CSLB General Building (B)Planning and EstimatingHard
A general contractor is estimating the quantity of 2x4 lumber needed for the top and bottom plates of a 40-foot long wall. The wall will have a single top plate and a single bottom plate. The lumber is sold in 16-foot lengths. How many 16-foot 2x4s are needed, assuming no waste is generated from cutting?
- A4
- B6
- C3
- D5
Show answer & explanationAnswer & explanation
Correct answer: D. 5
The total length of plates needed is 40 feet (bottom) + 40 feet (top) = 80 feet. Since lumber comes in 16-foot lengths, you divide the total length by the length of each board: 80 feet / 16 feet/board = 5 boards. This assumes perfect cuts with no waste, which is specified in the question.
Why the other options are wrong
- A. Incorrect. This would only cover 64 feet of plates.
- B. Incorrect. This would provide 96 feet of plates, more than needed.
- C. Incorrect. This would only cover 48 feet of plates.
Lumber Plate Quantity
Estimating lumber for wall plates involves calculating the total linear feet required and dividing by the standard length of available lumber.
- Top and bottom plates run the full length of a wall.
- Multiply wall length by number of plates (e.g., 2 for single top/bottom).
- Divide total linear feet by board length, rounding up if necessary for partial boards.
Memory trick: Plates are Long, so Sum and Slice.