The first thing that needs to be understood about wheelchair ramps is that there are federal building code requirements that govern how much incline the ramp is allowed to have. In a majority of cases, this requirement will preclude converting steps directly into a wheelchair ramp. One the other hand, the existing steps can be incorporated in the ramp design, saving an impressive amount of money and materials. To do this, extend the form walls at least 2 inches beyond the edge of the existing steps, and build out the forms without modifying the steps at all.
Americans With Disabilities Act
The Americans With Disabilities Act was created to help people with physical disabilities gain access to homes and businesses. One aspect of that legislation was to set a standard incline for wheelchair ramps of 1 inch of fall for every 12 inches of length. As a quick example, if the top of the landing will be 12 inches above the sidewalk or driveway, then the ramp must be at least 12 feet long. It is okay to use a longer ramp, but 1 foot for every inch is the minimum allowed by law.
Type 1: Straight Ramps
One of the easiest types of wheelchair ramp is a straight ramp that extends either directly out from the landing or runs parallel to the dwelling in a straight line. Straight ramps are the simplest to lay out but are often avoided because they utilize a tremendous amount of yard space.
Type 2: Switchback Ramps
Switchback wheelchair ramps use two or more short ramps, each one doubling back parallel to the previous. This zigzag pattern uses the least amount of space but is the most complicated of the three to lay out.
Type 3: L-Shaped Ramps
When possible, L-shaped ramps are the easiest to lay out, and take up little, if any, additional room to what would already be required for a sidewalk. Typically, an L-Shaped ramp extends along the side of the dwelling, turns a corner, and continues down to the drive or sidewalk.
Forming the Ramp
When building the forms for the ramp, place form stakes no more than every 3 feet. Some experts will say that every 4 feet is sufficient. This is true for the last 8 inches or so of fall, but the deeper the form becomes, the more frequently stakes should be placed. If the ramp will be more than 18 inches at it's the highest level, the stakes should be placed even closer, at around 2 feet apart.
Notes on Pouring Concrete Ramps
Just as the AWDA mandates how much slope the ramp can and must have it also has regulations regarding pouring concrete for the ramp. By law, the place where the concrete ramp merges with the driveway or sidewalk must have an approved anti-slip texture and must finish level with the existing surface. The texture must extend a minimum of 4 feet up the ramp, and the remainder of the ramp should be finished to a swept finish. Wheelchair ramps should never have a smooth or gloss finish.