Changes in Level and Floor Surfaces (2010 ADA Standards 302, 303)

Up to 1/4 in a change may be VERTICAL -- a square edge, no transition. From 1/4 to 1/2 in it must be BEVELED at 1:2 or flatter, meaning the run has to be at least twice the rise, so a strip cut at 1:1 looks beveled and is not. Over 1/2 in it becomes a RAMP under 405: a 5/8 in change needs 7.5 in of run at 1:12 against the 1 in a bevel would have taken, plus landings, edge protection, and handrails. One sixteenth of an inch is the difference, which is why grinding the change down to 1/2 in almost always beats ramping it.

change in level <= 1/4 in may be vertical; > 1/4 in and <= 1/2 in must be beveled at a slope no steeper than 1:2, so the required run = 2 x the rise; > 1/2 in must be ramped under 405 or 406, so the run = rise x the ramp run per rise (12 for 1:12). Carpet pile <= 1/2 in. Openings must not pass a sphere over 1/2 in, and elongated openings run perpendicular to the dominant direction of travel.

2010 ADA Standards for Accessible Design, 302.2, 302.3, 303.2, 303.3, and 303.4. A US federal standard in the public domain, quoted directly.

The 2010 ADA Standards are published in full at no cost at ada.gov and by the US Access Board.

Estimate. AHJ and licensed professional govern.

Field names used by the API: level_change_in, bevel_run_in, opening_elongated, opening_perpendicular, ramp_run_per_rise, required_bevel_run_in, bevel_run_deficit_in, bevel_slope_run_per_rise, vertical_allowance_in

• Vertical 1/4 in high maximum2010 ADA Standards 303.2
• Beveled over 1/4 in to 1/2 in, at a slope no steeper than 1:22010 ADA Standards 303.3
• Ramped greater than 1/2 in, complying with 405 or 4062010 ADA Standards 303.4
• Carpet pile height 1/2 in maximum2010 ADA Standards 302.2
• Openings no sphere over 1/2 in; elongated openings perpendicular to the direction of travel2010 ADA Standards 302.3
• Ramp slope editable; 1:12 is the 405.2 maximum for new construction2010 ADA Standards 405.2