Side by side · New Jersey
Compare ADU rules across New Jersey
Flexible on where you build? The same backyard cottage can be routine in one city and impossible next door. This table puts 14 New Jersey cities side by side so you can shortlist the friendly ones before reading a single ordinance, or narrow it to just the cities you are deciding between. Every value is summarized from the city's own code; open a city's page for the full notes, citations, and fine print.
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| City | Detached ADU | Attached / internal | Max size | Owner occupancy | Extra parking | Approval |
|---|---|---|---|---|---|---|
| Asbury Park | Allowed | The ordinance text is written around ADUs in separate structures: Section 30-75.4.l requires an ADU to be constructed in the rear yard behind the principal building, and the definition requires a separate entrance and fully independent cooking and sanitary facilities. The city's FAQ states Asbury Park will consider an ADU in the main house only if the owner lives in the smaller unit. Two-family homes with both units in the principal building may add an ADU only in a separate structure per Section 30-75.4.u. Section 30-15 (definition), Section 30-75.4.j, l, u (Ord. 2024-6); city ADU FAQFull rules for Asbury Park Ordinance read July 2026 | No fixed square-footage cap. For ADUs in a new structure or an expanded accessory structure, the ADU's floor area and building coverage may not exceed that of the principal use and structure; maximum building height is 20 feet in all districts; minimum of two rooms, one of which must be a bathroom; the ADU counts toward district building and lot coverage limits (affordable or accessible ADUs may exceed permitted building coverage by 5%, combinable to 10%). | Required | Minimum one parking space for the ADU; the space may be allocated within an existing driveway with Planning and Redevelopment Department approval. The ADU may not eliminate or reduce required parking for the principal use, and no additional street curb cut may be built if one already exists (an alley curb cut is allowed). The parking requirement is waived for deed-restricted affordable ADUs. | Permitted use |
| Belmar | ADUs are allowed only as a conditional use, and only by converting an existing accessory dwelling structure (a detached secondary building already containing a dwelling unit) or by demolishing such a structure and replacing it with one newly constructed accessory dwelling structure containing not more than one unit. Existing accessory dwelling structures in all single-family residential zoning districts that contain existing accessory dwelling units are eligible; the ordinance does not authorize a brand-new ADU on a lot that never had an accessory dwelling structure. Ordinance read July 2026 | Not allowed | No floor-area cap stated for converting an existing structure. A newly constructed replacement accessory dwelling structure may not exceed the greater of 650 square feet or the footprint of the demolished structure (excluding garage area), and in no case more than 10 percent of lot area (the Director may allow a deviation of up to 15 percent of that area for a more efficient design). It must be one story, maximum 12 feet from average grade to the eaves; attics and basements are allowed only as non-habitable space. | Not required | None. The ordinance states that no additional parking demand shall be deemed created, and no additional off-street parking shall be required, as a result or condition of the conversion of an accessory dwelling unit. | Creation of an ADU is a conditional use subject to the conditions of § 40-6.14.3 and a site plan application to and approval by the Planning Board, with review of the unit's appearance for consistency with the main dwelling and neighborhood. Separately, § 40-6.14.4(a) says no bulk variances or site plan approvals are required unless the Director of Code Enforcement determines that proposed deviations from the replacement-structure design standards exceed the Director's discretion, in which case relief goes to the Zoning Board of Adjustment by minor site plan application with variances. Ordinance read July 2026 |
