202 23RD AVE
Mann · LR2 · 7,847 sq ft lot
202 23RD AVE (Mann, LR2): a backyard cottage is blocked at physical fit — rear-yard clear span is too narrow.
This place has a history
Duwamish, Suquamish & other homelands. Indigenous relationships to this land continue today.
Homeland boundaries and nearby place names are approximate context, not records about this lot.
1869Inside Seattle's first city limits
Area of First Incorporation
ordinancePlattedYesler # 42 & 47
Plat name from the King County Assessor; its recording year is not in the State Archives index.
See the complete timeline
Tap a record for its explanation and evidence. Missing dates and records remain unknown.
OngoingDuwamish, Suquamish & other homelands
Indigenous relationships to this land continue today. Approximate regional context from Native Land Digital and source-recorded place names. Nearby landscape references are schematic; exact historic map sheets and positional accuracy are not established. These sources do not determine this lot’s former shoreline, elevation, name, or legal/archaeological status. Explore the former tidal landscape around this neighborhood. These are schematic regional references, not a lot classification.
1850sDonation claim of Henry L. Yesler (Nos. 42 & 47)
Free federal land for settlers under the 1850 Donation Land Claim Act. The claim is named in this lot's King County legal description.
1855Treaty of Point Elliott signed
Signed in 1855 and ratified in 1859. The treaty records land cession and retained fishing, hunting and gathering rights; it did not end Indigenous relationships to the land. This is regional context, not a deed for this lot.
Museum: Treaty of Point Elliott1869Inside Seattle's first city limits
Area of First Incorporation
ordinancePlattedYesler # 42 & 47
Plat name from the King County Assessor; its recording year is not in the State Archives index.
Sources & limits
Lot records combine the King County Assessor, Washington State Archives plat index, Seattle annexation records and federal survey context. A plat is a recorded map dividing land into lots; an early index date may be a later recording.
These records do not reconstruct an ownership chain or establish a racial covenant, displacement event or historical community at this lot. Nearby museum stories are wider context.
Indigenous relationships to this land continue today. Approximate regional context from Native Land Digital and source-recorded place names. Nearby landscape references are schematic; exact historic map sheets and positional accuracy are not established. These sources do not determine this lot’s former shoreline, elevation, name, or legal/archaeological status. Explore the former tidal landscape around this neighborhood. These are schematic regional references, not a lot classification.
Treaty context and sourcesWhere the screen stops
Stages are evaluated in a fixed order. A later constraint is only named as the reason once every earlier stage has resolved, so an unknown never gets reported as a failure.
- 1. legal capacityPasses
The verified LR2 rule set permits a detached accessory dwelling unit.
- 2. physical fitBlocked
The citywide screen rejected this lot: DADU blocked: widest clear span behind the house is 12.3 ft, below the 16 ft cottage width
- 3. financial plausibilityPasses
Under screening rule gap-dadu-financial@v1, modeled income covers modeled debt service at the favorable end of the assumed cost range.
- 4. affordable-program applicabilityNot evaluated
Public program applicability is evaluated only where the physical screen passes; physical fit is blocked for this parcel, so no program conclusion is asserted.
- 5. verification readinessPasses
Every screening input this artifact depends on is present; field verification is still required before relying on the result.
What blocks it: Rear-yard clear span is too narrow
The widest measured clear span in the retained-house envelope is below the 16-foot screening width for the reference cottage. Screen reason: DADU blocked: widest clear span behind the house is 12.3 ft, below the 16 ft cottage width Lot on record: 7,847 sqft, regular, no alley access.
- What would resolve this
- Verify rear-yard dimensions on a survey and test a narrower or lot-specific cottage plan.
- Capability this needs
- plan
Limitations of this screen
- Public-data screen only. It includes no site visit, survey, title review, or permit determination.
- Legal capacity comes from joined zone rules; physical fit comes from the citywide parcel screen. A parcel can pass one and not the other.
- The citywide physical screen covers the NR, RSL, LR, MR, HR, and legacy SF residential zone families. Outside them physical fit is reported as unknown, never as a physical failure.
- Current SMC 23.42.022 (Ord. 127375/127376, 2025) allows accessory dwelling units as a housing use in every zone where housing uses are allowed. The former 2023 lowrise principal-unit-type gate and 650-square-foot cap no longer apply; the current cap is 1,000 square feet.
- A parcel that intersects the official Seattle Shoreline Environments overlay is reported as legally unknown, not blocked. Current SMC 23.42.022.A requires Shoreline District ADUs to comply with Chapter 23.60A, which this screen has not read per environment; earlier evaluations (through gap-dadu-v1.6) reported the overlay as a prohibition.
- Standing structures are measured spatially against the lot (dadu-footprint-evidence-v1), not by the footprint layer's parcel identifier. A lot with a King County building record but no measured footprint is reported as physically unknown; a lot with neither is reported with a no-principal-dwelling caution.
- The physical screen treats every standing structure as immovable. Where a lot fails only because of its own garage or outbuilding, the screen also reports whether the reference cottage would fit with the house alone retained; that is a caution on a blocked result, not a pass.
- Financial plausibility applies a published screening rule to explicit planning assumptions and a HUD SAFMR rent basis. It is not a bid, quote, appraisal, or forecast, and no Seattle cost calibration supports it.
- The financial stage varies only by ZIP-level one-bedroom HUD SAFMR. All parcels in the same SAFMR geography receive the same result under the citywide cost assumptions; this is not parcel-specific financial evidence.
- Financial geography patterns are rent-basis patterns, not observed construction-cost or project-outcome patterns. They must not be used to deprioritize investment in the neighborhoods they name.
- Public program applicability describes whether a listed program reaches this site. Household eligibility — income, ownership, occupancy, disability, financing — is never collected or inferred.
- The first detected blocker is the first blocking condition under the published stage and within-stage detection order, and attribution is withheld when an earlier stage is unknown. It is not a claim that other constraints matter less.
- Stages are evaluated independently wherever their inputs allow, so a later-stage blocker does not imply that earlier stages passed.
Provenance and reuse
Screen gap-dadu-v1.7 under plan family Backyard cottage / DADU screen, read from the warehouse on . Unlike a published gap brief, this page tracks the warehouse and will change when the underlying evaluation does — cite the screen version and date above alongside the URL.
This is a screen, not a permit determination, and no part of it has been reviewed by the City of Seattle. You are welcome to use it without asking us, and to disagree with it. The full citywide artifact and the methodology carry the rules, sources, and exclusions behind every statement here.