How to Build Stud Walls on an Uneven Floor

Measure the distance that the wall needs to span in feet. Divide the result by eight, which is the length of a standard 2-by-4. The result is the number of sections you need for the wall. If the result is not a whole number, then the last section needs to be shorter than the others.

Lay two of the 2-by-4s on the floor next to each other so that the ends line up. Draw a line across both boards that is 15-1/4 inches from the right end. Lay a carpenter’s square across both boards to make sure the lines are in exactly the same place.

Draw additional lines every 16 inches after the first set. Mark an "X" on the left side of each line.

Place one of the marked 2-by-4s on the floor so that the right end of the board is at the right-hand end where the wall will go. Measure the distance from the top of the end of the 2-by-4 to the ceiling. Subtract the thickness of the other 2-by-4. Cut a length of one of the unmarked 2-by-4s equal to this distance. The thickness of a 2-by-4 is rarely exactly 2 inches. Measure the thickness of yours instead of just subtracting 2 inches.

Set the board that you just cut on the right end of the marked board on the floor. Hold it straight up and nail it to the board on the floor. Be careful not to drive the nails out the bottom and into the floor.

Measure the distance from the top of the left end of the board on the floor to the ceiling. Subtract the thickness of a 2-by-4. Cut another unmarked board to this length. Nail it to the left end of the board.

Set the other marked board on top of the two sticking up from the first. Nail them to this board so that you have a rough rectangle. Make sure that the "Xs" on the top board are facing down and that they are on the left sides of the lines.

Measure the distances between the two horizontal boards at every line that you drew on them. Cut 2-by-4s for each length and nail them between the boards to that the "Xs" on the top and bottom are covered up.

Measure the gaps between each pair of studs in the wall frame section you made. Cut one brace for each gap and nail it into the gap. Set each brace higher or lower than the previous one in order to make nailing easier.

Make additional frames in the same manner until you have constructed a stud frame for the entire wall. Set them up end to end and nail them together.

Mount drywall boards on the wall with drywall screws. Cut the boards to fit, as needed, with a utility knife.