How many 2x4 needed to frame 800 square feet?

Answer 1

The answer depends on the spacing of the 2x4s and the design of the structure (i.e. roof, the number of windows, & doors, etc). In general, though, if you figure there will be one 2x4 every 16 inches on center for the walls, you can roughly solve the problem as follows:

1. You can take the square root of your 800 SF to calculate the length of the walls. This would produce a structure that is approximately 28' 3" x 28'3" square (28.28 ft^2 = sqrt (800)).

2. Since you will have 4 walls and each wall will have at least 22 studs in it (22=28.28' * 12" / 16") then you will need at least 88 studs for the walls (88 studs =22 studs * 4 walls).

3. Assuming you make a simple slanted roof with no soffit overhang and 20" rafter spacing, you would need a minimum of 34 2x4s for rafters & a center support beam. (34 = (28.28' * 12" / 20" * rafters placed on both sides of a center support beam).

4. You will need 36 (2x4x10's) for wall sole & wall caps (36 = (28' 3" / 10 * 4 walls * 3 layers (1 sole + 2 cap layers))

Therefore, you would need a minimum of 158 (2x4s) (158=88+34+36).

You would of course need more 2x4s for framing windows, doors, & any interior walls, closets, etc.