Home Addition & ADU Cost in Queens, NY (2026 Guide)

Adding livable square footage — through an addition, dormer, or accessory dwelling unit (ADU) — is one of the most valuable projects a Queens homeowner can undertake. Here's what it costs in 2026.

Cost Ranges

• Garage conversion to livable space: $30,000–$70,000
• Basement legalization / apartment conversion: $40,000–$90,000+
• Dormer / second-story addition: $150,000–$400,000+
• Ground-up detached ADU / cottage: $200,000–$500,000+

Ranges are illustrative for 2026 NYC-market projects and depend heavily on zoning, site conditions, and finishes.

Zoning Comes First

Before any budget is firm, the right first step is a zoning and feasibility review. What you can build — and how big — depends on your zoning district, lot size, setbacks, parking, and whether the unit is attached or detached. New York State has expanded homeowner access to ADUs, but NYC has its own layered rules. Read our ADU laws guide for context.

What Drives Addition Cost

• Foundation & structure — new footings, framing, and structural engineering.
• MEP systems — extending plumbing, electrical, and HVAC into the new space.
• Egress & code — ceiling height, windows, exits (critical for basement units).
• Permits & DOB filings — additions require plans, filings, and multiple inspections.

Permits & Compliance

Additions and ADUs require full DOB permitting, filed architectural plans, and inspections. We handle the entire compliance process and work within current NYC and Nassau County requirements. See our compliance guide.

Curious what's possible on your lot? Request a feasibility consultation with Dream Homes Remodeling.

Frequently Asked Questions