The Bellevue City Council has identified simplifying permitting for detached accessory dwelling units (DADUs) and cottage housing as a priority. With the adoption of middle housing code changes in 2025, these housing types are now allowed on residentially zoned lots, providing the foundation for this work. Development of a new program will occur in three phases, beginning with community engagement to shape design criteria and tools to support future applicants, resulting in a pre-approved plans program that offers city-reviewed building plans for purchase.
Background
The Bellevue City Council established a set of priorities for 2024 to 2026 to guide policy and implementation work across the city. Twelve priorities were identified to advance council goals, including a priority to simplify permitting for DADUs and cottage housing by creating a pre-approved plans program. This direction reflects council’s interest in reducing regulatory barriers, improving predictability and supporting broader use of these housing types.
On June 24, 2025, council adopted middle housing code changes that allow ADUs and nine types of middle housing on all lots zoned predominantly for residential use, including DADUs and cottage housing. With this regulatory framework now in place, the city is positioned to develop and implement a pre-approved plans program that supports the council priority.
What housing types are included
Cottage housing
- Maximum size: 1,500 square feet
- Maximum height: 24 feet
DADUs
- Maximum size: 1,200 square feet
- Maximum height: 24 feet
Note: While the code allows up to 28 feet when a DADU is built above an existing garage, that scenario will not be included in this program due to site-specific variability (structural capacity, existing footprint and height, and design compatibility) that limits plan standardization.
Program phases
The proposed pre-approved plans program will allow community members to purchase city-reviewed building plans at a predetermined price. The program will focus on cottage housing and DADUs. These housing types are modest in scale and are anticipated to be more attainable than a conventional single-family home, making them well suited for a pre-approved plans approach that reduces barriers and supports incremental housing development.
Phase 1: Engage and imagine
Phase 1 focuses on building momentum, awareness and enthusiasm for the program.
Activities include:
- Outreach and messaging to clearly explain the program’s purpose, scope, and benefits
- Hosting a hackathon-style event in partnership with Govstream.ai and subject matter experts to identify tools and strategies that support successful implementation, including
- Using GIS mapping tools and zoning data to help customers assess site feasibility
- Creating tools that guide applicants through the permitting process
- Providing early resources to help property owners explore financing, professional contacts, and other practical considerations
- Community engagement to establish evaluation criteria for plan options. Example criteria may include:
- Broad applicability across typical Bellevue lot conditions
- Compatibility with Bellevue’s historic, existing or evolving architectural character
- Overall usability and homeowner preferences
Phase 1 is expected to conclude with a set of ideas and tools generated through the hackathon and a community-informed evaluation framework to guide plan selection.
Phase 2: Design and decide
Phase 2 centers on selecting designs for pre-review and pre-approval.
Activities include:
- Issuing a formal call for designs to the design and development community
- Reviewing submissions through a volunteer review panel
- Narrowing which plans move forward based on the Phase 1 evaluation criteria
- Advancing top-ranked designs into the Development Services Department pre-review to assess technical code alignment
Phase 3: Final review and program launch
Phase 3 completes plan approvals and prepares the program for public release. This phase will include department pre-approval of up to 10 selected plans and creating the public-facing webpage that will host and distribute plans for purchase.
Project timeline and scope
Work on the pre-approved plans initiative is expected to begin after council initiation. The overall schedule is planned to align with the goal of making the program available for community use around the time the next state building code update is adopted by council.
March 10, 2026 City Council Study Session