ADU Contractor in New Jersey
Accessory dwelling units solve real problems for New Jersey families: aging parents who want independence nearby, adult children saving for a down payment, a home office that needs separation, or rental income on a property that already has the land for it.
Strong Construction LLC builds in-law suites, garage conversions, above-garage units, and detached accessory structures across Northern and Central New Jersey. We handle the zoning research, the design, the permits, and the construction under one contract, with pricing in writing before demolition.
Zoning comes first, because it decides everything
New Jersey has no single statewide ADU rule. Permission comes from your municipality, and towns differ enormously. Some allow an accessory apartment by right with owner-occupancy conditions, some allow it only for family members, some permit detached structures with strict size caps, and some prohibit second kitchens outright. We research your zoning ordinance and your district's specific limits on lot coverage, setbacks, accessory structure height, and parking before design begins, then tell you plainly whether the unit is achievable by right, achievable with a variance, or not achievable at this address.
Attached suites, garage conversions, and detached units
An attached in-law suite added to the side or rear of the house is usually the simplest path, sharing utilities and foundation work with the existing structure. Garage conversions are cost-effective when the slab and framing are sound, but require insulation, a proper floor assembly, egress, heating and cooling, and often a raised or replaced slab. Above-garage units need verification that the existing structure can carry the load, plus a compliant stair and fire separation. Detached units are the most flexible design and the most expensive, since they carry their own foundation, roof, and utility runs.
Code, life safety, and utilities
An ADU is a dwelling unit, so it is held to dwelling standards: compliant egress from every sleeping room, fire separation between units, hard-wired interconnected smoke and carbon monoxide alarms, proper ceiling heights, ventilation, and often a separately metered or clearly subpanel-fed electrical supply. Water, sewer or septic capacity, and heating source all have to be evaluated. Properties on septic frequently need a system capacity review before an additional bedroom is approved, and that review can take longer than the construction permit itself.
Budgets and written scope
Garage conversions typically run $120,000 to $220,000 depending on foundation and utility work. Attached in-law suites generally run $350 to $600 per square foot of finished space. Detached units usually start higher because of site work, utility trenching, and a full building envelope. Your proposal breaks out site work, foundation, framing, roofing, siding, windows and doors, insulation, electrical, plumbing, HVAC, drywall, trim, kitchen and bath finishes, flooring, paint, and final clean, with named dollar allowances so you can compare our number to anyone else's line by line.
Where we build ADUs
We build accessory dwelling units throughout Bergen, Hudson, Essex, Passaic, Union, Morris, Middlesex, and Monmouth counties. Ordinances vary sharply between neighboring towns, so we begin every project with a zoning memo specific to your lot. In denser Hudson County neighborhoods the practical path is often an interior conversion within an existing legal two-family. In Bergen and Morris County suburbs with larger lots, a detached or above-garage unit is usually feasible if coverage and setback limits allow. Where a variance is required, we prepare the application drawings and work alongside your land-use attorney through the zoning board hearing.
What Every Project Includes
Counties We Serve
Frequently Asked Questions
Are ADUs legal in New Jersey?
There is no statewide right to build one. Each municipality sets its own rules, and some permit accessory apartments by right while others require a variance or prohibit them. We research your specific zoning district before you spend money on design.
How long does an ADU project take?
Plan on two to five months for zoning research, design, and permitting, then four to eight months of construction depending on whether the unit is a conversion or new detached construction. Septic capacity review or a variance hearing can extend the approval phase.
What do renovations in this area typically cost?
Most Bergen County kitchens land between $45,000 and $85,000. Simpler refreshes that keep the existing layout can start near $35,000, and full-gut renovations with custom cabinetry and premium stone run $110,000 and up. Most bathrooms run $20,000 to $40,000, with high-end primary baths between $40,000 and $75,000. Every number we give you is written into a fixed-price proposal before any demolition begins.
How does your design-build process work?
We start with an on-site consultation, measure and photograph the space, and talk through how you actually use it. From there we produce drawings, a selection list, and a line-item proposal with real allowances. Once you approve, we file permits, order long-lead items, and publish a schedule you can follow week by week. One team owns design, permits, and construction, so nothing falls between a designer and a builder.
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