| Hoboken | Not allowed | Not allowed | Not specified; no ADU size standard exists because the code has no ADU provisions. For the one Court Street garage-apartment situation in R-1, the accessory building may measure 30 feet above average grade and may not exceed one dwelling over grade-level parking; through lots there are limited to 20% lot coverage for the Court-Street-fronting building. | Not addressed anywhere in the code. Because Hoboken has no ADU authorization, no owner occupancy standard for accessory units exists; the accessory apartment definition and the Court Street provision are silent on occupancy. Ordinance read July 2026 | No ADU-specific standard exists. Residential buildings require no off-street parking for the first 5 dwelling units and 1 space per dwelling unit after the first 5. A conversion that adds a dwelling unit must meet the off-street parking requirement for the new use before a new certificate of occupancy issues. | There is no ADU permit path because no district lists an accessory dwelling as a permitted or conditional use. Accessory uses in the R districts are limited to items such as private garages, home occupations, signs, and 'other uses customarily incidental to principal uses'; the conditional use article (§§ 196-36 to 196-38) contains no accessory dwelling standard. Adding a unit as a conversion to a permitted residential use requires meeting all requirements for the new use plus a new certificate of occupancy. Ordinance read July 2026 |
| Jersey City | Allowed | Not allowed | No square footage cap; size limited by accessory building standards: maximum height 18 feet (and two stories in RH-2, R-1, and R-2), side yard setback 2 feet (3 feet in R-2), and lot coverage limits (R-1 allows an extra 5% lot coverage when an ADU is present) | Not required | None in RH-1, RH-2, and R-1, where ADUs are expressly exempt from any minimum parking requirement; in R-2 the general residential standard applies (0.3 spaces per bedroom on lots wider than 50 feet; off-street parking is prohibited on lots 50 feet wide or less) | Permitted use |
| Maplewood | Allowed | Allowed | No more than 40% of the living area of the principal dwelling unit, no more than 800 sq ft, no less than 300 sq ft, and no more than two bedrooms; a fully handicapped-accessible ADU (NJ Barrier Free Subcode) earns a 5% increase in total maximum floor area, applicable to the principal dwelling, the ADU, or both | Required | No ADU-specific parking requirement; the exhaustive condition list in § 271-90 contains no parking standard | Permitted use |
| Montclair | Allowed | Allowed | Living area no more than 40% of the habitable area of the principal building, up to a maximum of 800 sq ft, and no less than 300 sq ft; no more than three rooms excluding kitchen and bathroom. Adaptive reuse ADUs that are fully accessible under the NJ Barrier Free Subcode get a 5% floor area bonus. Detached ADUs may not exceed 40 feet in length or width in any one direction. | Required | At least one off-street parking space must be provided for an ADU. | Permitted use |
| Newark | ADUs (detached or attached to the principal residence, one per property) are listed as a conditionally permitted accessory use only in the R-1 Detached Single-Family Residential district in Table 4-1; the row shows C for R-1 and a dash (not permitted) for R-2 through R-6, and ADUs appear in no other district use table. Conditional uses require an application to the Central Planning Board under MLUL Section 54 procedures. Detached ADUs must meet bulk standards: max 20 feet height, minimum 20% primary facade transparency, setbacks of 10 feet from one side and 5 feet from the other, 5 feet from rear line, principal building, and other accessory structures, and may not be located in the front yard beyond the principal building's front facade. Ordinance read July 2026 | Section 41:6-2-1 allows one ADU per property, detached or attached to the principal residence, as a conditional use in R-1 only. However, an ADU shall not be permitted in a basement, cellar, or attic, and conversion of an existing garage into an ADU is prohibited, which rules out the most common internal-conversion forms. Ordinance read July 2026 | Maximum 600 sq ft floor area; minimum floor area is 400 sq ft or 25% of the principal dwelling's floor area. Detached ADUs may not exceed 20 feet in height. | Required | One off-street parking space required for the ADU. | ADUs are a conditional use: Table 4-1 marks them C (conditionally permitted) in R-1, and the standards sit in Chapter 41:6 Conditional Use Standards. Section 41:6-1 requires an application to the Central Planning Board, heard under the procedures of Section 54 of the NJ Municipal Land Use Law (C.40:55D-67); the Board may deny a conditional use it judges detrimental to health, safety, and general welfare. Ordinance read July 2026 |
