Residential Building Inspector B1Public Safety and Special ConstructionHard
A ramp is being constructed as an accessible route to a dwelling. What is the maximum allowable slope for this ramp?
- A1 unit vertical in 12 units horizontal
- B1 unit vertical in 10 units horizontal
- C1 unit vertical in 16 units horizontal
- D1 unit vertical in 8 units horizontal
Show answer & explanationAnswer & explanation
Correct answer: A. 1 unit vertical in 12 units horizontal
IRC R311.8.1 specifies that ramps shall have a maximum slope of 1 unit vertical in 12 units horizontal (8.3-percent slope). This ensures accessibility for individuals using wheelchairs or other mobility aids.
Why the other options are wrong
- B. This slope is also too steep for an accessible ramp.
- C. While a gentler slope and acceptable, this is not the maximum allowed by code.
- D. This slope is too steep for an accessible ramp and would not meet code.
Accessible Ramp Slope
The slope of an accessible ramp is critical for usability and safety, with codes setting a maximum ratio of vertical rise to horizontal run.
- Applies to ramps serving as accessible routes.
- Expressed as vertical rise per horizontal run.
- Maximum 1:12 slope.
Memory trick: Ramps for all, one in twelve, to prevent a fall.