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FAQ_REDMOND / CITY_GUIDE

Redmond ADU FAQ

Real, locally-grounded answers about building an accessory dwelling unit in Redmond, WA — from someone who pulls Redmond permits every month. Permit windows, zoning, cost ranges, rent comps and incentives, all current to 2026.

Permit window
10–14 wk
Min lot size
5,000 sqft
Cost index (Seattle=1.00)
1.04×
Neighborhoods covered
6
FAQ / REDMOND

Building an ADU in Redmond — answered

  • What's Redmond's tree retention requirement?

    RZC 21.72 requires 35% existing canopy retention on residential lots, the strictest in King County. We do an arborist walk before locating the ADU pad — sometimes a 5-foot footprint shift saves a significant tree and a replanting plan.

    Go deeper: Read the Eastside deck cost & permits: cedar, IPE, composite (2026) guide

  • Can I build both a DADU and an AADU on a Redmond lot?

    Yes, RZC 21.08.220 allows one of each per lot, provided combined floor area stays within FAR limits and lot coverage is ≤45%.

    Go deeper: Read the DADU vs AADU in Puget Sound: which to build (2026) guide

  • Will my Redmond ADU need its own water meter?

    Not always. Sub-metering off the existing service is allowed. A separate meter is required only if combined fixture count exceeds the existing service size — usually 1" line is sufficient.

    Go deeper: Redmond ADU overview

  • Is owner-occupancy required in Redmond?

    No, Redmond removed the owner-occupancy requirement in 2022. Both units can be rented out long-term.

    Go deeper: Redmond ADU zoning lookup

  • How long does Redmond plan review really take?

    10–14 weeks from intake on a clean submittal. The civil/stormwater review is typically the long pole — we engage civil engineering during schematic design to compress that timeline.

    Go deeper: Redmond ADU permit timeline

  • What does an 800 sqft DADU cost in Redmond, WA?

    Based on our 2024–2025 bid archive, an 800 sqft detached ADU in Redmond lands at $485k–$600k all-in — design, permits, site work, construction, and utilities. A 600 sqft AADU (converting interior space + adding a separate entry, kitchen and bath) typically runs $260k–$350k, and a clean garage conversion lands at $145k–$205k. The variance inside each range comes from foundation type, slope, side-sewer condition, and finish level.

    Go deeper: Redmond ADU cost breakdown

  • How long does the Redmond permit process actually take?

    Plan on 10–14 wk for plan review once we submit a complete package. Pre-application work (zoning verification, site survey, soils report when ECA is in play, energy calcs) adds another 4–6 weeks before submittal. The cities that move fastest are the ones with a pre-approved plan program; Redmond's typical path is moderate for the Puget Sound.

    Go deeper: Redmond ADU permit timeline

  • What zoning rules apply to ADUs in Redmond?

    R-4 through R-8 — ADU + DADU permitted under RZC 21.08. Minimum lot size is 5,000 sqft. The biggest constraints we plan around are: Tree retention: 35% canopy retention required — Redmond is the strictest in King County; Stormwater: any net new impervious >2,000 sqft triggers full LID design. We pull GIS, zoning, and overlay data for your specific parcel during the feasibility step so we don't design something the permit reviewer will reject.

    Go deeper: Redmond ADU zoning lookup

  • Can I rent the ADU in Redmond as short-term (Airbnb)?

    Washington HB 1337 removed the statewide owner-occupancy requirement, but short-term rental rules are set city-by-city. In Redmond, you'll want to confirm whether the city requires an STR license, caps the number of STR units per host, or restricts STRs to the owner's primary residence. Long-term rental (30+ day leases) is allowed without any STR-specific licensing in every city we cover.

    Go deeper: Read: Long-term vs. short-term rental ADU in Seattle

  • What rent can I expect from a new ADU in Redmond?

    Current comps for a new-construction 1-bedroom (500–750 sqft) in Redmond sit around $2,300/mo. A 2-bedroom (750–1,000 sqft) runs ~$3,025/mo. Yields are best on 1-bedroom units near transit corridors; 3-bedroom units are rare and command a premium but only when zoning allows a 1,000–1,200 sqft DADU.

    Go deeper: Redmond ADU overview

  • Do I need a separate utility meter for the ADU in Redmond?

    For a DADU, yes — separate power and water meters are standard, financeable, and what lenders expect. For an AADU or garage conversion, meters are usually shared with the primary home and tenants are billed via a RUBS (Ratio Utility Billing System) addendum to the lease. We coordinate the utility tap, meter installation, and PSE/SCL/SPU paperwork as part of the build.

    Go deeper: Redmond ADU overview

  • What incentives or fee waivers are available in Redmond?

    Redmond hasn't published a standing ADU fee-waiver program at this time, but income-restricted ADUs and ADUs serving aging-in-place needs sometimes qualify for state-level grants (Washington Housing Trust Fund, AARP/Mercy programs). We track the active funding cycles and flag any you qualify for during feasibility.

