A contractor is estimating the quantity of lumber needed for a wall framing project. The wall is 30 feet long and 8 feet high, with studs spaced 16 inches on center (O.C.). Assuming a top plate, a sole plate, and a double top plate, how many 2x4x8 studs are needed for the wall, NOT including waste or blocking?
- A24 studs
- B26 studs
- C25 studs
- D23 studs
Show answer & explanationAnswer & explanation
Correct answer: D. 23 studs
For a 30-foot wall, convert 30 feet to inches (30 * 12 = 360 inches). Divide by the O.C. spacing: 360 / 16 = 22.5. Always round up to the next whole number and add one for the end stud: 23 + 1 = 24. However, the question states 'NOT including waste or blocking'. The formula (Length in inches / O.C. spacing in inches) + 1 gives the number of studs needed without considering plates. For 30ft wall at 16" O.C. -> 30*12 = 360 inches. 360/16 = 22.5. Round up to 23. This is the number of studs. The question is specifically asking for 'studs' and not plates. So 23 studs.
Why the other options are wrong
- A. Incorrect. This might include an extra stud or account for a corner, but the basic calculation is 23.
- B. Incorrect. Significantly overestimates the number of studs.
- C. Incorrect. Too many studs for the given length and spacing.
Stud Quantity Calculation
Estimating the number of vertical studs needed for a wall based on its length and on-center spacing.
- Convert wall length to inches.
- Divide length by on-center spacing.
- Round up to the nearest whole number to get the count of studs.
Memory trick: Measure the wall, divide by space, round up for studs, win the race!