Sometimes the old attic stairs just won't do. They're cumbersome or even dangerous. In that case, you can replace them with a little time, elbow grease, and DIY knowledge. Here are some step-by-step directions to have you installing new attic stairs in no time.
Find a New Set of Stairs
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 the gypsum board (drywall) and cutting some of the horizontal structural framing members (joists). If you must enlarge the opening, first check around it for pipes, ducts, and wires that might obstruct access through the new opening. If there is insufficient clearance, you will have to move or re-route these.
Make a New Opening If Necessary
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 1/4 inch around the entire perimeter. Attic access doors can vary in size, but 24x54 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 needs to be removed.
Now, use a circular saw, jigsaw, or Sawzall, to cut back the joists and 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.)
Nail the 2 re-sized, doubled joists (trimming the width) 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.
Cut the 2 remaining doubled trim joists to fit the length of the new opening and nail them 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.
Install the New Stairs
Lower the new unit into the 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 1/2 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 joists with screws as indicated by the manufacturer’s instructions. Install finished trim boards (typically 1x4 inches), surrounding the access door, onto the ceiling, and flush with the stair frame.