    Go deeper: Redmond ADU cost breakdown

  • Which Redmond neighborhoods do you build in most?

    Our recent Redmond projects cluster in Education Hill, Idylwood, Grass Lawn, Sammamish Valley, and Bear Creek, Overlake. Each neighborhood has its own quirks — historic overlays, narrow lots, side-sewer age, ECA exposure — and our project list page for each one calls them out so you know what to expect before you call us.

    Go deeper: Read the Eastside deck cost & permits: cedar, IPE, composite (2026) guide

FAQ / BY_SERVICE

Frequently asked, by service type

  • How big can a detached ADU (DADU) be in Seattle?

    Under current Seattle SDCI rules, a DADU may be up to 1,000 sq ft of gross floor area on most single-family lots, with a maximum height of roughly 18–24 ft depending on roof form and lot size. We confirm the exact envelope against your zone (NR1/NR2/NR3) and lot coverage before design starts.

    Go deeper: Read the DADU vs AADU in Puget Sound: which to build (2026) guide

  • Can I convert my Seattle basement into an attached ADU (AADU)?

    In most cases, yes. The two hard requirements are code-compliant egress (a window or door per IRC R310) and minimum 7 ft ceiling height in habitable areas. We frequently underpin or saw-cut for an egress window-well and add a code-compliant exit during the conversion.

    Go deeper: Seattle ADU overview

  • Can my detached garage be legally converted to a rental in Seattle?

    Most can. SDCI treats a detached garage conversion as a DADU when it adds a kitchen and bath. The slab must meet frost-depth and moisture-barrier requirements (often retrofitted), and the structure typically needs new shear walls, a foundation upgrade, and full insulation per WSEC 2021.

    Go deeper: Read: Seattle ADU rental comps in 2025

  • Do I need a permit for a home addition in Seattle?

    Yes — any addition that increases floor area, alters the building footprint, or modifies structural framing requires an SDCI building permit. Mechanical, plumbing, and electrical sub-permits run in parallel. We handle the entire SDCI submittal and inspection cycle in-house.

    Go deeper: Seattle ADU permit timeline

  • Are you a licensed general contractor in Washington State?

    Yes. Golden State ADU Builders holds Washington L&I contractor license GOLDESA747LZ, carries general liability and workers' comp, and is bonded per RCW 18.27. We can provide a current Certificate of Insurance naming you as additional insured before contract.

    Go deeper: Explore General Contracting

  • What does a feasibility study actually include?

    Zoning + setback analysis against the live SDCI / Bellevue / Kirkland code, a buildable-area diagram on your survey, utility capacity check (water, sewer, power), order-of-magnitude cost range, schedule range, and a rental-yield projection — delivered as a written report plus a 30-min review call.

    Go deeper: Glossary: Feasibility Study

MATRIX / COST_×_SERVICE

Redmond ADU cost by build type

All-in pricing for a Redmond build, normalized to the local cost index (1.04× Seattle baseline). Click any service for a full Redmond-specific scope, deliverables, and contract.

Build typeTypical sqftRedmond all-inBuild timeDeep dive
DETACHED ADU in Redmond400–1,000 sqft$146K–$416K6–8 monthsRedmond cost data →
ATTACHED ADU in Redmond300–800 sqft$99K–$333K4–5 monthsRedmond cost data →
GARAGE CONV. in Redmond200–600 sqft$68K–$250K3–4 monthsRedmond cost data →
MODERN ADDITIONS in RedmondCustom$125K–$499KProject dependentRedmond cost data →
GENERAL CONTRACTING in RedmondAnyCustomProject dependentRedmond cost data →
FEASIBILITY STUDIES in Redmond$1,500 – $3,5001–2 weeksRedmond cost data →

Need the math behind these numbers? See our Redmond ADU cost-per-sqft breakdown or the 2026 Puget Sound ADU cost report.

COMPARE / REDMOND_VS_NEIGHBORS

Redmond vs. nearby cities — at a glance

How Redmond compares to surrounding Puget Sound markets on permit window, minimum lot, and the 800 sqft DADU all-in price. Each row links to that city's full FAQ.

CityPermit windowMin lot800 sqft DADUCost index
Redmond (this page)10–14 wk5,000 sqft$485k–$600k1.04×
Kirkland ADU FAQ10–14 wk7,200 sqft$485k–$605k1.05×
Sammamish ADU FAQ12–16 wk8,400 sqft$485k–$605k1.05×
Bellevue ADU FAQ10–14 wk10,000 sqft (varies)$500k–$620k1.08×
Woodinville ADU FAQ10–14 wk8,400 sqft$465k–$575k1.00×
Bothell ADU FAQ10–14 wk7,200 sqft (with 25% reduction for ADU lots)$450k–$560k0.97×
Mercer Island ADU FAQ12–16 wk8,400 sqft$530k–$655k1.14×
CTA / TALK_TO_US

Question we didn't answer?

