Construct an Attic Stairs Cover Box

Written by  The U.S. Department of Energy's Office of EERE

To insulate your attic stairs access, you can construct a lightweight, moveable box that will rest on the stair frame from the attic side.

Construct an Attic Stairs Cover Box

Pay careful attention to inside and outside dimensions plus height requirements for the specific measurements of the attic staircase being installed. The cover box should rest squarely on top of the attic stairs frame. Shim and seal the gap between the frame and rough opening and install weatherstripping.

 

 

Materials Needed

You'll need the following materials to construct an attic stairs cover box:

Instructions

Use the template in the illustration below to cut pieces from a single, 4X8 foot sheet of 1/2-inch rigid insulation for a box 53 1/2-inches long (51 1/2-inches inside), 24 3/4-inches (22 3/4 inches inside), and 9 inches of depth inside. The box will fit stairs with an outside framing dimension of 53 1/2 inches by 24 3/4 inches. Adjust dimensions to fit the specific stairs being installed. Carefully measure both the inside and outside dimensions to the appropriate length, width, and depth clearances to cover the box.

Template showing the following pieces cut from a 4 foot by 8 foot  sheet of half-inch rigid insulation for a box 53 1/2-inches long (51  1/2-inches inside), 24 3/4-inches (22 3/4 inches inside), and 9 inches  of depth inside: Two end pieces, 9 1/2 inches by 24 3/4 inches; two  small end pieces, 9 inches by 23 3/4 inches; two side pieces, 9 1/2  inches by 52 1/2 inches; two small side pieces 51 1/2 inches by 2 1/2  inches; one cover piece, 52 1/2 inches by 23 3/4 inches; one brace, 23  3/4 inches by 2 1/2 inches. The caption reads: All pieces can be cut out  of a 4 foot by 8 foot sheet of rigid insulation. Use a table saw for  smooth, accurate cuts.

Create the box as shown in the illustration below:

  • Apply adhesive/mastic and use roofing nails to construct the two end and two side pieces.
  • Assemble the side and end pieces into a box using adhesive and longer nails.
  • Add the center support brace and cover piece with glue and nails.
  • Glue a faced insulation batt to the cover piece with adhesive applied to the paper backing (optional).
Diagram showing the construction of an attic stairs cover box  using the materials cut from the template above. The larger side and end  pieces form the outside of the box, and the smaller side and end pieces  fit inside to form a second layer. The brace is placed in the cutouts  in the smaller side pieces, and the cover drops into the top of the box.  The length between the outside edges is 53 1/2 inches, and the width is  24 3/4 inches. The length between the inside edges of the outer layer  of board is 52 1/2 inches, and the width is 23 3/4 inches. The length  between the inside edges of the inner layer of boards is 51 1/2 inches,  and the width is 22 1/2 inches. The box is secured together with one  nail at each corner, one nail on each end of the brace, and three nails  on each inside end board. The caption reads: Assemble side pieces, end  pieces, and brace as shown. The cover piece will drop in and be attached  with adhesive and nails.

Article source: The U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE). For the most up-to-date information please visit the EERE website.
Last modified on Mon, Oct 25, 2010
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