What's the steepest slope allowed for a residential ramp?
Ramps are limited to a 1:12 slope, about 8.3 percent (IRC R311.8.1).
Residential ramps may not be steeper than 1 unit vertical in 12 units horizontal — roughly an 8.3 percent slope, or one inch of rise per foot of run.
A steeper slope, up to 1:8, is permitted only where site constraints make 1:12 technically infeasible. Landings are required at the top and bottom of a ramp and where it changes direction.
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Need this scoped to your jurisdiction?
Adopted edition and local amendments vary by city and county. Ask Donnie checks your jurisdiction and cites the exact adopted section.
Ask Donnie →General information based on the International Residential Code (a model code). This is AI assistance to verify — not legal advice. Confirm the adopted edition and any local amendments with your local building department (AHJ) and a licensed professional before you build.