I stood under my attic access door last January and could feel cold air pouring down like someone left a window open. The attic was fully insulated — R-38 fiberglass, the whole thing — but the access door was just a piece of drywall with no insulation at all.

That one uninsulated panel was basically a 2-foot by 3-foot hole in my ceiling insulation. My heating bill that month was $340. It dropped $40 the month after I fixed this.

What You Need

• A piece of rigid foam insulation board (2-inch thick, R-10 or higher). Cut to the size of your attic access opening.
• Weather stripping — adhesive-backed foam tape, 1/2 inch wide.
• A utility knife for cutting the foam board.
• Construction adhesive or screws with large washers to attach the foam to the door.

How to Do It

1. Measure the access opening. Not the door itself — the opening it sits in. Measure length and width.
2. Cut the foam board. It should be slightly smaller than the opening (about 1/4 inch less on each side) so the door still closes easily. Score it multiple times with a utility knife, then snap it on the scored line.
3. Attach foam to the attic side of the door. Use construction adhesive or screws with wide washers. The foam faces up into the attic.
4. Add weather stripping. Foam tape around the lip of the opening where the door rests. This seals the gap so air cannot leak around the edges.
5. Optional: add a latch. If the door is lightweight and tends to lift, a simple hook-and-eye latch holds it tight against the weather stripping.

This took me 25 minutes and cost about $18 in materials. The return on investment was immediate — literally the next month’s energy bill.