DADU feasibility · Green Lake
Building a DADU in Green Lake
Green Lake is one of the flattest DADU markets in Seattle — just 2.7% of its 4,885 parcels sit on steep slope. But 72% of lots are under 5,000 sq ft, so the lot-wide floor-area budget, not the ground, decides most projects.
Green Lake is one of the flattest DADU markets in Seattle, which removes the constraint that kills the most projects elsewhere. This profile is measured from City of Seattle open data across 4,885 parcels in Green Lake — not estimated, and not the same numbers as any other neighborhood on this site.
Lot sizes in Green Lake
Green Lake is dominated by lots under 5,000 sq ft — the platting is tight and consistent. That does not disqualify a cottage under current code, but it puts FAR and lot coverage in charge of the outcome rather than setbacks.
Parcel counts by lot size, Green Lake. Source: King County parcels via Seattle's ADUniverse dataset.
72% of parcels here are under 5,000 sq ft and 28% are 5,000 sq ft or larger — a low share among the 18 areas profiled here. Seattle repealed the old 3,200 sq ft minimum lot area for a DADU, so small lots are no longer excluded; they are simply governed by the floor-area budget instead.
What the ground looks like
Almost no landslide-prone ground and very little steep slope. Where Green Lake does get complicated is liquefaction: the low ground nearer the lake carries a meaningful share of mapped liquefaction-prone soils, which is a foundation-cost question rather than a permit blocker.
Green Lake against the median of the 18 Seattle areas profiled here. Hazard layers clipped to the neighborhood boundary; canopy is area-weighted by census block group.
What decides feasibility here, in order
Ranked by what this neighborhood's own measurements say — not a generic checklist.
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01
Side sewer, water and electrical capacity
53% of buildings here predate 1940 and 12% were built between 1940 and 1975. Older stock means older side sewers and smaller electrical services — the two utility findings that most often reset a DADU budget.
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02
Physical fit on a small lot
72% of parcels here are under 5,000 sq ft. Lot size no longer disqualifies a DADU, but on a tight lot the lot-wide FAR and lot-coverage budget — which ADU floor area now counts toward — usually binds before setbacks do.
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03
Liquefaction and soil conditions
12% of Green Lake sits on mapped liquefaction-prone soils (Seattle median here: 8.7%). This rarely stops a project, but it changes foundation design and belongs in the budget before you price a build.
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04
Protected trees
Tree canopy covers 25.5% of Green Lake (Seattle median here: 26.9%). Seattle's tree code (SMC 25.11) protects trees by tier, and a Tier 2 tree with its root protection area falling across your rear yard can move or shrink a cottage even on a large lot.
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05
Slope and landslide-prone ground
2.7% of Green Lake is mapped as steep slope (40% or greater) and 0% as potential landslide area, against Seattle medians of 7.7% and 4.4% across the areas profiled here. Land inside an Environmentally Critical Area under SMC 25.09 triggers additional review and, in practice, a geotechnical report before design.
Zoning and utilities
Zoning mix
- SF 50003,728 parcels
- LR3357 parcels
- LR2267 parcels
- LR190 parcels
- MR58 parcels
76.9% of parcels are Neighborhood Residential or Residential Small Lot; 15.3% are Lowrise. Zone labels reflect the parcel dataset's legacy single-family categories, which map into today's Neighborhood Residential zone under Ordinance 127376.
Housing age
- Before 194053%
- 1940 – 197512%
- After 197532%
Housing is mostly interwar and mid-century. Panel capacity is the more common surprise here than sewer condition — a 100-amp service will not carry a second full dwelling without an upgrade.
Green Lake DADU questions
Can I build a DADU in Green Lake?
In almost all cases the zoning allows it. 76.9% of parcels in Green Lake sit in Neighborhood Residential or Residential Small Lot zoning, where detached accessory dwelling units are permitted, and Seattle removed both the old minimum-lot-size test and the owner-occupancy requirement. The real question is whether a compliant cottage physically fits your lot and whether utilities can serve it.
How big can a DADU be in Green Lake?
The citywide caps apply: 1,000 sq ft of gross floor area for an ADU with up to two bedrooms, or 1,200 sq ft with three or more. On top of that, your lot has a single FAR and lot-coverage budget shared with the existing house — which is what actually limits most projects. With 72% of Green Lake parcels under 5,000 sq ft, the cap is usually academic here — the lot-wide budget runs out first, and a 600–800 sq ft cottage is the realistic target.
What is most likely to block a DADU in Green Lake?
Side sewer, water and electrical capacity — 53% of buildings here predate 1940 and 12% were built between 1940 and 1975. Older stock means older side sewers and smaller electrical services — the two utility findings that most often reset a DADU budget.
Read these before you spend anything on Green Lake
Free, written for Seattle's code, and picked from Green Lake's own numbers rather than a generic list.
All 20 guides and notes → · every record we can read on a Seattle parcel →
Next step
Get the report for your address in Green Lake.
This page tells you what Green Lake looks like as a whole. The customized feasibility report runs your specific address through the same review — setbacks and FAR headroom, tree tiers, mapped critical areas, side sewer and panel capacity, and a permit path — measured from City records and reviewed by a person. Prefer to self-study? The Pro Guide covers the same rules.