Accessibility
Building an Accessible Ramp
A ramp is one fixed vertical rise divided among runs, landings and handrails - spend that slope allowance before the first form board goes down.
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The rise is the whole allowance
Every ramp problem starts as one vertical measurement and turns into an argument about horizontal distance. Shoot the finish floor at the door, shoot the finish grade where the ramp will meet the walk, and the difference between them is the whole allowance you have to spend. Nothing downstream changes that number - not the handrail detail, not the mix design, not how the owner feels about switchbacks. Read the rise wrong by an inch and you find out at the top landing, in cured concrete, on the morning the inspector shows up.
Shoot to finished surfaces, not to whatever is under your feet today. A threshold scheduled for replacement, a walkway due for a two-inch asphalt overlay, a stoop that has settled since the building went up - each moves the rise after the run has already been committed on a site plan. On renovation work, take the reading at three points across the door opening. Existing slabs are rarely level, and the corner with the most rise is the corner your allowance has to cover.
Thresholds deserve a separate reading. Changes in level at a doorway are treated on their own terms in the accessibility standards, and a raised sill can eat a fraction of the allowance before the ramp begins - or hand you back an inch if it can be reset during the same job. Where the door swings out over the top landing, the swing takes plan area as well, a different account that overdraws just as fast.
What an inch of rise buys
The published maximum for a ramp on an accessible route in the United States is 1:12 - one unit of rise for every twelve of run - under the ADA Standards for Accessible Design, carried through ICC A117.1 and the accessibility chapter of the International Building Code. At that exchange rate an inch of rise costs a foot of run. Residential work permitted under the International Residential Code follows a different path and allows a steeper ramp where a shallower one is technically infeasible; which document governs your job is a question for the building official, not for the drafter.
Designing to the maximum is how a ramp fails inspection while being built exactly as drawn. Forms move, screed rails deflect, a finisher chases a low spot, and the surface ends up a fraction steeper than the line on paper. Draw at 1:16 or 1:20 wherever the site allows and ordinary field variation still lands inside the limit. Draw at 1:12 and every variation becomes a violation. The standards acknowledge conventional industry tolerances, but no inspector has a published number to grant you, so the only margin you can rely on is the one you built in yourself.
A second charge lands on the account before you have spent a foot: a ramp run may rise no more than thirty inches before a landing interrupts it. Forty inches of rise is therefore never a single ramp. It is two runs and at least three landings, and landings are not free. Sketching a total rise as one continuous sloped line is the most reliable way to hand an owner a footprint that comes out fifteen feet short once it is drawn properly.
Rise, design slope, the thirty-inch run ceiling and the landings it forces all pull against the same total, so settle the geometry here before a footprint gets committed to a site plan.
Total ramp horizontal length
53 ft
This restates the fixed ADA 2010 Standards ramp geometry requirements (1:12 max slope, 30in max rise per run, 60in min landing length) for total horizontal length planning — it does not check ramp width, cross slope (max 1:48), edge protection, surface requirements, or handrail specifications (see the companion handrail extension calculator), all of which are separately required for full compliance.
- Number of ramp runs
- 2 runs
- Intermediate landings required
- 1 landings
Code thresholds this tool can check — United States
Each check below names the body that published the limit it uses. Switching market re-runs them. This is not a code review and has no official standing.
These checks cover only the specific numeric limits listed below. They are not a complete code review: fire separation, egress, structural capacity and accessibility provisions are outside their scope, and only the handful of local amendments offered in the selector are modelled — your municipality may have others. Passing every check here does not make a design compliant. Final approval rests with your local building authority.
WITHIN LIMIT — Maximum running slope 1:12; maximum rise 30 in (762 mm) per run.
Rise of 48 in exceeds 30 in, so 1 intermediate landing(s) are mandatory — they are included in the length above.
US Access Board · 2010 ADA Standards §405.2 / §405.6 · 2010 ADA Standards §405.6
For the dimensions entered, expect a total ramp horizontal length of 53 ft. Set for United States. The market selector changes the units and the trade terminology; any standard behind the formula is cited under sources.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Landings are a fixed charge
Landings come out of the allowance as a fixed charge rather than a rate. Every ramp needs one at the top and one at the bottom, each at least sixty inches long, at least as wide as the run it serves, and level in both directions within the same cross slope limit that governs the ramp surface. That last requirement catches people out: a landing is not a place to shed the water you did not want on the ramp.
