BOISE—The City of Boise is making it easier for residents to add more housing options on their properties by providing free pre-approved blueprints to build Accessory Dwelling Units (ADUs).
By making available pre-approved ADU plans, the city can further support more housing in our existing neighborhoods. Residents are now able to choose from a catalog of eight plans based on site conditions and preferences, from single-story to over-garage designs.
The pre-approved ADU plans save residents time and money. Property owners can complete the approval and permitting process in a few simple steps and cut down the design and permitting time to a matter of weeks. In addition, a custom ADU design can cost upwards of $10,000. The free city designs also include cost-saving measures that lower construction and operating expenses.
“ADUs support the city’s vision for thoughtful infill growth and for creating a variety of housing options for our residents, providing housing that is less water and energy consumptive, and enabling Boiseans to live where they work and play,” said Maureen Brewer, Planning and Development Services director for the city. “Although not the entire solution, ADUs have the potential to meaningfully contribute to our city’s housing supply in such a way that is particularly mindful of the affordability challenges we are facing together.”
Plans Designed for Boise Neighborhoods
Boise has experienced a growing interest in ADUs from residents who are looking to build in-law suites or similar converted spaces in their homes or properties. Between 2019 and 2023, there
was an average of 61 ADUs being built in Boise per year. In contrast, there were 130 ADUs in 2024 and 82 in 2025 either built or approved to do so.
The city’s free, pre-approved ADU plans were designed by the team at Parke Architecture, led by architect Eamonn Parke, AIA. His Boise-based architecture practice, selected by the city through a request for qualifications (RFQ), designed the eight plans ranging from 280 to 695 sq feet. Through a team effort with city staff, each ADU was named after different birds from the Boise Parks & Recreation "Field Guide to Boise Birds."
“These plans are designed to balance efficiency, livability and neighborhood compatibility, giving homeowners a practical path to add housing while positively contributing to our community’s fabric,” said Parke. “Accessory Dwelling Units are an important part of expanding housing choice in our neighborhoods while maintaining the character that makes Boise special. By offering thoughtfully designed, pre-approved plans, we’re helping reduce barriers for homeowners and making it easier to create flexible living spaces.”
ADUs from the pre-approved plan catalog include a range of designs that can fit a variety of Boise lots, from studio to two-bedroom configurations. These plans were made specifically for Boise, designed to fit the patterns of our existing neighborhoods while still offering room for customization, including options for Historic District compatibility, so the ADUs can adapt to the existing surrounding structures and the owners’ preferences.
In addition to the cost-effective measures included in the pre-approved plans, some of the designs are also user-friendly for DIY builders, adding to the total savings of the project. Homeowners should still be prepared for site-specific costs and work, such as utilities and impact fees.
You can learn more about the pre-approved plans, get a list of steps to build your ADU, and review the free blueprints at cityofboise.org/pre-approved-adu-plans/. Email PDS at zoninginfo@cityofboise.org or call 208-608-7100.