Dimensional Tolerances in Construction and for Surface Accessibility

1.1.5 A maximum design cross slope for accessible exterior pedestrian paving and ramps of 1.5% (1:67 or about 3/16 in. per ft. [15 mm per m]) is recommended. This allows for a potential plus tolerance of +0.5% while still providing for drainage. ADA/ABAAG states a maximum cross slope requirement of 1:48 (1/4 in./ft. [20 mm/m] or about 2%). Pervious concrete may also be considered for surfaces that are designed to be nearly level.