To: Honorable Mayor and Members of Town Council
Through: David L. Corliss, Town Manager
From: Tara Vargish, PE, Director, Development Services
Tammy King, Zoning Manager
Brad Boland, AICP Long Range Project Manager
Title
Ordinance Amending Various Provisions of Chapter 17.61 of the Castle Rock Municipal Code Regarding Accessory Dwelling Units (Second Reading - Approved on First Reading on June 17, 2025, by a vote 6-0)
Body
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Executive Summary
For second reading, staff has clarified that the size limitation set by the state is not a minimum of 750 sq ft, however a resident could go up to 750 sq ft if it was larger than 50% of the size of their primary unit. Updates to this topic in the staff report below are shown in bold.
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
• Allowing an interior ADU to either be 750 sq ft or 50% of the primary dwelling unit, whichever is greater. The owner could still choose a smaller size.
• 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 proceed with public hearings to adopt the proposed changes. On May 22, Planning Commission reviewed the proposed changes and recommended approval by a vote of 4-0.
Recommendation
Planning Commission voted 4-0 to recommend to Town Council approval of the proposed changes to the ADU regulations.
Proposed Motion
Option 1: Approval
“I move to approved the ordinance, as introduce by title.”
Option 2: Approval with Conditions
“I move to approve the Ordinance, with the following conditions: “ (list conditions)
Option 3: Continue item to next hearing (need more information to make decision)
“I move to continue this item to the Town Council meeting on [date], at [time].”
Attachments
Attachment A: Proposed Ordinance