Insulation: The Different Types and Their Advantages and Disadvantages

Asbestos
Urea formaldehyde foam insulation (UFFI)
Fiber glass
Mineral Wool
Cellulose
Cotton
Straw
Foam insulations
Other considerations regarding insulation

Over the years, there have been many health concerns that have arisen due to insulation materials such as asbestos and urea formaldehyde foam insulation. Here are the different types of insulations that have been and are being used along with their advantages and disadvantages:

Asbestos

Asbestos is a mineral fiber that has been used commonly in a variety of building construction materials for insulation and as a fire-retardant. Asbestos was commonly used before 1970 in building products because it was fireproof, a good thermal insulator, and easily made into fabrics, pipe coverings, and other materials. It was commonly found in:

• Pipe and furnace insulation materials, especially in homes built between 1930 and 1950.

• Oil and coal furnaces and door gaskets may have asbestos insulation.

• Hot water and steam pipes in older houses may be coated with an asbestos material or covered with an asbestos blanket or tape.

Asbestos is known to cause several cancers such as a type of lung cancer called mesothelioma and cancers of the gastrointestinal tract. Because it is a carcinogen, the US Environmental Protection Agency banned the use of asbestos in 1989, but the regulation was overturned in 1991 by the Fifth Circuit Court of Appeals in New Orleans.  Presently, the following asbestos-containig products are banned: corrugated paper, rollboard, commercial paper, speciality paper, flooring felt and new uses of asbestos, meaning asbestos cannot be used in products that have not historically contained asbestos.  

In addition, under the Clean Air Act most sprayed-applied surfacing asbestos containing materials are banned.  These include sprayed-on application of materials containing more than one percent (1%) asbestos to buildings, structures and conduits, unless the material is encapsulated with a bituminous or resinous binder during spraying and the materials are not friable after drying; wet applied and pre-formed asbestos pipe insulation, and pre-formed asbestos block insulation on boilers and hot water ganks.

For more information and clarification on which asbestos-containing products are banned and which are not, visit the EPA website at http://www.epa.gov/asbestos/ban.html.

Asbestos-containing products that were applied before 1981 can still be found in buildings. For example, in November 2000 a medium-security correctional facility in Minnesota was fined $18,000 for asbestos safety violations. Guards had been complaining for years about white dust falling from tattered insulation around pipes that were overhead in tunnels they had to patrol. They thought it might be asbestos and they were right. There was damaged insulation and exposed asbestos in over 25 places. More than 40 correctional officers may have been exposed.¹ 

In August 2000, the federal government announced that some vermiculite insulation, which is found in millions of attics and walls across the United States, might contain asbestos. The assistant U.S. surgeon general warned that handling of Zonolite insulation could expose people to the hazards of asbestos. Recent studies of Zonolite insulation have shown that even casual handling of the insulation can expose workers or homeowners to 150 times the asbestos level considered safe under federal law. Vermiculite was heat-treated until it expanded; it was then marketed as Zonolite insulation that was stuffed between rafters and inside walls. Tests have shown that even installing a light fixture or ceiling fan through an attic floor insulated with Zonolite can produce dangerous levels of airborne asbestos.²

Urea Formaldehyde Foam Insulation (UFFI)

In the 1970s there were concerns about health effects of insulation materials when improperly installed urea formaldehyde foam insulation (UFFI) caused high levels of formaldehyde emissions in tens of thousands of homes. No insulation materials in use today exhibit indoor air quality problems approaching those of UFFI, but the rapidly growing interest in healthy homes is spurring a close examination of health impacts.

Fiber Glass

Fiber glass is a soft wool-like material that is usually pink or yellow. It is used as insulation, in weatherproofing, and as textile material. It was originally used as a "safe" substitute for asbestos. Fiber glass was used as a liner inside air supply ducts and air handler compartments of the ventilation system of homes and buildings built from the early 1960s through the late 1980s. It was used in ventilation systems as an insulator to prevent loss of hotor cold air and to reduce the noise from the blower fan. Fiber glass liners inside ducts were a problem because if it got wet it could become a breeding ground for microorganisms.

There are a few more problems with fiber glass. One is there are some health problems associated with it. For example, it can cause a skin allergy and there is debate on whether or not fiber glass may cause cancer. It may also trigger reactions in those people who are chemically sensitive since most fiber glass insulation is produced using a phenol formaldehyde binder to hold the fibers together. These binder materials may release offending amine or "dear-fish" odors in high humidity situations.

