Products

Cellulose

Manufacturing Process:

Cellulose is one of the oldest insulation materials still in use today. Patents for its manufacture were issued as early as the 1800's. It is made from newspaper or paper stock. The paper is shredded and pulverized. As it goes through the final process, chemicals are added for flammability along with fungicides and insecticides.

Water Permeability and Moisture Absorption:

Water absorption averages about 15%. Paper is hygroscopic and absorbs water readily. The amount of water content depends on the humidity level in the building, the quality of the vapor and air barrier. Capillarity is apparent.

Fire Resistance:

Fire retardants are added to cellulose. This typically is boric acid, borax, aluminum sulfate or ammonium phosphate. In addition to fire, these additives also help protect against mold growth and insects. The settling out of the fire retardants and other additives has been a problem.

Content and Shipping:

Cellulose contains paper and additives. The additives average about 25% of the weight of the product. The product is bulky, resulting in high packaging use and higher fuel delivery costs.

Selections:

Cellulose is designed to be blown into ceilings or wet spayed into walls. No other selection is available.

Application:

For attic applications, dry cellulose is blown in using a pneumatic machine. Cellulose is prone to settling, so manufacturers' instructions for adding additional insulation to allow for the settling should be followed. Walls are installed by adding water to the cellulose, which is installed with a pneumatic machine. Here lies the real problem with any wet-sprayed material. The product should be dry before it is covered up. Most tests show that, during hot, dry months, wet-applied cellulose will almost completely dry out in 2 to 5 days. Total drying takes much longer, often up to a month. With cellulose, a vapor barrier is a necessity due to its water absorption properties. If a vapor barrier is installed without the product being completely dry, water becomes trapped in the wall cavity. In the winter, in cold weather climates, wet-spray cellulose will not dry. Instead, the water in the insulation near the exterior sheathing will freeze. Cellulose materials are the least expensive of all products, and the application labor is greater than fiberglass.