DADU feasibility · Fauntleroy & Seaview
Building a DADU in Fauntleroy & Seaview
Fauntleroy has large lots and heavy canopy on ground that slopes steadily toward the water.
This profile is measured from City of Seattle open data across 5,788 parcels in Fauntleroy/Seaview — not estimated, and not the same numbers as any other neighborhood on this site.
Lot sizes in Fauntleroy & Seaview
Lots run large — most above 5,000 sq ft with a substantial share above 7,200 and a real block above 10,000. Space to build is not the problem.
Parcel counts by lot size, Fauntleroy/Seaview. Source: King County parcels via Seattle's ADUniverse dataset.
28% of parcels here are under 5,000 sq ft and 72% 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 Seattle repealed the old 3,200 sq ft minimum lot area for a DADU, so small lots are no longer excluded; they are simply governed by the floor-area budget instead.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
A significant slide-prone share and meaningful steep slope, concentrated on the slopes running down toward Puget Sound. Canopy is the highest measured in this set, so trees and slope frequently constrain the same rear yard.
Fauntleroy & Seaview 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
Slope and landslide-prone ground
13.7% of Fauntleroy & Seaview is mapped as steep slope (40% or greater) and 20.6% 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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02
Liquefaction and soil conditions
14.4% of Fauntleroy & Seaview 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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03
Side sewer, water and electrical capacity
26% of buildings here predate 1940 and 38% 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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04
Protected trees
Tree canopy covers 33.7% of Fauntleroy & Seaview (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
Physical fit on a small lot
28% 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 50003,729 parcels
- SF 7200986 parcels
- LR1324 parcels
- LR2257 parcels
- RSL131 parcels
84.2% of parcels are Neighborhood Residential or Residential Small Lot; 14% 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 – 197538%
- After 197532%
Long runs on deep lots, plus grade. Trenching and foundation work carry more of the budget here than the cottage itself.
Fauntleroy & Seaview DADU questions
Can I build a DADU in Fauntleroy & Seaview?
In almost all cases the zoning allows it. 84.2% of parcels in Fauntleroy & Seaview 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 Fauntleroy & Seaview?
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. 72% of Fauntleroy & Seaview parcels are 5,000 sq ft or larger, so whether you reach the cap depends heavily on which block you are on.
What is most likely to block a DADU in Fauntleroy & Seaview?
Slope and landslide-prone ground — 13.7% of Fauntleroy & Seaview is mapped as steep slope (40% or greater) and 20.6% 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.
Do I need a feasibility study before designing a DADU in Fauntleroy & Seaview?
You are not required to have one. But the checks that decide feasibility — setbacks against the existing house, FAR headroom, tree tiers, mapped critical areas, side sewer condition, and construction access — are all cheaper to answer before you commit to an architect or a plan set than after. In Fauntleroy & Seaview specifically, the geotechnical question comes first: with this much mapped slope and slide-prone ground, a soils report can change the project before a designer draws anything.
Next step
Run these checks on your own Fauntleroy & Seaview lot.
This page tells you what Fauntleroy & Seaview looks like as a whole. The Seattle DADU Pro Guide walks your specific address through the same review — setbacks and FAR headroom, tree tiers, mapped critical areas, side sewer and panel capacity, the permit roadmap, and a scoring template you fill in yourself.