Boulder adopts state-aligned ADU rules aiming to expand accessory dwelling unit construction
Loading...
Summary
Council approved ordinance 86-50 to align local ADU rules with Colorado House Bill 24-1152, removing some lot-size and owner-occupancy barriers and establishing administrative approval to qualify for state ADU grants.
The Boulder City Council voted unanimously Thursday to adopt ordinance 86-50, revising the city’s accessory dwelling unit (ADU) regulations to comply with recent state requirements and to position Boulder for a state ADU incentive program.
The ordinance changes remove a 5,000-square-foot minimum lot-size requirement for most ADUs, eliminate an owner-occupancy requirement for market-rate ADUs, expand where ADUs are allowed in more zoning districts, and establish an administrative approval pathway consistent with House Bill 24-1152. The code also sets a minimum maximum floor area for attached ADUs at 750 square feet and allows at least 750-square-foot ADUs regardless of house size. For detached ADUs, the code sets a maximum height of 20 feet and building coverage limits so rear-yard ADUs are similar in scale to detached units in low-density neighborhoods.
Lisa Hood, principal city planner, told council the changes are needed so the city qualifies as an “ADU-supportive jurisdiction” under the state program; jurisdictions that meet the law’s standards may compete for grants that provide up to $15,000 per ADU to assist construction, preapproved plans, or technical assistance. Hood said Boulder’s previous code edits (adopted in 2023) already led to an uptick in ADU construction: 37 ADUs have been completed and occupied since September 2023 and 21 were in permit or construction at the time of the presentation.
Councilmember Lauren Folkerts asked whether height limits remain. Hood said the state bill is silent on height; Boulder retains a 20-foot height limit for ADUs. Councilmember Nicole Speer asked whether staff would pursue available grant funds; Hood said staff would coordinate with housing and human services to explore grant application logistics.
Public testimony included a resident who asked for clarity on how prior PUD (planned unit development) restrictions would interact with the new law. Hood said the ordinance voids prior PUD prohibitions on ADUs while acknowledging that PUDs can also include other site-specific size limits; ADUs must still meet applicable zoning limits such as height, floor-area limits and bulk requirements.
After a roll-call vote, council adopted ordinance 86-50 without any recorded no votes.
Why it matters: Aligning local regulations with state law preserves Boulder’s eligibility for competitive state funding and removes several regulatory barriers that staff say have already begun to increase ADU production in the city.
What’s next: Staff said they would follow up on grant-application logistics and provide additional implementation details to council as needed.
