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Bathroom Addition Cost Calculator — Seattle
Adding a bathroom in Seattle, Washington costs significantly higher than the national average. Type (half vs. full vs. master), proximity to existing plumbing, and finish level are the biggest cost factors.
Low estimate$6,400
Average$23,400
High estimate$71,600
Bathroom square footage
Bathroom square footage60
Quality Tier
Standard materials, solid craftsmanship
Scope of Work
Labor
Labor portion of total cost40%
Bathroom Addition Cost in Seattle: 2026 Guide
Use the calculator above to get a quick estimate. The guide below explains what drives bathroom addition costs in Seattle and what to expect from contractors in Seattle.
Typical Bathroom Addition Costs in Seattle
Project Scope
Low
High
Half bath (35 sqft, basic fixtures)
$2,200
$4,200
Full bath (60 sqft, mid-grade)
$6,400
$19,200
Full bath (80 sqft, tile shower)
$19,200
$23,400
Master bath (100+ sqft, premium)
$23,400
$71,600
What Affects Bathroom Addition Costs in Seattle?
Labor rates: Contractors in Seattle charge $58–$117/hour for bathroom addition work — significantly higher than the national average.
Material costs: Material prices in the West region are significantly higher than national average due to local supply, transportation costs, and market demand.
Project complexity: Site conditions, permitting requirements, and non-standard layouts can add 15–30% to total project cost.
Frequently Asked Questions
How much does a bathroom addition cost in Seattle?
Adding a bathroom in Seattle costs $6,400–$71,600. A half bath (toilet + sink, ~35 sqft) runs $6,400–$4,200. A full bath (60–80 sqft) costs $4,200–$23,400. A master bath with walk-in shower, double vanity, and premium tile can reach $71,600.
Is adding a bathroom worth it in Seattle?
Adding a bathroom typically returns 50–60% of the cost at resale in Seattle. Homes with only 1 bathroom gain the most value from a second bath. Half bath additions near living areas have the best ROI — typically $10,000–$25,000 added to home value.
How long does bathroom addition take in Seattle?
A half bath addition takes 2–4 weeks. A full bath addition takes 3–6 weeks. A master bath with custom tile work can take 6–10 weeks. In Seattle, allow 2–4 weeks extra for permit approval. Plan for the space to be unusable during construction.
Can I add a bathroom without breaking through walls in Seattle?
If you're converting existing space (large closet, unused room corner) and plumbing lines are accessible, you may minimize wall opening. However, new bathrooms need supply lines, drain lines, and venting — which almost always requires some wall or floor access. A licensed plumber in Seattle can advise on the least invasive approach.
Create Pro Estimates in 60 Seconds
Use Cost Estimator app to generate detailed bathroom addition estimates — share as PDF directly with clients.