Accessory Structures in Auburn, WA (2026)
3 verified accessory structures rules for Auburn, Washington, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Auburn allows two ADUs per residential lot outright in any residential zone that permits single-unit detached or middle housing, capping each unit between 300 and 1,000 square feet with no more than two bedrooms, attached, detached, or a mix of both.
Auburn Accessory Dwelling Unit Standards
Some RestrictionsAuburn City Code § 18.32.010(A)-(D)
A. Accessory dwelling units (ADUs) are permitted outright in all residential zones that permit single-unit detached or middle housing, and may be developed with new or existing development. The development standards of the underlying zone and the following siting and performance standards shall apply to all accessory dwelling units as defined by ACC 18.04.018. B. Two ADUs may be permitted per r...
Shed & Carport Rules
Auburn lets you skip a building permit for a one-story detached tool or storage shed only if its floor area stays at or under 200 square feet. Go bigger, or add plumbing or wiring, and the shed becomes a permitted structure subject to the zone's setback and height table.
Auburn Backyard Shed Permit and Size Rules
Some RestrictionsACC 15.08A.025; ACC 18.07.030 Table 18.07.030 (H, E.8)
105.2 Work exempt from permit. ... Permits shall not be required for the following: Building: 1. One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided that the floor area is not greater than 200 square feet. ... H | Maximum height of accessory buildings and structures | RC 35 | R-1 35 | R-2 24 | R-3 24 | R-4 24 | R-NM 24 | R-F 24 ... 8 | R...
Garage Conversions
Auburn lets homeowners convert garage space into an accessory dwelling unit, but ACC 18.32.010(E)(3) requires the garage door be swapped out for materials matching the house's exterior, and the converted square footage cannot count toward the ADU's minimum size.
Auburn Garage Conversion Rules
Some RestrictionsACC 18.32.010(E)(3)
E. Exterior Appearance/Modifications. 1. Any alterations shall not change the appearance from that of a single-unit detached dwelling, as determined by the planning director. 2. Any exterior stairs shall be placed in the rear or side setback and no closer than 10 feet to an adjoining property line. 3. Where garage space is converted to living space, the garage door shall be replaced with materi...
Looking for King County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Auburn city rules.
Accessory Structures in King County →