Garden State ADU helps New Jersey homeowners bring an existing second unit into compliance: a basement apartment, a finished attic with a kitchen, a garage someone has been living in.
Some were set up by a previous owner, some for a family member years ago. The question is rarely whether the space is comfortable. It is whether the town will recognize it, and that depends on two things in a fixed order.
Everything else follows from this. In New Jersey each municipality writes its own zoning, so the answer is in your town's ordinance and in the zone your lot sits in. There are three possibilities.
Your zone permits it. Some zones allow two-family houses. Some towns permit an accessory apartment or an accessory dwelling unit under conditions. If your unit fits what the ordinance allows, the problem is paperwork and construction, not zoning. Our town-by-town guide lists the towns we have verified.
Your town permits a family-only suite. A number of New Jersey towns have a mother-daughter provision. If the person living in the unit is family and you are not charging rent, that may be the category your unit belongs in, with its own conditions.
Your zone permits neither. This is a common case. It does not end the conversation, but it changes the routes available, which are the next section.
The zoning board of adjustment can permit a use in a district that is restricted against it. State law sets the bar: the board may do it in particular cases for special reasons, and only where it can be granted without substantial detriment to the public good and without substantially impairing the zone plan. It is a hearing, and the outcome is the board's decision. Some owners win these. It is not the route to count on.
The Municipal Land Use Law says a nonconforming use existing at the time an ordinance is passed may be continued. It also lets an owner apply for a certification that the use existed before the ordinance made it nonconforming, from the town's administrative officer within a year of the ordinance's adoption, or from the board of adjustment at any time. If your house has been a two-family since before your town's zoning said otherwise, and you can show it with tax records, old permits or similar documents, this is the route to look at.
Some towns publish a process for exactly this kind of question. Woodbridge Township lists an application titled "Legalize a Two-Family or Multi-Family Dwelling" on its Planning and Zoning forms page, alongside its variance application. Check your own town's forms page for something similar before assuming there is no path.
Many New Jersey towns treat a second kitchen as the thing that makes a second dwelling unit. Removing the range and its hookups, and opening the unit back up to the rest of the house, can turn an illegal apartment into a finished basement or an in-law suite that is part of one residence. You give up the separate apartment and keep the finished space, legally.
Once the zoning question has an answer, the construction side begins. New Jersey's Uniform Construction Code makes it unlawful to alter a structure, or change the use of part of one, without a construction permit, and it requires a certificate of occupancy before a changed use begins. Legalizing work that was done without permits means applying for them now. In practice that means drawings of what exists, permit applications to your local construction office, and inspections of work that is already covered up. Expect the inspectors to ask for some finished surfaces to be opened so they can see wiring, plumbing and framing.
For an existing house the state's Rehabilitation Subcode is the starting point. The Department of Community Affairs describes it as the place where every project in an existing building begins, because it sets out which parts of the code for new construction apply. One useful example from the Department: finishing an existing basement for habitable use does not, by itself, require raising the ceiling to the height required in new construction.
A separate apartment raises more questions than a finished basement does. The ones that decide most basement units are how someone sleeping there gets out in an emergency, ceiling height, the separation between the two units, and smoke and carbon monoxide alarms. We do not quote dimensions here, because the construction official applies the code to your building, not to a general case. We look at those items on site before you file, so you know what the work is.
If the unit will be rented, there is one more state rule to know. Before a one- or two-family home is sold, leased or otherwise changes occupancy, the owner has to obtain a certificate of smoke alarm, carbon monoxide alarm and portable fire extinguisher compliance from the local enforcing agency. Some towns, Woodbridge among them, also publish their own rental inspection form.
Start with the free zoning check. Send your address and ZIP and tell us what exists on the property now. We read your municipality's rules without contacting the town and email you a first read on which route you are likely on. A real person follows up within 1 to 2 business days.
In Central Jersey we can then look at the unit, tell you what the construction side is likely to involve, prepare the permit applications, and do the work to bring it up to code or to return the house to a single dwelling. Elsewhere in New Jersey we can connect you with a builder in your area. We are contractors, not attorneys. Where a variance or a nonconforming-use certification is involved, you will likely want a land use attorney to present the case, and we supply the plans and the facts about the building.
Sometimes. It turns on whether your zone allows a second dwelling unit on your lot. If it does, the route is construction permits, inspections and a certificate of occupancy. If it does not, the routes are a use variance from the zoning board, proof that the unit lawfully existed before the zoning changed, or removing the second kitchen so the house is a single-family home again.
Free zoning check on your address. We read the rules without contacting your town.
Where we build
We build in Central Jersey ourselves: Middlesex, Monmouth, Mercer, and Somerset counties. Anywhere else in New Jersey we still run your zoning check and can connect you with a builder in your area, and we vet anyone before we refer you.
Statewide NJ · NJ HIC #13VH13918800