Call (425) 642-4142 or send us your lot address — we'll come back with a feasibility read in 48 hours.

CITY_DOSSIER / REDMOND· 47.6740°N 122.1215°W

Built in Redmond — what we know that the spec sheet won't tell you.

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.

Map · King CountyOpen ↗
Redmond
Drive-time from yard · ≈ 26 min via 520© OpenStreetMap contributors
Population78,213
Median lot7,800 sq ft
ADU permits / yr64 (2024)
Build cost band$330–380 / sq ft
Right now in Redmond
Air quality · US AQI
Source · Google Maps PlatformAffects pour windows + finish schedule
LIVE_INTEL / REDMOND · 6 SIGNALS
Pour-feasibility · todayLoading
/ 100 · Awaiting feed
  • Weather feed loading
Derived live · Redmond weather + AQI
Sun rhythm · RedmondNight
5:25 AM
9:05 PM
15h 40m daylight
Golden hour · 8:18 PM
98% of June peak
NOAA solar formulas · computed
Moon · cure-week planner
Loading

We track lunar weeks for slab pours — clear nights drop ambient temperature faster, which slows surface curing. Schedule wet slabs midweek under waxing light.

Conway approx · computed
Seismic · 24h within 60 miLoading
USGS earthquake.usgs.gov
On-site clock · Redmond
—:—
· Pacific

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.

America/Los_Angeles · live
Build-rules pulseWithin window
7:00–17:00
Power-tool window · Mon–Fri
ADU permits YTD pace

Sunday exterior work is restricted in most Puget Sound jurisdictions. We sequence interior trades around it.

Redmond municipal code · annualized
SPEC_02 / CITY_INTEL

Environmental & locational intelligence

03 / SOLAR_POTENTIAL

Rooftop solar at this address

04 / POLLEN_FORECAST

Tree · Grass · Weed (3-day)

05 / WALK_SCORE

0.5-mile amenity density

06 / NWS_ALERTS

Active NWS weather alerts

LOCATIONAL_INTEL / REDMOND
Drive times from RedmondLoading

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.

Google Routes API · traffic-aware
Street view · RedmondLive imagery
Recent Google Street View imagery centered near Redmond

Lot context matters as much as zoning. We pre-screen access, slope, and tree canopy from imagery before scheduling the site visit.

Google Street View · proxied
Tidal window · RedmondLoading

Waterfront lots: shoreline excavation and barge access windows depend on these. We schedule pours away from extreme low tides when the soils dry unevenly.

NOAA · — mi away
Recent permits · RedmondLoading

Open-data signal of nearby construction velocity — useful for ADU comps and for anticipating examiner workload.

data.seattle.gov · ~3 mi radius
Permit counter · Redmond
Redmond Planning & Community Development
15670 NE 85th St, Redmond 98052
Mon–Fri 8a–5p · digital pre-app required
Local zoning quirk

Education Hill & Grass Lawn lots often hit tree-retention thresholds before FAR — plan crown protection early.

Sourced from Golden State ADU field PMs · WA Lic. GOLDESA747LZ
Best build window
May → October

Bar shows pour-friendly months · dot marks the current month.

  • Seismic
    SDC D · stable plateau geology
  • Soil
    Glacial till on plateau, peat pockets near Sammamish River
  • Climate
    Slightly drier than Seattle (≈34″/yr), east-of-lake sun bonus
  • Topography
    Mostly gentle slope
  • HOA prevalence
    ≈ 28% — Education Hill, Grass Lawn, Idylwood
Transit signal
2 Line Downtown Redmond + Marymoor Village stations (2024)

Station-area lots earn the largest rent premium in this market.

School signal
Lake Washington School District

Rental yield estimate: $2,900–3,700 / mo · Microsoft proximity drives demand

Local incentive

Tech-corridor zoning allows live/work ADU configurations near Overlake

Hidden gem

Tree-retained DADUs in Education Hill pre-lease in <14 days.

Build cost · Redmond vs Puget Sound
+$30 vs regional median
$250 / sqftRedmond$355$425 / sqft
Other cities we hold a permit history in
FAQ_REDMOND / ASK

Redmond FAQ didn't cover it? Ask the team direct — personal reply in 24h.

We answer Redmond owner questions personally. No chatbots, no templates — just a licensed PM with hands in Redmond permits daily.

  • Personal answer tied to Redmond code, not generic ADU info
  • Includes setback / fee numbers where useful
  • Free even if you're months from building
Replies within 1 business day
WA Lic. GOLDESA747LZBuilding since 2012
Direct line · Golden State ADU(425) 642-4142

We reply within 1 business day. No spam, ever.

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