Stair & Ramp Builder

Units

Round measurements to1/16"

The readout & drawings round to the nearest fraction of an inch you pick (½ → 1/32). The 3D model and OBJ export stay exact.

Mode

Stair

Floor-to-floor height (mm)

Target riser height (mm)

Going / tread (mm)

Width (mm)

Layout

View

Export

OBJ is the 3D model in millimetres. SVG is the dimensioned plan + developed section, sized true to scale. PNG snapshots the current 3D view.

Sources & method

What the checks actually encode (hard-coded thresholds; the readout shows them in whichever units you choose). Stair mode: riser 100–180 — brackets the IBC §1011.5.2 riser band of 4–7 in (102–178 mm); going ≥ 250 (ideal 280) — a studio minimum that is less strict than US code: IBC §1011.5.2 requires treads ≥ 279 mm (11 in) in most occupancies, the residential IRC R311.7.5 ≥ 254 mm (10 in); 2R + G = 600–640 — Blondel's step-proportion rule (F. Blondel, Cours d'architecture, 1675–83; the band as tabulated in Neufert, Architects' Data, Wiley) — a comfort heuristic, not a US code clause; headroom ≥ 2000 — shown as a reminder only (the floor opening isn't modelled); IBC §1011.3 requires 2032 mm (80 in). Ramp mode encodes the 2010 ADA Standards §405: running slope ≤ 1:12 (§405.2) and ≤ 760 mm (30 in) rise per run (§405.6), with level landings inserted automatically. Two honest deviations: the tool's 1500 mm landing is slightly under the ADA minimum clear length of 1525 mm / 60 in (§405.7.3), and the 9000 mm per-run cap is simply the run a 1:12 ramp reaches at its full 760 mm rise (≈9150 mm), rounded — not a code clause. The tool defaults to imperial; the accuracy slider rounds displayed dimensions to your chosen fraction of an inch (½–1/32), while the 3D model and OBJ export stay exact.

Sources. International Building Code §1011 (stairways: risers, treads, headroom) and ICC A117.1 (accessible buildings) — International Code Council, codes.iccsafe.org. 2010 ADA Standards for Accessible Design §405 (ramps) — U.S. Department of Justice, ada.gov (technical criteria by the U.S. Access Board, access-board.gov). Blondel's rule and stair proportion history: Stairs.

Scope. Typical US model-code values for studio use — your jurisdiction's adopted code and amendments govern, and real stairs also carry width, handrail, guard, nosing, landing and egress rules this tool doesn't check. Verify any stair or ramp you intend to build with a licensed architect or engineer and your code official.