Turns cost more than straight landings. A change in direction requires a landing at least sixty inches by sixty inches, and a switchback consumes that square plus the width of both runs plus the clearance the handrails need between them. Lay a switchback out on the survey before quoting it. The footprint is regularly twice what an owner has pictured, and the second run frequently ends up over a planting bed, a downspout discharge or the drive aisle striping.
Doors complicate the top landing more than any other element. Maneuvering clearance is required on the landing side, and the dimension changes with the approach direction and with whether the user is on the push or pull side - the tables in the standards govern, and they are not interchangeable between a forward approach and a latch-side one. A landing sized only to the sixty-inch minimum often fails because the door needs more room than the ramp does.
Cross slope and drainage draw on the same account
Cross slope draws on a separate account with a much smaller balance: 1:48, roughly a quarter inch per foot, measured perpendicular to the direction of travel. That figure is a ceiling not to exceed rather than a target to hit, and it applies to landings as well as runs. A wheelchair on a surface tipped past the limit veers, and the user corrects with one arm the whole way up.
Water still has to leave the surface, and the same quarter inch per foot that drains a slab is the entire cross slope allowance. No room exists to crown a ramp. Pitch it one way, to one side, and confirm the receiving grade on that side actually takes the water instead of ponding against the curb. Landings are the harder case, since they must stay effectively level in every direction while still draining; on exterior work the surrounding grade usually does that job.
Texture and openings sit alongside slope among the things most easily lost during finishing. Exterior ramp surfaces must be slip resistant, which in cast concrete means a broom finish drawn perpendicular to the direction of travel, not diagonally to match the adjacent walk. Openings in the walking surface must not pass a half-inch sphere, and where a grating falls in the path the elongated openings run perpendicular to travel so a caster cannot drop in.
Handrails spend the budget past the ends of the ramp
Handrails become mandatory on both sides of a run once the rise exceeds six inches, with the gripping surface between thirty-four and thirty-eight inches above the ramp surface and continuous along the full length of each run. Gripping surfaces carry prescribed cross-section limits - a circular rail within a defined diameter range, a non-circular one within a defined perimeter - plus a required clearance between rail and adjacent wall. Rails that are structurally sound but the wrong diameter still get rejected, and replacing them afterward means new posts, new core holes and new patching.
Twelve inches of horizontal extension beyond the top and bottom of each run is the part of the handrail that spends site budget rather than ramp budget. Those extensions run level, parallel to the floor, and they land somewhere - on a landing, across a walk, past a door swing. They must not reduce the clear width required for whatever route they encroach on, and they cannot be trimmed because a door leaf hits them; the door or the landing moves instead. Ends get returned to a wall, a post or the ground so a sleeve or a bag strap cannot catch.
Switchbacks change the handrail geometry again. The inner rail on a switchback or dogleg runs continuously between the two runs rather than stopping and restarting at the landing, so the fabricator needs final landing geometry before bending anything. Edge protection belongs in the same pass: a curb, barrier or extended surface along each side of every run and landing, sized so a four-inch sphere cannot pass beneath near the walking surface. Providing it on the runs and stopping it at the landings is a routine punch item.
The extension past each run end is charged to the landing or walk it lands on rather than to the ramp, so work out that encroachment before posts are set and rail is bent.
Total handrail length needed
21.5 ft
This restates the fixed ADA Section 505.10.3 handrail extension requirement (12 inches minimum at each end) only — it does not check handrail height, gripping surface dimensions, or structural mounting requirements, which are separately specified.
At the values currently entered, the total handrail length needed works out to 21.5 ft. Figures are shown in United States units and terminology; switch the market above if you are building elsewhere.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
When the budget will not close
Sometimes the arithmetic will not close, and the honest move is to say so before anyone forms a footing. Lengthening the run is the first lever and switching back the second, but both assume site to spend. Where there is none, the productive question is whether the rise itself can be reduced: resetting a threshold, lowering the walk at the bottom, regrading the approach over a longer distance, or moving the accessible entrance to a face of the building where the grade already sits close.
Regrading gets dismissed too early on most jobs. Dropping the finish grade three inches at the bottom buys three feet of run at 1:12 and more at a gentler slope, and it often means resetting only a short stretch of walk that was going to be replaced anyway. Check what the drop does to surrounding drainage, to any catch basin rim, to tree roots, and to the continuous accessible route back toward parking or the public sidewalk, where right-of-way guidance rather than the building standards may govern.
