Can I build a backyard home in Burien?
Since 2023, Washington law lets most city lots hold up to two more homes. Burien writes its own rules on top. Here’s what the code says, in plain English — and a free report on what may fit on your lot.
What Burien allows.
The headline standards. Tap any one for the full wording and the code section.
ADUs per lot2 — any combination of attached and detachedFull wording
2 — any combination of attached and detached (BMC 19.17.070(2)(B); city ADU handout). ADUs count toward the baseline units per lot (BMC Table 19.15.015.2.C).
Max size1,000 sq ft for internal, attached and detached ADUsFull wording
1,000 sq ft for internal, attached and detached ADUs (BMC 19.17.070(2)(C)(i)). The director may allow more in existing buildings at least 5 years old (BMC 19.17.070(2)(C)(ii)). No exclusions stated.
Max heightNot confirmed yet — ask the cityFull wording
Not confirmed yet — ask the city.
Front setback20 ft in R-1Full wording
20 ft in R-1 (15 ft in R-2 and R-3) (BMC Table 19.15.015.2.C); new ADU structures must meet zone standards (BMC 19.17.070(2)(D)(i)).
Side setback5 ft interior setback in R-1 through R-5Full wording
5 ft interior setback in R-1 through R-5 (BMC Table 19.15.015.2.C).
Rear setback5 ft — the interior setback applies to rear lot linesFull wording
5 ft — the interior setback applies to rear lot lines (BMC Table 19.15.015.2.C; city ADU handout). A detached ADU may sit at the rear lot line if it abuts a public alley that is not routinely plowed (BMC 19.17.070(2)(D)(i)).
Lot coverage50% maximum impervious surface in R-1Full wording
50% maximum impervious surface in R-1 (70% in R-2, 80% in R-3) (BMC Table 19.15.015.2.B); the table has no separate building-coverage cap.
Parking0 spacesFull wording
0 spaces — 'No parking is required for ADUs' (BMC 19.20.045(1)(C)).
Where a city figure reads stricter than the state floor (RCW 36.70A.681), the floor may control — the report flags it for your parcel.
Living there, selling it, plans, time and fees.
Each answer is the code’s own wording, with the section it comes from. “Not published yet” means the city hasn’t posted a figure — the report asks the city, not the internet.
Are backyard homes allowed?
Yes — attached or detached ADUs are allowed as accessory to a single detached dwelling in any zone, or to middle housing in a residential zone (BMC 19.17.070(2)(A)).
Minimum lot size
None for an ADU; zone minimum applies to new lots (BMC Table 19.15.015.2.B)
Do you have to live there?
No — BMC 19.17.070, as amended by Ord. 868 (2025), has no owner-occupancy requirement.
Can it be sold on its own?
Not addressed; RCW 36.70A.681 floor applies
Pre-approved plans
None found
How long the city takes
Not published
Impact fees
Not found; RCW 36.70A.681 caps ADU impact fees at 50% of the principal unit's
Plans Burien has already approved.
A pre-approved plan skips the design review: Burien has already checked the drawings, so the permit review is about your lot.
Loading the plans…
Pictures are the official pages’ own. A pre-approved plan is not a permit: the city still reviews your site.
The code is half the answer. Your parcel is the other half.
Lines and easements
Where the lot lines really are, which setbacks apply on each side, and whether a utility or access easement takes the corner you had in mind.
Critical areas and slope
Steep slopes, wetlands and streams come with buffers that no citywide number shows. The report reads the county’s maps for your parcel.
Sewer, septic, water, trees
Whether sewer reaches the lot or it’s on septic, where the water service is, and which trees a city protects — the things that decide where a unit can actually go.
What Burien allows, what could fit on your lot, and a planning cost range. If something won’t fit, the report says so — and shows what might.
Where this page comes from.
Read from the Burien municipal code and the city’s own pages on November 5, 2026. The same table feeds the HousUp report, so the report and this page never disagree. Cities amend their codes; before you design anything, confirm the current wording with the city.
2 sources, read November 5, 2026
Find out what your property could become.
Type your address. Within a few hours: what Burien allows, what could fit, and a planning cost range. Free, no obligation.