives in rigid board insulation are available that do not use CFCs. (See Engineered Sheet Products section.) Any rigid expanded polystyrene insulation does not have CFCs.

Cementitious foam insulation is available commercially. There are no installers of this type of insulation in some regions. It is also more costly where available. This type of insulation is considered the most benign from an indoor air quality standpoint. Use installers who have a track record and can provide references.

Perlite insulation is in a loose form suitable to fill the cavities in building block. Perlite can be bound into other materials and used in sheet form. It is commonly used in commercial roofing material and can be used as an aggregate in concrete. It is non-flammable, lightweight and chemically inert.

Not listed is the use of rockwool insulation. Rockwool is recycled steel slag (a landfill material). It is available as blow-on wall insulation (a starch binder is used) and as loose blow-in attic insulation. It offers very good energy performance, will not burn, and is chemically inert.

Spray-in-place foam insulations are a fairly new addition. They offer the advantage of acting as a vapor barrier, effectively disallowing the cracks and gaps which can occur with rigid board or batt insulation methods. Some are made in part with soy oil instead of the more common petroleum oil, but its important to note that even the products with the highest percentage of soy oil still contain a majority of petroleum, and that the soy oil likely comes from genetically engineered plants which may be a negative in the view of some people.

Commercial wool insulation is available in limited areas. Being made from a naturally produced fiber, sheep wool insulation typically requires less than 15% of the energy required to produce than glass fiber insulation. Wool is a sustainable and renewable resource, that has zero ozone depletion potential and at the end of its useful life can be remanufactured or biodegraded. Sheep wool insulation is safe and easy to handle and no protective clothing or special breathing apparatus is required to install it.

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