What a Master Suite Addition Costs in Seattle (and ROI)

Updated January 2026 | Pricing based on 6 contractor bids in King County, October-November 2025

Contractor Quote: “A master suite addition in Seattle starts around $350 per square foot for basic finishes. Go to $450-500/sqft if you want heated floors, frameless glass shower, and custom tile work.” – Mike Chen, Ballard Design Build, November 2025

Seattle Master Suite Costs (2025-2026)

Based on actual bids I collected for a 400 sqft master suite addition in Ballard:

• Low end (builder grade): $140,000-$160,000
• Mid range: $180,000-$220,000
• High end (custom): $250,000-$320,000

Seattle permit fees alone run $8,000-$15,000 depending on scope. Plan review takes 6-12 weeks right now – the city is backlogged.

ROI by Seattle Neighborhood

Master suite additions typically recoup 50-70% of cost at resale. But neighborhood matters:

• Ballard, Fremont, Wallingford: Strong ROI (65-75%) – buyers expect updated primaries
• West Seattle, Beacon Hill: Moderate ROI (55-65%) – prices haven’t caught up to north Seattle
• Capitol Hill, Madison Park: Lower ROI (45-55%) – home prices already maxed out

Bathroom Planning

Plumbing location drives cost. If your new bathroom can share a wet wall with existing plumbing, budget $25,000-$40,000 for the bathroom portion. Moving plumbing to a new location adds $8,000-$15,000.

What to Expect Timeline-Wise

• Design and permitting: 3-5 months
• Construction: 4-6 months for a typical addition
• Total project: 8-12 months start to finish

Seattle winters slow exterior work. Starting in spring means finishing before the next rainy season.