• Cellulose insulation is made primarily from recycled paper.newspaper image by Photoeyes from Fotolia.com
  
  Blown cellulose insulation is an effective method of insulating spaces in older buildings to reduce heating bills. According to Bob Vila, cellulose insulation is composed mainly of recycled newsprint, treated with fire and pest retardants. It fills corners and openings well, and can be installed without the unpleasant itching of fiberglass, though goggles and respirators should be worn. Adding the appropriate amount of blown cellulose insulation to your attic can improve your home's energy efficiency.
  
  

Inches for R-Value

• According to Washington State University, blown cellulose insulation has an R-value, or insulation value, of 3.2 to 3.8 per inch. Most building codes recommend a higher insulation value for attics than for walls, because hot air rises and more heat can escape through the upper portions of a home.
  
  The specific number of inches of cellulose insulation recommended varies by location. For instance, in Washington State, the standard is R-38, or at least 10 inches of cellulose. In colder climates, such as the northern Midwest, attic insulation values as high as R-49 to R-60, or 13 to 16 inches of insulation, may be recommended. In warm climates, such as the Southeast, homeowners may require no more than R-30, or about 8 inches of cellulose.
  
  

Insulation Depth and Ventilation

• Up to a point, deeper insulation is better, since it will prevent heat from leaving the home through the attic. However, homeowners must take care not to install too many inches of insulation. The Cellulose Insulation Manufacturers Association recommends a well-vented attic and low humidity for buildings with cellulose insulation. Cellulose that is blown too deeply may cover light fixtures and vents, producing possible fire and mold hazards. CIMA notes that insulation must be installed so it doesn't block air intakes for furnaces, and must be at least 3 inches away from chimneys and flues.
  
  

Settled Inches

• Unfortunately, not all cellulose is installed properly. That means that the depth of the insulation that's blown in may not accurately indicate its R-value. According to Home Energy Magazine, many insulation contractors accidentally or deliberately over-fluff cellulose insulation when installing it in an attic. The result is an insulation depth that looks correct when first installed, but soon settles to a lower depth.
  
  To properly install cellulose insulation, contractors must account for this natural settling by adding more cellulose when dry blowing the insulation, or by dampening the cellulose to encourage it to settle quickly. Homeowners can check the installation by waiting for the cellulose to settle, then measuring its depth.