| North Wildwood | Not allowed | Accessory apartments (a single additional dwelling unit within a single-family detached dwelling, per the § 276-7 definition) are allowed only as conditional uses, and only in three zoning districts: R-1.5 Single-Family Residential (§ 276-15.1C(1), amended 10-17-2023 by Ord. No. 1916), MC-1 Motel Commercial 1 (§ 276-24E(1)), and MC-2 Motel Commercial 2 (§ 276-24.1E(1)). In each district they may be developed as an optional development scheme subject to enumerated standards: located inside the single-family detached dwelling, no studio apartments, one per lot, entrance on the front elevation or the front third of a side elevation, RSIS parking compliance, and ADA plus N.J.A.C. 5:94-3.14 accessibility and adaptability compliance. A full-text search of the code found no other district that lists accessory apartments. Ordinance read July 2026 | In the R-1.5 district, no larger than 25% of the total habitable floor area of the structure (§ 276-15.1C(1)(d)); in the MC-1 and MC-2 districts, no larger than 40% of the net habitable floor area of the single-family detached dwelling (§ 276-24E(1)(d), § 276-24.1E(1)(d)). All districts require at least the minimum net habitable floor area set by the city's Affordable Housing Ordinance whether or not the unit is an affordable unit. The § 276-7 definition separately caps accessory apartment units at 25% of the net habitable floor area of the principal dwelling and sets a 500 square foot minimum with at least two rooms; studio apartments are prohibited in every district. | Not required | Any increase in the number of bedrooms on the lot caused by adding an accessory apartment to an existing single-family detached dwelling requires compliance with the parking requirements of the New Jersey Residential Site Improvement Standards, RSIS (N.J.A.C. 5:21-1 et seq.). RSIS sets parking by bedroom count; § 276-15.1G(1) adds that if the applicant does not specify bedroom counts, each dwelling unit is charged at the RSIS four-bedroom rate. Stacked parking is limited (§ 276-15.1G(3)). | Accessory apartments are expressly listed under the heading 'Conditional uses permitted' in R-1.5 and 'Permitted conditional uses' in MC-1 and MC-2, and the R-1.5 purpose statement says the district exists 'to permit accessory apartments as a conditional use.' Conditional use approval in New Jersey runs through the planning board under N.J.S.A. 40:55D-67 (the statute the ordinance cites for its other conditional uses). Ordinance read July 2026 |
| Ocean City | The program covers voluntary conversion of existing single family or two family dwellings or accessory buildings, and eligibility extends to owners who occupy the principal structure on a lot on which an accessory unit will be located, so a unit in a detached accessory building is possible. It is allowed only through the deed-restricted affordable accessory apartment program, only in the R-2 and RMF zone districts excluding bayfront and oceanfront lots, and only on fully conforming lots. Ordinance read July 2026 | Conversion of an existing single family or two family dwelling to accommodate an accessory apartment is the core of the program, but only for owner-occupants who rent the unit to low- or moderate-income households, and only in the R-2 and RMF zones off the bayfront and oceanfront. The accessory apartment and any existing unit must each have a separate door with direct outside access, and the project may not add a door to the front facade of the principal structure. Ordinance read July 2026 | 950 square feet gross floor area maximum, 450 square feet minimum. The unit must contain one kitchen with sink, refrigerator, and cooking facilities and one full bathroom with sink, toilet, and tub or shower. | Required | Yes. Accessory apartments created by new construction must conform to the parking requirements of the zone district (R-2 or RMF); accessory apartments created through renovation or rehabilitation of existing structures must add one additional off-street parking space. All spaces must comply with the ordinance parking standards. | Permitted use |
| Princeton | Allowed | Allowed | 800 sq ft or 25 percent of the total floor area of the principal dwelling, whichever is greater; ADUs deed-restricted to low- and moderate-income occupancy under UHAC may reach 1,000 sq ft or 30 percent, whichever is greater; a fully barrier-free accessible ADU earns the property a 5 percent increase in total maximum floor area; maximum three habitable rooms (four for UHAC-restricted units); a detached ADU structure may not exceed the size of the principal dwelling | Not required | No additional off-street parking for ADUs with two habitable rooms; one additional off-street space for ADUs with three habitable rooms; the ADU may not eliminate the required parking for the principal single-family dwelling | Permitted use |
