When building or remodeling a house, the issue of insulation is an important one. With so many insulation types and sometimes-conflicting information on the safety of insulation materials, it's vital to weigh the pros and cons when choosing between fiberglass and polystyrene insulation. Polystyrene insulation is commonly known as foam insulation or by its brand name, Styrofoam.

Safety Issues

Many believe that fiberglass insulation is in itself a hazardous material, citing the fact that it had been found by the International Agency for Research on Cancer as "possibly carcinogenic" in 1988. While this is true, fiberglass was removed from the list of possible carcinogens in 2001 after further study. Both fiberglass and foam insulation can attract toxic mold if it's not installed and ventilated properly, though polystyrene is preferable for moist climates. Both types of insulation should be safety inspected after insulation.


Foam insulation, whether it's in the form of foam board sheets or spray-on insulation, requires a smaller amount of material to achieve the same amount of insulation. A thicker application of fiberglass, however, can prove to be a bit more efficient. According to the Hawaii Department of Business, Economic Development and Tourism, a ceiling insulated with a 5-inch thick bed of fiberglass insulation will save about $50 more per year in cooling costs than a ceiling insulated with 1.5-inch thick foam sheets.


Fiberglass is commonly installed from rolls that are cut by hand and placed inside walls, between floors and in the attic. Loose fill fiberglass can be blown into small or irregularly shaped spaces in attics and in between walls. Foam sheets are installed in the same places as fiberglass, but it's installed against the roof top in the attic, rather than against the ceiling. Foam insulation also can be sprayed. Insulation should usually be installed by a professional; be sure to take the proper precautions and follow installation instructions exactly if you decide to do it yourself.


Fiberglass is the least expensive type of insulation on the market, costing about half as much as foam insulation per square foot installed in most cases. Fiberglass is a less complicated job for do-it-yourselfers, making it potentially even less costly. Since the energy savings are about the same, foam is more expensive all-around.