How Much Does Room Addition Cost in Washington?
Washington pricing is above the national average. Updated for 2026.
Room Addition Pricing in Washington
In Washington, the average cost for room addition is $51,750 per project, which is 15% higher than the national average of $45,000. Most Washington residents pay between $23,000 and $92,000.
Washington has a higher cost of living than most states, which translates to higher labor rates and material costs. Urban areas within Washington may be even higher.
A room addition extends your home's footprint by building a new room — bedroom, family room, home office, or in-law suite. It's one of the most expensive renovations but adds significant living space and value.
Washington vs National Average
What Affects Room Addition Cost in Washington?
Size
Small (100 sq ft): $15,000-$25,000. Average (200 sq ft): $30,000-$50,000. Large (400+ sq ft): $60,000-$100,000+
Room Type
Basic bedroom: $20,000-$40,000. Bedroom + bathroom: $35,000-$65,000. In-law suite: $50,000-$100,000+
Per Sq Ft
Budget: $80-$150/sq ft. Mid-range: $150-$250/sq ft. High-end: $250-$400+/sq ft
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💡 Tips to Save on Room Addition in Washington
- 1.A bump-out (extending an existing room 2-4 feet) costs $5,000-$15,000 — much less than a full addition
- 2.Building over an existing garage or patio saves on foundation costs
- 3.A dormer addition (expanding attic space) costs 30-50% less than a ground-floor addition
- 4.Act as your own general contractor if you have experience — save 15-25% on management fees
📈 Room Addition in Washington Cost Trends (2020–2024)
Prices have increased +17.7% over the last 5 years
| Year | National Avg | YoY Change |
|---|---|---|
| 2020 | $43,956 | — |
| 2021 | $45,802 | +4.2% |
| 2022 | $48,779 | +6.5% |
| 2023 | $50,145 | +2.8% |
| 2024 | $51,750 | +3.2% |
Based on national averages adjusted for annual inflation. Actual costs vary by location and project scope.
💬 What Did You Pay?
Real costs reported by homeowners for Room Addition in Washington
Recent Reports
Frequently Asked Questions
Does a room addition increase home value?
Yes, though ROI varies: 50-65% for a standard room addition, 60-75% for a bedroom + bathroom addition. The value also depends on whether the addition fits the neighborhood — over-improving for your area yields lower returns.
How long does a room addition take?
Typical timeline: 2-4 weeks for permits and planning. 8-16 weeks for construction. Total: 3-5 months. Complex additions with full bathrooms or custom features can take 6-12 months.
Room Addition Cost in Other States
Related Cost Guides for Washington
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