What people use it for
- A whole basement Six walls pasted in one line, and a single number of studs to take to the yard.
- Odd openings One door and two windows on the same wall is where a hand count goes wrong.
- Taping the plate The marks come out in feet and inches, in order, so you mark the plate and cut.
Why the count is not just length divided by spacing
Take the wall length in inches, divide by the spacing and round up. That is how many bays you get. Then add one, because a stud stands at the start of the wall and one at every mark after it, the far end included. A 12 ft wall at 16 in has nine bays and ten studs. Miss that last one and the end of the drywall has nothing behind it.
When the length does not divide evenly the last bay is simply shorter. The count keeps that stud. A hand count on a 9.5 ft wall usually drops it, and 114 in at 16 in is 7.125, which is eight bays and nine studs, not eight.
Doors and windows
An opening is not one stud. Each door or window takes a full height stud on both sides of the frame, and a shorter jack stud beside each of those to carry the header, so this count adds four for every opening to the wall that carries it. Corners are not in the number: a corner takes two or three studs, and the quick way here is to count the corner as one more opening on that wall.
Cripple studs above and below the openings, blocking and the headers themselves are lumber too, and none of them are counted. Those come off the plan, not off a wall length.
What the marks are for
The last row is the layout of the first wall in the list, in order, in feet and inches. Tape the bottom plate, work down the marks with a square, and the plate is laid out. It saves the division, and it keeps every mark measured from the same end of the wall, which is where layout errors start.
| Wall | 16 in on center | 24 in on center |
|---|---|---|
| 12 ft | 10 studs | 7 studs |
| 20 ft | 16 studs | 11 studs |
| 24 ft | 19 studs | 13 studs |