More about The San Jose Cellulose Insulation San JosĂŠ cellulose insulation is a recycled product made from pulverized newspaper pulp. It is the about the least expensive, least energy- intensive, least toxic, most environmentally benign form of insulation available on the market. The natural mineral boron is added as a fire retardant (usually in the form of boric acid) to make cellulose one of the least combustible forms of insulation. It has a respectable R- value of about 3.7 per inch and cuts air infiltration better than fiberglass insulation. With a resume like that one may wonder why a person would bother with any other type of insulation. The reason is versatility. Cellulose is ideal for insulating framed wall cavities and flat ceilings where there is access to the attic, but is not suited for other uses. Homeowner can purchase bags of loose cellulose insulation to do on own attic installation, but homeowner will need to hire a contractor to install the insulation in wall cavities. When retrofitting older homes homeowner can drill holes in the walls and blow in the dry insulation, but in new construction the cellulose is mixed with water and sprayed in the walls before the sheetrock goes on. Hiring a contractor raises the price, but not unreasonably so in comparison to other types of insulation. Choosing the Contractors Some of the contractors or homeowners never used cellulose for two simple reasons. First, contractors build with stone and log, so there are no framed walls on the exterior to insulate. contractors could build a framed wall along the inside of the masonry walls, but this would be an unnecessary duplication of the structural wall, and besides, heat would still conduct out through the studs in the frame work. Second, contractors prefer spacious cat hedral ceilings rather than flat ceilings. Cathedral ceilings are usually insulated from underneath after the roofing goes on, but before the plasterboard. Air flow must be maintained over the top of the insulation to evaporate moisture away, so homeowner cannot spray the entire cavity full of insulation, and the insulation cannot be allowed to slide or slump in any way that it blocks the flow of air over it. Some of them might have reluctantly chosen fiberglass batts as the available alternative. Someone could probably make a lot of money if they invented cellulose batts. It is important to consider the best San Jose cellulose insulation or fiberglass insulation which is ideal for that particular climate or region.