Assess Your Insulating Needs

• Before purchasing insulation, determine what areas of your attic crawlspace require it. This will help you estimate how much and what type of insulation you need. If there is already insulation in your attic, check the depth of your insulation with a ruler. If the insulation is less than 6 inches, you should consider adding more. Check for air leaks around air vents, wiring and the crawlspace door. Even though these areas are small, you will need to insulate them to avoid gaps that can increase your heating and cooling bills. You also need to determine if the crawlspace has ventilation. If the attic is ventilated, you can insulate the floors or leave the space unventilated and insulate only the underside of the roof to still allow some air movement. Ventilation helps keep the air flowing through a space, preventing moisture from condensing and becoming water, which can lead to mold and mildew growth.
  
  

Buying Insulation

• Compare materials by their R-value when shopping for insulating materials. The R-value represents the insulation's ability to interfere with the flow of heat from one room to another. You will also need to know your temperature zone when buying insulation since northern regions need a higher R-value than those in warmer, southern climates.
  
  Fiberglass blankets (in batt or roll form) and fiberglass loose-fill insulation are the most common types of insulation used in attics and attic crawlspaces. Batt and roll insulation is available in precut pieces in white, pink or yellow. Batts fit between floor joists while fiberglass rolls fill the stud cavities on walls and ceilings. Loose fill is considered environmentally friendly since it contains 30 to 60 percent recycled material that has been treated with pest- and fire-resistant chemicals. Fiberglass loose-fill insulation is often easier to install in difficult to reach crawlspaces, but it does require the use of special equipment and proper training.
  
  

Installing Installation

• Most types of blanket insulation have vapor barriers with thick flaps on the side for fastening the material to joists and studs. If you are installing new insulation over existing insulation, do not use materials with vapor barriers. Firmly insert the insulation between the joists and staple the flaps to the studs. For batts without vapor barriers, tuck the insulation between the floor joists. To insulate an attic with loose-fill insulation, tape off all vents and holes. Home improvement stores rent blowing machines and sell loose-fill insulation by the bag. To achieve an R-value of 38 for your attic, you must have 14 to 17 inches of fiberglass loose-fill insulation installed.