Building Codes and Barrier-Free Design 275
as those whose mobility is otherwise restricted. In general, designers should use the least possible
slope, but in no case should a ramp have a slope greater than 1:12 (1 inch in rise for every 12 inches in
run). The maximum rise for any ramp is typically limited to 30 inches (762 mm), after which a level land-
ing is required. A slope of up to 1:8 is permitted if the maximum rise does not exceed 3 inches (76 mm).
In all cases a nonskid surface should be in place to enable traction in inclement weather.
A ramp’s clear width must not be less than 36 inches, with landings that are at least as wide as the
widest segment of the ramp leading to them. Landing lengths must not be less than 60 inches (1525
mm), and, if ramps change direction at a landing, the landing must be at least 60 inches square.
Handrails on both sides of ramps are to be incorporated if the ramps have a rise greater than 6
inches (152 mm) or a length exceeding 72 inches (1825 mm). The top of the handrail should be from 34
(864 mm) to 38 inches ((965 mm) above the ramp surface. Handrails must extend at least 12 inches (305
mm) beyond the top and bottom of the ramp segment and have a diameter or width of gripping surface
from 1 1/2 (32 mm) to 1 1/2 inches (38 mm) for both ramps and stairs. Notice that the new ADAAG
handrail guidelines are more flexible than the current guidelines (Figure 11.11).
Figure 11.10 A. A typical accessible bathroom in a senior living complex in Maryland. B. A prefabricated
shower unit with strong grab bars (source: Charles A. Riley II).