Running surface widths can range from 36" to 48", depending on the personal assistance or mobility equipment involved. 36" may be appropriate for someone walking or using a cane, crutches, or a walker. (32" may be appropriate for persons who need to lean on both railings when moving.) 42" to 48" is appropriate for someone using a wheelchair, or where a person can walk with assistance at the side.

Surface height changes from the doorsill and top landing to the bottom landing shouldn't vary more than 1/2". Higher bumps can abruptly stop a wheelchair, or trip people walking, particularly those with an irregular gait.

All ramp runs and landings must be level from side to side. A cross slope (slope perpendicular to the direction of travel) can upset a person's balance and require more strength and effort on the person's "downhill" side. Even the almost unnoticeable slope (1:96) built into public sidewalks to aid with water runoff can be tiring for a wheelchair user to negotiate.

It is advisable for ramps to have an "anti-slip" running surface; depending on local building code enforcement, this may be a requirement. On wooden ramps, treatments that are used include commercially-available "grit" tapes, strips of rolled roofing or shingling, or laying down coats of polyurethane into which sand is sprinkled. For concrete ramps, the surface can be brushed with a broom before it hardens to create a rough texture.

Safety Features: Installation of safety features including handrails, guardrails, "crutch stops", guttering and sheltering should also be considered for a rampbuilding project.

Handrails should account for variables including a person's height, arm and hand strength, how the rails are used, and any local building code requirements that may apply. For example, standing users who lean on rails for support with arms extended often need a very different rail height than that used by persons propelling a wheelchair by pulling along the rails. 31 " to 34" is the typical height range, and the rails should be capable of supporting a 250 lb. load at any point along the length. The diameter should be no more than 1 1/2", and may need to be smaller for children or adults with impaired grip strength. The preferred material is wood. Metal piping is sometimes used, but may present a problem for exposed skin in the wintertime.

Guardrails and edging called "crutch stops" or "bump boards" are also good safety factors that keep users from slipping off the side of a ramp or landing. Guardrails are mounted along the structure's perimeter, usually at a seated person's knee height-18" to 20" or so. "Crutch stops" are curbing mounted on, or a few inches above, the surface of the structure's perimeter.

Two additional safety features to consider are guttering and sheltering. If not present, roof gutters may be advisable for ramps running close to a home to handle water runoff that may create slipping hazards. In cases where the person's mobility is severely restricted, some form of rampway sheltering may also need to be considered. Depending on siting and home roofline, one strategy for ramps hugging a house is to build a small extension off the roof. Support for the lower edge can be provided by extending the ramp's posting vertically.