How to Build a Sub Wall (Half Wall)
A sub wall, usually called a half wall or a knee wall, separates two areas without closing the space in. This defines living areas without making the spaces look smaller and gives both spaces a larger, roomier appearance. Sub wall construction uses the same techniques used to build interior, non-load bearing walls, except the walls are often two to three times as thick, especially when they don't join another wall at one end. Does this Spark an idea?
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Things You'll Need
- Tape measure
- 2-by-4 lumber
- Circular saw
- Combination square
- Hammer
- 16d nails
- 4-foot level
Instructions
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Measure the length of the wall with the tape measure. If one end of the wall does not abut another wall, subtract the thickness of the wall covering. Transfer the measurement to four 2-by-4 boards and mark them. Use the combination square to draw a straight line across the boards and cut them to the length measured with the circular saw. These boards are the top and bottom plates.
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Subtract 3 inches plus the thickness of the material that will cover the top of the wall from the wall height. This is the length of the studs. Divide the length of wall by 16 and round the number down, then add 1. The result is the number of studs for the wall frame. Multiply the result by 2 -- a sub wall requires two frames. Measure and cut all the studs.
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3
Lay all four wall plates on edge with the ends flush. Measure from the left and make a mark on one board at 15 1/4 inches, then every 16 inches thereafter. Place the combination square with the flat edge against the face of the front 2-by-4 at each mark and draw a line across all four boards. Mark an "X" to the right of each mark. These are the stud locations. Mark an "L" on the left end of each board.
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Place two wall plates on edge with the stud location marks up and the "L" on the left. Place a stud between the plates at each end with one face flush with the end of each plate. Place additional studs between the plates at each stud location with the left face flush with the marks. This leaves the "X" centered on each stud. Nail the top and bottom plates to each stud with two nails through each plate into the end of the stud. Build a second wall frame the same way.
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Mark the location of one side of the wall on the floor at both ends. Remember to offset the mark by the thickness of the wall covering if the sub wall meets another wall at a corner. Stand a wall frame on one plate and align it with the two marks. Nail it to the floor with one nail at each end. Place the second frame 1 1/4 inches away and parallel to the first frame. Nail it to the floor at both ends.
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Plumb the wall frames by placing the edge of the 4-foot level against a stud and moving the top of the wall until the bubble in the level is centered between the vial marks. Nail the wall frames to the adjoining walls with six nails; two at the top, two at the bottom and two in the middle of each end stud. Finish nailing the wall frames to the floor with two nails placed approximately every 16 inches.
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Complete the wall by installing a sheathing product such as drywall or paneling on the two wall faces and the end of the wall. Finish the wall sheathing product with molding or drywall joint compound. Add a top surface using a hardwood board such as oak and allow it to overlap on each side and the end. Stain or paint the hardwood to your taste.
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Tips & Warnings
If your sub wall meets two walls or columns, you can leave out the second wall frame. The second frame add stability and makes a wider ledge on the top.
Using 1/2-inch drywall as a wall covering gives the wall described a finished wall thickness of approximately 9 1/4 inches, suitable for adding a top plate of 1-by-12 hardwood that overlaps the sides by 1 inch on each side, leaving room to finish the piece with decorative molding.
Always wear safety glasses, hearing protection and a dust mask while cutting lumber. Wear safety glasses while pounding nails with a hammer.
Make sure you have a stud in the adjoining wall to which to nail the frames. If not, you'll have to add 2-by-4 nailers between studs to anchor the wall's frames.
