Howell, NJ Accessory Structures: ADU Rules (2026)

Howell Township Code § 188-178H, part of the Special Mount Laurel requirements, is the Township's accessory apartment rule. It authorizes the Planning Board to issue a special use permit for an accessory apartment in single-family dwelling units served by water and sewer facilities within any residential zoning district. An accessory apartment is a self-contained unit with its own kitchen, sanitary facilities and private entrance, created inside an existing single-family home, through conversion of an existing accessory building on the same site, or by addition to either.

Site conditions come first. Adequate off-street parking is required for both uses under § 188-106, with turnaround areas so vehicles do not back into a roadway. Where the primary and accessory units are used together, the owner of the lot must occupy the primary unit. The home must keep the appearance of a single-family residence to the degree reasonably feasible, no additional entrance is permitted on the front of the principal dwelling, and no unit can sit above the second floor. Accessory apartments are not permitted on lots of less than 20,000 square feet.

Size is capped by the size of the house. The apartment's net floor area must be at least 400 square feet, and it is limited to a maximum of two bedrooms. For a house under 3,000 square feet the ceiling is 40% or 1,000 square feet, whichever is less. For a house of 3,000 up to 5,000 square feet it is 30% or 1,200 square feet, and for 5,000 square feet or more it is 20% or 1,500 square feet. House area counts every story and the basement, measured from the outside faces of the exterior walls, but not roofed unenclosed porches or carports.

Affordability is built in. The Planning Board requires a deed restriction recorded in the County Clerk's office for a minimum of 10 years, limiting occupancy to low- or moderate-income households, with rents excluding utilities held to 30% of gross monthly income. Efficiency units are priced for one-person households, one-bedroom units for two-person households and two-bedroom units for three-person households. Construction and any modification also follow the Uniform Construction Code of New Jersey, including a building permit and certificate of occupancy.