The Expected Lifetime of Blown-In Cellulose Insulation

Blown-in insulation typically comes in two different types -- fiberglass and cellulose. Cellulose is often chosen because it is considered a "greener" home insulation and the costs are slightly less. However, this type has its limitations, namely its overall life expectancy and the reduction in its energy saving benefits as it ages.

What is Cellulose Installation?

Cellulose is a mixture of recycled newspaper and wood. According to the Cellulose Insulation Manufacturers Association, if you insulated a 1500 square foot home with this material, it would equal the amount of newspapers used for one person over a period of 40 years. The material is typically treated with a chemical that provides both fire and pest resistance. The R-value, measure of thermal resistance, for cellulose insulation is estimated at R3.5 for every inch of thickness.

How Long Does it Last?

Cellulose insulation has a typical lifespan of around 20 to 30 years. Since it is made of recycled newsprint, it will degrade over time, faster than fiberglass insulation. However, during its lifetime it does provide air-blocking properties that fiberglass does not. This offsets the shorter lifespan since cellulose is a more efficient insulation. Although it is water and fire resistant, if your roof has a major leak, it will shorten the lifespan of the cellulose.

Installation Considerations

Cellulose insulation is blown in just like fiberglass. The material comes in large bags, which are emptied into a blower system. For attics and crawl spaces, it is blown in through the openings for the space. In walls, it is necessary to cut holes in the drywall or wall material to fill in the spaces between the studs. In order to reap the air-blocking benefits, it must be packed in tightly.

When Fiberglass is a Better Choice

Fiberglass insulation typically lasts from 30 to 50 years. If you are looking for a longer-term solution that does not require blowing in insulation again, fiberglass is the better choice. You do not need to use as much as you do cellulose, which can affect the cost. For a smaller area that is sealed tightly, fiberglass is typically the least expensive option. However, the R-value is R2 per inch of thickness, making it a better option for homes in warmer climates.