There are three primary kinds of attic door insulation: weather stripping, rigid foam board, and fiberglass batt insulation. These types of insulation are usually used in conjunction with each other to create a proper seal and thorough padding. The combination a homeowner selects should be based on where the attic is located, the kind of door it has, and the location of the house.
Weather stripping is used to block leaks around windows and doors. Self-adhesive foam weather stripping is one of the easiest kinds of weather stripping to apply, and is often preferable for attic door insulation. It's usually made from cushioning poly foam sponge and has a self-adhesive back.
In some cases, particularly when a permanent seal is needed, caulking will be used in the place of weather stripping. This is most common in attics with pull-down stairs. Acrylic latex caulking is often used as a general purpose sealant because it sticks well to wood.
Rigid foam board, sometimes called rigid insulated sheeting, is usually made from polystyrene, polyisocyanurate or polyiso, and polyurethane. These are stiff, firm panels of insulation that can be used on almost any part of a home. In many cases, the rigid foam board is placed directly against the inside of the door to reduce heat loss.
Batt insulation comes in rolls, or batts, and is the most common type of insulation. It is generally made of flexible fiber or fiberglass, but other materials are available. Fiberglass batts are usually preferable for attic insulation.
The location of your attic will determine what kind of—if any—attic door insulation should be used. A garage attic may not need insulation at all, while an attic that leaks air through a closet or hall should be insulated for efficiency and comfort. The type of attic door insulation selected will also depend upon the R-value designated for your part of the country. R-value indicates the insulation's resistance to heat flow. Of course, the location of your attic will have also an impact on the R-value necessary.
There are several general rules of attic door insulation, which vary according to the type of door. A hatch usually needs weather stripping, two layers of foam board, and batt insulation on top. Pull-down stairs should be caulked or weather stripped to close gaps, then a box made from rigid foam board topped with batt insulation should be placed on top of the stairway frame. For knee-wall doors, the door should be sealed with weather striping before rigid foam board is fixed to the attic side.