| South Orange | Allowed | Allowed | 350 to 750 square feet; must have less total square footage than the principal dwelling; maximum two bedrooms; detached ADUs capped at 25 feet in height and must be smaller in size and height than the principal building | Required | One additional off-street space per ADU, on top of the parking required for the principal dwelling | Permitted use |
| Teaneck | Allowed | Allowed | Attached ADU: up to 40% of the primary dwelling's floor area or 800 sq ft, whichever is greater; if deed-restricted for low- and moderate-income occupancy under UHAC (N.J.A.C. 5:80-26.1 et seq.), up to 50% of the primary dwelling's floor area or 1,200 sq ft, whichever is greater. A fully handicapped-accessible ADU (NJ Barrier Free Subcode) earns the property a 5% increase in total maximum floor area, applicable to the PDU, the ADU, or both. Detached ADUs are capped at 24 feet in height; the ordinance's square-footage formula in Sec. 33-56(e) is worded for attached ADUs, and a garage attached to a detached ADU may not exceed the allowable combined square footages otherwise allowed on the lot. | Required | One parking space per ADU; the space must be located within the setbacks and in an existing driveway as tandem parking. | Permitted use |
| Toms River | Not allowed | Accessory apartments inside a detached, owner-occupied single-family dwelling are permitted, but only in the R-800, RR, R-400C and R-400 zoning districts, only on lots that otherwise conform to the district's bulk requirements, and only as deed-restricted affordable units rented to low- or moderate-income households; the townwide program is capped at 10 units. The unit must be self-contained (kitchen, complete sanitary facilities, sleeping quarters) with a separate door and private entrance, and must consist of at least two rooms, one being a full bathroom. Ordinance read July 2026 | No fixed square-footage cap; the accessory apartment may not exceed the gross floor area of the existing principal dwelling on the lot. Minimum size is two rooms, one of which must be a full bathroom. The Township may not restrict the number of bedrooms. | Required | Minimum of two on-site parking spaces provided exclusively for the accessory apartment, in addition to the spaces required for the existing principal dwelling. | Permitted use |
| Wildwood | Not allowed | An additional dwelling unit may be created by adding an accessory apartment within a single-family dwelling on lots in the R-1, R-2, R-3, RM, WR, WR-1, and MC-R districts, as a Planning Board conditional use. The definitions chapter defines ACCESSORY APARTMENT UNITS (IN-LAW SUITE) as a single additional dwelling unit within a single-family detached dwelling with at least two rooms and sanitary and cooking facilities for the exclusive use of its occupant. § 17-503A, H; § 17-201 (definition of ACCESSORY APARTMENT UNITS (IN-LAW SUITE))Full rules for Wildwood Ordinance read July 2026 | No larger than 25% of the net habitable floor area of the dwelling unit, with a minimum of 500 square feet; must contain at least two rooms | Not required | Per the § 17-608 off-street parking schedule, accessory apartments require, for each dwelling unit: 1.0 space for 1 bedroom, 1.5 spaces for 2 bedrooms, 2.0 spaces for 3 bedrooms | Accessory apartments are listed under Section 500, Conditional Uses and Supplemental Regulations. Section 17-503H requires application to the Planning Board for a conditional use before a construction permit or certificate of occupancy is issued for creation of an apartment involving enlargement of an existing dwelling, and the Planning Board's conditional use review includes any required site plan review under the chapter. Ordinance read July 2026 |
Summarized from each city's ordinance text, most recently read July 2026. Tap a value marked with an info icon to see exactly what it depends on, straight from the ordinance. Nearly every value has zone, lot-size, or process caveats beyond that; the per-city pages carry the full notes and code citations. Treat this as orientation, not a permit determination.
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Reading the table
- Detached ADU is the make-or-break column for backyard cottages: minimum lot sizes (often 8,000 to 14,500 sq ft) hide behind many of the "Allowed" values, so check your lot before celebrating.
- Attached / internal (basement apartments, additions) is legal almost everywhere and is usually the path of least resistance.
- Approval: "Permitted use" means staff-level sign-off; "Conditional use" means a public hearing, which adds time, cost, and uncertainty.
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