ADA Checklist for Existing Facilities

Accessible Slopes

You can measure slope with a 24 inch level and a tape measure. Put the level on the surface in the direction you are measuring.  Put one end at the high point of the surface and raise the other end so that the bubble is in the middle of the level’s gauge. The level is now level. Measure the distance between the end of the level at its bottom point and the surface. 

For a ramp the maximum running slope allowed is 1:12. That means for every inch of height change there should be at least 12 inches of ramp run. If the distance between the bottom of the level and the ramp surface is 2 inches or less, then the slope is 1:12 or less (2:24 = 1:12 and 1.5:24 = 1:16 which is a more gradual slope than 1:12). If the distance is greater than 2 inches, the ramp is too steep. For example, if the distance is 3 inches, then the slope is 1:8 (3:24 = 1:8 which is a steeper slope than 1:12). 

For the parts of an accessible route that aren’t a ramp, the maximum running slope allowed is 1:20. That means for every inch of height change there must be at least 20 inches of route run. The distance from the bottom edge of the level to the surface should be no more than 1.2 inches (1.2:24 = 1:20).

For the cross slope of an accessible route the maximum slope allowed is 1:48. The distance from the bottom edge of the level to the surface should be no more than ½ inch (.5:24 = 1:48). The cross slope of an accessible route is the slope that is perpendicular to the direction of pedestrian travel.

Slopes may also be measured using a digital level. Be sure to read the instructions. Measure with the percent calculation rather than the degrees calculation. For a ramp the maximum running slope allowed is 8.33% (8.33% is a 1:12 slope). For an accessible route without a ramp the maximum running slope allowed is 5% (1:20). For the cross slope of an accessible route the maximum slope allowed is 2.083% (1:48).