How to Build a Small Handicap Ramp in the Garage

Measure from the bottom of the door opening, called a doorjamb, down to the garage floor with a measuring tape. Record the result as the total handicap ramp rise. Multiply by the rise to run slope desired: multiply by 12 for a 1 to 12 slope, by 8 for a 1 to 8 slope -- the typical minimum for building code -- and by 6 for a 1 to 6 slope. A 1 to 6 slope is the steepest slope safely possible and is designated for temporary ramps and assisted use.

Using a 2-step rise of 15 inches, for example, a ramp might require 15 feet of ramp (1 to 12 translates into a foot for every inch), 10 feet for a 1 to 8 slope and 7 1/2 feet at 1 to 6 slope.

Determine the width of the door opening to which the ramp leads. Add at least 2 inches to the measurement to allow space for side curbs on the ramp surface. The ADA recommends a minimum of 36 inches ramp width clearance, but 48 inches provides plenty of room for the helper to maneuver.

Cut three 2-by-4 boards to the length of the ramp required. Have a helper hold one of the boards in place, against the door opening, while you measure from where the board meets the garage floor straight back to the house wall. Cut three additional 2-by-4s to this length. Use 1-by-2 boards if the ramp rise is less than 4 inches, which is the thickness of two 2-by-4s and a sheet of 1-inch plywood. To determine the length of the bottom ramp boards mathematically, apply the Pythagorean Theorem, using the rise as A squared and the length of the ramp as C squared. Thus, A squared plus B squared equals C squared.

Angle one end of each 2-by-4 board to allow the boards to join at a 45-degree angle. Hold one board in place, level with the doorjamb, extending out. Lay the other board flat, in place. Allow the bottom board to sit just in front of the top board and where the bottom board overlaps the top, draw a line straight across horizontally. Switch the boards around so the top overlaps the bottom board instead. Draw another line. Cut the boards where the lines indicate to create a ramp that transitions to the garage floor fairly smoothly. Use the cut boards to mark the other four ramp boards.

Cut a section of 2-by-4 board to the ramp rise, from garage floor to doorjamb, minus 4 inches to allow for the thickness of the top and bottom frame boards and the plywood surface. Angle one end of the 2-by-4 board to follow the angle of the ramp. Set the bottom ramp board in place. Hold the short board, which will be the first stud in the ramp frame wall, against the house wall. Extend the top board out in position. Mark the stud where the top board overlaps and cut. Use this method for every stud angle involved.

Attach the first stud to first the top board, then the bottom board, using two wood screws per end. At the opposite end of the same piece, screw the top board directly to the bottom board. The result is a triangle-shaped stud wall frame that will support the ramp. Repeat with the remaining two frames to create three total.

Create additional studs to fit between the top and bottom ramp board on either side and in the middle of the ramp. Make one stud for every 12 inches, gradually decreasing the height as the ramp grows smaller. Angle the ends and insert each stud in place. Drive screws through the top and bottom boards into the stud ends to secure.

Cut a sheet of 1-inch-thick plywood to measure the width of the ramp by the length. Allow a slight overhang at the end of the ramp to create a seamless transition to the garage floor. Secure the plywood to each frame wall, sides and center, with screws spaced every 8 to 10 inches.

Make ramp curbs to form stops on either side of the ramp. Cut and screw to attach strips of 1-by-1-inch-thick wood the length of the entire ramp. These will help prevent accidentally rolling off the ramp edge. Slide the ramp in place to use. Move when not in use, or remove the screws holding the plywood in place to store the ramp in four pieces.