DADU feasibility · Mount Baker
Building a DADU in Mount Baker
Mount Baker's 2,360 parcels split evenly at the 5,000 sq ft line, and 52% predate 1940. Its 13.4% potential-landslide mapping along the ridge makes the geotechnical question come first.
Mount Baker's ridge gives it the view — and the slide-prone ground that comes with it. This profile is measured from City of Seattle open data across 2,360 parcels in Mt. Baker/North Rainier — not estimated, and not the same numbers as any other neighborhood on this site.
Lot sizes in Mount Baker
A smaller-lot profile than its southern neighbours, with a meaningful share under 3,200 sq ft. Combined with grade change, that pushes many Mount Baker cottages toward custom design rather than a standard plan.
Parcel counts by lot size, Mt. Baker/North Rainier. Source: King County parcels via Seattle's ADUniverse dataset.
50% of parcels here are under 5,000 sq ft and 50% are 5,000 sq ft or larger — a middling 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 Seattle repealed the old 3,200 sq ft minimum lot area for a DADU, so small lots are no longer excluded; they are simply governed by the floor-area budget instead.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
Substantial potential-landslide mapping along the ridge, plus steep slope and a notable liquefaction share on the lower ground toward the lake and the valley. This is a neighborhood where the geotechnical question comes first.
Mount Baker 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
9.5% of Mount Baker is mapped as steep slope (40% or greater) and 13.4% 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
Side sewer, water and electrical capacity
52% of buildings here predate 1940 and 10% 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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03
Liquefaction and soil conditions
12.6% of Mount Baker 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
Physical fit on a small lot
50% 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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05
Protected trees
Tree canopy covers 31.5% of Mount Baker (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.
Zoning and utilities
Zoning mix
- SF 50001,291 parcels
- LR1314 parcels
- SF 7200186 parcels
- LR2152 parcels
- RSL143 parcels
68.6% of parcels are Neighborhood Residential or Residential Small Lot; 23.1% 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 194052%
- 1940 – 197510%
- After 197531%
Older stock on sloped sites. Both access and utility routing are commonly the deciding costs rather than the building itself.
Mount Baker DADU questions
Can I build a DADU in Mount Baker?
In almost all cases the zoning allows it. 68.6% of parcels in Mount Baker 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 Mount Baker?
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. 50% of Mount Baker 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 Mount Baker?
Slope and landslide-prone ground — 9.5% of Mount Baker is mapped as steep slope (40% or greater) and 13.4% 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.
Read these before you spend anything on Mount Baker
Free, written for Seattle's code, and picked from Mount Baker'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 Mount Baker.
This page tells you what Mount Baker 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.