How to Build an ADU or DADU in Seattle: New Laws, Big Benefits, and Smart Next Steps
Building an Accessory Dwelling Unit (ADU) or Detached Accessory Dwelling Unit (DADU) in Seattle has become increasingly popular, thanks to recent legislative changes, streamlined permitting processes in certain neighborhoods, and a growing need for flexible housing solutions. Whether you're considering multigenerational living, generating rental income, or increasing your property's value, here's what you need to know.
Why Consider Building an ADU or DADU in Seattle?
1. Multigenerational Living
ADUs and DADUs offer an excellent solution for families wishing to live close together while maintaining privacy. They provide independent living spaces for aging parents, adult children, or extended family members, providing options for supporting those you care about without compromising personal space.
2. Rental Income Potential
With Seattle's competitive rental market, ADUs and DADUs can serve as a steady source of income. Renting out these units can help offset mortgage payments or contribute to savings, building a passive income path to your financial goals.
3. Property Value Enhancement
Adding an ADU or DADU can increase your property's market value. These units make homes more attractive to certain groups of potential buyers seeking additional space or rental opportunities.
4. Lot Splitting and Future Sale
Seattle's evolving zoning laws may allow for the subdivision of lots with ADUs or DADUs, enabling homeowners to sell these units separately in the future. This flexibility can be a strategic financial move, offering long-term investment benefits.
Recent Legislative Changes Facilitating ADU and DADU Construction
Seattle has implemented several reforms to encourage the development of ADUs and DADUs:
House Bill 1337 (2023): This state legislation mandates cities to relax ADU regulations, including removing owner-occupancy requirements and allowing two ADUs per lot. Seattle aims to implement these changes ahead of the July 2025 deadline to boost housing creation sooner. You can read more about this bill and others that came before it on The Urbanist.
One Seattle Comprehensive Plan: Mayor Bruce Harrell's initiative focuses on increasing housing diversity and affordability by allowing multiple units on a single property, promoting the construction of family-sized homes (aka larger ADU units) and expanding homeownership opportunities through streamlined permitting processes. It also simplifies the selling process by reducing the need to form an HOA, which has presented a challenge to many of those who choose to to build.
Pre-Approved DADU Designs: The City of Seattle offers a gallery of pre-approved DADU designs, simplifying the permitting process and reducing construction timelines. You can view some of these designs on the ADU Universe website.
Key Considerations Before Building
Before embarking on your ADU or DADU project, consider the following:
Zoning and Property Eligibility: Ensure your property meets the necessary zoning requirements. Tools like ADUniverse can help determine feasibility by simply typing in your property address.
Design and Aesthetics: Choose designs that complement your existing property and meet your specific needs. Pre-approved plans can expedite the process.
Budget and Financing: Assess the total cost, including design, permits, construction, and utilities. These build outs can come with fairly hefty price tags attached so it’s important to understand the full cost before committing to the plan. Explore financing options such as a HELOC or HELOAN with your lender or consult with builders who offer comprehensive packages.
Permitting Process: Familiarize yourself with Seattle's permitting requirements to ensure compliance and avoid delays. You can find a complete guide for applying for permitting on the city of Seattle’s website.
Helpful Resources
ADUniverse: Seattle's official platform provides a step-by-step guide, pre-approved designs, and tools to assess property eligibility.
Sky DADU: One example of a builder offering end-to-end services, including design, permitting, and construction of DADUs in Seattle and surrounding areas.
City of Seattle’s Website: The city of Seattle has links to several other resources on their page about ADU’s and DADU’s to help those interested in building these structures find more information.
Conclusion
Building an ADU or DADU in Seattle is now more accessible than ever, thanks to supportive legislation and available resources. Whether for family, income, or investment purposes, these units offer versatile solutions to meet diverse housing needs. By understanding the benefits, staying informed about legal requirements, and utilizing available tools and professional services, you can successfully navigate the process and enhance your property's potential like never before.