ADA ramp rules: plan the landings before the slope

Reserve landing space before you choose a ramp slope. A slope calculation alone does not tell you whether an entrance fits.

A usable route needs space to approach, stop, turn, and open the door. Those spaces can control the layout before the inclined surface does. Draw them on the site plan before ordering a ramp.

Decide which requirements govern the site

This guide covers ordinary accessible-route ramps under the 2010 ADA Standards. It does not provide legal advice or certify compliance. The Department of Justice publishes the 2010 Standards, including their scope and exceptions.

Do not assume that every residential project falls under the ADA. Strictly private homes generally fall outside its coverage. Public housing and public accommodations within residential buildings can fall within its coverage. Other housing laws can apply independently.

The Access Board's guide to using the Standards explains these housing distinctions. It also explains that applicable state and local codes remain relevant. Ask the local building authority which requirements govern your project.

Curb ramps follow Section 406 and need a separate review. Walking surfaces at 1:20 or flatter follow Section 403 instead of the ordinary ramp provisions. Neither distinction removes the need to check the complete accessible route.

Keep each dimension attached to its rule

Running slope measures rise against horizontal run. Do not measure run along the inclined surface. Cross slope measures the sideways tilt across the route. A ramp can pass the running-slope limit and fail the cross-slope limit.

Section 405 contains these requirements. It requires landings at the top and bottom of each run. Section 405.7.5 permits door maneuvering clearances required by Sections 404.2.4 and 404.3.2 to overlap the landing.

The maximum slope is a limit, not a preferred design target. A shallower slope can improve usability, but it needs more horizontal space. The Access Board's ramp guide recommends the least practical slope and explains construction tolerances.

A calculated plan for a raised entrance

Consider an entrance with a 42-inch rise. Select inches, a 1:12 slope, a straight layout, and 36 inches of clear width. Enter these values in the wheelchair ramp slope calculator.

The calculator returns 42 ft 0 in (12.8 m) of horizontal ramp run. It divides the rise into 2 runs. Each run rises 21 in (53.3 cm) over 252 in (640.1 cm) horizontally.

The plan includes 3 landings. Its clear planning footprint measures 684 in (1737.4 cm) long × 36 in (91.4 cm) wide. The calculated grade is 8.33%; the angle is 4.76 degrees.

The footprint includes landing lengths; the headline ramp length does not. Neither value specifies structural member sizes or a finished outside dimension. Posts, rail thickness, foundations, and door access need their own space.

This example uses the calculator's equal-rise split. You do not need equal rises for every real design. Each proposed run still needs its own rise, slope, landing, and handrail review.

If the straight plan conflicts with a wall, compare a turning layout. Check the turning landing and the full site width before accepting it. The calculator's switchback model assumes no gap between lanes. Real rails and structure increase the required outside width.

Handrails and edge protection solve different problems

Section 405.8 requires handrails when a ramp run rises more than 6 inches. Section 505.2 places required handrails on both sides. Section 505.4 sets their gripping-surface height at 34 to 38 inches.

Keep the grip continuous through each run. Section 505.10.1 normally requires horizontal extensions of at least 12 inches beyond the run ends. Read the stated exceptions for continuous inside turns and particular alterations. The Section 505 handrail provisions also cover grip shape, clearance, and surface condition.

A handrail helps someone maintain balance or pull along the ramp. Edge protection prevents wheels or mobility-aid tips from leaving its side. Do not assume that a handrail supplies edge protection automatically.

Section 405.9 provides two edge-protection methods. Extend the surface at least 12 inches beyond the handrail's inside face. Alternatively, provide a curb or barrier that blocks the specified 4-inch sphere near the surface. Check the exact sphere test in Section 405.9.2.

Section 405.9 lists limited exceptions, including certain adjoining landing edges. Do not apply those exceptions to every exposed edge. Show the selected protection method on the drawing before measuring the final clear width.

Common mistakes before construction

• Using an alteration slope to rescue a new design. Section 405.2 permits steeper slopes only under specified existing-site space limitations.
• Ignoring the alteration rise caps. Table 405.2 limits the 1:10 category to 6 inches and the 1:8 category to 3 inches.
• Calling a landing clear while a post or door blocks it. Draw those obstructions before checking maneuvering space.
• Measuring deck width instead of clear width. Handrails can reduce the space available for passage.
• Treating the calculator's dimension checks as an inspection. It cannot measure cross slope, grip clearance, surface condition, or drainage.

Section 405.4 requires compliant surfaces, while Section 405.10 addresses water accumulation on exposed landings. Review those conditions with the actual materials and drainage plan. Keep the measured site dimensions beside the calculated segment plan so the designer can compare them directly.