Puyallup, WA Accessory Structures: ADU Rules (2026)

Puyallup Municipal Code (PMC) § 20.20.010(11) sets the accessory dwelling unit (ADU) standards for every RS single-family zone (RS-35 through RS-04). On a lot that meets or exceeds the zone's minimum lot area, an owner may add up to two attached and/or detached ADUs alongside the principal dwelling. On a lot smaller than the zone minimum, only one ADU is allowed, unless the second is built as stacked units, one detached plus one attached, or as a conversion of an existing structure combined with a new unit.

Each ADU is capped at three bedrooms and 1,000 square feet of floor area, excluding any garage, workshop or unfinished storage space. Detached ADUs must observe the applicable front and street-side setback for the zone, a minimum five-foot rear and interior side setback, and a 10-foot separation from the principal dwelling, five feet if fire-rated per building code for converted structures. Attached ADUs simply follow the principal dwelling's own setbacks and height, and every ADU's height, bulk and architectural style must be compatible with the principal home. Off-street parking for an ADU is governed separately under PMC § 20.55.010.

An ADU may be sold as a condominium unit or through a unit-lot subdivision independent of the principal home, and any illegal ADU already on a property must be legalized or removed. Puyallup's ADU allowance implements Washington's 2023 middle-housing law (HB 1110), which required cities of Puyallup's size to permit more units on lots that were formerly single-family only; the two-ADU allowance and the reduced setbacks reflect that state mandate rather than a purely local policy choice. Noncompliance is enforced as a Title 20 zoning violation under PMC § 20.95.020.