The short answer
Plan a home wheelchair ramp at 1 inch of rise for every 12 inches of length (a 24 inch rise needs about 24 feet of ramp), at least 36 inches of clear width, a level landing about 5 feet by 5 feet at the top, the bottom and any turn, no more than 30 inches of rise between landings, and handrails on both sides when the rise is more than 6 inches. Those numbers come from the ADA standards for public ramps, which are the usual guide for homes too.
Measure the rise first
Measure from the ground to the top of the threshold you need to reach. That number drives everything else.
Slope: 1 inch per foot
The ADA standard is a slope no steeper than 1:12, meaning 1 inch of rise for every 12 inches of ramp. A 24 inch rise needs 24 feet of ramp, not counting landings. Steeper ramps are hard to push up and dangerous coming down.
Landings and turns
Put a level landing at the top and bottom, and wherever the ramp turns. ADA landings are at least 60 inches long, and no single run should climb more than 30 inches before a landing. A landing at the door gives room to open it from a wheelchair.
Width and railings
Leave at least 36 inches of clear width between the railings. When the rise is more than 6 inches, put handrails on both sides, plus edge protection so wheels cannot roll off.
Materials
Pressure treated wood costs least up front but needs sealing and gets slippery and soft over time. Composite decking costs more but needs little upkeep and holds up to Michigan winters. Aluminum ramps are quick to install and can be moved later.
Where it fits
A long straight run, a switchback with a landing, or an L shape around a corner all work. The yard, the driveway and where the person gets out of the car usually decide it.
Permits
Many Michigan townships require a permit for a ramp, especially one attached to the house. Check with your local building department before building.
When to call a pro
A ramp people rely on every day should be built solid. Quality Finish plans and builds wheelchair ramps across Southwest Michigan. Call or text 269.998.0410 for a free estimate.
Wheelchair ramps and accessibility in Southwest MichiganCommon questions
How long should a wheelchair ramp be for 3 steps?+
Three typical steps are about 21 inches of rise, which needs roughly 21 feet of ramp at a 1:12 slope, plus landings.
How wide should a wheelchair ramp be?+
At least 36 inches of clear width between the railings.
Do I need a permit for a wheelchair ramp in Michigan?+
Often yes, especially for a ramp attached to the house. Ask your township or city building department.