How Many ADA Parking Spaces Does a Commercial Lot Need?

Modern Northwest Design and Build Team · Published September 1, 2026

A lot with 1 to 25 total spaces needs 1 accessible space. From there it is 2 spaces up to 50, 3 up to 75, and 4 up to 100, and at least one of every six accessible spaces has to be van accessible. That answers it for most commercial lots. What surprises people is the sizing: Oregon requires a 9 foot space with a 6 foot aisle, which is bigger than the federal minimum, so a lot striped to the national numbers can still fail here.

From the 2010 ADA Standards for Accessible Design, section 208.2. Oregon and Washington both adopt the same counts in their state building codes. Fractions always round up.

We build commercial projects and tenant improvements across Portland and Southwest Washington, and parking is one of the quieter ways a project gets held up. The count is easy. The dimensions, the slope, and the signs are where lots actually fail, and restriping a finished lot costs real money.

What is ADA parking?

"ADA parking" is the set of reserved spaces a commercial property has to provide under the Americans with Disabilities Act, along with the rules for how big they are, how they connect to the building, and how they are marked. It is not a courtesy space. The ADA parking requirements are enforceable, they apply to new construction and to alterations, and in Oregon and Washington the state building code layers its own version on top.

Two things make a space count. It has to meet the size and slope rules below, and it has to connect to an accessible route into the building without forcing anyone to travel behind parked cars. A correctly sized stall at the far end of a lot with a curb in the way is not compliant.

The van rule: one in six

At least one of every six accessible spaces, or fraction of six, must be van accessible. The fraction part matters. A lot with 3 accessible spaces still needs 1 van space, because 3 is a fraction of 6. A lot with 7 accessible spaces needs 2.

You may see an older figure of one in eight. That was the 1991 guideline and it is out of date. Current work in both Oregon and Washington runs on one in six.

Space and aisle sizes, and why the state matters

This is the part that catches people, because the federal standard is a floor and Oregon builds on top of it. Here is the same requirement in all three places:

Federal figures from the 2010 ADA Standards (502.2, 502.3, 502.4, 502.5, 502.6). Oregon figures from the Oregon Transportation Commission Standards for Accessible Parking Places (2023), which the Oregon Structural Specialty Code adopts in place of the national dimensions. Washington figures from the Washington State Building Code amendments 1101.2.7 and 1101.2.8.

Read that table row by row before you stripe anything. A lot laid out to the federal 8 foot space and 5 foot aisle is legal in Washington and undersized in Oregon. It is the same drawing, two different answers, and the fix after paving is a full restripe.

The Oregon rules people don't see coming

Oregon does not simply adopt the national parking dimensions. Under ORS 447.233 the Oregon Transportation Commission sets its own standards, and the state building code points at them. Four things differ from what a national spec will tell you:

• Bigger spaces and aisles. 9 feet wide with a 6 foot access aisle, and 8 feet of aisle where the space is van accessible or reserved for wheelchair users.
• A third sign that does not exist federally. Oregon uses a WHEELCHAIR USER ONLY sign (OR7-8c) alongside the standard reserved parking sign and the van accessible rider. It marks spaces with an 8 foot aisle that only vehicles with a wheelchair user placard may use.
• Signs go higher on posts. 7 feet, plus or minus 3 inches, from the ground to the bottom of the sign. On a building or pier it is 5 feet minimum. The federal standard says 60 inches, so a post set to the national number is low here.
• Every access aisle gets a NO PARKING legend painted in it, white or yellow and retroreflective, and the aisle sits on the passenger side unless two spaces share one between them.

None of these are hard to build. They are only expensive when nobody checks until the lot is poured and striped.

What Washington does differently

Washington keeps the 96 inch space, so an Oregon layout is always wide enough to work across the river, but not the other way around. The one real Washington amendment is on van spaces: the state requires a 96 inch access aisle for them rather than allowing the federal alternative of a 132 inch space with a narrower 60 inch aisle. In practice that means every van stall in Washington is the wide aisle version.

The two that fail inspection most often

Slope. Accessible spaces and their aisles cannot exceed 1:48, roughly 2.08 percent, in any direction. That is flatter than a lot needs to be to drain well, so a surface built purely for drainage will often miss it. Slope is measured after paving, which is the worst possible time to find out.

The route, not just the stall. The 98 inch vertical clearance applies to the van space, its access aisle, and the vehicle route serving them, so a canopy, a low soffit, or a parking structure beam anywhere along the drive can put a compliant stall out of compliance. Check the whole path a van takes to get there.

Where parking fits in a build-out

Parking counts get reviewed with everything else when your permit package goes through plan review, alongside occupant load and fixture counts. If you are working through those numbers too, our guide to how many bathrooms a commercial building needs covers the same kind of math indoors, and who pulls the permit explains how review actually runs in Portland, Multnomah County, Washington County, and Vancouver.

If you are taking a leased space, worth knowing: bringing a non compliant lot up to standard is usually a landlord and tenant negotiation, and it is the kind of item a tenant improvement allowance may or may not cover. Settle it before signing, not after.

Looking at a lot right now? We have been building commercial projects across the Portland metro since 2008. Send us the space count and the address, or call (360) 326-2747, and we will tell you how many accessible spaces it needs and whether the striping you have will pass.

Frequently asked questions

The bottom line

The count is the easy half and the table above settles it. The half that costs money is the sizing, and it depends on which side of the river you are building on: Oregon wants 9 by 6, Washington accepts 8 by 5, and both want one van space in every six. Check the lot against those numbers before it is paved, because slope and stall width are not things you fix with a paint gun.

Modern Northwest builds commercial construction and build-outs across Portland and SW Washington, and site accessibility is part of the permit package we handle on every job. Reach out for a free walkthrough.

Modern Northwest · Commercial general contractor since 2008 · (360) 326-2747
Serving Portland, Beaverton, Hillsboro, Gresham, Tigard, Lake Oswego and Vancouver, WA. Licensed in Oregon and Washington.