Building an Attic Trap Door

Find two adjacent ceiling joists in the area you wish to construct your attic trap door, using a stud finder. Mark the locations of the joists with a pencil. Note that the joists will act as two parallel sides of the framed opening for the door. Measure and mark two perpendicular lines between the two joists to indicate the desired length of the opening.

Cut through the drywall in ceiling on the rectangular pencil outline with a utility knife. Lower the piece of drywall carefully from the ceiling, as attic insulation may fall out of the hole. Save the piece of drywall cut out for use as the trap door.

Measure the width of the opening between the ceiling joists in the opening. Transfer this measurement to a piece of scrap lumber that is the same width as the joists and make a mark. Cut the piece to length with a circular saw. Cut another piece to the same length in the same manner.

Fit the two cut pieces of lumber into the opening perpendicular to the ceiling joists on each end of the opening. Nail pieces in place through each side of the ceiling joists with 16d common nails.

Measure the length and width of the opening with a tape measure. Use these measurements to cut lengths of 1-by-3-inch trim lumber that will overlap the edge of the opening by ½ inch all the way around. Note that this will give the attic trap door a lip to rest on when it is in place. Nail the trim pieces to the perimeter of the opening with 8d finish nails.

Peel the backing from a foam rubber weather strip and apply it to the upper side of the trim that overlaps the edge of the attic door opening. Cut a piece of fiberglass insulation to length with a utility knife and apply it to the back of the piece of drywall cut from the ceiling, using construction adhesive.

Insert the drywall into the opening at an angle. Lift the underside of the drywall with the tips of your fingers and slide it as needed until it fits into the opening. Ensure the edges of the drywall are resting on the foam rubber weather strip.