Garden State ADU builds in-law suite additions for New Jersey homeowners who want a parent, an adult child, or a caregiver close by without moving anyone into a spare bedroom. It is also, in most of this state, the path with the fewest obstacles between you and a permit.
An in-law suite is a private living space inside your home, with its own entrance, a bedroom, a full bath, a living area, and often a kitchenette. The person living in it can come and go without walking through your kitchen at seven in the morning. What separates it from an accessory dwelling unit is legal, not architectural: the suite stays part of one legal residence. One address, one set of utilities, one certificate of occupancy.
That distinction is the whole reason this page exists. It is what lets a suite move through your building department as an addition instead of arriving at the zoning board as a request to put a second house on your lot.
New Jersey has no statewide ADU law. Every municipality writes its own rules under home rule, and most of them have written nothing at all. In those towns a fully detached backyard unit needs a variance from the zoning board, which is a discretionary hearing with an uncertain outcome and a timeline you do not control.
An attached suite sidesteps that in most cases, because an addition to a single-family home is a permitted use nearly everywhere, subject to your zone's setbacks and lot coverage. Some towns go further and write the arrangement into the code directly. Middletown, for example, has a mother-daughter provision, Ordinance #504-203, that permits a family member's unit with its own cooking facilities, capped at one bedroom, with a deed restriction filed at the county clerk. It is family only and it is not rentable, and that trade is the point: you get certainty instead of a hearing.
The rules genuinely differ from one town line to the next, which is why the first step is reading your ordinance rather than picking a design.
NJ market range: $120k to $300k
New square footage attached to the house, built to whatever setback and coverage your zone allows. It gives you the most control over the layout because nothing is inherited from an existing structure, and it is usually reviewed as an addition rather than as a second dwelling.
NJ market range: $90k to $225k
An attached garage already has a foundation, a roof, and a wall shared with the house, so the shell cost drops. The work moves to insulation, egress, heating and cooling, and getting a bathroom's plumbing to the right place. Parking requirements are the constraint to check first, since some towns will not let you give up a garage space.
NJ market range: $90k to $225k
The cheapest square footage you already own, but the one most likely to be blocked by code rather than zoning. Ceiling height, a compliant second means of egress, and moisture control decide whether a basement suite is legal, not just comfortable.
Those figures are New Jersey market ranges across the industry, not a Garden State ADU quote. Your number depends on your lot, your existing structure, and what your town requires.
This is where most in-law suite projects get complicated, and it is worth understanding before you sketch anything. Many New Jersey towns treat a permanent stove as the line between a suite and a second dwelling unit. A sink, a refrigerator, a microwave and counter space usually read as a kitchenette inside one residence. An installed range can flip the same room into a second kitchen, and a second kitchen is often what triggers the harder review.
Some towns write the definition out plainly. Others leave it to the zoning officer. Either way, we design the kitchenette around your town's actual definition rather than a general rule, so the plan that goes to the building department is the plan that comes back approved.
Start with the free zoning check. Send your street address and ZIP and we read your municipality's current rules, then email you a first read on whether your town allows a detached unit, an attached suite, or an addition. A real person follows up within 1 to 2 business days.
From there we go down to your parcel: your zone, your setbacks, your existing coverage, how much you can actually build, and an honest budget range for it. In Central Jersey we design, permit, and build the suite ourselves. Elsewhere in New Jersey we can connect you with a builder in your area, and we vet anyone before we refer you.
An accessory dwelling unit is a legally separate second dwelling on your lot, with its own kitchen and, in most ordinances, its own entrance and utilities. An in-law suite is part of your house. It has its own entrance and its own private space, but it stays one legal residence, which is why it is permitted as an addition in many New Jersey towns that would send a detached ADU to the zoning board.
Free zoning check on your address. No cost, no obligation.
Statewide NJ · NJ HIC #13VH13918800