Cost to Basement Bathroom Addition in Seattle, WA
$8,960–$25,600 in Seattle
28% above the national average · 1.28x cost multiplier
In Seattle, a basement bathroom addition runs $8,960 to $25,600 on average — about 28% above what homeowners pay nationwide. The West Coast market's labor costs account for most of the gap, with material pricing and local permitting fees adding to the spread. Use the cost table below to compare budget, mid-range, and premium options side by side.
Cost Breakdown in Seattle
| Line Item | Low | Mid | High |
|---|---|---|---|
| Cost per bathroom | $5760 | $16000 | $32000 |
| Materials | $3,584 | $7,680 | $17,920 |
| Labor | $5,120 | $9,600 | $15,360 |
| Permits | $768 | $1,024 | $1,280 |
| Total | $9,472+28% vs. national avg | $18,304+28% vs. national avg | $36,480+28% vs. national avg |
Budget
Half bath (toilet and sink) added to unfinished basement near existing stack. Basic fixtures, standard tile, and minimal framing.
Mid-Range
Full 3-piece bath (toilet, sink, shower) with below-slab ejector or macerating toilet system, mid-range tile, standard vanity, and proper ventilation.
Premium
Full bath with tile shower, premium fixtures, custom vanity, below-slab plumbing with ejector pump, heated floor, and full exhaust ventilation system.
Material Options
Material prices below are national averages; availability in Seattle may shift costs slightly.
| Material | Cost/Unit | Best For |
|---|---|---|
| Macerating (Upflush) Toilet System | $700-$1,800 unit only | Budget basement bathroom additions, retrofit situationsNo concrete breaking required, lower upfront cost, relocatable |
| Below-Slab Ejector Pump System | $1,500-$4,000 for pump and pit only | Long-term reliable basement bathrooms, high-use situationsCode-compliant everywhere, gravity-fed to pump, quieter |
| Standard Ceramic Tile | $3-$10/sq ft materials only | Budget to mid-range basement bathroomsAffordable, durable, waterproof, wide selection |
| Luxury Vinyl Tile (LVT) | $3-$8/sq ft materials only | Budget installs, DIY-friendly flooringWarm underfoot, waterproof, easy DIY install |
| Porcelain Tile (Floor and Shower) | $6-$25/sq ft materials only | Premium basement bathrooms, shower surroundsMost durable, low water absorption, premium look |
Other Projects in Seattle
Seattle Estimate
Typical Range
$8,960–$25,600
vs. National Average
28% above national
Cost Multiplier
1.28x
Cost Per bathroom
$5760–$32000
Estimates apply Seattle's 1.28x regional cost multiplier to national averages. Actual bids vary by contractor, project scope, and timing.
See national average costs →