Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your New York City ADU cost →Building an ADU in New York City costs between $150,000-$450,000 for new construction, with per-square-foot costs averaging $300-$580. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $150,000-$280,000, while prefab/modular ADUs fall in between at $220,000-$450,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | 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). |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving New York City, where we have them — free, no obligation.
Get New York City builder quotes →Permit fees in New York City are 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).. The review timeline is 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., with 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).. Impact fees are 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).. Pre-approved plans: Yes: DOB's OTCR list shows 8 pre-approved backyard ADU designs from 6 design firms (September 2026), reviewed by DOB for code and zoning and by FDNY for sprinklers, and browsable in HPD's ADU for You Plan Library; the design firm still files a site-specific job..
| 1-Bedroom Rent | $2,500-$3,400/month |
| 2-Bedroom Rent | $2,900-$4,000/month |
| Annual Rental Income (est.) | $35,400/year |
| Payback Period (est.) | 8.5 years |
| Short-Term Rental | No, unless you live in the ADU yourself while hosting: stays under 30 days require Local Law 18 of 2022 registration with the Office of Special Enforcement, a host present and at most two guests (HPD ADU guidebook, Ch. |
| Overall ROI Estimate | 7-15% gross rental yield on a $220,000-$450,000 backyard build at $2,500-$3,400/mo; a $100,000-$230,000 basement conversion renting at one-bedroom rates can gross 13-30% (before taxes, vacancy, insurance and financing; a. |
A typical ADU in New York City generates approximately $35,400 per year in rental income based on average 1-bedroom rents. At an average construction cost of $300,000, the estimated payback period is 8.5 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in New York City and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in New York City: $150,000-$280,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $220,000-$450,000.
3. Pre-approved plans — available in New York City, which can save $3,000-$10,000 in design costs and 2-3 months in review time. See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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