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.
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 consultation — call 425-753-6452.
Ready to Start Your Project?
Piper Cole Architects offers a free initial consultation for all project types — residential, commercial, ADU, and renovation. No obligation. Based in Kirkland, WA. Serving the entire Seattle metro area since 2000.