Insulating Attic Access

Learn how to fill up attic spaces effectively.

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. Also, to find out where your home might be losing energy, consider conducting an energy audit.

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 dry-walled ceiling, located in a closet or hallway. To insulate an attic hatch, you need weather stripping, rigid foam board and fiberglass batt insulation. First, install foam weather stripping 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 nonexpanding foam in addition to the caulk. Add weather stripping 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 weather stripping. If the door doesn't have these, weather strip 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.

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