Housing model profileA5
Big-house conversion
3 homes, no new backyard building
A large existing house is converted into three rental flats without adding a new detached building.
Urban Acupuncture housing model
Repeatable program, parcel screening, schematic placement, and economics model — not City-pre-approved construction drawings.
- Homes
- 3
- Building type
- Three flats inside one existing house
- Existing house
- Keep + convert
- You end up with
- 3 homes, no new backyard building. Keep the structure; divide the interior without a backyard building.
- You put in
- Renovation or construction funds, cash or borrowed; ongoing operating costs. Get a site-specific budget before committing.
- Your role
- Owner commissioning the work; landlord if rented, or host for family housing.
- Timeline
- Interior/site assessment → design and permits → construction → occupancy. Ask the designer and contractor for durations; no project schedule is established here.
- It works when
- A sufficiently large existing house, generally 2,400 square feet or more; A workable interior layout for three complete homes; A code-compliant path for entries, egress, fire separation, and utilities.
- Main uncertainty
- Renovation/site costs and rent may leave a monthly loan shortfall. Family use does not produce rental income.
- Next step
- Bring measured plans or a survey to a residential designer, then request a contractor budget and financing proposal.
Representative site plan
Interior conversion only — 3 flats, no new building. Drawn on a typical lot — every real lot differs, so this is illustrative, not a site-specific layout.
The program
3 homes — 3 flats in the converted house.
+2 net new homes per lot (market-rate).
Workbook-baseline economics
At modeled rent and 80% permanent debt, rents fall $657/mo short of the loan payment.
- Monthly loan shortfall after rents
- $657/mo short
- Total project cost
- $725K
- Does it pencil?
- Rents fall short
- What to check first
- Parcel-specific inputs
At 80% permanent debt; excludes reserves and owner-specific costs.
$242K per home created
Modeled rent falls $657/mo short of the permanent loan payment.
Representative workbook baseline — not adjusted for a specific parcel.
Illustrative workbook baseline — a real packet adjusts these with the parcel's own assessor, market, and rent data.
Where it fits
Neighborhood-residential lots with a large single-family house, generally 2,400 sq ft or larger, where the main opportunity is interior conversion rather than a rear-yard build.
What must be true
- A sufficiently large existing house, generally 2,400 square feet or more
- A workable interior layout for three complete homes
- A code-compliant path for entries, egress, fire separation, and utilities
Verify before relying on it
- Measured floor plans and structural conditions
- Egress, fire/life-safety, utility metering, and accessibility scope
- Renovation cost and achievable rents
Check Big-house conversion at a Seattle address
Choose a parcel to open this exact model in the feasibility packet. We will test its screening match, place the program schematically, and adjust the economics with parcel data.
If the plan does not pass this parcel's screening, the packet will say so and offer other paths.
Funding and programs that may apply
Programs that may pair with this plan
Matched from plan facts only. Parcel geography, income, utility territory, and owner facts can change the final list.
Home Improvement Property Tax Exemption
King County Assessor / RCW 84.36.400
Temporary property-tax exemption on qualifying added improvement value.
Exempts added value up to 30% of original structure value
Washington State HEAR Electrification Rebates
Washington Department of Commerce / local HEAR administrators
Administrator-run rebates for eligible electrification equipment and installation. Measures, amounts, coverage and available funding vary by local administrator.