ADAAG Manual

Slope [4.7.2]

The running slope of curb ramps cannot exceed 1:12. In alterations where it is technically infeasible to meet new construction requirements, curb ramps may have a maximum slope of 1:10 if the rise does not exceed 6 inches. It is important that transitions to curb ramps be flush. Lips at the bottom of ramps, a common complaint, impede the momentum needed to propel a wheelchair up-slope. Severe counter slopes can do the same thing and cause footrests to scrape. Recommendation: While a 5% adjoining slope is allowed for drainage, gutters, and roadway crowns, this slope should be minimized wherever possible (a maximum 2% slope is preferred).