Planning Commission recommends ADU code changes to streamline approvals and align with state law

The Town of Castle Rock Planning Commission on May 22, 2025 voted 4-0 to recommend that Town Council approve proposed amendments to Chapter 17.61 governing accessory dwelling units (ADUs) (PC-2025-059). Staff said the changes bring the town’s ADU regulations into alignment with state law (House Bill 24-1152), simplify the permitting pathway and clarify size and setback rules.

Staff explained the 2018 ADU regulations allowed interior ADUs, detached ADUs and additions but placed detached ADUs and some exterior conversions through a Use by Special Review (UBSR) process that could require multiple neighborhood meetings and public hearings. "The intent of the town ADU regulations is to provide alternative housing options to make more efficient use of existing housing stock and infrastructure," staff said in the presentation.

Under the proposed amendments staff recommends: making all ADU approvals administrative rather than proceeding through the UBSR process; removing the perpetual owner-occupancy requirement while verifying owner occupancy at the time of building permit issuance; allowing interior ADUs to be up to 750 square feet (the code change will permit at least 750 sq ft or 50% of the primary dwelling, whichever is greater, per staff explanation); aligning ADU side-yard setbacks with accessory structure setbacks; and allowing ADUs in single-family areas regardless of prior PD limitations. Staff also said the Department of Local Affairs reviewed the draft ordinance and concluded the changes are consistent with HB24-1152.

Commissioners asked about guardrails to limit unintended consequences, such as a proliferation of short-term rentals or HOA prohibitions. Staff and Tara Vargas noted the town does not regulate whether a single-family home is rented and that state law limits some HOA enforcement over ADUs; staff emphasized that procedural streamlining is intended to reduce time and cost burdens on homeowners seeking to create ADUs.

Staff supplied a historical tally: since 2018 the town has processed approximately 81 ADU applications total; nine proceeded through the UBSR process and were approved. Staff said several applicants who went through UBSR found the length of the public-review process sometimes affected project costs and timing.

A motion to recommend adoption of the ADU amendments to Town Council passed on a 4-0 roll call. Vice Chair Kevin McHugh, Commissioner Tom Martinez, Commissioner Mitchell Swan and Commissioner Jeff Samuelson voted in favor. The recommendation will advance to Town Council for final action.