Lotline
King County · ADUs & Additions

See the plan before you commit a dollar.

Garage conversions, backyard cottages, and additions — with the price published and the drawing on the table. No moving. No mystery quote.

King County, WAPre-approved 2–6 wkTransparent pricing
Fig. A-101Axonometric cutaway of a Pacific Northwest modern backyard cottage showing its construction
Rendering — concept, not a photograph
Why us

The difference is what we show you.

The price is on the page

Vertical-build and all-in cost, published. Compare honestly before you call.

Permitted faster

City pre-approved plans clear permitting in 2–6 weeks on a clean lot.

One team, end to end

Design, permitting, and build under one roof — nothing lost in handoffs.

HB 1337 fluency

Two ADUs per lot, lot subdivision, the new state rules — handled.

What we build

Four formats, one honest process.

Published pricing

The price is on the page.

We publish both the vertical-build cost and the all-in number on a clean lot. Here's what's usually left out of a low bid — so you can compare honestly.

VerticalAll-in
Garage ConversionExisting slab, to-code rental
$95K$120K
Pre-Approved DADUCity pre-approved plan set
$250K$250K–$400K
Home AdditionRoom or second story
$150K$210K
Custom DADUPermit 8–14 wk
$320K$430K
Left out of a low bid
  • Site work on a sloped or rocky lot
  • Sewer / utility connections beyond 30 ft
  • Permit fees & SDC charges (paid to the city)
  • Design upgrades past the standard finish set

Ranges are for planning, not a bid. Your number depends on lot, slope, and finish level. A feasibility check returns a fixed-scope estimate for your address.

Feasibility check

See what fits your lot.

Enter your address and the format you're considering. You'll get a planning estimate and a permit timeline — no call required to see the number.

King County addresses only
Start with the drawing

Get the plan and the price for your address.

A feasibility check returns a fixed-scope estimate and a permit timeline — before you spend a dollar on design.