Commissioners debate detached ADU rules, utilities, parking and short‑term rentals; recommendation tabled

Sunset City’s Planning Commission spent much of its Aug. 14 meeting discussing external (detached) accessory dwelling units (ADUs), associated utility and infrastructure requirements, and how ADUs should be regulated alongside short‑term rentals. After an extended review of other cities’ ordinances and state law, commissioners voted to table a forward-ready recommendation and asked staff to return with clarified language and public-works input.

Staff and commissioners reviewed examples from Farmington, Mill Creek, West Point, South Salt Lake and Clinton. Public Works Director Monroe (not present to speak but described by staff) had advised staff that requiring separate culinary water and sanitary sewer laterals and utility meters for detached ADUs is technically preferable because small residential service lines (often 1-inch) may not be sized to handle the increased load. Staff said a separate sewer lateral can cost about $10,000; commissioners and staff flagged that cost as a significant deterrent for owners considering detached ADU construction.

Commissioners discussed a series of policy choices: whether ADUs should be owner-occupied, whether ADUs may be sold separately, whether short‑term rentals should be permitted inside ADUs, and how to limit overall household density (many commissioners favored one additional dwelling unit per lot). They reviewed possible numerical limits and thresholds used elsewhere: minimum lot sizes of 6,000 or 8,000 square feet, larger-lot thresholds (10,000–12,000) tied to larger allowable ADU square footage, and size caps in other cities ranging from about 650 to 1,500 square feet depending on lot size and ADU type.

State law on internal ADUs was quoted during the meeting: internal ADUs are defined and protected under state statute for long-term rentals (30 consecutive days or longer); the commission noted that municipalities cannot impose certain size or lot-size restrictions on internal ADUs under that law. Commissioners said that external ADUs can be regulated more strictly at the local level, but they must coordinate local definitions and the code glossary so “internal,” “attached,” and “detached/external” ADUs are consistently defined.

Commissioners expressed repeated concerns about the city’s infrastructure capacity (water and sewer), parking and enforcement, neighborhood character and privacy (height and setback rules), and the effect on school enrollment if more households locate in existing neighborhoods. They also discussed short‑term rentals separately; staff advised that the city’s current rental-license code does not allow rentals of less than 30 days and that the commission should treat short‑term rental regulation as a separate ordinance rather than folding those rules into an ADU ordinance. After discussion, the commission voted to table the external ADU recommendation and return with a consolidated ADU chapter (internal and external) that incorporates Public Works’ guidance on utilities, clearer definitions, and a draft table of lot-size and size limits.

Next steps: staff will (1) consult Public Works (Monroe) on utilities and infrastructure limits; (2) clean up the ADU definitions and the code glossary; (3) finalize a draft ordinance text and fill the ADU size/lot-size table; and (4) return the item to the commission for final recommendation to the City Council.