Broomfield moves to align ADU rules with new state law; council weighs owner‑occupancy, tiny‑home standards

Senior planner Ted Harburg presented a proposed accessory dwelling unit (ADU) code update and a set of policy questions tied to recently enacted state law referenced in the presentation as HB 24 11 52. The briefing described which Broomfield rules already comply, which rules must change and what policy choices remain for council.

Harburg told council Broomfield currently allows ADUs attached, detached or within principal units, limits ADUs to no more than 50% of the principal dwelling footprint and caps ADUs at no more than 800 square feet; the code requires one off‑street parking space per ADU and requires owner occupancy of either the ADU or the principal dwelling. The state law prohibits local governments from imposing certain “restrictive design or dimension standards” (for example, requiring an ADU to be smaller than 500 square feet in every circumstance), bars local bans on ADUs in jurisdictions that must allow them, and restricts local rules that would effectively prohibit ADU construction. The state law also limits local authority to require new off‑street parking for ADUs except in defined circumstances and allows municipalities to require owner residency only at the time of application in some limited situations.

Staff asked council five specific questions: (1) should the city set a minimum ADU allowance of 500 square feet so an ADU could always be at least 500 sq ft; (2) should the city continue to require construction of one parking space only on parcels that currently lack any off‑street parking or where on‑street parking is prohibited; (3) should Broomfield remove the owner‑occupancy requirement consistent with the state law; (4) should the code be clarified to allow tiny homes/tiny houses as ADUs and whether a permanent foundation should be required; and (5) should Broomfield seek “ADU‑supportive jurisdiction” certification to qualify for potential Department of Local Affairs grant programs (staff noted program details and awards are not yet final).

Council discussion mixed technical, legal and policy considerations. Council members who spoke broadly favored increasing the minimum ADU allowance to 500 square feet and opposed adding a new mandatory off‑street parking requirement in most circumstances. Several council members signaled they would accept removing the owner‑occupancy requirement to comply with state law but expressed concern about absentee landlords and wanted more enforcement or registration tools if owner occupancy is removed. On tiny homes, city building official Tim Pate explained staff’s preference for a permanent foundation or an engineered equivalent tie‑down system on account of local expansive soils and frost‑depth requirements: “The reason that staff, my group, would be supportive of keeping that in there is because of our soil conditions that we find throughout our city and expansive soil, etcetera,” Pate said. Several council members suggested allowing tiny homes but providing an engineered tie‑down or other safe alternative to a full conventional foundation to preserve affordability while addressing safety concerns.

On certification as an ADU‑supportive jurisdiction, staff told council that Broomfield already meets one or more of the strategies the state lists (for example, prohibiting use of ADUs as short‑term rentals) and could submit a preliminary report by the state’s June 30 deadline to enable potential grant eligibility; staff cautioned that grant details are not final and acceptance is not guaranteed. Council opinion was mixed; some members supported pursuing certification if the benefits outweigh staff time and implementation costs, while others said they were not convinced the likely benefits justify additional staff workload.

Staff proposed outreach via the project web page and public notices and, if directed, tentatively scheduled a first reading of the ADU code amendments for March. Council instructed staff to draft changes consistent with state law and to return with ordinance language and more analysis of enforcement, tiny‑home engineering options and HOA implications for homeowners who may plan ADUs after June 30, 2025.