Wheelchair ramps are constructed for wheelchairs, but they are also ideal for strollers, too, and can add resale value to your home. The Americans with Disabilities Act sets strict standards for ramps, so make sure that you install yours correctly. The slope, for example, must not be more than 1 inch of rising for every 12 inches of run. Ramps, therefore, tend to belong. You’ll need to build a ramp at least 20 feet long to reach a deck 20 inches in height.
Construct the ramp with pressure treated lumber to prevent the wood from rotting. Make sure you purchase the posts that are rated for burial in the ground. Before you start building, be sure to check your local codes for requirements, you might need to apply for a building permit in your area.
Measure up from the ground to find how many inches the ramp must rise. For every inch of rise, you’ll need a foot of run. A 20 inch high deck, for example, requires a 20 foot long ramp. To accommodate turning at the top of the ramp, lay out a 5 foot square landing with batterboards and mason’s lines. Level each line and apply the 3-4-5 triangle principle to square the corner. Slide the line along the batterboard until the distance between two points 3 feet and 4 feet from the corner is 5 feet.
Layout the outside edges of the ramp with batter boards and mason’s lines. Level the lines and square them by again applying the 3-4-5 triangle principle. Remove the sod from the site and excavate 2 to 3 inches of soil. Excavate an extra few inches deeper at the bottom of the ramp so you can build as close to ground level as possible.
Lay out post locations on mason’s lines with masking tape. You need posts at the corners of the landing and every 5 feet on center along the length of the ramp. Transfer the taped marks to the ground with a plumb bob and powdered chalk. Mark the position of the mason’s lines on the batterboards and untie them. With a posthole digger, dig holes for the posts at least 6 inches below the frost line, tapering them from 12 inches at the top to 18 inches at the bottom. Retie the mason’s lines so they mark the outside faces of the posts.
Cut fiber tube forms 6 inches shorter than the depth of the holes. Nail 2×4’s to opposite sides of the forms and suspend the forms in the holes so they sit about 8 inches from the bottom. Install posts in the holes, plumb them with a level, and brace them in place.
Prepare pre-mixed concrete following the directions on the bag and fill the fiber tube forms. Work a scrap board gently up and down in the concrete to eliminate air pockets. Level and smooth the concrete with a trowel. Let the concrete set for 48 hours, then remove the forms and backfill. With a mason’s line and a pencil, outline the height of the decking boards and the joists on each post. Mark lines on the bottom post as close to the ground as possible to minimize the size of the concrete pad you’ll need to build.
Lay down landscape fabric over the excavated site to prevent grass growing up through the ramp. Cover the fabric with 2 inches of gravel. Install 2×6 crossbeams across posts where the bottom of joists will be higher than 5 ½ inches above the ground. Measure between the outside faces of the posts and cut the crossbeams to this length. Bore holes for the 3/8 x 7 inch hex-head bolts, then install the bolts with washers and tighten the nuts.
Lay out and install 2×6 joists for the landing. Cut 2×6 outer joists to fit along the sides of the ramp between posts. To mark the joists at the top of the ramp for cutting, butt them against the header joist and trace the angle onto them with a straightedge. Install double header joists between posts at the ends of the outer joists with galvanized 10d (3-inch) nails. Cut outer joists at the bottom of the ramp so they extend a few inches past the posts. Nail a single header joist to the ends of these outer joists. Reinforce the corners between the outer joists and header joists with angle brackets.
Lay out inner joists on the header joists, spacing them no more than 16 inches apart on center. Nail one side of a joist hanger in place at each end marked point. Cut the inner joists to size, fit them into the hangers, and nail the other side of the hangers closed. Nail the hangers to both sides of the joists. Decking boards run across the joists. Measure the distance between the outside edges of the outer joists and cut (5) 4×6 boards to this length.
Attach the decking boards to the joists with galvanized 8d (2 ½ inch) nails or No. 8 deck screws. Butt the boards together, since they’re pressure treated, the boards will shrink as they dry to leave about an 1/8 inch gap. Add pressure treated wood for the railing to the top of your deck to complete the finished look. You can design your own railing that will give your ramp it’s own appealing look.