Quick Verdict
ADA site grading is the earthwork that makes an accessible route work: running slopes gentle enough to roll, cross slopes flat enough to feel level, and landings that are truly flat. On a commercial site it governs the parking, the path to the entrance, and the ramps, and it is inspected against tight numbers. The excavation and grading crew has to hit those tolerances in the field, often within a fraction of an inch, on real Oregon ground that never starts out level. Miss the slope on a single stall or ramp and the site fails inspection. Precision grading, not guesswork, is what passes.
Why ADA Grading Is a Precision Job
Most grading gives you an inch or two of leeway. ADA does not. An accessible route has hard limits, and inspectors check them with a level. The whole point of the earthwork is to deliver surfaces that meet those limits before pavement or concrete goes down, because you cannot fix a slope problem by pouring over it.
That puts ADA site grading in the same tolerance class as laser grading and fine grading, where the crew is chasing hundredths of a foot rather than shaping bulk dirt.
The Slope Numbers You Grade To
Design comes from the accessibility standards, but the grading targets crews build to look like this:
| Element | Typical Limit |
|---|---|
| Accessible route running slope | no steeper than 1:20 (5 percent) without ramp features |
| Ramp running slope | up to 1:12 (about 8.3 percent) max |
| Cross slope on route or ramp | no steeper than 1:48 (about 2 percent) |
| Accessible parking and access aisle | no steeper than about 2 percent in any direction |
| Landings at ramp tops and turns | essentially flat, within tolerance |
Building Tolerance Into the Earthwork
Hitting 2 percent cross slope in the field takes the right approach:
- Grade-control tools like laser or GPS machine control for the subgrade
- Tight staking and frequent checks with a smart level
- Building subgrade to a consistent depth so the pavement thickness stays even
- Coordinating with the paving or concrete crew so the finished surface, not just the dirt, meets spec
The dirt has to be right, but the finished surface is what gets inspected, so subgrade and surfacing have to be planned together.
Oregon Site Conditions to Plan For
- Sloping sites: Much of Oregon is not flat, so achieving a 2 percent accessible route across a site that falls 6 percent means cuts, fills, and sometimes ramps and retaining.
- Clay subgrade: Willamette Valley clay moves with moisture, so a compacted, stable subgrade matters or the finished slopes shift over time.
- Drainage: Accessible surfaces still have to drain, and doing that within a 2 percent cap takes careful planning of low points and inlets.
- Freeze-thaw east of the Cascades: heaving can throw a tight slope out of tolerance, so subgrade prep matters more in cold country.
What ADA Site Grading Costs
Cost tracks the precision and the amount of cut and fill, not just the square footage. Planning baselines only.
| Unit | Baseline Range |
|---|---|
| Grading and fine grading, per sq ft | $0.75 - $4.00+ per sq ft |
| Excavator or skid steer plus operator | $125 - $350+ per hour |
| Machine control or laser grading | premium over conventional grading |
| Import fill or spoil haul-off, per load | $250 - $750+ per load |
| Mobilization fee | $250 - $800+ flat |
These are industry baseline ranges for planning only -- actual pricing depends on site conditions, soil, access, depth, haul-off, and current market conditions. Get a site-specific quote.
Current Market Reality
Real costs often run 2 to 3 times baseline when clay, rock, unmarked utilities, permits, or disposal hit. A site that has to be re-graded because the first pass missed cross slope, or one where retaining is needed to hold an accessible route on a slope, climbs quickly.
Permits and Inspection
Accessible grading is part of a permitted commercial build and is inspected against the accessibility standards along with local code. The grading has to match approved civil plans, and the finished slopes are verified before the site is signed off. Call 811 before digging, and expect erosion control on disturbed ground. The relationship between site work, permits, and inspection is covered in our Oregon excavation contractor guide. The same tolerance discipline shows up in athletic work like sport field and ballfield grading.
New Construction vs Retrofits
There is a real difference between grading an accessible route on a fresh site and retrofitting one into an existing lot, and the retrofit is usually the harder job. On new construction, the accessible route is designed into the site grading from the start, so the crew can shape the whole surface to hit running and cross slope everywhere it matters. There is freedom to set finished floor elevations, parking, and paths together.
A retrofit has to work within what is already there: an existing building entrance at a fixed elevation, established parking, and pavement that may already drain the wrong way. Bringing a non-compliant lot into tolerance often means removing and repouring sections, adding a ramp where a slope is too steep, or regrading a parking aisle that sits at 4 percent down to under 2. Because the surrounding grades are fixed, the crew has less room to work and has to be surgical about where material comes out and goes back in.
Common retrofit triggers include a remodel, a change of use, or a complaint that puts accessibility under review. In those cases the grading and paving fixes are targeted rather than site-wide, which makes precise field measurement even more important, since a small correction still has to land inside the same tight tolerances.
A few things make retrofits go smoother:
- Survey the existing slopes first so you know exactly what is out of tolerance
- Identify fixed constraints, like the entrance elevation, before designing the fix
- Plan the drainage so corrected slopes still shed water within the 2 percent cap
- Coordinate demolition, grading, and repaving as one sequence
Whether new or retrofit, the finished surface is what gets measured, so the earthwork has to deliver compliant grades either way.
The Bottom Line
ADA site grading is pass-or-fail earthwork measured in fractions of an inch, so it belongs to a crew that grades to tight tolerance with the right tools. Hit the running and cross slope numbers on the subgrade and the finished surface, and the site passes the first time. Cojo is CCB licensed and insured, based in Hood River, and serves Oregon and the I-5 corridor. See our excavation services, then request a free estimate for your accessible site work.