ADUs Cost Guide in Seattle — Average Prices & Ranges

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For a Seattle address, plan on $1,418 to $4,396 per job for adu, with the midpoint near $2,497.

Because Seattle sits in Washington, local labour supply and material delivery shape much of the price. Confirm up front whether permits and cleanup are included.

Typical cost at a glance

United States planning figures, per job
LevelPrice
Low~$1,418
Typical~$2,497
High~$4,396

Cost by type

TypeLowTypicalHigh
Baseline transaction cost~$1,418~$2,907~$4,396
Below-median price scenario~$1,163~$2,626~$4,088
Above-median price scenario~$1,588~$3,827~$6,066
Lender and government fees~$170~$679~$1,187
Competitive or fast-moving market~$1,730~$4,206~$6,682

All figures per job.

Timing your adu

For adu, same-day and after-hours call-outs sit at the top of the range. A standard appointment booked in advance gives you the best chance of the typical figure.

How to compare quotes for adu

Cheapest is not the same as best value for adu. A slightly higher quote with a complete scope and no open-ended extras is often safer than the lowest figure with caveats.

What moves the price of adu

The scope you agree drives most of the cost of adu. Every extra task, upgraded material or access complication adds labour and risk, and the provider prices that risk into the quote.

What ADUs typically costs

ADUs does not carry one published price. Across Seattle, most jobs fall between $1,418 and $4,396 per job, and the number in between, about $2,497, is the fairest single figure to plan around.

Frequently asked questions

How much does adu cost?
Most adu falls between $1,418 and $4,396, with a typical figure near $2,497 per job. The low end is a straightforward job with no surprises; the high end covers complex scope, premium materials or urgent timing. It is worth testing that against a couple of quotes in Seattle.
What affects the price of adu?
No single factor decides it — scope, materials, access and timing all move the total, and the biggest swings usually come from access and scheduling. Local providers in Seattle can confirm how that applies to your area.
Is ADUs cheaper in smaller cities?
Often, but not always. Smaller markets can carry a travel or availability premium that offsets a lower local rate, so it is worth checking a nearby city before assuming the lowest published figure applies to you. In Seattle, that is worth confirming with a local provider before you commit.
How many quotes should I get for adu?
Two or three written quotes are enough to see the real market range. Compare the same scope side by side, and ask each provider what is excluded and what would change the price after the quote is accepted. The answer can shift with the Seattle market, so check locally.

Keep comparing

Related categories

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Cities in this region

These are planning ranges drawn from public price data and market research. They are not a quote, an offer or financial advice, and your actual price depends on the provider, the location and the scope of the work.