Seattle DADU Rules Now Allow Two Units Per Lot and More Flexibility for Builders
Seattle just made it easier for homeowners to build DADUs. As of July 1, 2025, the city rolled out new rules that simplify construction and increase flexibility. Property owners can now build up to two ADUs per lot—including two detached units. The city also raised height limits, reduced parking requirements, and eliminated certain street improvement fees. These changes give builders more design freedom and make it easier to meet zoning standards. For the first time, homeowners can also subdivide lots with a DADU, allowing for future resale or separate ownership. These updates give families, investors, and developers more control over their land and long-term plans.
If you’re considering a detached ADU or multi-unit setup, this guide explains how the latest rules affect your options. Our team at New Image Construction Management helps clients across Seattle navigate permitting, design, and construction—every step of the way.
Key Takeaways from Seattle’s New 2025 DADU Rules
- Two ADUs per lot are now allowed, including two detached backyard cottages on the same property.
- Height limits have increased—up to 32 feet in Neighborhood Residential zones and 40 feet in others.
- New flexibility in design and permitting makes construction faster, more affordable, and easier to customize.
- Unit lot subdivision is now possible, allowing separate ownership of homes built on the same lot.
- Transit-adjacent properties benefit from no parking mandates and reduced street improvement fees.
- Seattle DADUs are no longer fringe projects—they’re a core part of the city’s long-term housing strategy.
Key Changes to Seattle DADU Rules in 2025
Seattle’s updated DADU regulations reflect a major shift toward housing flexibility and increased density. These changes aren’t minor tweaks—they dramatically reshape what’s possible for homeowners, investors, and developers across the city. By removing outdated restrictions and streamlining critical requirements, Seattle is actively encouraging more backyard cottages, rental units, and multigenerational housing in residential neighborhoods.
Two ADUs Now Allowed on One Lot
Most importantly, property owners can now build two accessory dwelling units per residential lot. This includes any combination of attached and detached units—even two fully detached backyard cottages. As a result, homeowners now have more options to house extended family, generate rental income, or increase resale value with added living space.
Increased Height Limits Open New Design Options
To support better design flexibility, the city raised the maximum height limit for DADUs. You can now build up to 32 feet tall in Neighborhood Residential zones, and up to 40 feet in other zones. Therefore, more vertical space allows for improved layouts, sloped lot accommodations, and livable two-story units. For example, our Schooner and Diana floorplans take advantage of these generous height allowances to create spacious, comfortable interiors without compromising on curb appeal.
Fewer Design and Permit Restrictions
Seattle also introduced several rule changes that make it easier to design and permit a DADU. Builders now benefit from:
- Standardized code language across zoning types
- Relaxed requirements for entry and stair locations
- No parking mandates near public transit lines
- Reduced or waived street improvement fees in many areas
Because of these changes, DADU projects are more cost-effective and easier to permit. If you’re unsure whether your property qualifies for parking exemptions or reduced fees, our team can review your site and guide you through your Seattle DADU approval process.
Subdivision Now Allowed with a DADU
Perhaps the most game-changing update is the new right to subdivide a lot that includes a DADU. Previously, this wasn’t permitted. Now, homeowners can legally divide the land and create two separate ownership opportunities. This is especially helpful for families co-investing in a property or for those planning to sell one of the units. In addition, it opens the door to condo-style development in neighborhoods where space is available but zoning has been restrictive—such as West Seattle, Beacon Hill, and Columbia City.
If you’d like to explore how these zoning reforms connect with broader housing goals, visit our full breakdown on urban residential zoning and DADU projects in Seattle.
Why the New Seattle DADU Rules Matter
These changes aren’t just policy updates—they create real opportunities across Seattle. Whether you’re a homeowner caring for aging parents, a family planning for multigenerational living, or an investor adding rental units, the new rules make it easier to build. In the past, height caps, parking mandates, and ownership restrictions stopped many projects. Today, those barriers are gone or significantly reduced.
Because of these reforms, we expect more DADUs to appear in established neighborhoods like Ravenna, Greenwood, and Leschi. These areas have high housing demand but limited space. Seattle issued nearly 1,000 ADU permits in 2023 alone—a number that could rise sharply in the years ahead.
