A load bearing stud wall is any of the exterior walls in a wood framed house, or an interior partition that supports a distributed load (joists) or a point load (beams). The wall itself is composed of wood studs at 16 inches on center and is constructed in the same way as non-load bearing interior partitions.
A stud wall consists of a double-top plate and bottom plate made from linear (10 feet or longer) 2x4 lumber and wood studs (2x4x8 feet long). Headers and trim boards are assembled into rough openings which, along with the wood studs and plates, makes up the main wall components. Walls are typically built flat on the floor in position, then tilted upright and nailed in place.
Step 1 - Mark the Location of the Bottom Plate
Locate the outer or inner surface of the new wall and snap a chalk line on the floor. Measure over 3½ inches from this line and snap another line parallel to it. This will show the location of the wall’s bottom plate.
Step 2 - Layout the Top and Bottom Plates
If you are building on a concrete slab, you will need to use pressure-treated 2X4 lumber (chemically treated to prevent decay from being in contact with the concrete) for the bottom plate. Lay the top and bottom plates flat, side by side, and flush at the ends on the slab or decking. Layout the studs by hooking a measuring tape onto the butt end of a plate, make a mark at every 16 inches, and show the inside surface for each rough opening. Scribe a pencil line on each mark across both plates with a measuring square and mark an X on one side of the line on both plates.
Step 3 - Assemble the Wall
Stand the plates on edge and lay the wall components in place also on edge. The studs will be nailed aligned with the pencil lines on the side of the X. Make sure the studs are flush with the plates and remain within the wall surface. Drive two nails through the plates into the butt end of each stud. Nail into the blocks above headers, or directly into the headers if they are adjacent to the top plate, before attaching the upper top plate. Tilt the wall upright and align the bottom plate with the chalk lines.
Step 4 - Nail the Wall in Place
The bottom plate is either fastened to the slab with concrete nails at every other stud cavity or nailed through the plywood decking into the joists below. If the load bearing structure is in place above the wall, you may have to force the wall into a vertical position by striking the side of the top plate with a sledgehammer. Use a level to make sure that the wall is plumb before nailing the top plate in place. If the ends of the new wall meet an existing wall at a cavity, you will need to construct corner studs and insert them into the existing wall. Secure the new wall by nailing through the face of end studs into the corner studs.
Step 5 - Install Blocking
Cut blocking from 2x4 lumber and install it staggered between the studs, at a height of about 4 feet. The purpose of this is to provide fire blocking so that a fire will not quickly spread through the wall cavities.
The wall is now completely framed. Install doors and windows, sheetrock and trim.