Attic Insulation: Fiberglass or Cellulose, Which Is Best?

Attic Insulation: Fiberglass or Cellulose, Which Is Best?By maintaining a high level of attic insulation, you will improve your home’s comfort level and the energy efficiency of your HVAC system in all seasons. Attic insulation keeps your attic spaces from overheating in the summer and holds in heat to improve indoor comfort during the winter.

Two common material choices for attic insulation are fiberglass and cellulose. Cellulose insulation is made of ground-up newspaper that’s processed and formed into pellets and blown into place using specialized equipment. Fiberglass insulation is made of spun fibers of glass, sand and other inorganic material. Loose-fill fiberglass insulation is also blown into place. Both will provide adequate levels of insulation, but in most applications, fiberglass is a better choice for both convenience and performance.

  • Fiberglass maintains R-value: The R-value of insulation is a measure of how well it resists the flow of heat. The higher the R-value, the better the insulation. Cellulose insulation can settle over time, which decreases its thickness and, as a consequence, its R-value. Fiberglass insulation does not settle and lose R-value.
  • Fiberglass insulation is nonflammable: Fiberglass is made of noncombustible materials such as glass fibers. Cellulose insulation is made of flammable paper. Even though cellulose insulation is treated with fire-retardant chemicals before installation, these chemicals can lose effectiveness over time. Cellulose insulation can burn at about 450 degrees, which is the surface temperature of a standard 75-watt light bulb.
  • Fiberglass insulation does not absorb or hold water: If insulation gets wet or damp, its effectiveness decreases significantly. Fiberglass is not water-absorbent. The paper content of cellulose insulation, on the other hand, will readily absorb and hold water.
  • Fiberglass resists mold and insects: Since fiberglass insulation is nonorganic, it won’t develop mold, and insects are not attracted to it as a food source. Cellulose insulation can become moldy, and insects can find it very attractive as food.

Smedley Service offers professional heating, cooling and plumbing services to customers in Odgen, Layton and the surrounding Utah communities. Contact us today for more information on the benefits of attic insulation and for help deciding if fiberglass or cellulose is the best choice for your insulation job.

Our goal is to help educate our customers in Layton, Utah about energy and home comfort issues (specific to HVAC systems).  For more information about attic insulation and other HVAC topics, download our free Home Comfort Resource guide.

Image courtesy of Shutterstock

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