Determine the height the ramp will need to be. According to the U.S. Department of Justice ADA Standards for Accessible Design, the ratio for the slope should be no steeper than 1:12. This ratio means that as each dimensional unit of height changes the length projects out 12 units.
Provide a level ramp landing. If there is not enough space for a straight slope, the ramp rise is 30 inches or more or the ramp requires a change in direction, a landing size of 60 inches by 60 inches is required. A level landing should also be at the top and bottom of the ramp.
Build the ramp at a width of 36 inches. This is the minimum clear width for wheelchair access.
Provide a minimum of 2 inches of edge protection at the floor of the ramp. The raised edge can be cement, wood or a metal rod that is installed 2 inches above the floor of the entire run of the ramp. This will prevent people from slipping off ramps that have drop-offs.
Provide continuous handrails on both sides of the ramp. Use smooth wood or metal handrails secured to the sides of the ramp. The space between the handrail and any other surface should be 1½ inches. The top of the handrail should be 34 to 36 inches above the ramp surface with rounded ends or a returned to the wall, floor or post.