DADU feasibility · Seward Park
Building a DADU in Seward Park
Seward Park's 3,246 parcels are 76% at 5,000 sq ft or larger and 77.4% detached, so geometry is rarely the issue. The 33.5% tree canopy — among the highest measured — puts SMC 25.11 tree tiers at the center of feasibility.
Seward Park pairs some of the largest lots in south Seattle with some of the heaviest tree canopy. This profile is measured from City of Seattle open data across 3,246 parcels in Seward Park — not estimated, and not the same numbers as any other neighborhood on this site.
Lot sizes in Seward Park
Lot sizes run large — a substantial share above 7,200 sq ft and a real block above 10,000. On geometry, this is among the easiest places in the city to fit a cottage.
Parcel counts by lot size, Seward Park. Source: King County parcels via Seattle's ADUniverse dataset.
24% of parcels here are under 5,000 sq ft and 76% are 5,000 sq ft or larger — a high 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 Seattle repealed the old 3,200 sq ft minimum lot area for a DADU, so small lots are no longer excluded; they are simply governed by the floor-area budget instead.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
Stable ground with modest steep slope toward the lake. The binding constraint is trees: canopy here is among the highest measured in this set, which puts SMC 25.11 tree tiers at the centre of the feasibility question.
Seward Park 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
26% of buildings here predate 1940 and 42% 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
Protected trees
Tree canopy covers 33.5% of Seward Park (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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03
Liquefaction and soil conditions
9.7% of Seward Park 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
Slope and landslide-prone ground
7.7% of Seward Park 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.
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05
Physical fit on a small lot
24% 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.
Zoning and utilities
Zoning mix
- SF 50001,785 parcels
- SF 7200862 parcels
- SF 9600385 parcels
- LR3132 parcels
- NC2-5524 parcels
93.9% of parcels are Neighborhood Residential or Residential Small Lot; 5.1% 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 194026%
- 1940 – 197542%
- After 197527%
Larger lots mean longer utility runs. Budget trenching distance from the house to the rear of the lot, and expect an arborist report to be part of the permit path.
Seward Park DADU questions
Can I build a DADU in Seward Park?
In almost all cases the zoning allows it. 93.9% of parcels in Seward Park 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 Seward Park?
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 76% of Seward Park parcels at 5,000 sq ft or larger, most owners here have room to reach the cap rather than being cut off by it.
What is most likely to block a DADU in Seward Park?
Side sewer, water and electrical capacity — 26% of buildings here predate 1940 and 42% 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 Seward Park
Free, written for Seattle's code, and picked from Seward Park'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 Seward Park.
This page tells you what Seward Park 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.