How to Build an Interior Wall With a Rough Door Opening

Mark the installation location on the floor, ceiling and adjoining walls. Ensure that a stud lies underneath the wall sheathing at the point of attachment and that ceiling joists run perpendicular to the new wall or that one joist runs parallel and directly above the spot. Interior walls must anchor to existing walls and ceiling, in addition to the floor, for best stability.

Measure the length of the wall needed. Find the floor-to-ceiling height as well. Take height measurements in several spots and use the shortest one obtained to ensure a proper fit. Record all measurements as you take them, labeling them well.

Determine where you want the door located. Measure the door width and add 5 inches. Mark this dimension on the floor with bold Xs on both sides to denote the door opening. Find the wall length, from the opening back to the beginning of the wall, on both sides and record it. That will help you locate the opening on your wall plates.

Cut two 2-by-4-inch boards to the total length of the wall. These will form your top and bottom wall plates. If the wall is longer than 24 feet, the maximum standard length of 2-by-4s, divide the wall length in two, ensuring the door is at least a couple of feet inside one wall section. Build and attach the two walls similarly.

Set the plates, paired together, on your work surface with the wide face up and down. Ensure the ends are flush. Measure across the plates to the beginning of the door opening as previously determined. Place a square across the plates and mark both at once. Mark the other side of the door opening similarly.

Draw additional lines to mark the other wall stud locations. Begin at the end of the plates and mark 1 1/2 inch to note the edge of the first stud, which sets flush with the plate end.

Continue across the length of the plates, making the second mark 15 1/4 inch from the end of the plates and 16 inches thereafter. This ensures each stud, which is 1 1/2 inches thick, is 16 inches on center. The studs on either side of the door opening marks may, however, be closer to the door opening than 16 inches, but this isn't a problem. End the wall with one stud mark 1 1/2 inches from the end, again regardless of the spacing between the previous and end stud.

Subtract 3 1/4 inches from the floor-to-ceiling height. Cut one stud per mark, including the marks outlining the door, to fit this dimension. When coupled with the plate thickness, which is 3 inches combined, and 1/4 inch clearance to allow you to erect a full height wall, the wall will fit precisely.

Flip the bottom plate on edge so the wide face runs vertically. Align the beginning stud, also on edge, flush with the plate end. Drive two 16d nails through the bottom of the plate into the stud end to secure. Stagger the nails slightly to avoid splitting the stud. Continue down the length of the plate, attaching one stud per mark. Line the top plate up with the free ends and nail in place similarly.

Measure and cut a section of 2-by-4-inch board to span the width of the door opening. Find the height of the door and add 2 inches. Attach the board, called a header, between the king studs outlining the door at the appropriate height.

Cut two additional studs, called trimmer or jack studs, to fit between the header and the bottom plate. Push these snugly against the king studs, one on either side, and nail through the plate, header and into the king stud to secure.

Measure the distance from the header up to the top plate. Cut two or three short lengths of 2-by-4-inch boards to fit. Nail through the header and top plate to anchor in place. These are referred to as cripple studs.

Cut the bottom plate flush with the edge of the jack studs. Use a handsaw to avoid cutting into the studs and weakening them.

Erect the wall, walking and tilting it up into place. Hold a level against the wall and check for plumb. After ensuring everything is square and fits, shove shims between the wall and floor to wedge it into place securely. Nail through the end studs into existing walls, through the bottom plate into the floor and through the top plate into the ceiling wherever the plate contacts a ceiling joist. If you built two wall sections, join them together with additional nails. Insulate and sheath the wall as desired to complete.