An ADU builder in New York City is a licensed contractor who designs and constructs accessory dwelling units — detached backyard units, garage conversions, attached additions, and junior ADUs (JADUs). Because an ADU is a complete second dwelling, the builder coordinates foundation, framing, plumbing, electrical, and HVAC work and pulls it through New York City's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in New York.
What ADU Builders Cost in New York City [15][16][17]
Based on our New York City cost data, expect the following ranges from local ADU builders. Quotes for the same scope typically vary 20-40% between contractors, so getting at least three bids is the single best way to control cost.
| New Detached ADU (all-in) | $150,000-$450,000 |
| Cost per Sq Ft | $300-$580 |
| Garage Conversion | $150,000-$280,000 |
| Prefab / Modular ADU (installed) | $220,000-$450,000 |
| City Permit & Plan Review | DOB filing fee (Admin. Code 28-112.1): a detached ADU filed as a New Building pays $0.06 per sq ft with a $100 minimum, so $100 for 800 sq ft; an interior conversion filed as an Alt-CO pays $170 for the first $5,000 of work plus $2.60 per $1,000 above that (about $550 on a $150,000 job). |
| Impact Fees | None. New York City levies no development impact fee; beyond the DOB filing fee, expect a DEP site-connection permit for new water or sewer lines and a higher property tax assessment once the unit is on the Certificate of Occupancy (HPD ADU guidebook). |
For a full line-item breakdown, see our New York City ADU cost guide. To confirm what you're allowed to build before you hire, review the New York City ADU rules (max detached size: 800 sq ft of zoning floor area (ZR 12-10), which counts toward the lot's floor area ratio; a backyard ADU may also cover no more than one-third of the required rear yard (ZR 23-341(b)(4)), so a 500 sq ft footprint needs a 1,500 sq ft rear yard. Converting a garage or shed that existed before Dec 5, 2024 is not a 'backyard ADU' and is allowed even where new ones are barred.; owner-occupancy: At the time the ADU is first occupied, the zoning lot must be the primary residence of an owner of that lot (ZR 12-10(f); 1 RCNY 105-08(d)(2)); DOB may require the proof of primary residence listed in 19 RCNY 46-03. The code writes no continuing owner-occupancy requirement after that point; a Plus One ADU loan adds its own 15-year regulatory agreement.).
Get Free ADU Quotes in New York City
Tell us about your project and we'll pass it to ADU builders serving New York City. Free, no obligation — you choose who to work with. We don't have builders in every area yet; if nobody covers yours, we'll email you to say so.
Takes about a minute.
Up to 5 independent local ADU builders — never more, and we tell them nothing you don't submit here.
Compare quotes, verify license & insurance, hire (or don't). No spam either way.
🔒 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.
How to Vet an ADU Builder in New York City
- License: Confirm a current contractor's license in New York and that it's in good standing. Ask for the license number and verify it with the state board.
- ADU-specific experience: Ask how many ADUs they've completed in or near New York City and request addresses or photos. ADU permitting and setbacks differ from a kitchen remodel.
- Portfolio & references: Get references from recent ADU clients and, if possible, visit a finished unit.
- Insurance: Verify general liability and workers' compensation coverage. Ask for a certificate of insurance.
- Written, detailed bid: Insist on an itemized, fixed-price or clearly-scoped bid — not a verbal estimate. It should state whether permits (DOB filing fee (Admin. Code 28-112.1): a detached ADU filed as a New Building pays $0.06 per sq ft with a $100 minimum, so $100 for 800 sq ft; an interior conversion filed as an Alt-CO pays $170 for the first $5,000 of work plus $2.60 per $1,000 above that (about $550 on a $150,000 job).), plan check (Standard plan examination, or Professional Certification by the architect or engineer (DOB ADU FAQ). For a pre-approved plan, DOB's review is limited to site-specific items such as zoning analysis, foundations and utility connections (DOB OTCR page).), and impact fees (None. New York City levies no development impact fee; beyond the DOB filing fee, expect a DEP site-connection permit for new water or sewer lines and a higher property tax assessment once the unit is on the Certificate of Occupancy (HPD ADU guidebook).) are included.
- Permit handling: Confirm they manage New York City's permit process ("File in DOB NOW: Build (ADU filings accepted since September 30, 2025): an Alt-CO-GC job for a unit inside the house, or a New Building-GC job for a detached or fire-wall-separated unit, answering the Ancillary Dwelling Unit questions on the PW1. A NYS-licensed architect or engineer files; detached ADUs get their own BIN, house number and Certificate of Occupancy (1 RCNY 105-08(e)).", typically DOB publishes no ADU-specific review time. ADU jobs may be filed Professionally Certified by the architect (DOB ADU FAQ), except pilot-program legalizations; HPD's ADU guidebook puts design-to-completion at two months to two and a half years depending on the ADU type.) and who is responsible if revisions are required.
- Payment schedule: Avoid large upfront payments. A reasonable schedule ties payments to completed milestones.
Questions to Ask Before You Hire
- How many ADUs have you built in New York City in the last two years?
- Is your bid fixed-price, and what would trigger a change order?
- Are permits, plan check, and utility connection fees included?
- What's a realistic timeline, including permit review (DOB publishes no ADU-specific review time. ADU jobs may be filed Professionally Certified by the architect (DOB ADU FAQ), except pilot-program legalizations; HPD's ADU guidebook puts design-to-completion at two months to two and a half years depending on the ADU type.) and construction?
- Who is my point of contact and how are delays communicated?
- What warranty do you provide on workmanship?
- Can you share three recent New York ADU client references?
Finance Your ADU Project
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
Are you an ADU builder? Get New York City leads
Homeowners on this page submit real ADU project requests in New York City. Each one goes to up to five local builders — that is what the homeowner agrees to — so claiming never takes it from anyone and there is no bidding. In practice far fewer ever make contact, which is why the number is five rather than three. A flat $50 only on the leads you accept: no subscription, no contract, and you deal with the homeowner directly.
Get New York City ADU Leads →Frequently Asked Questions
How much do ADU builders charge in New York City?
How do I find a good ADU builder in New York City?
Do ADU builders in New York City handle permits?
How long does it take to build an ADU in New York City?
Get Free ADU Builder Quotes in New York City
Compare bids from experienced local New York City ADU builders. Free, no obligation.
Get Free Quotes →