DADU feasibility · Greenwood & Phinney Ridge
Building a DADU in Greenwood & Phinney Ridge
Greenwood and Phinney Ridge are the north end's most consistent DADU market: mid-size lots, stable ground, and high owner-occupancy.
This profile is measured from City of Seattle open data across 8,574 parcels in Greenwood/Phinney Ridge — not estimated, and not the same numbers as any other neighborhood on this site.
Lot sizes in Greenwood & Phinney Ridge
A large, even spread across the 3,200–7,200 sq ft range, with a meaningful number above 7,200. This is the profile where a standard pre-approved plan has the best chance of fitting without redesign.
Parcel counts by lot size, Greenwood/Phinney Ridge. Source: King County parcels via Seattle's ADUniverse dataset.
61% of parcels here are under 5,000 sq ft and 39% 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 Seattle repealed the old 3,200 sq ft minimum lot area for a DADU, so small lots are no longer excluded; they are simply governed by the floor-area budget instead.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
Very little slide-prone ground. The notable local feature is peat settlement-prone soil, which shows up across a measurable share of the area and is a foundation-design question your geotech will want to see early.
Greenwood & Phinney Ridge 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
55% of buildings here predate 1940 and 16% 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
61% 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
Protected trees
Tree canopy covers 25.4% of Greenwood & Phinney Ridge (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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04
Liquefaction and soil conditions
5.7% of Greenwood & Phinney Ridge 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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05
Slope and landslide-prone ground
2.1% of Greenwood & Phinney Ridge 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 50007,118 parcels
- LR2263 parcels
- RSL206 parcels
- LR3197 parcels
- LR1172 parcels
85.4% of parcels are Neighborhood Residential or Residential Small Lot; 8.7% 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 194055%
- 1940 – 197516%
- After 197527%
Solid mid-century stock. The most common constraint is not the sewer but the rear-yard grade change along the ridge, which affects how much excavation a slab or crawlspace needs.
Greenwood & Phinney Ridge DADU questions
Can I build a DADU in Greenwood & Phinney Ridge?
In almost all cases the zoning allows it. 85.4% of parcels in Greenwood & Phinney Ridge 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 Greenwood & Phinney Ridge?
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 61% of Greenwood & Phinney Ridge 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 Greenwood & Phinney Ridge?
Side sewer, water and electrical capacity — 55% of buildings here predate 1940 and 16% 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.
Do I need a feasibility study before designing a DADU in Greenwood & Phinney Ridge?
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 Greenwood & Phinney Ridge specifically, start with the side sewer and the panel — on flat, stable ground like this, utilities are what most often reset the budget.
Next step
Run these checks on your own Greenwood & Phinney Ridge lot.
This page tells you what Greenwood & Phinney Ridge 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.