When considering a home, health and safety of building materials are a home buyer priority—and insulation is no different. In terms of health and safety properties, not all types of insulation are equal. Below are some key factors to consider when evaluating insulation safety and health implications.

Fire safety

Flame resistance is, naturally, a primary consideration for insulation in the home. As such, one factor in evaluating insulation safety is its resistance to fire.

  • Fiberglass and mineral wool insulation
    Materials are noncombustible, and remain so for the life of the product. They require no additional fire-retardant chemical treatments—in fact, unfaced fiberglass and mineral wool are accepted as a fire block in wood frames. Note that some fiberglass and mineral wool facings (kraft paper, foil) are combustible, but when properly installed with a code-approved barrier, don’t pose a fire hazard. Kraft facing should never be left exposed.
  • Cellulose insulation
    Products are largely made of newspaper and other combustible materials. Even though it’s heavily treated with fire-retardant chemicals prior to installation, it is a recognized fire hazard by the Consumer Product Safety Commission (CPSC).1
  • Spray Foam insulation
    Spray foam insulation will ignite at 700°F.2
  • Perimeter Fire Barrier Systems
    Building owners and occupants often take fire safety for granted. They assume that buildings are constructed with fire safety in mind and significant attention has been paid to building codes. Nevertheless, there exists one particularly critical juncture frequently overlooked in fire safe design – the void space between an exterior curtain wall and the edge of the floor. This area can be addressed by perimeter fire barrier systems.

Indoor Air Quality

Optimal indoor air quality (IAQ) is key to achieving safe, healthy, relaxing living and working environments. In most cases, comfort is the biggest consideration when evaluating air quality; but with the growing prevalence of asthma and allergies, good IAQ is seen as increasingly critical to health and general well-being.

Ensuring good air quality is no simple task. IAQ can be impacted by many factors in a building, meaning there’s no simple fix if your air quality isn’t what it should be. However, the issue can be broken down into 3 essential approaches.

  1. Controlling indoor pollutants
  2. Being mindful of products brought into the home
  3. Controlling outdoor pollutants

For more details on improving indoor air quality, download Building Science 101.

Health Impacts

Not all insulation materials have undergone the same level of testing and scrutiny when it comes to health and safety.

  • Fiberglass insulation
    Fiberglass insulation is the most thoroughly tested insulation material available. The International Agency for Research on Cancer (IARC), the US National Toxicology Program (NTP) and the California Office of Environmental Health Hazard and Assessment have all stated that fiberglass and mineral wool thermal and acoustic insulations are not considered classifiable as carcinogens.
  • Cellulose insulation
    Questions about the health and safety aspects of cellulose insulation persist in the building industry because very little medical or scientific testing of the products has been conducted. There’s still a need for full toxicological testing of dust from cellulose building insulation and dust from pure cellulose fibers.3 Insulation safety conclusions can’t really be drawn until extensive testing is completed.
  • Spray foam insulation
    The safety of spray foam insulation is still being evaluated. According to the California Department of Toxic Substance Control, one of the main ingredients in spray foam, methylene diphenyl diisocyanate, could pose a number of health risks, including lung damage and asthma.

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Methylene diphenyl diisocyanate is known to damage lungs, cause asthma, and trigger asthma attacks in workers who install foam, per to the California Department of Toxic Substances Control. The US EPA has made comparable statements, detailed here.

Different spray foam manufacturers publish different guidelines for length of evacuation times during installation and curing. Note that there are no established evacuation timelines from any government agency.


You may see claims about the presence of formaldehyde in fiberglass and mineral wool and what this means for insulation safety. It’s important to know that the Consumer Product Safety Commission has determined that “fibrous glass insulation and ceiling tiles would have little impact on in-home formaldehyde levels.”4 If the issue is still a concern, finding formaldehyde-free residential products is not hard, as 90% of the residential fiberglass insulation on the market today is in fact formaldehyde free.


Mold can grow in any environment where there’s moisture and food for mold spores, so many organic materials can be food for mold. Even though some products claim to be mold-resistant, mold can grow on ANY surface under moist conditions if organic material exists to support the spores. Understanding how mold grows is crucial to fully evaluate insulation safety.

  • Fiberglass, mineral wool, and spray foam insulation are all inorganic, and therefore don’t feed mold growth.
  • Cellulose insulation is composed of organic material, so it can be a food source for mold unless properly treated with chemicals or other agents that can prevent or inhibit mold growth. Mold can grow on all insulation types, but not all insulation products provide a food source for mold growth.


Risk of corrosion to pipes, wires and fasteners is a factor to consider at all phases of home building.

  • Fiberglass insulation is not corrosive and contains no chemicals that can corrode pipes and wires.5
  • Cellulose Insulation contains certain chemicals routinely applied as a fire retardant to some cellulose insulation. These chemicals, particularly the sulfates, can cause the corrosion of pipes, wires, and fasteners under some conditions.6



  1. www2.buildinggreen.com/article/flame-retardants-under-fire
  2. Thermal Barriers for the Spray Foam Industry, SPFA (2000)
  3. J.M.G. Davis, “The need for standardized testing procedures for all products capable of liberating respirable fibers; the example of materials based on cellulose,” British Journal of Industrial Medicine 1993: 50: 187-190, p. 189.
  4. Consumer Product Safety Commission Memorandum – September 22, 1983 – Summary of the Formaldehyde in Products Project
  5. X K. Sheppard, R. Weil, and A. Desjarlais, “Corrosiveness of Residential Thermal Insulation Materials Under Simulated Service Conditions,” Insulation Materials, Testing and Applications, D.L. McElroy and J.F. Kimpflen, Eds. (ASTM: Philadelphia, PA, 1990), pp. 634-654; K. Sheppard, R. Weil, and A. Desjarlais, “Corrosiveness Testing of Thermal Insulation Materials – A Simulated Field Exposure Study Using a Test Wall,” Report ORNL/Sub. 78-7556/4, September 1988.
  6. Donald W. Belles and Associates, Inc., “Loose-Fill Cellulose Insulation – An Aging Problem,” J. Applied Fire Science, Vol. 30, 295-303, 1993-94; Mark McLees, “‘Going Green’ May Make You ‘See Red,’” Firehouse, June 2008.