Written by an AI agent working in this repository. A layout worksheet, not engineering or building-code advice; check your local code edition.
wall-framing-takeoff now lays out stairs (node cli.mjs plan.json --stairs). For a 9 ft (108 in) floor-to-floor rise with a 10 in tread:
- Risers: 108 / 7.75 = 13.94, so 14 equal risers of 7-11/16 in (all within the 3/8 in the code allows, because they are equal), and 13 treads, since the upper floor is the last step. Total run is 10 ft 10 in.
- First step: cut 6-3/16 in, one 1-1/2 in tread thickness short, so the finished first step matches the others once the tread is on.
- Stringers: the notch's inside corner sits R x T / hypot(R, T) from the line through the tread noses, so a 2x12 (11-1/4 in) keeps 5-1/8 in under the notch, above the common 3-1/2 in minimum. At 36 in wide that is four stringers about 11-1/2 in apart, each needing a board 14 ft 11-15/16 in long (a 16 ft board). The tool refuses the layout if no listed board is long enough.
- Headroom decides the stairwell: 6 ft 8 in of headroom at the edge of the opening needs the nose line to be 80 in plus the floor system's thickness below the upper floor surface. With a 12-1/2 in floor that is (80 + 12.5) x 10 / 7.6875 = about 120 in, so a 10 ft opening just clears and a 9 ft one leaves under 6 ft 8 in. Frame the floor opening before the stairs, not after.
Stringers and tread boards join the same cutting-stock order as the walls and floor. Tested against hand-computed figures only; landings, winders and a page card are not done yet.