More importantly, the city now sees DADUs as part of its housing future—not as exceptions. Detached units are being welcomed as standard additions to residential neighborhoods. This gives property owners more freedom to build, improve property value, and meet changing household needs. The Urbanist highlights how the city pushed through these updates just ahead of the state’s legislative deadline, signaling a strong commitment to long-term housing reform.
At New Image Construction Management, we help clients navigate the new rules with confidence. From planning and permits to design and construction, we manage every step. If you’re unsure what’s possible on your property, we offer feasibility reviews and layout ideas to get you started.
For inspiration, explore our full range of Seattle DADU floorplans. Models like the Anna, Diana, and Anita are designed for comfort, flexibility, and code compliance.
How to Get Started with a DADU Project Under Seattle’s 2025 Rules
Now that Seattle has made DADU construction easier, many homeowners are eager to move forward. However, they often don’t know where to begin. The good news? With the right support, you can go from concept to permits in just a few weeks. Because the new regulations simplify many of the old roadblocks, it’s now more realistic than ever to complete a detached unit on your property. That said, every successful DADU still requires clear steps and experienced guidance. That’s where we come in.
Step 1: Review Your Property and Goals
First, identify your goals for building a DADU. Are you creating a home for family, planning a long-term rental, or building for future resale? These goals will influence design, placement, and project scope. Therefore, our team always begins with a free site assessment and a planning session to explore what’s possible under the current rules. We’ll help you evaluate your lot, its zoning, and the new height or setback allowances that apply to your area.
Step 2: Choose the Right Floor Plan
Once we confirm your lot is eligible, it’s time to select the right layout. Thanks to the new 2025 DADU rules, you now have more design freedom than ever before. Whether you prefer a compact cottage or a taller multi-level unit, we can help. For example, the Schooner layout offers a contemporary footprint with great rental potential, while the Anna provides easy single-level access for aging-in-place. You can explore all of our Seattle DADU floorplans or talk with our design team about custom options.
Step 3: Navigate the Permitting Process
Next comes permitting, which is much more straightforward under the new rules. Because Seattle reduced many parking and improvement requirements, the application process is now faster and more affordable. Even so, it still involves zoning reviews, energy code documentation, and SDCI coordination. That’s why we handle all of it for you. We submit plans, manage revisions, and keep your project moving. If you want to understand more about the approval process, check out our detailed guide on Seattle DADU permits and zoning.
Step 4: Begin Construction with a Trusted Team
After permits are issued, we move quickly into construction. At this stage, quality and experience make all the difference. That’s why we assign a dedicated project manager to oversee every detail. Our team handles excavation, framing, electrical, and finishes—keeping you updated at each milestone. Because we build across Seattle and surrounding cities like Bellevue, Redmond, and Kirkland, we’re already familiar with the local requirements and neighborhood expectations.
Step 5: Finalize, Move In, or Rent Out
Once construction wraps up, we complete a final walkthrough to ensure everything meets your standards. Depending on your goals, you might move in, list it as a rental, or prepare for resale under the city’s new unit lot subdivision rule. Either way, you’ll walk away with a high-quality DADU built to meet the latest Seattle regulations. For inspiration, we invite you to browse our completed projects or preview current builds in our project pipeline.
Plan Your Seattle DADU Project with Confidence
Seattle’s updated DADU rules open the door to smarter housing choices, whether you’re planning for family, rental income, or long-term growth. With fewer barriers, greater design freedom, and new opportunities for ownership, there’s never been a better time to build. That said, it still takes expert guidance to bring your vision to life and avoid costly mistakes along the way.
At New Image Construction Management, we help homeowners, investors, and developers navigate every step of the DADU process—from site planning and permit approvals to custom construction and final inspection. We’ve completed projects across Seattle and surrounding cities and can help you take full advantage of the new code updates.
If you’re ready to get started or want help exploring your options, we’re here to guide you. Request a project quote, or call us at (206) 552-9448 to schedule your free consultation. Let’s build something great—together.