CAP_14 / FINANCING / SEATTLE
An honest, builder-side walkthrough of how Seattle homeowners actually fund an ADU in 2026 — HELOC, construction-to-perm, cash-out refi, and renovation loans — with real numbers from current Seattle projects, not a generic lender brochure.
Cost is anchored to our 2023–2025 Puget Sound trade-bid archive scaled by Seattle's cost multiplier. Home-value estimate is a directional median, not a site-specific appraisal. Replace with your own numbers before signing anything.
We don't originate loans, so this isn't a sales sheet. Each row is what we've actually watched close on Seattle projects in the last 24 months.
OPT_01
Prime + 0.5–2% (≈ 8.75–10.25%)
LTV Up to 85% combined LTV
Most Seattle owners with 5+ years of equity. Draws as we hit milestones; you pay interest only on what's drawn.
Watch Variable rate — model worst-case at Prime + 3% before committing.
OPT_02
Prime + 1–3% during build, then locked refi
LTV 75–80% of as-completed value
Ground-up DADUs in Seattle where you'd rather not touch your primary mortgage. Single close, draws funded by the bank as inspections clear.
Watch Appraisal is done on plans + comps; lender chooses the appraiser. We supply the comp set.
OPT_03
Market + 0.25–0.75% (≈ 6.75–7.5% as of writing)
LTV Up to 80% LTV
Seattle owners still sitting on a 4–5% note rarely want this; owners with a 6.5%+ note often net better all-in by resetting.
Watch You're re-amortizing 30 years on the entire balance — model the lifetime interest delta, not just the rate.
OPT_04
Market + 0.5–1.5%
LTV Up to 97% of as-completed value (owner-occupied)
Seattle buyers wrapping the ADU build into a purchase, or low-equity owners. Single 30-year loan, no HELOC stack.
Watch HUD-style draw schedule with consultant sign-offs — adds 2–3 weeks to permitting timeline.
Local incentive Permit fee waiver of ~$2,500 available for income-restricted ADUs through the Office of Housing.
A typical 800 sqft detached ADU in Seattle runs around $425k all-in (design, permits, construction, utilities). Garage conversions land 35–45% lower; attached ADUs (AADU) split the difference. These numbers are pulled from our active Seattle bids, not generic per-sqft averages.
Go deeper: Read the Seattle ADU financing: 7 loan products compared (2026) guide
Empirical King/Pierce/Snohomish appraisals 2023–2025 show $1 of ADU build returns roughly $0.70–$0.85 of appraised value. For a $425k build in Seattle, expect an appraisal lift around $330k against an estimated median home value of $920k. Rental income is the bigger long-term return.
On a $300k construction-loan draw at ~8.25% interest-only, expect about $2,063/mo during the build. Seattle permit reviews currently average 12–16 wk, so plan for that many weeks of pre-construction carry before draws begin.
On a $425k all-in basis at ~6.2% blended financing plus a 30% operating buffer (taxes, insurance, vacancy, maintenance), break-even rent works out to about $2,855/mo. Long-term 1–2 BR market rents in Seattle typically exceed that, which is why ADUs pencil here.
Go deeper: Read the King County side sewer permits for ADUs: cost & timeline (2026) guide
For owners with 30%+ equity, HELOC wins on speed and flexibility. For ground-up DADUs without significant existing equity, construction-to-perm is the default. Cash-out refi is rare unless the existing note is above 6.5%. Renovation loans (HomeStyle/CHOICERenovation) work best when the ADU is bundled into a new purchase in Seattle.
Yes — the assessor will reappraise the parcel after the certificate of occupancy. Expect the assessed value to rise by roughly the appraisal lift figure above (~$330k). At Washington's 1% statutory cap plus voter levies, that's an extra $303–$358/mo on your tax bill. Underwrite that into your pro forma.
Go deeper: Read the Seattle ADU financing: 7 loan products compared (2026) guide
Yes for construction-to-perm and HomeStyle/CHOICERenovation, no for HELOC. Most lenders will credit 75% of projected Seattle market rent against debt-to-income once you provide a signed lease or a Form 1007 rent schedule from the appraiser. We supply local comparable rent sets for the appraisal package.
Permit fee waiver of ~$2,500 available for income-restricted ADUs through the Office of Housing. Beyond that, Washington's statewide ADU bills (HB 1337, HB 1110) preempt local fee waivers for affordability-restricted units. We help clients in Seattle navigate eligibility for any active program at scope-of-work.
Go deeper: Read the Cold-weather concrete pours in the Puget Sound (2026 field guide) guide
INTERNAL_LINKS / Deep Map
A live dossier from our field PMs: the permit counter, the soils, the bylaw that just changed, and the streets where ADUs are already cash-flowing.
We track lunar weeks for slab pours — clear nights drop ambient temperature faster, which slows surface curing. Schedule wet slabs midweek under waxing light.
Loading. Our standard crew window is 7:00–17:00 weekdays — noise ordinances in most Puget Sound cities allow exterior power tools only inside that band.
Sunday exterior work is restricted in most Puget Sound jurisdictions. We sequence interior trades around it.
Calculating live drive times to four metro anchors…
Real commute time matters for ADU rent comps — and for our crews. We keep installs within a 60-minute radius of our Puget Sound yard.
Data provenance
Drive times pulled live from the Google Routes API (traffic-aware matrix). Each request is timestamped so you can see exactly when the numbers were last refreshed — no stale brochure data.
Lot context matters as much as zoning. We pre-screen access, slope, and tree canopy from imagery before scheduling the site visit.
Waterfront lots: shoreline excavation and barge access windows depend on these. We schedule pours away from extreme low tides when the soils dry unevenly.
Open-data signal of nearby construction velocity — useful for ADU comps and for anticipating examiner workload.
“Since 2019, one AADU + one DADU on most single-family lots — no off-street parking required if you're within ¼ mile of frequent transit.”
Bar shows pour-friendly months · dot marks the current month.
Station-area lots earn the largest rent premium in this market.
Rental yield estimate: $2,400–3,100 / mo for a 600–800 sq ft DADU
MFTE-adjacent ADU rentals can qualify for property-tax relief in select tracts
“Alley-loaded DADUs in Wallingford routinely pencil $80k above appraisal at refi.”
“They pre-checked the FAR before we signed — saved us redrawing the loft twice.”
Big-bank ADU lending in Seattle is a maze. We'll match you to three regional lenders we've personally closed with this year.
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