Attic Access Door Replacement

Replacing an attic access door usually requires replacing the existing folding stair unit. Before purchasing a new attic stair unit, be sure to match the swing clearance and the landing length of the stairs to the ceiling height at the rough opening, so that the stairs can be ascended at a comfortable angle while taking up minimal landing space.

Much work can be saved if the frame of the new stair unit has the same dimensions as the old stair unit. Otherwise the size of the rough opening in the ceiling will have to be altered. This will involve removing gypsum board (drywall) and cutting some of the horizontal structural framing members (joists). If this is the case, the first step is to check around the rough opening for pipes, ducts and wires that might obstruct access through the new opening. If there is not sufficient clearance they will have to be moved or re-routed.

When sizing the new rough opening, allow for the opening to be slightly larger than the unit frame so that there is a clearance of approximately ¼” around the entire perimeter. Attic access doors can vary in size, but 24 x 54 inches is the general standard. After removing the old stair unit, pry loose the trim boards surrounding the door with a hammer claw or a small crowbar. Remove all wood, gypsum board, screws, nails and fasteners until you are left with the exposed joists that form the rectangular opening. Mark the length and width of the new opening onto the ceiling from below and cut away the gypsum board with a utility knife. There are usually double trim joists (2 joists nailed side to side) around the perimeter of the rough opening that need to be removed.

With a circular saw, jigsaw or “saws-all”, you can now cut back the joists to form the new opening. Joists run parallel and so only have to be cut back in one direction. (If the new opening is smaller than the existing opening, joists can be extended with a “sister” or “scab” joist of the same height nailed side to side.) The 2 re-sized doubled joists (trimming the width) are nailed perpendicular to the butt end of the cut-back joists and perpendicular to the sides of the 2 closest joists beyond the width of the new opening. These boards trim the opening but also act as bridging to brace the entire assembly. The 2 remaining doubled trim joists are cut to fit the length of the new opening and nailed in at the proper width, perpendicular to those just installed. Using a carpenter’s framing square, or simply by measuring diagonally from corner to corner, make sure that the rough opening is square.

The new unit is best installed by lowering it into the new opening from the attic above. Nail or screw 2 scrap boards, strong enough to support the stair unit, across the width of the rough opening at each end. Nail into the trim joists from below so that the boards extend ½ inch into the opening. This will hold the stair unit in place for the final adjustments, while allowing the stairs to unfold. Secure the stair frame to the sides of the trim joists with screws as indicated by the manufacturer’s instructions. Finished trim boards (typically 1 x 4 inches) surrounding the access door are installed flat onto the ceiling and flush with the stair frame.