Alpine homeowners who want to build a backyard apartment for an aging parent or a rental unit for extra income have one more chance to weigh in before the city locks in its rules.

The Planning Commission will hold a public hearing Tuesday, Aug. 18, at 6 p.m. at Alpine City Hall, 20 North Main St., to take comments on a proposed zoning code allowing detached accessory dwelling units on most single-family lots. If the commission recommends approval, the code advances to the City Council for a formal adoption vote ahead of a state-mandated Oct. 1 deadline.

The hearing is the last major public comment window. Planning Commission Chair Alan MacDonald signed the notice Friday, Aug. 7.

What the code allows

Under the proposed rules, as we reported Aug. 3, freestanding units would be permitted on lots of at least 11,000 square feet. Alpine already allows interior ADUs such as basement apartments under an ordinance adopted in October 2023. The new code adds detached structures as a separate category.

Key conditions include:

  • The property owner must live in either the main home or the ADU.
  • No short-term rentals. Units cannot be rented for fewer than 90 consecutive days.
  • One ADU per lot, whether internal or detached.
  • The ADU must match the main home's design and cannot exceed its size.
  • No units in front yards, public utility easements or recorded easements.
  • Parking: up to two on-site spaces required for units 650 square feet or larger; one space for smaller units.

If a homeowner converts a detached garage, any displaced parking must be replaced on-site. The city can also deny a permit if sewer, water or stormwater systems lack capacity.

Why the deadline matters

Utah's Senate Bill 284 requires every city with a population of 5,000 or more to allow detached ADUs by Oct. 1. Alpine's estimated population is 10,444. Under the state law, the city cannot require a conditional use permit for a detached ADU in a residential zone, according to the Aug. 4 agenda packet.

Properties covered by development agreements signed on or before May 6 may not be eligible.

Infrastructure concerns

At a Jan. 27 City Council work session, engineer John Schiess of Horrocks Engineers told the council that a few new ADUs probably would not strain Alpine's water and sewer systems, but if many are added, capacity would need to be reevaluated. Mayor Carla Merrill said at that session, "I am concerned about detached ADUs because it will increase capacity, and we have large lots in Alpine that could accommodate detached ADUs."

How to participate

The Aug. 18 hearing begins at 6 p.m. at Alpine City Hall, 20 North Main St. Supporting documents will be posted at alpineut.gov before the meeting. Residents can also call the City Recorder at 801-756-6347, ext. 3. The meeting will be streamed on Alpine City's YouTube channel.