Free NJ Cost Tool
NJ Home Addition Cost Calculator
Choose the type of addition and enter the new square footage. Add a bathroom or design fees and see what a New Jersey addition costs per square foot in your region.
Step 1 of 2
Tell us about the project
Typical NJ Projects
Home Addition Costs in New Jersey
Bump-Out Addition (under 200 sq ft)
Cantilevered or shallow-footing extension of an existing room.
$35,000 – $65,000
Single Room Addition
New foundation, framing, roofline, and full interior finishes.
$65,000 – $130,000
In-Law or Primary Suite
Bedroom, bath, and utility connections. May require structural reinforcement.
$100,000 – $200,000
Second Story Addition
Full second floor added to a ranch or cape cod. Engineer review required.
$150,000 – $380,000+
How We Calculate
- →Per-square-foot prices cover foundation, framing, roofing, windows, insulation, drywall, flooring, and finish carpentry for the addition type selected.
- →Ranges come from the same NJ pricing published in our cost guides and on our service pages.
- →The location adjustment reflects higher labor and disposal costs in North Jersey and lower costs in South Jersey.
- →Totals round to the nearest $500. A written fixed price after a site visit replaces this estimate.
FAQs
Home Addition Cost Questions
How much does a home addition cost per square foot in NJ?
Home additions in New Jersey typically cost $250 to $600 per square foot. Bump-outs run $250 to $400, single-story room additions $350 to $550, and second-story additions $450 to $600 or more because of the structural work.
How much does it cost to add a second story in NJ?
A second-story addition in NJ runs $450 to $600+ per square foot because the existing roof comes off and the walls and foundation often need reinforcement. Ranches and cape cods are the most common candidates. Design, engineering, and permits come on top of construction.
How much does a sunroom addition cost in New Jersey?
Three-season sunrooms in NJ cost $250 to $400 per square foot. Four-season sunrooms with insulated walls, Low-E glass, and HVAC cost $400 to $700 per square foot. Most projects land between $25,000 and $100,000.
Do I need zoning approval for an addition in NJ?
Every NJ addition needs a construction permit. If it exceeds your lot coverage, setback, or height limits, you also need a variance from the town zoning board, which can add 2 to 4 months. We check zoning before design starts.
Cost Guides
Turn the Range Into a Fixed Price
Free site visit. Written price before any work starts.