Residential drafting in Beaverton, Oregon
Beaverton is mostly postwar suburban: 1950s through 1970s ranches and split levels, later cul de sac subdivisions, attached housing, and newer growth toward South Cooper Mountain.
The first question on any Beaverton project is jurisdiction, not design. The city boundary is irregular and interwoven with unincorporated Washington County, and a property with a Beaverton mailing address may be reviewed by the county instead. That has to be confirmed against the tax lot before anything else, because it changes which code applies and who issues the permit.
Split levels are the hard case in the existing stock. The floor height changes, stair geometry, and stepped foundation make an attached addition considerably more involved than the same work on a ranch.
Lower level and basement conversions come with the usual questions about ceiling height, escape openings, moisture, and seismic connection.
ADU standards
Setback, size, and parking rules for an accessory dwelling unit in Beaverton.
| Maximum size | 800 sq ft. There is no percentage of the house test (60.50.03.C.1) |
|---|---|
| Whole level conversion | Converting an entire existing level, such as a basement, attic, or second story, may exceed 800 sq ft provided no new floor area is added at the same time (60.50.03.C.2) |
| Setbacks | The underlying zone standard. Rear may reduce to 5 ft for a one story unit no taller than 15 ft (60.50.03.E) |
| Separation | At least 6 ft from the house and other structures unless attached. It may not sit in an easement (60.50.03.E) |
| Height | The underlying zone limit, except 15 ft when using the reduced rear setback (60.50.03) |
| How many | One, alongside a single detached dwelling (60.50.03.A) |
| Parking | No minimum parking is required for any use in Beaverton (60.30.10.3.A.1) |
| Review | A Type 1 accessory dwelling unit land use application is required (40.05.15) |
Beaverton's whole level conversion exception is the most useful rule here. Converting an entire existing level, a basement, attic, or second story, can exceed 800 square feet as long as no new floor area is added in the same project (60.50.03.C.2). On a house with a full basement, that is a substantially larger unit than the headline number suggests.
There is no percentage of the house test in Beaverton's code. Some summaries claim a 50 percent cap. That is not in the current ordinance.
The five foot reduced setback applies to the rear only, and only for a one story unit no taller than 15 feet (60.50.03.E). There is no matching side setback reduction.
Unlike most cities here, Beaverton requires a land use application for the unit. It is a Type 1 review handled by Planning, separate from the building permit (40.05.15).
Beaverton has no system development charge waiver for accessory units. The current schedule charges them directly, including a parks district charge and a transportation development tax. Some utility charges can avoid a second unit assessment where the property stays on a single small water meter, but that is a calculation, not a waiver.
Planning office: Beaverton Community Development
Sources: Beaverton Development Code 60.50.03. Beaverton Development Code 40.05.15. ORS 197A.425. Last checked August 2026.
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