ADU rules in Federal Way, WA — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Federal Way allows up to 2 ADUs per single-family lot under FWRC 19.200/19.265, updated for WA HB 1337 (2023). Max 1,000 sq ft each, attached or detached. Owner-occupancy is no longer required.
Washington HB 1337, passed in April 2023, preempts restrictive local ADU rules statewide. It requires cities planning under the Growth Management Act (including Federal Way) to allow at least two ADUs per single-family lot, remove owner-occupancy requirements, remove off-street parking mandates within one-half mile of major transit, allow attached and detached configurations, and permit ADUs of at least 1,000 square feet. Federal Way City Council adopted initial ADU amendments in July 2023 to reduce barriers and expedite review. Additional updates were anticipated by mid-2025 to fully align with HB 1337. Under current FWRC Chapter 19 provisions, detached ADUs may be up to 1,000 sq ft, attached ADUs up to 50 percent of the primary unit or 1,000 sq ft (whichever is less), and conversions of existing structures including Junior ADUs (JADUs) are allowed. Impact fees are capped at 50 percent of the principal-unit fee. Permit applications go through the Community Development Department. Planner on Duty: (253) 835-2655.
Unpermitted ADU construction: stop-work order, civil infraction under FWRC 1.15, and required retroactive permit or removal. Short-term rental of ADUs may require STR registration.
Federal Way, WA
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Federal Way, WA
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Federal Way, WA
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Federal Way, WA
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Federal Way, WA
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Federal Way, WA
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Side-by-side rule comparisons with other cities in King County.
See how other cities in King County handle adu rules.
See how Federal Way's adu rules rules stack up against other locations.
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