If your ceiling joists are spaced so that they make up the other two sides of the rough opening check the opening for squareness by measuring across the diagonals.
How to frame an attic access opening.
The frame for the rough opening requires four sides.
The access door also serves as a ceiling vent for removing fumes from the room to.
Build a box to frame the opening with lumber boards the same depth as floor joists.
The measurements should be within 1 8 inch to be considered square see figure 13.
The headers make up two of those sides.
In this video i will show you how to build and install a attic access door.
Use an electric screwdriver to drive screws in the framing as well.
Nail this framing into place around the perimeter of the attic access opening.
This diy home improvement project will make your attic stairs fit nice and square.