Watch the video on Insulating Attic Access.
If you've ever had to venture into an unconditioned attic during the dog days of summer, you know why builders, from an energy perspective, don't think of an attic as part of the home. The hot, sultry air creates a climate that's unfit to stand in for more than a couple minutes. An unconditioned attic is no better in the winter, as warm air from the home rises and condenses on the cold attic surfaces, creating the potential for mold growth.
Since heat naturally travels from hot to cold areas, hot air will enter and leave a conditioned home through leaks and holes, the largest of which are usually in the attic. To slow heat transfer through a home, builders install a layer of insulation on the floor of unconditioned attics. However, there's a problem. You have to be able to access the attic, but an attic access puts a hole in the layer of insulation covering the attic floor.
If the attic access is located in an unconditioned part of the home, such as a garage, insulation and air sealing may not be needed. More often, however, the attic access is located in a closet or hallway, where there's a direct pathway for air to move between the unconditioned and conditioned spaces of the home. Whether the attic access is an attic hatch, pull-down stairs, or a knee-wall door, you should install insulation with the proper R-value for your climate, based on the Department of Energy's recommendations (www.eere.energy.gov/buildings/info/documents/pdfs/26450.pdf).
Here's how to insulate attic hatches, pull-down stairs, and knee-wall doors:
Attic hatch (scuttle hole)
The attic hatch, or scuttle hole, is a removable panel in the drywalled ceiling, located in a closet or hallway. To insulate an attic hatch, you need weatherstripping, rigid foam board, and fiberglass batt insulation. First, install foam weatherstripping on the inside of the trim or directly onto the hatch. Cut out two pieces of rigid foam board that are 1/4-inch smaller than the hatch, so homeowners can slide the attic access panel open easily. Attach the two layers of foam board together, and apply them to the hatch. Install fiberglass batt insulation on top of the foam board. Make sure the R-value of the insulation on the hatch matches the R-value of the insulation in the rest of the attic.
Pull-down stairs
For insulation, create a lightweight box that fits over the stairs and can be moved to allow entry. You can construct the box from rigid foam board. It should rest squarely on top of the stairway frame. Adhere batt insulation to the top panel of the box. For air sealing, add caulk if the gap between the rough opening and frame is less than 1/2 inch; if the gap is larger, use non-expanding foam in addition to the caulk. Add weatherstripping or gasket material to the frame or attic access panel.
Knee-wall door
Knee-wall doors provide access through the knee walls to the unconditioned parts of the attic. You can buy knee-wall doors that have built-in insulation and weatherstripping. If the door doesn't have these, weatherstrip it to provide a tight seal, and make sure the latch pulls tightly against the frame. Attach the rigid foam insulation to the attic side of the door.
When you insulate and seal the attic access, you help prevent heat transfer between the attic and the conditioned home, improving energy efficiency, which is reflected in lower heating and cooling costs for homeowners.
Related Articles:
Blown-In and Wet-Spray Cellulose Insulation
Spray Foam Insulation
Roof Insulation to Reduce Ice Dams
To learn more about insulating an attic access, visit:
www.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11400
www.eere.energy.gov/buildings/info/documents/pdfs/26450.pdf
www.toolbase.org/techinv/techDetails.aspx?technologyID=299
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