Residential Building Inspector B1Public Safety and Special ConstructionHard
An inspector is evaluating a ramp that provides an accessible route to a dwelling. The ramp has a rise of 24 inches (610 mm). What is the minimum required length of the ramp to meet the maximum allowable slope?
- A20 feet (6.10 m)
- B16 feet (4.88 m)
- C30 feet (9.14 m)
- D24 feet (7.32 m)
Show answer & explanationAnswer & explanation
Correct answer: D. 24 feet (7.32 m)
The maximum allowable slope for an accessible ramp is 1:12, meaning for every 1 inch of rise, there must be 12 inches of run. With a rise of 24 inches, the minimum length is 24 inches * 12 = 288 inches, which converts to 24 feet (288 / 12 = 24).
Why the other options are wrong
- A. This length would result in a steeper slope than 1:12 (24/20 = 1:10).
- B. This length would result in a steeper slope than 1:12 (24/16 = 1:8).
- C. This length would result in a gentler slope than required, but is not the minimum.
Accessible Ramp Length (1:12 Slope)
The minimum horizontal length (run) required for an accessible ramp based on its total vertical rise and the maximum 1:12 slope.
- Maximum slope is 1:12 (1 inch rise per 12 inches run)
- Length = Rise * 12
- Ensures accessibility for wheelchairs and mobility devices
Memory trick: One-twelve is the rule, multiply rise by twelve, that's the cool tool.