How to Support a Weight Bearing Wall

Location and Design

• 1

  Build a weight-bearing wall directly over another weight-bearing wall. Exterior walls that support the weight of the roof rafters are weight-bearing, and the load transfers from the rafters down through the wall framing to the masonry foundation walls, and finally to the footers that lie beneath the foundation. The house may also have interior weight-bearing walls.

• 2

  Go to the basement or crawl space and look for a wall that runs perpendicular to the floor joists. Typically, these walls are near the center of the house. If the floor joists are cut where they sit on top of the wall, it is a weight-bearing wall. Another sign of a weight-bearing wall is the presence of a large beam that runs perpendicular to the floor joists and is supported by columns. The beam is probably weight-bearing, but an engineer should look at it before you build a wall on the floor above.

• 3

  Line up wall studs so they sit directly over the floor joists, which should be directly over the wall studs below. Standard spacing of wall studs matches that of floor joists, and the most common spacing is 16 inches apart, although there are exceptions. For the best load transference, locate the studs in the new wall over the joists and wall studs below.

Interior Wall Support: Building Headers

• 4

  Transfer a vertical weight load to adjacent framing members when you install a door or window in a weight-bearing wall. Cutting the studs interrupts vertical weight transference and requires the construction of horizontal structural headers.

• 5

  Size headers to suit span and load. This means the header over a door or window must be adequate to disperse the load coming from above. Requirements vary, but a general rule when framing a 2-by-4 bearing wall is to use 4-inch lumber to match the depth of the header to the span of the opening. For example, if the window span were 4 feet, minimum header depth would be 4 inches. If the window span were 8 feet, minimum header depth would be 8 inches.

• 6

  Support headers with trimmer studs. Trimmer studs are studs that hold the header in place at the outside edges. The header sits on top of two trimmer studs, which form the sides of the rough opening.

• 7

  Add king studs to the outsides of trimmer studs to add support. King studs are the same length as standard wall studs, but they fit flush against the outside of the trimmer studs and they attach to the trimmer studs for additional support.

• 8

  Use cripple studs as braces. Cripple studs are the short studs that support the bottom sill of a window rough-in and offer support above window and door openings. While the location of trimmer and king studs depends on desired door and window locations, cripple studs follow the spacing of wall studs. That means that the cripple studs will be positioned in accordance with the rest of the wall studs. If the studs are 16 inches apart, the cripple studs will follow that same 16-inch spacing rule, just as if they were full-length studs.