ADA Ramp Requirements: Slope, Width, and Landings Explained (2024)

A 1-inch rise over 12 inches of run. That ratio — 1:12 — is the ADA’s maximum running slope for new construction ramps. Get it wrong and the accessible route fails. A failed accessible route blocks the certificate of occupancy.

Here is every number from ADA §405, organized so plan review goes clean.

What is a ramp under the ADA?

A ramp is any walking surface with a running slope steeper than 1:20, per ADA 2010 Standards §405.1. That threshold matters because slopes up to 1:20 are walkways, not ramps — and walkways do not trigger §405’s requirements for handrails, landings, and edge protection. The distinction is measurable: 1:20 equals 5.0%, while 1:12 equals 8.33%. Any surface between 5.0% and 8.33% is a ramp. Anything steeper than 8.33% is non-compliant in new construction — no variance, no exception. The only relief for steeper slopes appears in alteration projects with documented space constraints, and even then the steeper slopes carry reduced maximum rises.

What is the maximum running slope for an ADA ramp?

The running slope — measured in the direction of travel — is 1:12 maximum for new construction, per ADA §405.2. That is an 8.33% grade. Existing sites, buildings, and facilities with documented space limitations may use steeper slopes, but the steeper the slope, the shorter the permitted run.

The 30-inch maximum rise per run applies to new construction at the standard 1:12 slope. A ramp run at 1:12 rising 30 inches requires 30 feet of horizontal run — 360 inches. That geometry surprises teams on constrained sites. Multiple runs with landings between are permitted without limit on total number.

What is the cross slope requirement for ADA ramps?

Cross slope is the slope perpendicular to the direction of travel. The ADA caps cross slope at 1:48 on ramp runs, per §405.3. That is 2.08% — tighter than many assume. The rationale is stability: a wheelchair user ascending a ramp is already managing forward force. Side slope adds lateral drift that makes steering and braking difficult. Cross slope applies across the full width of the ramp surface. Drainage detailing must achieve the required slope without exceeding 1:48 in either cross direction, which constrains standard paving grading assumptions. Ramp run surfaces must also comply with §302: firm, stable, and slip-resistant. Level changes on the ramp run surface — other than the running slope and cross slope — are not permitted under §405.4. In practice, 2.08% is close enough to standard paving tolerances that field measurements sometimes fail what the drawings showed as passing. A slope of 1:48 leaves almost no margin for construction variance, so designing to 1:60 (1.67%) at the centerline is a common mitigation strategy.

How wide does an ADA ramp need to be?

Clear width is 36 inches (915 mm) minimum between any handrails, per ADA §405.5. The 36-inch dimension is the clear passage width — measured between the handrail gripping surfaces, not the ramp structure edge. Where handrails project into the clear width, that projection counts against the 36 inches. One exception applies in employee work areas: clear width may be reduced by equipment essential to the work function. That exception does not apply to public or common-use paths. DataDrivenAEC’s comparison of §405.5 with IBC §1012.3 shows the IBC uses the same 36-inch minimum for ramp width in most occupancies — the standards align on this dimension, so one calculation serves both. State building codes in California (CBC) and Massachusetts (521 CMR) carry the same 36-inch minimum but impose additional handrail projection limits. The ADA sets the floor. State codes sometimes raise it. Always confirm against the applicable state accessibility standard before finalizing ramp width on the drawings.

What are the landing requirements for ADA ramps?

A landing is a level platform at the top and bottom of each ramp run, required by ADA §405.7. Landings interrupt the slope and give users a place to stop, turn, and open doors. The slope of a landing is 1:48 maximum in any direction — the same as cross slope on a ramp run. Level changes on landings are not permitted. Clear length is 60 inches (1,525 mm) minimum per §405.7.3. Clear width is at least the width of the widest ramp run leading to the landing, per §405.7.2.

Where a ramp changes direction between runs, the landing must be at least 60 inches by 60 inches. A standard 60-inch-long, 36-inch-wide landing is not enough when the next run goes a different direction. Landings in wet conditions must drain to prevent water accumulation, per §405.10.

When are handrails required on ADA ramps?

Handrails are required on both sides of a ramp run when the rise exceeds 6 inches (150 mm), per ADA §405.8. A run with a rise of 6 inches or less does not require handrails — but ramps with 30 inches of maximum rise at 1:12 always trigger this requirement. Handrails must comply with §505. Gripping surface height is 34 inches (865 mm) minimum to 38 inches (965 mm) maximum above the ramp surface. Circular cross-section diameter is 1¼ inches (32 mm) minimum to 2 inches (51 mm) maximum. Handrails must be continuous along the ramp run and return to the post, wall, or floor at the ends. One exception applies in employee work areas: handrails are not required if the ramp is designed so handrails can be added later without reducing clear width below 36 inches.

What edge protection is required on ADA ramps?

Edge protection is required on both sides of every ramp run and at both sides of every ramp landing, per ADA §405.9. Two methods comply. The first: extend the floor or ground surface 12 inches (305 mm) minimum beyond the inside face of the handrail — §405.9.1. The second: install a curb or barrier that blocks passage of a 4-inch (100 mm) diameter sphere within 4 inches (100 mm) of the finished floor — §405.9.2. Three exceptions exist. Edge protection is not required on ramps that do not require handrails and have sides complying with §406.3. Edge protection is not required on landing sides that adjoin a ramp run or stairway. Edge protection is also not required on landing sides where the vertical drop is ½ inch (13 mm) maximum within 10 inches (255 mm) of the landing area. These exceptions are specific — verify each one against the drawing conditions before waiving edge protection on any side.

The part everyone gets almost right — DataDrivenAEC

Confusing handrail trigger with rise, not with run length. The handrail requirement triggers when rise exceeds 6 inches — not when the ramp runs a certain length. A 20-foot ramp rising only 5 inches needs no handrails. A 6-inch ramp rising 7 inches does. The number that matters is vertical, not horizontal.

Using landing slope instead of landing dimensions. The 60-inch minimum landing length is separate from the 1:48 slope maximum. Both apply. A sloped landing at 1:60 that is only 48 inches long fails on length, not slope.

Forgetting direction-change landings. A 60 × 60-inch landing is required wherever the ramp changes direction between runs, per §405.7.4. The standard 60 × 36-inch landing fails this condition. Switchback ramps on constrained sites are the most common place reviewers flag this.

Applying new construction slopes to alteration projects. The 1:10 and 1:8 exceptions apply only to existing sites with documented space limitations. Teams sometimes apply them to new additions. Plan review rejects these because the addition is new construction.

Skipping edge protection on short ramps. Edge protection is required on every ramp run and landing side. The three exceptions in §405.9 are specific; they are not a general waiver for low-rise ramps.

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