• There are many factors to consider in the building of wheelchair ramps.handicap image by Byron Moore from Fotolia.com
  
  The Americans with Disabilities Act (ADA) provides for equal access to buildings and facilities for individuals with disabilities. Under the ADA, all public buildings and facilities must be wheelchair-accessible. For both public and residential access, the ADA stipulates that wheelchair ramps must be built to particular specifications.
  
  

Parts of a Wheelchair Ramp

• The parts of a wheelchair ramp covered by ADA specifications include the run (the long, sloped section), the landing (flat portion either at the top of the ramp or elsewhere along the ramp, if it changes direction), the handrails, the slope (the incline) and the rise (height of the incline).
  
  

Specifications for the Slope and Rise

• Slope and length both impact the ease with which a wheelchair user can negotiate a ramp. The goal is to produce a ramp with the least possible slope, for greatest ease of use. Any surface with a slope greater than 1:20 (1 inch of rise for every 20 inches of run) is considered a ramp. Ramp slopes should preferably be from 1:16 to 1:20. The maximum slope of any new ramp is 1:12, and the maximum rise for any run is 30 inches.
  
  

Specifications for Width

• The ADA does not place a maximum on ramp width, but states that the clear (unimpeded) width of the ramp must be at least 60 inches.
  
  

Specifications for Landings

• Landings on ramps must also be built to certain specifications.escaliers image by pucci raf from Fotolia.com
  
  According to Mobility-Advisor.com, each ramp and ramp run must have level landings at the top and bottom. A landing must be at least as wide as the ramp run to which it is connected. There is no maximum length, but each landing must be at least 60 inches. If the direction of the ramp changes at the landing, the landing must be at least 60 inches x 60 inches. If the landing adjoins a doorway, the latch side of the door must have at least 44 inches of clearance.
  
  

Specifications for Handrails

• Most handrails are built to adult specifications, and lower handrails for children are built as needed (for example, in elementary schools). ADA specifications require that a space of 9 inches minimum must exist below upper and lower handrails to avoid accidental entrapment. If the run of a ramp projects horizontally more than 72 inches or has a rise of greater than 6 inches, both sides of ramp segments must have handrails. There must be a continuous surface to grip. The space between a handrail and a wall must range from 1 to 1 1/2 inches. Handrails must either return smoothly to a post, wall or floor, or be rounded at the ends. Handrails must not be loose.
  
  

Cross Slope and Surfaces

• Mobility-Advisor.com states that the cross slope (or tilt) of a ramp must be a maximum of 1:50. The surface of the ramp must meet the same standards set for floors and ground surfaces by the ADA.
  
  

Specifications for Edge Protection

• The ADA requires that ramps or landings that drop off must have a projecting surface, railing, wall or curb to prevent users from slipping from the ramp. Curbs must be at least 2 inches high.
  
  

Specifications for Outdoor Conditions

• The ADA also addresses outdoor ramp safety conditions.man in wheelchair image by jimcox40 from Fotolia.com
  
  Mobility-Advisor.com also states that ramp approaches and ramps that are outdoors must be constructed in such a way that water cannot accumulate on their surfaces.