Home Additions in Seattle
When you love your Seattle neighborhood but need more room, an addition beats moving — especially at today’s prices. We add space that looks like it was always there.
Bump-outs, second stories & dormers
From a kitchen bump-out to a full second-story addition or a dormer that turns an attic into a primary suite, we design additions that fit your home’s scale and the neighborhood’s character — not a boxy mismatch bolted onto a Craftsman.
The structural reality
Adding upward or outward means foundations, framing loads and often a seismic upgrade to the existing structure. We engineer it properly so the new and old work together and pass inspection — this is where cut-rate additions fail.
Matching the envelope
An addition is only as good as where it ties into the existing wall and roof. We detail the flashing, siding and roofline transitions so the seam stays watertight through Seattle winters.
Typical Seattle pricing
| Option | Typical Seattle range |
|---|---|
| Single-room bump-out | $95,000 – $180,000 |
| Dormer / attic conversion | $120,000 – $250,000 |
| Full second-story addition | $300,000 – $600,000+ |
Prices in USD. Every project gets a written, fixed-scope estimate after a free in-home consultation.
Home Additions — your questions
How much does an addition cost in Seattle?
A bump-out starts around $95k; dormers and attic conversions run $120k–$250k; a full second story is typically $300k+. Foundation and seismic work affect the number — we’ll scope it precisely.
Do additions need a seismic upgrade?
Often yes — adding load to an older home usually triggers structural and seismic requirements. We handle the engineering and permits.
Will the addition match my home?
That’s our specialty — matching rooflines, siding, trim and proportions so it reads as original, not added-on.
Get your free Seattle estimate
A licensed design-build team, honest numbers up front, and no surprise change-orders.