How to Make an Attic Door Cover

Use your retractable razor knife, tape measure and straight edge to cut your 4-by-8 foot insulation board into the following pieces: Cut two pieces to measure 9 1/2-by-24 3/4 inches. Cut two pieces to measure 9-by-23 3/4 inches. Cut two pieces to measure 9 1/2-by-52 1/2 inches. Cut two pieces to measure 2 1/2-by-51 1/2 inches. Cut one piece to measure 23 3/4-by-52 1/2 inches, and cut one piece to measure 2 1/2-by-23 3/4 inches.

Lay your two 9 1/2-by-52 1/2 inch strips parallel to one another, on a flat surface. These will serve as the external side walls of the box. Lay your two 9 1/2-by-24 3/4 inch strips at each end of the box sides. These will serve as the external ends of the box.

Lay your two 9-by-23 3/4 inch strips inside the two external end pieces. These will serve as the internal ends of the box. Lay your two 2 1/2-by-51 1/2 inch strips inside your two side pieces. These will serve as the inner rim of your box sides. Lay your 2 1/2-by-23 3/4 inch strip at the center of your pieces, so it bridges the gap between your two sides. This will serve as the brace, which will add stability and strength to your box.

Use construction adhesive to assemble the box. Squeeze a bead of adhesive along the inner side of the external end pieces. Press the internal end pieces against the adhesive, so they are centered on the slightly larger external pieces. Press the end edges of your two side pieces against the adhesive, so that a box with one layer on its sides, and two layers at its ends is formed.

Apply a bead of adhesive to the lower 2 1/2 inches of the inner side of your two side pieces. Press your two inner rim strips against the adhesive.

Apply a bead of construction adhesive to the bottom side of each end of your brace. Lay the brace across your box, at its mid point. The brace piece should rest atop the two inner rim strips you have just installed. Allow the adhesive to dry according the manufacturer's instructions.

Use a hammer and 1-inch roofing nails to fasten the box more firmly. Drive one nail into each corner of the box from the end piece into the external side piece. Drive three nails into the end pieces from the inside of the box, outward. Space the nails evenly. Drive one nail through the side of the box and into the brace from the outside.

Install the cover piece. Apply a bead of adhesive around the top edge of your box. Lay your 23 3/4-by-52 1/2 inch cover piece onto the adhesive. Drive nails into the cover piece all around the edge so it remains securely in place. One nail every 8 inches or so should suffice.

Install a piece of weather stripping to the wooden frame around the attic stairs. The frame should form an upward facing box when the stairs are closed, and your attic cover box should rest directly on this weather stripping so that a tight seal is formed.

Apply a bead of adhesive to the top of your box cover, and lay a piece of paper-backed insulation on top so that it lays on the outside of the cover above the attic door cover box. This will provide an extra layer of insulation so that air does not penetrate. Allow the adhesive to dry according to the manufacturer's instructions.

Install heavy-duty, construction-grade fabric fasteners to the bottom of your attic door cover, and the top edge of your attic door staircase frame. These strips will hold the cover in place when the door is opened, and ensure that it does the job when the door is closed.