a slope of no more than 1:12 building code guidelines specifies strict slope requirements ramp specifications from the ADA United States Access Board https://www.access-board.gov/ramps and curb ramps section on the ADA’s ramp requirements The ADA has very concise guidelines Chapter 4: Ramps and Curb Ramps United States Access Board Chapter 4: Ramps and Curb Ramps a slope of no more than 1:12 American Disability Association guidelines very specific guidelines