Spray Cellulose Insulation Techniques

Details

• Cellulose insulation is made from the finely shredded material of wood fiber products, usually newspapers. The fibers are combined with chemicals to make the insulation insect- and fire-repellent. Cellulose insulation has an average R-value – the unit of thermal resistance, with higher numbers indicating better effectiveness as an insulator – of between 3.6 and 3.8 per inch. By comparison, blown-in fiberglass insulation has an average R-value of between 2.2 and 2.7, and rock wool averages between 3.0 and 3.3. per inch.

Spray

• Cellulose insulation is usually installed using a pressurized-air sprayer. The insulation is applied in its dry form, a process you can perform with a rented sprayer. With moisture added, the process typically requires professional installation. A holding tank contains the cellulose, which is then pushed through a flexible hose that is moved to cover the required area effectively. The cellulose is then sprayed in attics, typically in the stud bays, or onto basement walls and ceilings. It is effective at insulating hard-to-reach areas because it conforms to the shape of the space.

Precautions

• Before you apply cellulose insulation, all piping from furnaces or any other heat source should be either covered with metal flashing to prevent the cellulose's coming into contact with them, or blocked off entirely during the installation process and subsequently insulated with fiberglass batts, which are naturally more fire-resistant than cellulose. Cover air ducts to prevent the insulation's entering the venting system, and erect a cardboard barrier across the door to the attic or basement to prevent the material from blowing back into the house. Fill in gaps around doors, windows and vents by hand rather than with the blowing machine.

Cavity Walls

• Cellulose insulation is often installed in cavity walls. Small holes are drilled into the walls, and the cellulose, mixed with water, is sprayed into the cavity. It hardens within minutes but may take up to a week to settle. The holes are sealed up. Professional installation is recommended to ensure that the correct volume of insulation is injected for the most effective and efficient results.