GuidelineRecommended
Exterior ramps: maximum slope 1:12, minimum 36 inch clear width
HUD FHA Design Manual Chapter Two §2.7Description
Ramps on accessible routes must have a maximum slope of 1:12 (8.33%). Less-steep ramps (1:16 or 1:20) are preferred where space allows. Ramp clear width minimum 36 inches between handrails. Landings required every 30 feet of ramp run.
Why this exists
ANSI A117.1 ramp dimensions; same standard adopted by ADA for accessible routes. Single-family designs with grade changes should use these dimensions wherever possible.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
maxSlope | max | 8.33 | % | Maximum ramp slope |
clearWidth | min | 36 | in | Ramp clear width |
maxRun | max | 30 | ft | Maximum run between landings |
Categories
AccessibilityCirculationSite
Applies to
- When:
- aspires to visitability / universal design
Source
HUD (US Department of Housing and Urban Development)no manifest entry
Fair Housing Act Design Manual (1998 revised)
Section: Chapter Two §2.7
Published 1998-08-01 · last verified 2026-05-10
Solver enforcement
Browsable only — the solver does not currently enforce this directive (no spec-level data to check against). This entry exists so the architect personas can cite it in conversation and the user can read what the rule says.
Related directives
- Universal-design wider doorways · HUD UD §3.2
- Universal design features encouraged for residential accessibility under Section R320.3 · Virginia USBC 2021 Amendment 33 (IRC R320.3)
- Covered multifamily dwellings: at least one building entrance on an accessible route · HUD FHA Design Manual Requirement 1 (Chapter One)
- Public and common use areas must be readily accessible to and usable by people with disabilities · HUD FHA Design Manual Requirement 2 (Chapter Two)
- All doors must provide a clear opening of at least 32 inches when open 90 degrees · HUD FHA Design Manual Requirement 3 (Chapter Three)
Last reviewed 2026-05-10.