Mountlake Terrace, WA · RENTAL_ROI_2026
3-Bedroom ADU rental ROI in Mountlake Terrace
What a new-build 3-bedroom adu ADU actually returns in Mountlake Terrace — real rent comps, all-in cost, cap rate, and 10-year wealth build.
Market rent
$3,400/mo
Cap rate (net)
9.3%
Payback
10.8 yrs
All-in build
$388K
10-year ROI projection
Conservative assumptions: 8% vacancy, 4% maintenance reserve, no rent growth, and a flat 45% appreciation across 10 years (Puget Sound 15-year median).
| Gross annual rent | $41K |
| – Vacancy + maintenance (12%) | –$5K |
| = Net operating income | $36K |
| All-in build cost | $388K |
| 10-yr rental income | $359K |
| 10-yr appreciation (45%) | $174K |
| 10-yr total return | $533K |
Rare and premium — best when zoning allows a 1,200 sqft DADU.
Other rental sizes in Mountlake Terrace
3-Bedroom ADU ROI in nearby cities
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Request a Mountlake Terrace pro formaFrequently asked
What ROI can I expect on a Mountlake Terrace ADU at $2,200–$2,800/mo rent?
At $2,200–$2,800/mo long-term rent on a $210K all-in 600 sqft DADU in Mountlake Terrace, unleveraged cap pencils 4.8–6.2% in 2026. Leveraged cash-on-cash (75% HELOC at 8.5%) is 7.5–11%. Tax benefits (depreciation, mortgage interest, operating expense write-offs) typically add 1.5–2.3% to after-tax yield for owners in the 32–37% federal bracket. Mid-term rentals (30–90 day) on the same unit raise gross by 12–22% but add management complexity. 10-year IRR including appreciation lands 9–14% in our Mountlake Terrace rental hold models.
How long until a Mountlake Terrace ADU pays for itself?
Cash-on-cash payback (rent net of all expenses recovers down payment + closing) on a Mountlake Terrace ADU at $2,200–$2,800/mo rent typically lands year 8–11 on a leveraged build, year 14–18 on all-cash. But payback is the wrong metric — total return including appreciation, principal paydown, depreciation shield, and Section 121 exclusion of up to $250K/$500K capital gain on sale is what matters. With those included, Mountlake Terrace ADUs typically hit IRR breakeven (above your cost of capital) by year 3–4 on a leveraged build.
Should I rent my Mountlake Terrace ADU long-term, mid-term, or short-term?
Default to long-term (30+ days) for highest after-tax IRR in Mountlake Terrace because of WA's lack of state income tax and no STR management overhead. Mid-term (30–90 days, often furnished, traveling nurses or insurance-displaced) is the sweet spot in Mountlake Terrace submarkets near Swedish, Overlake, UW Medicine — adds 12–22% gross with manageable turn frequency. Short-term (≤30 days) faces Mountlake Terrace-specific permitting friction and platform fees that erode the apparent premium; only recommended in very specific Mountlake Terrace sub-markets near tourist anchors.
Go deeper: Read: Long-term vs. short-term rental ADU in Seattle
What's the expected appreciation on a Mountlake Terrace ADU?
Mountlake Terrace's 10-year median single-family appreciation (FHFA index) runs 5.8–7.2%/yr. Adding a permitted, separately-metered ADU typically adds 30–50% to parcel value at sale — appraisers value via either income approach (cap rate on rental NOI) or sales comp. The marginal value-add ratio (parcel-with-ADU vs parcel-without) is 1.18–1.32 in Mountlake Terrace based on our 2024–2025 sales comp pulls. Expect appreciation to track the broader Mountlake Terrace market post-build.
Does a Mountlake Terrace ADU make sense if I plan to sell in 5 years?
Math depends on entry price vs market spread. Owner-occupants who build for personal use (in-law, aging-in-place) usually recoup 75–95% of build cost at 5-year sale; the gap is the cost of personal use. Investors building for rental should not exit in 5 years — too short to capture full IRR after closing costs and cap-rate compression risk. The right Mountlake Terrace ADU horizon is 10+ years; 7+ if you anticipate refinancing or selling into a yield-hungry market.
What are typical Mountlake Terrace ADU operating expenses?
Annualized opex for a turn-key Mountlake Terrace long-term rental DADU: property tax increment $1,900–$3,100, insurance increment $400–$700, utilities (if landlord-paid; typically tenant-paid via separate meters) $0–$1,200, maintenance reserve 5% of rent, management 8% of rent if outsourced, vacancy 5% of rent. Total opex 28–34% of gross rent, leaving 66–72% NOI. Self-managed owners can compress to 22–26% but trade time for margin.
How do I value a Mountlake Terrace ADU for sale?
Two methods to triangulate: (1) sales comp — pull arm's-length sales of ADU-equipped Mountlake Terrace parcels within 1 mile, 12 months; (2) income approach — annual NOI / cap rate (currently 5.5–6.8% in Mountlake Terrace for stabilized 1BR rentals). The two should converge within 8–12%. Appraisers in Mountlake Terrace now apply both and weight toward the higher value when sales comps are thin. Bring both packets to listing.
What's the Mountlake Terrace ADU rent trajectory through 2030?
Long-term Mountlake Terrace rent growth from 2014–2024 averaged 4.6%/yr including the 2020 dip. Forward-looking, with WA's housing supply catching up under HB 1110 (middle housing) and HB 1337 (ADUs), expect Mountlake Terrace 1BR rent growth to moderate to 2.8–3.8%/yr through 2030. That still beats CPI inflation by ~120 bps, which preserves real-rent escalation on Mountlake Terrace ADU pro formas. Underwrite at 3% to be conservative.
Is leveraged Mountlake Terrace ADU yield better than unlevered?
Yes, currently. At 75% LTV, 8.5% HELOC, $210K build, $2,500/mo rent, after-debt cash flow lands $480–$720/mo (3.0–4.5% cash-on-cash before tax) vs unlevered 4.8–6.2% cap. Leverage looks worse on cap-rate math but better on cash-on-cash because the debt-service spread to gross rent is positive after ~year 3 as rent compounds against fixed-rate debt. Inverts only if HELOC variable rate spikes above ~10.5%.
What's the depreciation benefit on a Mountlake Terrace ADU?
Residential rental real estate depreciates over 27.5 years straight-line (IRC §168). On a $210K build with land allocated to primary parcel, depreciable basis is roughly $180–$210K. Annual depreciation deduction: $6,500–$7,600. At a 32% federal bracket that shields $2,080–$2,432 of taxes per year — a meaningful boost to after-tax IRR. Cost segregation can accelerate components (appliances, flooring, cabinetry) into 5–7 year buckets, lifting early-year deductions by 30–40%.
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