Accessory Dwelling Units (ADUs) are becoming one of the most popular home improvement projects in Seattle, WA and nearby areas. Whether you’re looking to create rental income, provide housing for family members, or add value to your property, building an ADU offers serious benefits.
Before starting your ADU project, there are key factors Seattle homeowners should be aware of in 2025, from permits and zoning to design considerations.
Understand Seattle’s ADU Regulations
Seattle has relaxed ADU regulations in recent years, but there are still rules to follow. Key points include:
- Detached and attached ADUs are both allowed.
- Lot size requirements have been reduced or eliminated.
- Owner-occupancy restrictions are more flexible in 2025.
- Height and size limits vary by neighborhood zoning.
Interbay Construction helps homeowners in Seattle navigate the permitting and zoning process for ADUs, ensuring your project meets all local requirements.
Plan for the Right ADU Design
ADUs in Seattle can serve many purposes:
- Backyard cottages
- Basement apartments
- Garage conversions
When designing your ADU, think about who will use it. Will it be a rental? A guest suite? An office space? Our team specializes in functional ADU layouts that balance privacy, comfort, and curb appeal.
Budget for Construction Costs in 2025
Building an ADU isn’t cheap, but it’s often more affordable than buying a second property. In Seattle, ADU construction costs typically range from $120,000–$350,000+ depending on:
- Size and design complexity
- Utilities and site prep
- Materials and finishes
Interbay Construction offers transparent cost estimates and project timelines upfront, so you’ll know exactly what to expect.
Consider Hardscaping and Outdoor Access
Adding pathways, patios, or private entrances is a smart move when building an ADU. Hardscaping helps ADUs blend with your existing property and ensures easy, independent access for tenants or guests.
We handle complete hardscaping solutions as part of our ADU services in Seattle and surrounding areas.
Why Hire Interbay Construction for ADU Projects in Seattle?
- Licensed, insured, and local to Seattle
- Full-service ADU design and construction
- Permitting and zoning compliance assistance
- Kitchen, bathroom, and hardscaping integration
Final Thoughts
ADUs provide extra living space and property value in a city like Seattle where real estate is in high demand. If you’re considering building an ADU in 2025, make sure you partner with an experienced contractor.
Contact Interbay Construction today to schedule your ADU consultation. We’re here to help you expand your property’s potential—from initial design to final walkthrough.
