Compare ADU zoning rules across 4 New Jersey cities. Average ADU score: 6.8/10.
| City | Max Size | Setbacks | Permit Fees | Build Cost | 1BR Rent | Score |
|---|---|---|---|---|---|---|
| Jersey City | No square-footage cap — size is limited by the 18 ft/2-story height limit, setbacks and lot coverage (R-1: maximum lot coverage increases by an additional 5% for an ADU; R-2: 80% lot coverage; RH-1: 75% lot / 55% building coverage; RH-2: 75% lot coverage) | R-1: 2 ft (per building code); R-2: 3 ft; RH-1 and RH-2: none | Confirm with the Division of Zoning and Division of Construction Code Official — no published ADU fee schedule | $150,000-$300,000 | $2,900-$3,400/mo | 7/10 |
| Montclair | 300-800 sq ft, and no more than 40% of the habitable area of the principal building, whichever is less; no more than 3 rooms excluding kitchen and bathroom; detached ADUs must be located in the rear yard | Accessory-building setbacks of the underlying zone apply — confirm with the Montclair Department of Planning & Community Development | An ADU zoning permit fee applies (see the township's ADU zoning permit application); confirm the current amount and construction permit fees with the Planning Department | $175,000-$325,000 | $2,200-$2,800/mo | 6/10 |
| Princeton | 800 sq ft or 25% of the principal dwelling's total floor area, whichever is greater; +5% total floor area if the ADU is fully accessible under NJ's Barrier Free subcode; 1,000 sq ft or 30% if deed-restricted to low/moderate-income occupancy (Ord. 2024-32) | Per the accessory-structure setbacks of the underlying district — confirm with the Princeton Planning Department; detached ADUs must be at least 5 ft from the habitable portion of the main house | Confirm with the Princeton Zoning Office and Building Department — zoning permit plus UCC construction permit fees scale with project value | $180,000-$350,000 | $2,400-$2,900/mo | 8/10 |
| Trenton | 800 sq ft gross floor area, and in no case more than 40% of the primary dwelling's floor area (§ 315-9.4B.7-8). The footprint of a single detached accessory structure also cannot exceed the footprint of the principal building (§ 315-9.4A.5). | 10 ft from the rear lot line for a detached ADU (§ 315-9.4B.6) | Confirm with the Trenton Construction Office — zoning permit plus UCC construction permit fees, which scale with project value | $140,000-$260,000 | $1,545/mo | 6/10 |
Tell us about your project and we'll connect you with ADU builders serving New Jersey. Free, no obligation — you choose who to work with.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Just browsing? Search ADU builders near you by ZIP code.
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more