StairSolver pre-check
Start with two tape-measure numbers. The calculator updates the stair drawing, layout options, baseline IRC risks, and project questions as you type.
Step 1
Use inches. Rough numbers are fine for the first pass; refine them when you have better measurements.
Your first check updates here
Treads may be too shallow
These fields do not block the first result. Add them when you want the report to check width, turns, headroom, landings, and local questions.
Live result
This layout has at least one serious fit or baseline-code red flag.
Baseline risk check, not local permit approval.System recommendation
What this drawing means
L-shaped stair fits these measurements.Confirm the landing depth and both flight runs before treating it as buildable.
Before you build, buy, or schedule
The current numbers create at least one serious fit or baseline-code risk. Get the missing dimensions or a revised layout before cutting, buying, or scheduling work.
Only if no normal stair can fit
These are checks, not recommendations. Do not pick these yourself. Use the linked code sections to ask the local authority what is allowed for this exact room.
Homeowner question
Short answer: Maybe, but spiral stairs have their own special-stair rules. Local approval can depend on the room use, egress path, diameter, tread, handrail, and headroom.
Would the authority having jurisdiction allow a spiral stair for this exact room use, and what diameter, tread, handrail, headroom, and egress limits apply?
Homeowner question
Short answer: Usually not for a normal required stair. Alternating-tread devices and ship ladders are limited-use stair types that need local approval for the exact room use.
Is an alternating-tread device or ship ladder allowed for this room use, or is a full stair required?
9.33" treads are below the common residential baseline of 10".
Can this stair get more run, a landing, or another layout so the tread depth is not too shallow?40.3 degrees is steeper than a comfortable residential target.
What layout change would reduce the stair angle without shrinking the tread?Why this report is credible
When you need a record
Calculation, risk sources, questions, and boundary statement in one file you can send to a contractor or keep before work starts.
The PDF is free and for planning reference only. It is not permit approval.
Before paying or starting work
Use this check before paying a deposit, buying materials, or scheduling work.
Paste contractor text above to create proposal-specific findings.
Use these questions before treating the plan as locally approved in Austin, TX.
StairSolver shows baseline risk, not local code approval. Confirm the final answer with the authority having jurisdiction.
Which office approves residential stair work for Austin, TX?
Which residential code edition and local stair amendments apply to this project?
Does this scope require a permit, inspection, or licensed trade sign-off before work starts?
What handrail, guardrail, baluster spacing, and finished clear-width rules will be inspected?
Where will the contractor mark the minimum headroom and landing dimensions on site?
Does this basement stair affect required egress, door swing, mechanical clearance, or ceiling-height approval?
Runs explicit baseline risk rules from measured stair facts.
Used as installed dependency: json-rules-engine.Cross-checks stringer length, cut angle, fractional inches, and cut-list structure.
Downloaded locally; LICENSE says MIT, package.json says ISC. Both are permissive, so StairSolver reimplements the math in TypeScript and keeps attribution.