A home addition in Seattle typically costs between $30,000 and $180,000, with most homeowners paying around $72,000. Local construction costs in Seattle run well above the national average, so prices here differ from the U.S. typical of $60,000.
Here's roughly how a typical $72,000 home addition in Seattle breaks down by component:
| Component | Typical range |
|---|---|
| Foundation & framing | $15,800 – $20,200 |
| Roofing & exterior | $10,800 – $14,400 |
| Interior finish | $14,400 – $18,700 |
| MEP & permits | $10,800 – $15,800 |
The biggest factors are project size and scope, the materials and finishes you choose, structural or permit work, and your contractor's rates. Because labor and materials in Seattle, WA are well above the national average, the same project can cost noticeably more or less than in other metros.
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⚡ Check my quote freeMost home addition projects in Seattle, WA run between $30,000 and $180,000, with a typical project around $72,000. Your final price depends on size, materials and the contractor.
Construction labor and materials in Seattle are well above the U.S. average, which is why local prices sit higher than the national typical of $60,000.
Compare each line item to the breakdown above, and get at least three itemized bids. You can also upload your quote to Bylder's free AI checker to instantly flag overpriced items.