Platform lifts are a last option rather than an equivalent one. Permitted only in limited circumstances under the accessibility standards, they carry an ongoing maintenance and inspection obligation and leave the owner with a device that can be out of service on the day it matters. A ramp that fits, even an ugly one switching back twice across a lawn, is a better handover than a lift that fits only the drawing.
Building to the budget you drew
Settlement converts a compliant 1:16 into a non-compliant 1:11 without anyone touching the ramp, which makes the footings an accessibility detail and not merely a structural one. Bear below the local frost depth, isolate the structure from the building so differential movement does not tip the top landing, and compact fill under a slab-on-grade run in lifts rather than one dump. Retrofit ramps poured on unprepared fill against an existing foundation are the ones that come back.
Set screed rails to elevations, never to a percentage. Establish top and bottom finish elevations from the same benchmark used for the original rise reading, string or laser between them, and mark intermediate stakes every eight to ten feet so a sagging rail shows before the pour rather than after. Calibrate the digital level on a surface you have verified flat, then check it again after it has ridden in a truck bed for a week; an instrument reading two tenths of a degree light will pass a ramp that the inspector's instrument fails.
Pour sequencing decides how the transitions come out, and transitions accumulate most of the slope error. Place runs, landings and any integral curb together where the pour size allows, so the joint between them is not also a change in plane. Put an isolation joint at the building, control joints at spacing suited to the slab thickness and mix, and keep every joint square to the path of travel. Vertical lipping at a joint is limited to a quarter inch, and anything between a quarter and a half inch has to be beveled.
Where the inspection finds the overspend
Inspectors measure with a short digital level, commonly twenty-four inches, walked along the run and across it, and the worst reading governs rather than the average. That single fact reframes the whole job: an average of 1:14 is worth nothing if a two-foot stretch reads 1:11. Measure it yourself the same way before calling for inspection - at the top transition, at the bottom transition, at mid-run, and diagonally across each landing.
Four failures recur often enough to check by name. The bottom two feet, where a crew feathered the new ramp into an existing walk and picked up the walk's slope. The cross slope at the top landing, tipped to move water away from a door. The handrail extension cut short to clear a door leaf or a column. And edge protection run along the ramp but stopped at the landing, which is exactly where a caster goes off.
Fixing a finished ramp costs far more than the error suggests. Grinding corrects a small high spot and destroys the broom finish doing it; slab jacking moves a panel but rarely lands it inside a quarter inch per foot; most real corrections mean saw cutting, removing and repouring a section, then rebuilding the handrail anchored to it. Beyond that, ADA obligations run as civil rights law rather than as a building code ticket, so a ramp signed off and later measured out of compliance stays the owner's exposure long after the permit closes.
Slope budget takeoff
Six numbers decide whether the ramp closes on the site you actually have. Fix them before ordering steel or forming anything.
- Total rise, read at finished surfaces — Three readings across the door opening; account for any planned overlay or threshold change.
- Run length at design slope, not maximum slope — Draw 1:16 or 1:20 where site allows so field variation stays inside the 1:12 ceiling.
- Landing schedule: one per thirty inches of rise, plus top and bottom — Sixty inches minimum length, sixty by sixty at every change of direction.
- Handrail extensions, twelve inches horizontal past each run end — Confirm they clear door swings and do not narrow the walk they land on.
- Edge protection continuous along runs and landings — Curb, barrier or extended surface; the landing is the piece most often skipped.
- Cross slope verified at 1:48 or flatter — Twenty-four-inch digital level, calibrated, worst reading governs - check transitions first.
Opens the calculators above on one screen with the dimensions from this article already filled in. Quantities only — this site publishes no price list, because local prices vary too much to publish honestly.
Drawn from
- 2010 ADA Standards for Accessible Design, U.S. Department of Justice
- ICC A117.1, Accessible and Usable Buildings and Facilities
- International Building Code, Chapter 11 - Accessibility
- International Residential Code
- Architectural Barriers Act (ABA) Accessibility Standards, U.S. Access Board
- Accessibility Guidelines for Pedestrian Facilities in the Public Right-of-Way (PROWAG), U.S. Access Board
- CSA B651, Accessible Design for the Built Environment
Guidance, not a specification. Local codes, the engineer of record and the product manufacturer’s instructions govern where they differ from anything written here.