Cost guide · Seattle & King County
Seattle MasterFix project ranges for Seattle and King County, WA, shown next to cited public market benchmarks. Every job is priced as one written project estimate for the agreed scope after a free on-site visit.
MasterFix ranges
Typical Seattle MasterFix project ranges, final price after free on-site estimate
Typical Seattle MasterFix project ranges, final price after free on-site estimate
| Band | MasterFix | Notes |
|---|---|---|
| Starting at | $92,200/project | Entry scopes |
| Typical | $157,700/project | Most common mid scopes |
| High planning | $261,800/project | Complex or premium scopes |
Starting aligns with simpler attached/conversion scopes; typical near DADU mid less about 20%.
Public 2025–26 estimates from cited sources — shown for comparison, not as a MasterFix quote. Sources are linked below. Washington sales tax may apply on a signed contract.
| Band | Market | What it represents |
|---|---|---|
| Low | $123,069/project | Seattle attached-ADU permit median 2023–2025 (city estimated project cost) |
| Typical | $210,944/project | Cost vs. Value 2025 Seattle Accessory Dwelling Unit |
| High | $350,000/project | Larger / custom DADU planning band (local ADU cost guides) |
Seattle open-data DADU 2025 median estimated cost $196,326; AADU 2023–2025 median $123,069. CvV Seattle ADU $210,944.
How we work
Yes — full general contracting for ADU / DADU projects.
Seattle MasterFix Precision Craftsmanship (Seattle MasterFix Precision Craftsmanship) is a Washington-registered contractor #SEATTMP744NL, based at 5415 6th Ave NW, Seattle, WA 98107. Service area: Seattle and King County, WA. Related pages: /services/drywall/ · /services/paint/ · /services/tile/ · /services/laminate/.
FAQ
Typical Seattle MasterFix project ranges, final price after free on-site estimate: starting about $92,200, typical about $157,700, high planning band about $261,800. Public Seattle market midpoint used for comparison is about $210,944. Starting aligns with simpler attached/conversion scopes; typical near DADU mid less about 20%. Final price is after a free on-site estimate.
Cost vs. Value 2025 lists a Seattle Accessory Dwelling Unit at about $210,944 typical job cost with ~32.3% cost recouped at resale. Actual AADU/DADU prices vary widely by size, site work, and finish level.
Per SDCI, adding an attached or detached ADU requires a construction addition/alteration permit and must meet current building, mechanical, electrical, energy, land-use, and ECA standards. King County sewer capacity charges apply.
Yes. Seattle MasterFix Precision Craftsmanship provides full general contracting for attached and detached ADU projects in Seattle & King County (WA Lic. #SEATTMP744NL), coordinating permits and the build.
Photos
Placeholder slots for project photos. No images are claimed here until real job photos are added.
Sources
Open sources used for the ranges on this page. Always verify current figures before you budget.
Estimates are non-binding until a written contract is signed. Compare two or three written bids on the same scope, and verify any contractor on WA L&I before you sign.
Call (206) 550-4576 or send an estimate request. We will walk the scope and write a project quote — never an hourly guess.
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