ADU Construction in Seattle
ADU Construction in Seattle, WA
ADU Construction in Seattle. Local pricing, permits through SDCI, and an honest number on paper before demo.
The promise
A Seattle ADU, feasibility first, then built as a real home
We check whether your Seattle lot qualifies before you spend on design, then build an ADU warm and dry enough to rent or move family into, with one licensed team.
Why choose us
Why choose us for your Seattle ADU
01
We check if your lot qualifies first
Lot size, setbacks, coverage, and zoning decide an ADU before anything else. We run feasibility before you spend on design, and if it will not work, we tell you early.
02
An honest number, before we build
ADU budgets get surprised by utility connections, site work, and fees. We itemize the whole scope and lock it before we start.
03
Built as a real home
An ADU you can rent or move a parent into has to be warm, dry, and quiet. We build it to the same standard as the main house, not a finished outbuilding.
04
We handle the Seattle permit
An ADU goes through its own permit and plan review through the Seattle Department of Construction and Inspections. We prepare the submittal, pull the permit, and manage the inspections.
Cost
What an ADU costs in Seattle
ADU Construction costs depend on the level and your finishes. Here are the levels and local ranges, with your real number set against your actual project.
Level 01
Garage or basement conversion
Turning existing space into a legal attached ADU.
- Convert existing footprint
- Add a kitchen and bath
- Egress, insulation, systems
Typical Seattle range: TKTK local range
Level 02
Detached ADU (DADU)
A new backyard cottage, built from the ground up.
- New foundation and structure
- Full kitchen and bath
- Utilities run to the unit
Typical Seattle range: TKTK local range
Level 03
Custom or two-story DADU
A larger detached unit with more rooms.
- Two-story or garage-under
- Full systems and insulation
- Higher-end finishes
Typical Seattle range: TKTK local range
Ranges are placeholders until local pricing is confirmed. See our ADU guide for what drives the cost.
Permits
ADU permits in Seattle
Most ADU projects in Seattle that go beyond cosmetic need a permit. Here is how it works and how we handle it.
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When a Seattle ADU needs a permit
An ADU goes through its own permit and plan review. A cosmetic scope often does not. We tell you which you are up front.
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Through SDCI
ADU Construction permits run through the Seattle Department of Construction and Inspections. We prepare the submittal and manage plan review and inspections. TKTK confirm current process and portal.
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Permit timelines in Seattle
Review times vary with scope and the city queue. We build the permit window into your schedule and flag it early. TKTK typical review windows.
Local homes
What Seattle homes mean for your ADU
ADU Construction projects come with Seattle quirks. These are the local realities we plan around.
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Lot feasibility in Seattle
Setbacks, coverage, and zoning decide whether your Seattle lot can carry an ADU and where it can sit. We check before design, not after.
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Washington ADU rules
State law has expanded ADUs, and Seattle sets its own limits within it. We confirm the current rules for your lot. TKTK confirm Seattle rules.
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Utilities and the side sewer
A second dwelling may need a new side sewer, water line, or electrical service, sometimes with capacity fees. We scope these early.
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The right unit for the use
A rental, an aging parent, and a home office want different layouts and entrances. We design around the actual use, not a generic box.
FAQ
Seattle ADU FAQs
Can I build an ADU on my Seattle lot?
Maybe, and we check before you spend on design. Lot size, setbacks, coverage, and zoning decide it. Washington has expanded ADU rules, so more lots qualify than before. We run feasibility first.
What is the difference between an attached ADU and a DADU?
An attached ADU (AADU) is within or attached to your house, often a basement or garage conversion. A detached ADU (DADU) is a separate structure, usually a backyard cottage. They permit and cost differently.
Do I have to live on the property in Seattle?
Owner-occupancy rules have relaxed in much of Washington, but they vary by city and can change. We confirm the current rule for your Seattle address. TKTK confirm.
Can I rent it out in Seattle?
Usually yes, and rental income is a common reason to build one. Rules on short-term versus long-term rental vary by city. We will tell you what applies. TKTK confirm.
How long does an ADU take to build in Seattle?
A garage conversion is faster than a ground-up DADU, and permits and utilities drive the timeline. We put a schedule in writing. TKTK typical ranges.
How much does an ADU cost in Seattle?
It depends on type, size, site, and utility connections. We price against your real conditions rather than a national average. TKTK local cost ranges.
Ready when you are
Get a free Seattle ADU estimate
Tell us about your Seattle project and we will call within one business day, walk the space, and put a written estimate together with no pressure to sign.