Wheelchair ramps are becoming more common every day. Many are being built by do-it-yourselfers. A ramp is a fairly straightforward piece of work, but before you design your plan, review the rules on slope.
Slope is represented by a ratio expressed as the number 1, a colon, and a second number, e.g., 1:20. This means there is one inch of elevation in the ramp for every 20 inches of length.
The preferred range of wheelchair slopes is 1:16 to 1:20. Wheelchair users are not only meeting resistance from the slope, but sustained resistance from the length for those who lack stamina. Longer ramps should tend to lower slopes.
The absolute maximum slope for the ramp is 1:12. This slope can only be used for runs of 30 inches or less. In every case, the rule is to make the slope as low as possible consistent with the design.