Helonic

Curb Ramp Slope on Site Plans

Helonic is an AI construction drawing analysis platform for teams researching accessibility during drawing review.

A curb ramp running slope steeper than 1:12, a cross slope over 1:48, or a flare steeper than 1:10 fails the civil sheet.

AccessibilitySeptember 24, 2026

Curb ramp slope on a site plan fails when the running slope is steeper than 1:12, the cross slope is steeper than 1:48, or the side flare is steeper than 1:10. Helonic checks those callouts on civil and architectural site sheets. The 1:20 accessible route limit stays on the ADA guide. A curb ramp is a ramp, not a walking surface.

Which slopes does the civil sheet have to show?

A single 'match existing' note is not a slope. The ramp, the landing, and the flares each need a number.

  • Running slope 1:12 maximum on the ramp run.
  • Cross slope 1:48 maximum.
  • Flares 1:10 maximum where pedestrians cross the flare.
  • A level landing at the top, clear of the door swing behind it.
  • Detectable warnings at the street edge where the standard requires them.

How do you review the ramp without regrading the site?

Read the spot elevations at the gutter, the landing, and the door. The difference over the ramp length is the slope. If the architectural door threshold and the civil gutter do not use the same datum, the ramp on one sheet is fiction.

Helonic compares those two callouts and marks a run that cannot make 1:12 in the length drawn.

Frequently Asked Questions

What is the maximum curb ramp slope on a site plan?
Running slope 1:12, cross slope 1:48, and flares 1:10 where people walk across them, under the 2010 ADA Standards for curb ramps.
Is a curb ramp the same as an accessible route?
No. An accessible route stays at or under 1:20 or it becomes a ramp. A curb ramp is already a ramp and uses the 1:12 limit. Those rules live on different pages here.
What should the drawing call out besides slope?
Landing size at the top, detectable warnings at the curb, and a door swing that does not land in the ramp. Spot elevations should share a datum with the architectural sheet.
Why do curb ramps fail plan check?
The sheet says 'match existing grade' and the existing gutter is steeper than 1:12 in the length available. The ramp was never given enough run.
MG

Manas Gandhi

Co-founder & CTO, Helonic

Manas is the co-founder and CTO of Helonic, where he leads engineering and AI research for construction drawing analysis. He works directly with structural, MEP, civil, and fire protection engineers to translate the way they review drawings into AI systems that flag the issues that actually matter in the field. Before Helonic, he built machine learning pipelines for technical document understanding and has spent the last several years interviewing licensed design engineers and discipline leads to ground product decisions in real practice rather than industry assumptions.

Areas of focus
  • AI for technical document understanding
  • Cross-discipline coordination workflows
  • Code compliance automation (IBC, NEC, NFPA, IPC, IMC, ASCE)
  • Structural and MEP drawing review systems

How this page was researched: Slope limits were checked against the 2010 ADA Standards for curb ramps, including running slope, cross slope, and flares. Accessible-route slope at 1:20 remains on the ADA accessibility guide so the pages answer different queries.

Last reviewed by Manas Gandhi · September 24, 2026

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Keep exploring

Related guides, comparisons, and features for coordination teams.

ADA Accessibility Guide

Accessible routes at 1:20, which this page does not repeat.

Site Grading Review

Grades around the ramp landing.

Parking Lot Design Standards

Stall and aisle layout next to the ramp.

Accessibility Checking

ADA flags on plans and site sheets.

Check Curb Ramps on the Civil Set

Helonic reads site and architectural sheets for curb ramp slopes, landings, and detectable warnings that do not meet the ADA ramp rules.