ADU rules in Ogden

Detached ADUs are expressly regulated (300 to 800 sq ft, no more than 25% of the rear yard) and an ADU is a listed permitted use in the R-1, R-2, R-3, R-4, R-5, R-2EC, R-3EC and R-2S zones, but only on a lot containing a single-family dwelling, one per lot, and never in a PRUD, apartment building, group dwelling, or condominium project. ADUs are barred in a mapped part of the Mount Ogden planning community, and the R-2A zone's use list does not name them. Since 10-1-2026, Utah Code 10-21-304(1)(a) says a specified municipality "shall adopt a land use regulation that permits a detached accessory dwelling unit on any lot or parcel that is 11,000 square feet or larger and contains a single-family dwelling"; Ogden has not yet amended its code to match, so on lots of that size the local exclusions conflict with state law.

The code defines an ADU as a functionally separate living space on the same lot or in the same building as the single-family dwelling, and §15-13-39 regulates units inside the dwelling (its appearance must remain that of a single-family residence, and any new separate entrance must be on the side or rear). The same parcel limits apply: single-family lot only, one ADU, and no PRUD, apartment, group dwelling, or condominium lots. Utah Code 10-21-303 separately makes an internal ADU a permitted use in residential zones; Ogden's only zone exclusion is the mapped Mount Ogden area.

A detached ADU shall not be less than 300 or more than 800 square feet and may not occupy more than 25% of the rear yard area. The section sets no square-footage limit for ADUs within or attached to the main dwelling. State law allows these limits: 10-21-304(4) lets a city regulate structure size and lot coverage of a detached ADU.

The property owner (titleholders included) must occupy either the primary dwelling or the ADU as their permanent and principal residence. The owner may keep a seasonal residence for up to 4 months a year but may not rent out the vacant permanent unit while away, and a change of ownership voids the ADU permit. Utah Code 10-21-304(4)(c) expressly allows this requirement for detached ADUs.

The lot must already have the two off-street spaces required for a single-family dwelling. No new front or side yard parking (a parking slab or widened driveway) may be added for the ADU; tandem parking in the existing driveway is the designated means of parking, provided it does not extend over the property line or public sidewalk. This sits within Utah Code 10-21-304(3)(b) and (c), which bar requiring more than two on-site spaces for a detached ADU of 650 sq ft or more, or more than one for a smaller unit.

An ADU is a listed permitted use (not conditional) in the R-1, R-2, R-3, R-4, R-5, R-2EC, R-3EC and R-2S use lists, and approval is staff level: after review by the Building Services and Fire Divisions, the Planning Division approves or denies and issues a land use permit. An accessory dwelling permit is required in addition to any building permits, and the city records a certificate with the Weber County Recorder. This is consistent with Utah Code 10-21-304(3)(a), which bars a conditional use permit for a detached ADU in a primarily residential zone.

While the owner occupies the main dwelling or the ADU, the other unit may be rented. The non-owner-occupied unit is limited to no more than two related or unrelated adults, with or without their minor children. Under §15-13-39.C.5 a short-term rental may not be housed in the ADU unless the associated primary single-family dwelling is owner occupied; the short-term rental section, §15-13-38.C.3, words it more loosely (a short-term rental may use the ADU or the main house as long as one or the other is owner occupied) and requires a city short-term rental license.