Compare ADU zoning rules across 3 New Jersey cities. Average ADU score: 7.0/10.
| 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 |
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