How to Pour a Concrete Patio: A Step-by-Step Guide for First-Timers
Plan, form, pour, finish and cure a concrete patio. Real material numbers for a 12×12 slab, joint spacing, curing time and the mistakes that cause cracks.
Key points
- Maximum riser height: 7¾ in. Minimum tread depth: 10 in.
- Risers and treads may vary by no more than ⅜ in within one flight.
- Minimum headroom: 6 ft 8 in. Minimum width: 36 in.
- Four or more risers need a handrail on at least one side.
The numbers that matter
Most US jurisdictions build on the International Residential Code (IRC). Section R311.7 sets the core stair dimensions. Your local version may differ, so always confirm with your building department.
| Rule | IRC requirement |
|---|---|
| Riser height | 7¾ in maximum |
| Tread depth | 10 in minimum |
| Variation within a flight | ⅜ in maximum (risers and treads) |
| Headroom | 6 ft 8 in minimum |
| Clear width | 36 in minimum |
| Handrail | Required on at least one side for 4 or more risers |
How to lay out a stair, step by step
- Measure total rise from finished floor below to finished floor above. Use finished heights — adding flooring later changes the top or bottom step.
- Divide by 7¾ and round up to get the number of risers.
- Divide the rise by that number to get equal riser heights.
- Treads = risers − 1, because the upper floor acts as the last step.
- Total run = treads × tread depth. Check you have that much floor space, plus a landing at the bottom.
Example: a 108 in rise ÷ 7.75 = 13.9, so 14 risers of 7.71 in. That gives 13 treads; at 10½ in each, the total run is 136½ in (about 11 ft 4 in), and the stringer is about 14½ ft long.
Stair CalculatorLay out a straight stair: risers, treads, total run and stringer length, checked against common US code limits.
Open calculator →Code-legal is not always comfortable
A stair at the limits — 7¾ in risers and 10 in treads — is steep. Many builders aim for something closer to a 7 in rise and an 11 in tread. A traditional check is that two risers plus one tread should land around 24–25 inches.
The ⅜ inch rule catches people out
Your brain sets its stride from the first few steps. A step that is noticeably taller or shorter is a trip hazard, which is why the code limits variation to ⅜ in within a flight. The usual culprit is the top or bottom step after flooring is added — plan for finished thickness from the start.
Deck and concrete steps
Exterior stairs follow the same dimensional rules. For poured steps, our concrete steps calculator estimates the concrete, including the landing; for deck stairs, the stringer length from the stair calculator tells you what lumber to buy.
Concrete Steps CalculatorEstimate concrete for solid poured steps and a top landing, like a front stoop or garage entry.
Open calculator →This guide summarizes common IRC requirements. Your local code, as adopted and amended by your jurisdiction, is the rule you will be inspected against.
Other rules you will meet
Beyond risers and treads, the IRC includes several details that inspectors check. Confirm the exact wording in the edition your area has adopted:
- Nosing: stairs with solid risers generally need a nosing projection of about ¾ to 1¼ inches, unless treads are at least 11 inches deep.
- Open risers: on stairs with a total rise over 30 inches, the openings between treads must not let a 4 in sphere pass through.
- Handrail height: typically 34 to 38 inches, measured vertically from the line of the tread nosings, and graspable along its length.
- Guards: open sides of stairs and landings more than 30 inches above the floor or grade below need guards.
- Landings: a landing is needed at the top and bottom of each stair, at least as wide as the stair and generally at least 36 inches deep in the direction of travel.
Worked example: deck stairs
Say your deck surface sits 40 inches above a concrete landing pad. 40 ÷ 7.75 = 5.16, so you need 6 risers of 6.67 inches and 5 treads. With 11 in treads, the total run is 55 inches. That 55 inches of horizontal space, plus a 36 in landing at the bottom, is the footprint you need to plan for before you build.
Stair CalculatorLay out a straight stair: risers, treads, total run and stringer length, checked against common US code limits.
Open calculator →Cutting stringers without surprises
- Drop the bottom riser. The bottom step of a stringer is usually cut shorter by the thickness of one tread, so that every step ends up the same height once treads are installed.
- Use a framing square with stair gauges set to your riser and tread dimensions so every step is identical.
- Cut one, test it, then copy it. Use the first stringer as a template for the others.
- Space stringers according to the tread material — composite treads typically need closer support than thick lumber.
Before inspection
Measure every riser and tread with a tape and write them down. If the tallest and shortest differ by more than ⅜ inch, fix it now. Check the handrail height at several points and confirm the headroom along the full length of the stair, not just at the top.
Frequently asked questions
What is the maximum step height for stairs?
Under the IRC, 7¾ inches per riser for residential stairs. Commercial stairs under the IBC are stricter, typically 7 inches.
What is the minimum tread depth?
10 inches under the IRC, measured from the front edge of one tread to the front edge of the next.
Do outdoor deck stairs follow the same rules?
Yes. Deck stairs are stairs, and the same riser, tread, handrail and guard rules apply.
How many steps do I need for a 9-foot ceiling?
It depends on the finished floor-to-floor height, including the floor framing. For a 108 inch rise you need 14 risers of about 7.71 inches and 13 treads.