Depending on what is available and fits in your budget, design a wheelchair ramp out of concrete, aluminum or pressure-treated wood. Wooden uprights should be buried securely in the ground for stability, and the entire structure should be attached to the building to prevent the formation of gaps. Add sand-girt strips or other non-skid surfacing for better traction. Include adequate lighting on the top and bottom landings as well as down the length of the ramp.
The maximum slope for a wheelchair ramp is 1 inch rise to 1 foot of run. In other words, the top of a 12-foot straight ramp should not be more than 12 inches from the bottom of the ramp. For some wheelchair users, even this slope is not gentle enough to allow them to navigate up the ramp by themselves. A slope of 1:16 or even 1:20 is often used in these cases, depending upon the needs of the disabled person. Figure out the needed slope from where the ramp starts and where it will end, because sometimes the ground drops away farther out from the building exit.
If the building is quite high off the ground, a wheelchair ramp will need to be pretty long. For example, some manufactured homes are built 3 feet off the ground, which would necessitate at least a 36-foot ramp. This is usually not feasible due to space limitations, but you can bend, loop or zigzag a ramp to fit. At each turn, however, you should insert a landing—a level area large enough (usually 5 feet square) for the wheelchair user to easily turn around in. Landings should always be built at the top of a ramp and securely attached to the structure.
Design your ramp with handrails on both sides. These smooth-surfaced rails of aluminum or wood should be 34 to 38 inches from the floor and 1 1/2 inches away from walls. The ends of these handrails should be rounded or folded under if metal and planed and sanded if wood.