How to Build & Nail a Knee Wall Partition

Take a chalk line tool and stretch the string over the attic rafters along the horizontal length of the wall at the height you wish to build. Snap the string, which will leave a chalk mark on the rafters to use as a guide as you continue.

Take a tape measure and obtain the distance between the floor and the chalk line.

Place a 2-by-4 board vertically alongside a rafter. Set a ruler on the 2-by-4 at exactly the angle of the rafter, and mark the line with a pencil. Cut the board to length with a circular saw. Use the the height you obtained by measuring from the floor to the chalk line, subtracting 3 inches for the top and bottom plates on which the studs will rest. Cut the board to the angle on the pencil mark.

Cut the rest of the studs to the same length and angle as the first board.

Take two 2-by-4s and cut them to the horizontal length of the wall. Use one for the top plate and one for the bottom plate.

Place the bottom plate on the floor and position the studs about 16 inches apart. Toenail the studs to the bottom plate with 16d nails.

Place the top plate over the angled tops of the studs and use a hammer to nail them together with two 16d nails.

Place the framed wall against the chalk line on the rafters. Check for plumb with a carpenter's level. Nail the bottom plate to the joists and the top plate to the rafters.