Carbondale planners debate raising Old Town Residential impervious cap to enable ADUs

CARBONDALE — The Planning and Zoning Commission on Oct. 23 debated whether to relax Old Town Residential (OTR) impervious-lot-coverage limits to make detached accessory dwelling units (ADUs) feasible on lots with rear garages and long driveways.

At the start of the meeting, staff recapped earlier decisions: a proposed ADU minimum size of 250 square feet, a likely maximum of about 1,000–1,200 square feet, a 60/40 main-building-to-ADU ratio, and a unanimous preliminary decision to prohibit short-term rentals for ADUs. The bulk of the evening’s public comments and commissioner debate then focused on whether OTR’s current 42% limit should rise to 52% (the town’s low‑density residential maximum) or to a number between 42% and 52%.

“That extra 10% would give me 550 extra square feet,” said resident Kenny Titler, describing a 1940 home on cinder blocks with a long driveway and a garage at the rear. Titler said keeping his driveway intact under the 42% cap would limit a detached ADU there to about 240 square feet; increasing coverage to roughly 52% would let him build a 380–400 square-foot unit without ripping out the driveway and garage access.

Commissioners and other speakers raised competing concerns. Supporters said a modest increase would make ADUs attainable for many older OTR properties where foundations, lot layout or historical development pattern prevent practical modifications. “This would make it so much easier for me to build,” Titler told the commission.

Opponents and cautious members urged restraint. Several commissioners noted the 42% cap was intended to preserve tree canopy, front- and back-yard green space and the low-scale character of the historic neighborhood. “When you open it up by 10%, it will change things,” said a commissioner, noting risks of larger homes, increased hardscape and “looming mass” on small lots. Commissioners discussed intermediary options — for example, lifting OTR coverage toward the mid-40s rather than the full 52% — and requested parcel-by-parcel data to understand how many OTR lots would be affected.

Staff told the commission that the OTR design-guideline update is nearing completion and will come to the Historic Preservation Commission before final code amendments; staff recommended bringing HPC feedback and parcel‑distribution data back to P&Z before selecting a coverage number. Commissioners generally supported returning to the issue after HPC review rather than making a final change immediately.

The commission did not adopt a coverage change at the meeting; instead it directed staff to obtain parcel statistics and to seek HPC comment and continued the public hearing on the Unified Development Code amendments to Nov. 13, 2025.

Provenance: First related remarks appear in the public-comment section (Kenny Titler, 13:23) and the topic discussion runs through later commissioner deliberations (last related comments at 01:12:10).