What is the 2026 cost range for a junior adu (jadu) scope adu in Seattle?

$78,750-$166,250, with the median landing near $122,500. The range reflects finish tier and layout complexity within the junior adu (jadu) scope; the Seattle labor multiplier of 1.25× vs national median is baked in.

How long does a junior adu (jadu) scope adu take in Seattle?

10-18 weeks of on-site construction for the junior adu (jadu) scope, plus 8-18 weeks of permit review in Seattle if the scope requires a permit. Cosmetic-only refreshes often skip permits; anything touching plumbing, electrical, or structural does not.

What is the single biggest budget-overrun risk for this scope?

Owner-occupancy covenants in some jurisdictions limit resale financing options — buyer must also commit to occupancy, reducing resale pool.

ADU — Junior ADU (JADU) Cost in Seattle, 2026

Low

$79K

$78,750

Median

$123K

$122,500

High

$166K

$166,250

Scope timeline: 10-18 weeksSeattle permit window: 8-18 weeksUpdated 2026-04-24

Why junior adu (jadu) × Seattle produces this band

A junior adu (jadu) scope for a adu in Seattle combines two price levers: scope and metro labor rates. JADUs carve a ≤500 SF unit out of the existing primary structure with an efficiency kitchen (no range, induction cooktop allowed) and a shared or private bath. Cheapest ADU class when the jurisdiction recognizes it. Against the national median remodel labor rate, Seattle runs 25% above the national median — so the junior adu (jadu) band comes in 65% below the mid-range, then scales 25% above the national median on top of that. Permit timelines for residential work in Seattle typically run 8-18 weeks, which is the window you plan your design and decision sequence against. This page gives you the actual 2026 Seattle bands for this exact combination, plus the three cost drivers Baily asks about first when scoping the project live.

What drives cost for a junior adu (jadu) scope

·Efficiency kitchen with limited plumbing (no garbage disposal in many jurisdictions)
·Independent entrance cut into an exterior wall
·Owner-occupancy covenant recording
·Shared utility metering (no new service drop)

What makes Seattle different

Labor — WA LNI-licensed trades required on most work — contractor registration verifiable via online lookup.
Labor — Wet-season (Oct-Apr) labor premium for exterior trades (roofing, siding, decks).
Labor — Urban Forestry and tree-retention requirements add arborist labor on some remodels.
Material — Green building incentives favor FSC-certified lumber, heat-pump HVAC, and higher-R insulation — 5-10% material uplift for Energy Star targets.
Material — Port of Seattle is a primary entry for Asian-sourced finishes (tile, fixtures) — generally competitive.

Seattle rules that affect this scope

Seattle DCI runs SDCI plan review — typical residential turnaround 8-18 weeks depending on Land Use review.
Seattle Energy Code (SEC 2021) exceeds IECC — mandatory heat-pump water heater and HVAC on most new work.
Design Review required on most multi-family remodels above the small-project threshold.
Shoreline Management Act affects lakeside and riverside parcels (Lake Washington, Lake Union, Duwamish) — adds 8-14 weeks.

Scope your adu with Baily.

Baily asks the eight questions that determine where your project lands inside the $79K-$166K band for Seattle and hands the scoped brief to one licensed builder.

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Questions LA homeowners actually ask

$78,750-$166,250, with the median landing near $122,500. The range reflects finish tier and layout complexity within the junior adu (jadu) scope; the Seattle labor multiplier of 1.25× vs national median is baked in.