One of the first questions homeowners ask when planning a home addition is: how long will this take? The honest answer involves several phases, each with its own timeline. Here is a realistic breakdown for a typical home addition in the Seattle area in 2026.
Phase 1: Design (8-16 Weeks)
Schematic design through construction documents. Time depends on scope and revision cycles. A straightforward primary suite addition at 400 sq ft: 8-10 weeks. A full second story: 12-16 weeks.
Phase 2: Permitting (6-14 Weeks)
Standard residential addition permit review at SDCI: 6-10 weeks for initial review. One correction cycle adds 4-6 weeks. Total with one correction: 10-16 weeks. Projects in jurisdictions with faster review (Kirkland, Bellevue, Redmond) may permit in 4-8 weeks.
Planning a project?
Want a number for your addition?
Send David the address and a few lines about what you want. The first feasibility check is free and usually takes about a day: what the site and the code are likely to allow, and what to check first.
Architect since 1996, member of the AIA and NCARB. Three Masonry Excellence Awards for commercial projects; the Carr residence was featured in Above The Lake and Lux magazines.
Phase 3: Contractor Bidding (3-5 Weeks)
Soliciting bids from 2-3 general contractors, reviewing proposals, and selecting a contractor. Note: start contractor outreach during the permit review phase to save time.
Phase 4: Construction (3-8 Months)
- Small addition (200-400 sq ft): 3-4 months
- Medium addition (400-800 sq ft): 4-6 months
- Full second story addition: 6-8 months
Total Timeline: What to Expect
Small addition, fast jurisdiction:
9-12 months from first meeting to move-in
Medium addition, Seattle permit:
12-16 months
Full second story, Seattle permit:
16-22 months
How to Speed Things Up
The biggest time savings come from working with an architect who submits complete, code-compliant drawings on the first try. Each correction cycle adds weeks. Start contractor outreach during permitting, not after. Piper Cole Architects coordinates both phases to minimize total timeline. free feasibility check, call 425-753-6452.
