Cellulose insulation

Fiberglass is the insulation material of around 90% of North-American new homes. But there are other good alternative insulators, namely sprayed foams, mineral wool, and cellulose. This page deals with cellulose, comparing it to fiberglass. See Fiberglass and Mineral wools for details about fiberglass and mineral wool insulation.

Cellulose composition

Cellulose is mostly made from recycled newsprint, cardboard, paperboard and other waste paper products treated with chemical to obtain fire-resistant and insect-resistant properties. Cellulose is presented as loose-fill or as a wet-sprayed material.

Cellulose and the environment

Cellulose has environmental advantages over fiberglass (and mineral wools or plastic sprayed foams). Cellulose is a typical “green” home product, with a much higher recycled content. Besides, it’s an excellent air sealer and has superior acoustical properties.

Note:
The potential health risk posed to installers is lower than that of fiberglass insulation, but it exists. So, be careful, when installing cellulose insulation in your home. Pay attention to the manufacturer instructions.

Performance of Cellulose insulation

Tightly packed cellulose insulation is more thermally efficient than fiberglass. Although cellulose R-value (around 3.7 per inch) is very similar to hard fiberglass batts, it has a big advantage over fiberglass: cellulose blocks air leakage through cracks, voids and gaps in a particularly efficient way (only surpassed by sprayed synthetic foams).

Uses of cellulose insulation

Cellulose can be used in attics (dry cellulose fiber or damp fiber) and walls (usually damp fiber, sprayed into the wall cavities). Dry-blown cellulose is more common in retrofit applications, namely in attics.

cellulose insulation Prices

Cellulose prices are usually higher than those of fiberglass. They are often close to those of synthetic sprayed foams for homes: 1 to 2 times the price of fiberglass insulation.

Cellulose and Fire Rating

Official tests confirm that undeteriorated cellulose is highly fire-safe. The tightly cellulose fibers prevent air combustion and the spread of fire through walls and other cavities or gaps of the house. The fire-risk problem is very remote and usually associated with the deterioriation caused by moisture.

Mildew and cellulose insulation

Cellulose insulation can absorb more moisture than most other types of insulation. If the wall cavities aren’t perfectly dry, if there is the risk of wetting, then cellulose may favor mildew growth. In other words: the use of cellulose requires dry walls and attics. If you can't ensure it, look for other solutions.

Cellulose installation

Surfaces and walls should be carefully sealed before cellulose installation.

Dry-loose cellulose demands specific pneumatic equipment and installers should pay attention to the time demanded by the material to attain the required settling-density-R-value. The manufacturer's demands on this issue should be strictly respected.

Damp-sprayed cellulose installation requires a professional. The material is applied into the open wall cavities, which should not be closed before it acquires less than 25% water content (otherwise, walls could get moisture and mildew in the near future).