To: Members of the Planning Commission
From: Tara Vargish, PE, Director, Development Services
Tammy King, Zoning Manager
Brad Boland, AICP Long Range Project Manager
Title
Accessory Dwelling Unit Regulations Amendment
Body
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Executive Summary
In 2018, the Town of Castle Rock adopted regulations allowing accessory dwelling units (ADUs) town-wide, with a mix of administrative approvals for internal units and a public hearing/Use By Special Review (UBSR) process for detached units or additions. While intended to provide housing flexibility in allowing an ADU, the UBSR process-requiring neighborhood meetings and public hearings-has proven burdensome for many homeowners looking to add a detached or expanded unit. All ADU applications that have gone through the UBSR process were unanimously approved with no public opposition.
In May 2024, the State of Colorado passed House Bill 24-1152 (HB24-1152), which mandates that many municipalities, including Castle Rock, allow at least one ADU per single-family lot and approve them through an administrative process. The law also limits restrictive local regulations, including those related to setbacks and owner-occupancy.
Castle Rock’s existing ADU regulations are largely consistent with the new state law. However, to ensure full compliance and improve the homeowner experience, staff recommends several updates to the ordinance. Key changes include:
• Eliminating the UBSR process for all ADUs in favor of administrative review
• Removing perpetual owner-occupancy requirements, while requiring proof of owner occupancy at the time of permit
• Setting a minimum size for interior ADUs at 750 sq ft
• Clarifying setback rules to ensure they are not more restrictive than those for primary structures
• Expanding allowance of ADUs in all single-family areas, including those with prior PD limitations
These updates reflect feedback the Town has received from ADU applicants and aligns with state law while maintaining the original goals of the ADU program: providing alternative housing options, increasing housing flexibility, and supporting evolving family needs.
Staff presented the proposed amendments to the ADU regulations to the Town Council at its April 15, 2025, meeting to seek direction on whether to proceed with bringing the changes forward for further consideration. Town Council directed staff to bring back a code amendment at a future public hearing.
Attachments
Attachment A: Proposed Ordinance