CAP_14 / FINANCING / SAMMAMISH
An honest, builder-side walkthrough of how Sammamish homeowners actually fund an ADU in 2026 — HELOC, construction-to-perm, cash-out refi, and renovation loans — with real numbers from current Sammamish projects, not a generic lender brochure.
Cost is anchored to our 2023–2025 Puget Sound trade-bid archive scaled by Sammamish'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 Sammamish projects in the last 24 months.
OPT_01
Prime + 0.5–2% (≈ 8.75–10.25%)
LTV Up to 85% combined LTV
Most Sammamish 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 Sammamish 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
Sammamish 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)
Sammamish 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.
A typical 800 sqft detached ADU in Sammamish runs around $446k 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 Sammamish bids, not generic per-sqft averages.
Empirical King/Pierce/Snohomish appraisals 2023–2025 show $1 of ADU build returns roughly $0.70–$0.85 of appraised value. For a $446k build in Sammamish, expect an appraisal lift around $350k against an estimated median home value of $1700k. 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. Sammamish permit reviews currently average 12–16 wk, so plan for that many weeks of pre-construction carry before draws begin.
On a $446k all-in basis at ~6.2% blended financing plus a 30% operating buffer (taxes, insurance, vacancy, maintenance), break-even rent works out to about $2,996/mo. Long-term 1–2 BR market rents in Sammamish typically exceed that, which is why ADUs pencil here.
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 Sammamish.
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 (~$350k). At Washington's 1% statutory cap plus voter levies, that's an extra $321–$379/mo on your tax bill. Underwrite that into your pro forma.
Yes for construction-to-perm and HomeStyle/CHOICERenovation, no for HELOC. Most lenders will credit 75% of projected Sammamish 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.
Sammamish doesn't currently publish an ADU-specific incentive program, but Washington's HB 1337/1110 preemption removed many fee barriers statewide. Some Puget Sound Energy and Seattle City Light efficiency rebates apply to new ADU envelopes and heat pumps.
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.
“Tree-retention is the #1 constraint — every >10″-DBH conifer counts. We design footprint AROUND the canopy.”
Bar shows pour-friendly months · dot marks the current month.
Station-area lots earn the largest rent premium in this market.
Rental yield estimate: $3,100–3,900 / mo — Lake Washington SD premium
Critical-area incentive: ADU bonus FAR when preserving 70%+ tree canopy
“Klahanie DADUs near the village center pre-lease faster than any city we build in.”
Big-bank ADU lending in Sammamish is a maze. We'll match you to three regional lenders we've personally closed with this year.
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