Another thing that should be considered when choosing insulation are the ingredients that go into it. The largest fiber glass insulation manufacturers all use at least 20 percent recycled glass in their insulation products to comply with the US Environmental Protection Agency (EPA) recycled-content guidelines. One of the raw materials that is used to make fiber glass more flexible and fire retardant is boron. However, there are only two large deposits of boron in the world: one in the southwest US and one in Turkey. Since the total known US reserves of boron is just 200 years, other renewable alternatives should be considered.³

Mineral Wool

While mineral wool was at one time the most common type of insulation, its market share was largely lost to fiber glass in the 1960s and 1970s. In the past few years, however, the product appears to have begun a comeback. There are currently several manufacturers of mineral wool in the US and about eight plants that produce it. "Mineral wool" actually refers to two different materials: slag wool and rock wool. Slag wool is produced primarily from iron ore blast furnace slag, an industrial waste product. Rock wool is produced from natural rocks. Slag wool accounts for roughly 80 percent of the mineral wool industry, compared with 20 percent for rock wool. Given the relative use of these two materials, mineral wool has, on average, 75 percent post-industrial recycled content.

Cellulose

Cellulose is perhaps the best example of recycled material use in insulation. Most cellulose insulation is approximately 80 percent post-consumer recycled newspaper by weight; the rest is comprised of fire retardant chemicals and, in some products, acrylic binders. The biggest long-term performance concern with cellulose insulation is possible loss of fire-retardant chemicals. Because borates are water soluble, they can leach out if the insulation gets wet.

Cotton

This type of insulation uses cotton and polyester mill scraps with plastic fiber added for three-dimensional loft and borates added for pest and combustion resistance. This insulation costs about 15 percent to 20 percent more than comparable fiber glass insulation.

Straw

Bales of straw have been used for exterior wall insulation. Of course, precautions need to be taken to prevent insect infestation and well as moisture intrusion.

Foam Insulations

There are different types of foam insulation materials. These include:

• Polyisocyanurate

• Polyurethane

• Polystyrene

Styrene, like that used in polystyrene insulation, can cause irritation of the eyes, nose, and respiratory system; headache, fatigue, dizziness, confusion, malaise (vague feeling of discomfort), drowsiness, weakness, unsteady gait; possible liver injury; and reproductive effects. Many foam insulations use recycled plastic resin such as that found in some extruded and expanded polystyrene (EPS). Of the foam insulations, polystyrene is easier to recycle than polyisocyanurate or polyurethane since it can easily be melted down and reformed into other products. The simplest recycling involves crumbling the old EPS into small pieces and re-molding them into usable shapes. Polystyrene used to be blown with chlorofluorocarbons, or CFCs, that destroy the earth's protective ozone layer. Now extruded polystyrene (XPS) uses hydrochloro-fluorocarbons (HCFCs) that are not as dangerous but can still be detrimental to the earth's protective ozone layer.

EPS is the only common rigid foam board stock insulation made with neither CFCs nor HCFCs. During manufacture, polystyrene beads are expanded with pentane, which is a type of flammable gas. An advantage of board stock insulation is that if it can be removed without breaking up, it can often be reused.

Two new types of foam insulations that do not use CFCs or HCFCs are:

• Icynene: Icynene is a foaming agent that uses a mixture of carbon dioxide and water. Though it does not have polyurethane's HCFC-related environmental problems, it also has a lower insulation rating (R-value). Like polyurethane, Icynene is foamed into wall cavities, but the resultant open-cell foam is soft, not rigid.

• Air Krete: Air Krete™ is an inorganic foam produced from magnesium oxide (derived from sea water). It is foamed under pressure with a microscopic cell generator and compressed air; no CFCs or HCFCs are used.

Other Considerations Regarding Insulation³

• Some loose-fill fiber insulation will settle and get displaced because of wind and rodent infestation. It is also possible that, over many decades, dust and dirt accumulation could reduce the insulation rating (called the R-value) by either compressing the insulation or by filling air pockets.

• In some parts of the country, foam insulation materials are prone to infestation of wood-boring insects, such as carpenter ants. Tunnels and nesting cavities will reduce thermal performance and may affect the structure as well.

• Insulating materials should be durable so that they do not have to be replaced every few years, thus contributing to the solid waste problem.

• Be sure that your home or building is well insulated to save energy. Reducing the energy use of a building is usually the single most important thing you can do to reduce the building's overall environmental impact.

• If you are using an insulating material that has a lower R-value (insulation rating), increase the thickness of the insulation.

• Try to avoid foam insulation materials that contain HCFCs. Though HCFCs are less destructive to stratospheric ozone than CFCs, they are still damaging to the environment.

• Try to choose insulation materials that have large amounts of recycled materials. For example, with cavity-fill insulation, cellulose and mineral wool have higher recycled content than fiber glass. Also, choose an insulation contractor who recycles scrap insulation.

References

1. Associated Press. Guards say asbestos fears ignored at state prison in Faribault. Associated Press State and Local Wire, November 26, 2000.

2. Gordon G. Officials flag asbestos insulation risks; Public health officials are worried that even minimal handling or brief inhalation of vermiculite attic insulation poses a serious risk. Minneapolis Star Tribune. August 15, 2000:4A.

3. Insulation materials: Environmental comparisons. Environmental Builders News. 1995 Jan/Feb;4(1): www.buildinggreen.com/features/ins/insulation.html.