ADA ramp requirements

Slope. 1:12 maximum running slope means one inch of rise for every twelve inches of run. That is a ceiling, not a target — a gentler ramp is easier to use, and if you have the space, use it. Cross slope — the side-to-side tilt — is capped at 1:48. Cross slope is the requirement homeowners most often lose, because a ramp built to shed water too aggressively will pull a wheelchair sideways.

Rise and landings. No single run may rise more than 30 inches (§405.6). Level landings are required at the top and bottom of every run (§405.7), and where a ramp changes direction the landing must be at least 60 inches clear wide by 60 inches clear long. That 60-by-60 figure is what makes switchback ramps take up so much yard, and it is the specification most commonly shaved by a cut-price builder.

Width. 36 inches clear minimum (§405.5), measured between the handrails where handrails are present. Note the measurement point — a 36-inch ramp deck with handrails mounted inboard does not give you 36 inches of clear width. This is exactly the kind of detail a power chair user discovers on day one and a salesperson discovers never.

Handrails and edge protection. Handrails are required on both sides of any ramp with a rise greater than 6 inches (§405.8). Edge protection is required along ramp runs and landings (§405.9), satisfied by a curb at least 4 inches high, a rail configured so a 4-inch sphere cannot pass, or an extended surface reaching at least 12 inches beyond the inside face of the handrail. Edge protection is what stops a caster dropping off the side — it is a safety element, not trim.

Scope, honestly. The Access Board is explicit: the ADA does not apply to individually owned or leased private-sector housing, including single-family homes, condominiums and apartments. It covers state and local government facilities, places of public accommodation, commercial facilities and transportation facilities. Residential builders follow ADA geometry because it works, not because it is legally required at your house — and your local building code may impose different or additional rules.

How to choose

Treat 1:12 as the maximum, not the design goal

A shallower ramp is meaningfully easier for a manual chair user and safer in rain and ice. Use the space if you have it.

Check cross slope with a level, not by eye

1:48 is a subtle number. A ramp that looks flat side-to-side can be well over it, and the user will feel it immediately.

Verify clear width between handrails

The 36-inch minimum in §405.5 is measured between handrails where provided. Ask the builder to state clear width, not deck width.

Count your landings before you sign

Top, bottom, and 60 by 60 inches at every direction change. If the drawing has fewer landings than the rise requires, the footprint on the drawing is wrong.

Don't accept a ramp without edge protection

§405.9 accepts a 4-inch curb, a rail blocking a 4-inch sphere, or a surface extending 12 inches beyond the handrail face. Any of those is fine. None of them is not.