ADU rules in Gretna

Gretna's Zoning Regulations (Ord. No. 2000 of July 5, 2017, posted as modified through October 2022 and amended by later ordinances read separately) contain no accessory dwelling unit, guest house, granny flat or second-dwelling use. Section 4.6.1 allows no 'more than one principal building on a lot unless otherwise provided', the R-1, RE and RE-A districts permit a single family dwelling as the only dwelling use, and §4.26 declares every use not listed in a district prohibited. The code does define 'accessory living quarters' inside an accessory building, but only for temporary guests with 'no kitchen facilities' and 'not rented or otherwise used as a separate dwelling unit', and no district lists it, so a backyard cottage or garage apartment with its own kitchen cannot be permitted anywhere. Detached garages and sheds in R-1 to R-3 are capped at 720 sq ft in total (§4.14.10).

There is no attached, basement or internal accessory apartment use. The only way to put a second unit inside or onto a house is to make it a two-family dwelling ('a building designed or used exclusively for the occupancy of two families living independently of each other and having separate kitchen and toilet facilities for each family'), which is a permitted use by right in R-2 Medium Density (§5.10.2), R-3 High Density (§5.11.2, restated by Ord. No. 2191 of 12-16-2025) and R-4 Highest Density (§5.11A.2, restated by Ord. No. 2208 of August 2026), and in the MUC district. The duplex must meet the district's two-family lot rules: 12,000 sq ft and 80 ft wide in R-2, 10,000 sq ft and 80 ft in R-3. R-1 Low Density, the main single-family district, and RE, RE-A, TA and AG permit only single family dwellings, so no second unit is possible there without a rezoning.

Because the code has no ADU use, it sets no ADU floor-area or percentage cap. A two-family dwelling is bounded by the district lot table instead of a unit cap: in R-2 a 12,000 sq ft lot, 80 ft width, 35 ft height and 40 percent building / 55 percent impervious coverage; in R-3 a 10,000 sq ft lot, 80 ft width, 45 ft height and the same coverage (Ord. No. 2139 of 4-18-2023 restated the R-3 table without changing the two-family row). Accessory buildings in R-1, R-2 and R-3 are limited to two structures, a detached garage of up to 720 sq ft and a shed of up to 144 sq ft, 'Provided that the total area of all of the accessory structures does not exceed 720 square feet', with a 17 ft height limit (R-2 allows 20 ft beside a two-story house) and 10 percent lot coverage; none of that space may be a separate dwelling.

No owner-occupancy rule appears in the Zoning Regulations. The duplex route in R-2, R-3 and R-4 is a permitted use with no residency condition, and the code defines a dwelling unit as 'a separate, independent housekeeping establishment for owner occupancy or lease on a weekly, monthly, or longer basis', so both units of a duplex may be rented. Nebraska has no state ADU statute that would set or bar an owner-occupancy rule.

The §8.03 schedule requires 'Two spaces per dwelling unit' for a duplex and, for single-family attached and detached residences, 'Two spaces per dwelling unit with one required to be enclosed', so converting a house into two units doubles the requirement. Ord. No. 2192 (2025) amended §8.03 only for medical clinics and offices, and Ord. No. 2195 (2026) amended the shared-parking rules in §8.04 and the MUC district; neither touched the residential rows.

There is no ADU permit. A two-family dwelling is a listed permitted use in R-2, R-3 and R-4, so adding or converting to a duplex there needs only the city's residential building permit, with no Planning Commission hearing. Nothing ADU-like is listed as a conditional use in any district, and a Planned Unit Development may include only uses permitted in R-1 through R-3 and the nonresidential districts (§5.19.3), so a second unit on an R-1 lot would require a rezoning to R-2 or higher, a legislative decision by the City Council after a Planning Commission recommendation.

The Zoning Regulations say nothing about short-term rentals and the city has no rental licensing or registration ordinance (the 2014 to 2026 ordinance folders and Municipal Code Chapter 5 show none). Guest quarters in an accessory building must be 'not rented or otherwise used as a separate dwelling unit' (§2.3.5), while a dwelling unit may be leased 'on a weekly, monthly, or longer basis' (§2.3.177). Ord. No. 2170 (2025) added Chapter 5, Article 12 to the Municipal Code, levying from April 1, 2025 a 5 percent occupation tax on any 'facility where the public may obtain sleeping accommodations for payment', including a 'tourist home' or 'bed and breakfast', for rooms rented for no more than 30 continuous days; whether the city applies it to whole-home short-term rentals was not confirmed. Neb. Rev. Stat. 18-1758 bars the city from prohibiting short-term rentals.