ADA Curb Ramp Width Spec: 36-Inch Minimum + Landing Rules
Direct Answer (60 words): ADA curb ramps require a minimum clear width of 36 inches measured between obstructions, top and bottom landings at least 48 inches deep, side flares at 1:10 maximum, and a 24-inch detectable warning surface across the full ramp width at the gutter line. The 36-inch number is a clear-width minimum, not a curb-to-curb concrete dimension.
ADA ramp width is the second-most cited compliance failure we see on commercial parking-lot inspections, behind only running slope. The 36-inch number sounds simple, but the underlying ADAAG language measures clear width between obstructions, not just the concrete edge. This guide walks each width-related rule, where it comes from, and how we verify the result on real projects.
What does ADA require for ramp width?
The 36-inch minimum clear width comes from the 2010 ADA Standards for Accessible Design, Section 405.5, with parallel rules for curb ramps in Section 406. The U.S. Access Board publishes the technical baseline (Access Board ADA Standards).
| Width Rule | Minimum |
|---|---|
| Ramp clear width (between obstructions) | 36 inches |
| New construction recommended width | 48 inches |
| Top landing depth | 48 inches |
| Top landing width | At least equal to ramp width |
| Bottom landing (gutter / roadway) | At least equal to ramp width |
| Detectable warning surface depth | 24 inches |
Why 36 inches and not less?
The 36-inch number reflects the wheelchair maneuvering clearance documented in U.S. Department of Justice Title III ADA Technical Assistance (DOJ ADA.gov). A standard manual wheelchair measures 24 to 27 inches across the wheels. The 36-inch lane provides clearance plus the maneuver buffer needed to keep tracking on the ramp.
What does "clear width between obstructions" mean?
The 36 inches must be free of:
- Sign posts
- Bollards
- Drain inlets
- Light pole bases
- Parked-vehicle overhang
- Snow piles
- Landscape edges or planters
A 48-inch concrete ramp with a sign post 8 inches into one edge is a 40-inch-clear ramp at that point. Inspectors measure with a 36-inch rod between obstructions.
What is the landing depth requirement?
The top of every curb ramp needs a landing where a wheelchair user can pause, turn, or yield. The landing must:
- Measure at least 48 inches deep in the direction of travel
- Span at least the ramp width
- Hold a maximum slope of 1:48 (2.08 percent) in any direction
- Connect to the accessible route without level changes greater than 1/4 inch
The Access Board notes that landings shorter than 48 inches force wheelchair users into the parking surface to maneuver, which is a strict liability ADA violation.
How does the detectable warning surface fit into the width rule?
The detectable warning is a 24-inch deep panel at the gutter line. It must span the full width of the ramp. If the ramp is 36 inches wide clear, the panel is 36 inches wide. If the ramp is 48 inches wide, the panel is 48 inches wide.
The U.S. Department of Transportation's Public Right-of-Way Accessibility Guidelines specify the dome geometry and panel placement (DOT PROWAG).
What about side flares?
Side flares are the angled transitions on either side of the ramp. They are not counted in the 36-inch ramp width.
| Flare Rule | Maximum Slope |
|---|---|
| Standard side flare | 1:10 |
| Side flare in pedestrian travel path | 1:12 |
| Returned (vertical) curb flare alternative | Permitted where flares would interfere |
Width rules for parallel and combination ramps
| Ramp Type | Width Rule |
|---|---|
| Perpendicular ramp | 36 inch minimum clear ramp width |
| Parallel ramp | 36 inch minimum clear ramp width |
| Combination ramp | Each segment 36 inch minimum |
| Diagonal ramp at corner | 48 inch bottom landing required |
Common width-related failures
| Failure | Why It Fails |
|---|---|
| Sign post intruding into ramp | Reduces clear width below 36 inches |
| Drain inlet at edge of ramp | Reduces clear width and creates hazard |
| Top landing only 36 inches deep | Less than the 48-inch required depth |
| Detectable warning narrower than ramp | Does not span full width |
| Returned curb at flare without warning | Confusing transition for low-vision users |
Industry Baseline Range for ADA ramp width work
| Component | Range |
|---|---|
| New ADA ramp at 36-inch clear width | $1,200 to $2,500 each |
| Wider 48-inch new ramp | $1,800 to $3,200 each |
| Width retrofit (saw, demo, re-pour) | $2,500 to $5,500 per ramp |
| Sign-post relocation to clear ramp | $400 to $900 per post |
| Drain inlet relocation | $1,500 to $4,500 per inlet |
Current Market Reality
Oregon 2026 ADA retrofit pricing reflects the high cost of demo and re-pour around obstructions. A ramp that needs sign-post and drain-inlet relocation can land 2 to 4 times the cost of a clean new build. Insurance carriers increasingly require post-install measurement documentation, which adds engineer time.
Real install reference
In March 2026, Cojo retrofitted 8 non-compliant ADA ramps at a Hood River medical campus. Six of the eight failed inspection on width: a sign post sat 7 inches inside the ramp edge, reducing clear width to 31 inches. We relocated the post 18 inches outside the ramp edge, resawed the ramp to a 42-inch concrete width, and installed surface-applied detectable warning panels at 42 inches. Final clear width measured 42 inches across all 8 ramps.
Frequently Asked Questions
What's the minimum width of an ADA curb ramp? 36 inches clear between obstructions. We aim for 48 inches on new construction so construction tolerance and any later additions (a sign, a pole) don't push us under the line.
Does ADA require a wider ramp at corners? Diagonal corner ramps need a 48-inch deep bottom landing because pedestrians arrive from two travel directions. The ramp itself still has to hit 36 inches clear.
Can a sign post sit at the edge of an ADA ramp? Only if it's outside the 36-inch clear envelope AND outside the 48-inch landing. Anything intruding into the clear width is non-compliant.
Do landings need to match the ramp width? Landing width has to equal or exceed ramp width. Wider is allowed and recommended on new construction.
How wide does the detectable warning surface need to be? 24 inches deep in the direction of travel, full ramp width at the gutter line.
Cojo installs ADA-compliant curb ramps across Oregon. To plan your project, start with our concrete curb guide, see the ADA curb ramp slope requirements, or get a quote on ADA curb ramp installation in Salem.