ADU rules in Park City

Detached Accessory Apartments are allowed, but only on lots of 3,750 sq ft or greater; they must meet the zoning district setbacks for single-family dwellings, stay within recorded plat disturbance limits, and may not exceed 18 feet in height from existing grade. The LMC definition also lets an Accessory Apartment be created within a detached garage.

Two attached paths exist. An Accessory Apartment may be created by adding on to or within a single-family dwelling (per the §15-15-1 definition), and a separate Internal Accessory Dwelling Unit is allowed inside a single-family dwelling on a lot of 6,000 sq ft or greater under §15-4-7.1. Zone use tables checked (HRL, E-40, RC districts) list Accessory Apartment as an allowed use with an administrative permit.

Accessory Apartments must be between 280 and 1,000 sq ft, no more than one third of the dwelling size, and limited to two bedrooms; they may not push the structure over the maximum floor area allowed by the LMC or subdivision approval. §15-4-7.1 sets no floor-area cap for Internal ADUs, only a 6,000 sq ft minimum lot size.

Depends on ADU type. For Internal Accessory Dwelling Units the single-family dwelling must be occupied by the owner and the unit may not be sold separately (§15-4-7.1, Ownership). No owner-occupancy requirement appears in §15-4-7 for Accessory Apartments; its deed restriction runs with the land and transfers automatically on sale.

Parking is allowed only in approved garages and on paved driveways; spaces need not be covered. Tandem parking is allowed if the driveway is at least 25 feet long or to preserve significant vegetation. In residential historic districts, tandem parking needs extra approval: an administrative permit with findings for Accessory Apartments, a conditional use permit from the Planning Commission for Internal ADUs.

Both types go through a staff-level Administrative Permit from the Planning Department: for Accessory Apartments the department shall approve the permit if the §15-4-7 criteria are met, and Internal ADUs are reviewed for final action under §15-1-8. Exception: an Internal ADU in a single-family dwelling designated Significant or Historic on the Park City Historic Sites Inventory is an Administrative Conditional Use reviewed against historic design guidelines and conditional use criteria.

Nightly rentals are prohibited in Accessory Apartments and rental terms must be at least 90 days, enforced through a recorded deed restriction. For Internal ADUs, neither the single-family dwelling nor the ADU may be rented for less than 30 days, and only one of the two units may be rented (the owner must occupy the other), also recorded as a deed restriction.