ADU rules in Gillette

Gillette's December 2024 zoning rewrite created the city's first ADU pathway, and it is broad. Table b. E of Section 2.b states that ADUs are allowed in all residential zoning districts on lots that are individually owned and contain single-family dwellings, which covers R-R, R-S, R-1, R-2, R-3, R-4, M-H, E-MH and E-MH-RS. There is no conditional-use hearing, no minimum lot size in the ADU table and no zone-by-zone split; Table b. C routes the accessory use 'Residential occupancy - with restrictions' in every residential district to that same ADU table. The gates that actually bite are ownership and the principal use: one ADU per lot, the lot must be individually owned, and it must contain a single-family dwelling, which excludes duplex, multi-family, condominium and townhouse lots and rented pads in a mobile home park.

The ordinance never distinguishes an attached or internal ADU from a detached one: Table b. E states a single set of requirements for Accessory Dwelling Units regardless of where the unit sits, and Section 11 defines an Accessory Structure as one that may be detached or attached to the primary structure but must be subordinate and customarily incidental to it. Nothing in Table b. E requires detachment. The 'must be on a permanent foundation' line reads as an anti-RV and anti-shipping-container rule (Table b. F separately says a shipping container is not allowed as an ADU) and a basement or addition conversion satisfies it trivially. Table b. C's neighbouring row, 'Accessory use in detached structures', is the one expressly limited to detached buildings, while the 'Residential occupancy' row that points to the ADU table is not. Because the code is silent rather than explicit on internal conversions, get the Zoning Administrator's reading in writing before drawing plans; the 800 sq ft cap, owner occupancy, parking and utility requirements apply either way.

Table b. E sets a flat cap of 800 square feet maximum, with no percent-of-primary-dwelling alternative and no larger allowance on larger lots. Two other limits can bind first. Table b. C caps the gross floor area of an accessory use in a detached structure at the gross floor area of the permitted use on lots of 22,000 sq ft or less in R-1, R-2, M-H, E-MH, E-MH-RS, R-3 and R-4 (1.5 times the primary structure on larger lots, and throughout R-R and R-S), so a small house can pull the effective cap below 800 sq ft. Table b. E's 'Setbacks and Open Space' line then imports the district's accessory-use standards, including the open space requirement of 50 percent of the lot in R-1, which is usually what constrains a tight in-town lot since off-street parking does not count toward open space. Height follows the accessory-structure column of the district table: 35 feet in R-R, R-S, R-1, R-2, R-3, R-4 and M-H.

The first line of Table b. E is 'Occupancy: Owner must live on-site in either the primary dwelling or the ADU.' It is written as a continuing condition on the use rather than a one-time statement at application, and it can be satisfied from either unit, so an owner may move into the ADU and rent out the main house. Wyoming has no statute that limits or preempts local owner-occupancy conditions on accessory dwellings, so nothing overrides it. The code does not require a recorded deed restriction or affidavit and specifies no lapse procedure; enforcement runs through the general zoning provisions in Section 1.d.5, where each day of non-compliance is a separate misdemeanor carrying a fine of up to $750 plus court costs.

Table b. E requires one additional off-street paved parking space measuring 9 feet by 18 feet in addition to the primary dwelling's parking requirements, and Section 5's parking table backs it with a dedicated row: 'Residential: Accessory Dwelling Unit, 1 space per dwelling unit', against 'Residential, 2 spaces per dwelling unit' for the house. A single-family lot with an ADU therefore needs three off-street spaces in total. Section 5.b supplies the geometry: parking must sit on the same lot as the primary structure, each space must be at least 9 by 18 feet, parking areas must be at least 5 feet from side lot lines, required entrances, exits and driveways must be all-weather asphalt or concrete, and scoria is not allowed for off-street parking in residential districts. There is no transit-proximity, small-unit or lot-width exemption.

Administrative, with no discretionary hearing anywhere in the path. An ADU is an accessory use rather than a listed principal use, and Section 1.d.4.b provides that no building or structure may be constructed, erected or altered unless a zoning permit has been issued by the Zoning Administrator, while Section 1.d.4.g makes the decision ministerial: the Zoning Administrator will grant the permit if the proposed construction or use complies with the Zoning Code, and must state reasons in writing on denial. The zoning ordinance contains no conditional-use or special-use permit process at all (full-text searches for both phrases return nothing), and the Board of Adjustment hears only appeals and variances. A building permit follows under City Code Chapter 5, which adopts the 2024 International Residential Code (Ord. No. 4081, 6-16-2026, effective 7-1-2026); Table b. E requires the ADU to comply with the current Building Code as adopted by the City. Because Gillette zones under W.S. 15-1-601 and has adopted an IRC version, the new Fast Track Permits Act (W.S. 16-13-101 and 16-13-102, 2026 Wyo. Sess. Laws ch. 42) now applies to residential building permit applications filed on or after July 1, 2026: a completeness notice within 10 business days, a decision on a complete application within 30 calendar days, and deemed approval if that deadline lapses.

The only tenancy rule in Table b. E is the owner-occupancy line, so with the owner living on-site the other unit may be rented; nothing in the code sets a minimum lease term or requires a rental license or registration. Gillette has no short-term rental regime: full-text searches of both the Zoning Ordinance and the City Code on enCodePlus for 'short-term rental', 'vacation rental', 'transient' and 'lodging' return no land-use provision. The one nightly-lodging use expressly allowed in residential districts is a Bed and Breakfast Home, defined in Section 11 as a private owner-occupied home where a portion provides temporary accommodations for up to 30 consecutive days for a charge to registered guests, capped at four lodging units, requiring one or two family-style meals in a 24-hour period plus a state bed-and-breakfast license and a city use permit; it is permitted in R-R, R-S, R-1, R-2 and M-H. Because the code addresses nightly lodging only through that use, treat short-term rental of a whole ADU as unsettled and ask the Planning Division. Day cares are expressly prohibited in ADUs, and there is no separate-sale pathway: Table b. E allows one ADU per lot on an individually owned lot.