ADA Ramp Slope, Runs, and Landings (IBC 1012 / ADA)
The full layout of an accessible ramp, not just the slope.
Example
You enter
- Total vertical rise (in) 24
- Slope ratio run:rise (12 = 1:12 max) 12
- Landing length between runs (in) 60
You get
- Run (in) 288
- Slope (%) 8.33
Details, formula, and sources
run = rise x the slope ratio (max 1:12 / 8.33%), the number of runs = ceil(rise / 30 in) because a single run may rise only 30 in before a >=60 in landing, the landings that adds, and the total ramp length; handrails are required where the rise exceeds 6 in. A 24 in rise at 1:12 is one 24 ft run with handrails; a 40 in rise needs 2 runs and a 60 in landing for 45 ft of total ramp. A layout aid; the adopted code and ADA/ANSI A117.1 govern slope, width, and handrail details.
run = rise x slope_ratio; slope_pct = 100 / slope_ratio; runs = ceil(rise / 30); landings = (runs - 1) x landing_len; total = run + landings; handrails if rise > 6 in.
IBC §1012 (ramps) and the ADA Standards for Accessible Design (2010) §405 / ICC A117.1, by name.
IBC is viewable through the ICC public-access reader; ADA Standards are free at ada.gov.
Estimate. AHJ and licensed structural engineer govern.
Field names used by the API: rise_in, slope_ratio, landing_in, run_in, slope_pct
- Max slope / run 1:12 (8.33%) running slope; run = rise x slope ratioADA §405.2 / IBC §1012
- 30 in rise per run a level >=60 in landing after each 30 in of rise; runs = ceil(rise / 30)ADA §405.6-405.7
- Handrails required both sides where rise > 6 inADA §405.8 / IBC §1012.8