Blown-in cellulose insulation is an excellent option for insulating your house. It has a good R value (the value indicating its efficiency as an insulator), is nontoxic and is made from 80 per cent post-consumer recycled material. However, like all forms of insulation, blown-in cellulose has its own drawbacks and problems. Weigh the benefits and drawbacks carefully to decide if cellulose is the right insulating material for your own house.
No matter what sort of insulation you have, you don't want it exposed to a leak, but cellulose insulation is especially sensitive to water. Cellulose is a hygroscopic material, meaning that it attracts and holds on to water. If it is exposed to leaks, it can sag and compress, lowering its R value. This can seriously compromise its ability to insulate your house. It can also increase the chance of water damage in areas with the insulation, since the blown cellulose does not dry easily.
Although the paper that cellulose is made of is not dangerous to metals, the fire retardent is. The borate used to treat the cellulose can corrode metals it touches, such as electric wires, pipes and metal fasteners. Corrosion is an especially serious threat if the insulation is exposed to water. If you do opt to use blown cellulose insulation, cover or reroute all exposed metal fixtures to protect them from corrosion.
Although blown-in cellulose is environmentally friendly, it does have a number of chemicals that can cause allergic reactions in sensitive people. Newsprint is made with solvents, such as turpentine and toluene, as well as a wide variety of resins, pigments, fragrances and other chemicals. The recycled newspaper the cellulose was made from could also have been contaminated with mould. Even though blown-in cellulose is treated so that it is mould retardant, it may have dead mould spores, which can still cause a reaction. Particles of cellulose insulation tend to get all over the house when it is installed, so wear a respirator and goggles. Chemically sensitive people may wish to avoid the house for several days until the cellulose dries and hardens, or choose a different insulator.