How Much Does Room Addition Cost in Seattle, WA?
Average room addition costs in Seattle range from $11,779 to $15,937. Get a free, customized estimate below.
Room Addition Cost Breakdown — Seattle, WA
| Item | Unit | Qty | Unit Price | Total |
|---|---|---|---|---|
| Foundation | sq ft | 200 | $19.50 | $3900.00 |
| Framing | sq ft | 200 | $15.60 | $3120.00 |
| Roofing | sq ft | 220 | $10.40 | $2288.00 |
| Electrical & Plumbing | lump sum | 1 | $4550.00 | $4550.00 |
| Estimated Total | $13,858.00 | |||
* Prices are estimates based on Seattle market rates. Actual costs may vary based on project specifics.
Estimate
Ref ID: EST-2026-006M
Date Issued
May 6, 2026
Client
Project Details
Site Address
Start Date
End Date
Scope of Work
Materials
| Material Specification | Units | Amount | Ext. Total | |
|---|---|---|---|---|
$ | $3,900 | |||
$ | $3,120 | |||
$ | $2,288 | |||
$ | $4,550 |
Labor
| Service Specification | Type | Hrs | Rate | Ext. Total | |
|---|---|---|---|---|---|
Craftsmanship Guarantee | $ | $600 |
Contractual Agreements & Conditions
Total
$14,458
Draft
Frequently Asked Questions — Room Addition in Seattle
How much does room addition cost in Seattle, WA?
The average cost for room addition in Seattle, WA ranges from $11,779 to $15,937, depending on project scope, materials, and labor rates. Seattle costs are above the national average due to higher labor and material costs in the region.
How do I get a free room addition estimate in Seattle?
Use Brixor's free online estimate generator above. Enter your project details, customize line items for your specific needs, and download a professional PDF estimate instantly. No signup or credit card required.
What factors affect room addition costs in Seattle?
Key factors include project size and complexity, material quality, labor rates in Seattle (WA), permit requirements, accessibility of the work area, and seasonal demand. Getting multiple estimates is recommended.