How to Frame a Wall in an Attic

Measure the length or width of the attic with a measuring tape to determine the length of the dividing wall.

Cut a section of a 2-by-4 pressure-treated board to the length of the dividing wall with a circular saw. This section will form the bottom plate of the wall. Lay the bottom plate in the desired position, square with the adjacent walls, and attach it to the subfloor by installing 4-inch wood screws with an electric screwdriver at 4-inch intervals.

Determine the angle of the roof joists with a protractor. Measure the distance between the bottom plate and the bottom of the roof joist on each end of the dividing wall.

Cut two sections of 2-by-4 lumber to fit between the bottom plate and the bottom edge of the roof joist along the adjacent walls. Miter one end of each of the sections to the angle of the roof joist with a miter saw to form the end studs.

Stand one of the end studs against each adjacent wall between the bottom plate and the roof joist and check the studs with a carpenter's level to ensure that they are vertical. Drill pilot holes through the end studs into the adjacent wall studs, and at 45-degree angles into the bottom plate and roof joist. Insert and tighten 4-inch wood screws through the pilot holes with an electric screwdriver.

Mark the bottom plate at 16-inch intervals between the end studs. Measure the distance between the bottom plate and the roof joist at each mark. Cut sections of 2-by-4 lumber to length to form the interior studs, and miter one end of each stud to the angle of the roof joist.

Install the interior studs at each mark by drilling pilot holes at 45-degree angles through the studs into the bottom plate and roof joists, and inserting 4-inch wood screws through the pilot holes.