Carbondale planning commission continues ADU code review after wide-ranging debate on size, review tracks and short‑term rentals

The Planning and Zoning Commission of Carbondale continued a public hearing on proposed amendments to the town's Universal Development Code concerning accessory dwelling units (ADUs) on Sept. 11, 2025, voting to reconvene the hearing on Oct. 9, 2025. The panel spent the meeting debating bedroom counts, minimum and maximum square footage, a 66/33 size ratio tied to the primary dwelling, parking and neighborhood impacts, and whether ADUs should be eligible for short-term rental use.

Commissioners said the changes could expand housing options but also carry neighborhood impacts that merit careful rules and staged implementation. Ellie (staff planner) summarized the current administrative baseline: "Our current process requires a minor site plan and a conditional or special use, which means there's a public hearing involved," she told commissioners, framing why the group was weighing alternatives to the existing public‑hearing path.

Most discussion centered on three linked issues: unit size and bedroom counts; how an ADU is measured relative to the principal dwelling (the 66/33 ratio currently in the code); and the approval process (administrative vs. public hearing). Jared Morck, a commissioner who identified himself as an architect, warned that unconstrained two‑bedroom ADUs could produce units larger than the primary house and "run into the issues" of scale and neighbor impacts. He emphasized parking and neighborhood effects, saying "parking, parking, parking and neighborhood impact ... has always been the number one thing." Commissioners discussed whether to regulate ADUs by bedroom count, by floor‑area ratio, or by a simpler maximum square footage.

Existing numeric anchors mentioned in the meeting: the town's zoning currently lists a 300-square‑foot minimum for ADUs; commissioners noted the 2024 International Residential Code (IRC) appendix suggests a lower minimum (about 170 square feet); the town's current ADU maximum referenced in the packet is 850 square feet for most situations and a tiered standard applies based on primary‑dwelling size. Several commissioners proposed an interim compromise of around 250 square feet as a potential minimum to balance habitability and cost.

On review procedure, commissioners coalesced around a tiered approach rather than an all-or-nothing change. The options staff will return with include: (a) administrative review (no public hearing) for low‑impact ADUs (for example, interior conversions or units that do not change a building footprint or elevation); (b) a simple notice-to-neighbors step that would trigger a hearing if there is objection; and (c) public hearings required for exterior additions that materially change height, massing or site footprint. Commissioners discussed preapproved plan sets and a path for pre‑designed ADUs to proceed without a hearing.

Short‑term rentals (STRs) in ADUs drew strong skepticism. Multiple commissioners said ADUs should primarily serve long‑term housing needs rather than short‑term commercial lodging. The commission did not adopt a code change at the meeting but asked staff to present options that would allow the commission and the Board of Trustees to decide whether to prohibit or tightly restrict STR use of ADUs.

Commissioners also discussed related topics staff will return with: parking standards tied to ADU size/bedrooms, storage standards (for bikes/skis/gear), different maximums for attached versus detached ADUs, and a streamlined amendment path for Planned Unit Developments (PUDs) that want to add ADU allowances.

Votes at a glance: The commission voted to continue the public hearing on ADU code amendments to Oct. 9, 2025. The motion was seconded by Commissioner Jesse Vogt and carried; the minutes record an "aye" vote and the chair announced, "Ayes have it." (See actions and provenance for the motion and vote.)

The commission directed staff to prepare draft amendment options and an administrative flowchart showing the proposed tiered review tracks, sample preapproved plans and neighbor-notice procedures for the commission's review at a future meeting. Staff said it will return with concrete recommendations, example tables illustrating different ratio/size scenarios, and proposed notice/appeal language for an administrative-to-hearing trigger.

Commissioner Franco Palumbo, who noted he lives in an ADU, said the discussion should balance resident needs and neighborhood character: "So fun fact, I do live in the ADU," he said, urging practical attention to storage and livability. Several commissioners reiterated that the goal from the Board of Trustees was to "make it easier" for people to build ADUs while protecting neighbors and public infrastructure.

The commission closed the session after the continuation vote and asked staff to circulate options in advance of the Oct. 9 public hearing so commissioners and the public can review examples and proposed thresholds.