Stair stringer for a 42" rise
A 42" (3' 6") total rise needs 6 risers of 7" and 5 treads at the code-maximum riser height. With 10" treads, the stairs project 4' 2" from the deck.
Layout options for a 42" rise
| Option | Risers | Riser | Treads | Total run | Stringer | Angle |
|---|---|---|---|---|---|---|
| Code max riser, 10" run | 6 | 7" | 5 | 4' 2" | 8 ft 2x12 | 35.0° |
| Code max riser, 11" run | 6 | 7" | 5 | 4' 7" | 8 ft 2x12 | 32.5° |
| 7½" target, 11" run | 6 | 7" | 5 | 4' 7" | 8 ft 2x12 | 32.5° |
| 7" target, 11" run (gentle) | 6 | 7" | 5 | 4' 7" | 8 ft 2x12 | 32.5° |
Shorter risers and deeper treads are easier to climb but need more room in front of the deck. With 6 risers, a handrail is required (4 or more risers).
Ready to build? Follow our guide on how to cut stair stringers and check the deck stair code requirements before you start.
Customize this layout
Change the run, riser target, width or tread boards to get your own cut diagram and materials list.
Ground or landing to the top of the deck surface
Code minimum 10"
Materials list
How to lay out the stringer
Planning estimate only. Based on IRC 2021 R311.7 and AWC DCA 6; your city or county may amend them. Confirm with your local building department before cutting.
Stair building guides
- How to Cut Stair Stringers (Step by Step)Measure the rise, lay out a 2x12 with a framing square, drop the stringer and cut clean notches. A complete walkthrough for deck stairs.
- Deck Stair Code Requirements (IRC 2021)Riser height, tread depth, width, handrails, guards and landings for deck stairs under the 2021 International Residential Code, in one checklist.
- How to Calculate Stair Rise and RunThe formulas for riser height, step count, tread depth and total run, plus the comfort rules builders use and how to handle sloped ground.
- How Many Stringers Do I Need for Deck Stairs?Stringer count by stair width and spacing, why composite treads need more, and when cut stringers need extra support.