General Contractor Services
ADU and DADU Builders
Licensed & Insured
534+ Projects Done
On-Time Guarantee
Zero Safety Violations
ADU Home Builders
Need more space but love your location? A home addition lets you expand your living area without the hassle and expense of moving. Westerly Ventures builds additions that seamlessly integrate with your existing home — from single-room bump-outs to full second-story additions.
We specialize in second-story additions, room additions, ADU and DADU construction, garage conversions, and sunroom enclosures. Our design-build approach ensures the new space matches your existing home’s architecture, roofline, and interior finishes for a cohesive look.
Every addition project includes structural engineering, permit management, foundation work (if needed), framing, roofing tie-in, siding match, and complete interior finishing. We handle the complexity so you can focus on enjoying your new space.
Key Features
- Second story additions
- ADU / DADU construction
- Garage conversions
- Seamless design matching

Our Process
01
Discovery
02
Planning & Permits
Our team creates detailed plans, secures permits, and coordinates all trades.
03
Construction
04
Final Inspection
Thorough walkthrough, punch list completion, and handover with all warranties documented.
- Schedule a Free Consultation
Get a free, no-obligation quote for your home additions project in Western Washington. We respond within 24 hours.
Other General Contractor Services
Home Additions Service Areas
We provide home additions services across King, Snohomish, and Pierce counties. Click a city below for local service details.
Ready to Start Your Project?
Get a free consultation and estimate for your concrete, roofing, or HVAC project. Serving the greater Seattle area and all of Western Washington.