How many steps for a 36 inch (3 ft) rise?
A total rise of 36 inches (3 ft) works out to 5 risers of 7.20 inches each, with 4 treads if the top riser lands on the floor or deck. At 10-1/2 in per tread the stairs run 42.0 inches (3.5 ft) horizontally, the stringer cut line is 55.3 inches, and you need 3 stringers cut from 6 ft 2 × 12s for a 36 in wide stair. The stair sits at 40.6 degrees.
Stair options for a 36 inch rise
| Target riser | Risers | Actual riser | Treads | Total run | Stringer board |
|---|---|---|---|---|---|
| 7 in | 5 | 7.20 in | 4 | 42.0 in (3.5 ft) | 6 ft 2×12 |
| 7.25 in | 5 | 7.20 in | 4 | 42.0 in (3.5 ft) | 6 ft 2×12 |
| 7.5 in | 5 | 7.20 in | 4 | 42.0 in (3.5 ft) | 6 ft 2×12 |
| 7.75 in | 5 | 7.20 in | 4 | 42.0 in (3.5 ft) | 6 ft 2×12 |
With 10-1/2 in treads and the top riser landing on the upper floor. Every option here is within the residential code limit of 7-3/4 in per riser.
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Lumber for a 36 inch rise, 36 inches wide
- Stringers: 3 pressure-treated 2 × 12 × 6 ft. Cut one, test fit it, and trace the rest from it.
- Treads: 4 treads. For a deck, two 5/4 × 6 boards per tread (8 pieces at 36 in, or 2 boards of 12 ft); for interior stairs, 4 pre-cut 11-1/2 in oak or pine treads.
- Risers: 5 riser boards at 36 in if the stair is closed, cut from 1 × 8 (2 boards of 8 ft).
- Hardware: stringer hangers or a ledger at the top, a 2 × 4 cleat anchored to concrete at the bottom, and 3 in structural screws. Deck stairs also need a landing pad: see the concrete calculator.
- Handrail: required with four or more risers, so yes for this stair: about 6 ft of rail with posts every 4 to 6 ft.
Checking a 36 inch stair against code
The 7.20 inch riser is under the 7-3/4 in maximum, the 10-1/2 in tread meets the 10 in minimum, and twice the riser plus the tread comes to 24.9, inside the 24 to 25 comfort range. If you have room, 11 in treads make the stair noticeably easier to climb: the run grows to 3.7 ft and the stringer board becomes 6 ft. Measure the total rise at the actual stair location, from finished floor to finished floor, and subtract one tread thickness from the bottom of the stringer so the first and last steps come out the same height. Headroom must be at least 6 ft 8 in measured plumb from the tread nosings.
Common questions
How many steps do I need for a 36 inch rise?
5 risers of 7.20 inches each, giving 4 treads when the top riser lands on the floor. With 7-3/4 inch risers at the code maximum it is 5 risers.
How long should the stringers be for a 3 ft rise?
The cut line is 55.3 inches with 10-1/2 in treads, so buy 6 ft 2 × 12s. With 11 in treads the board is 6 ft. Three stringers for a 36 in stair, four for 48 in.
How much floor space does a 3 ft rise staircase take?
About 3.5 ft of horizontal run with 10-1/2 in treads, or 3.7 ft with 11 in treads, plus a landing of at least 36 in at the bottom.