Jones Hollow Realty Group

Guide to Accessory Apartments in the Town of Brookhaven

Brad Wilson

Welcome to the Jones Hollow Realty Group resource center! If you’re a homeowner in the Town of Brookhaven considering adding an accessory apartment (also known as an accessory dwelling unit or ADU) to your single-family home, or if you’re buying a property that already has one, this guide is for you. Accessory apartments can provide affordable housing options, extra income, or space for family members, but they must comply with strict local regulations to remain legal and safe.

This guide is based on the Town of Brookhaven’s Zoning Code (Chapter 85, § 85-258) and related programs. Always verify details with Town officials, as rules can change. At Jones Hollow Realty Group, our experienced agents can help you navigate these processes during your home search or sale—contact us at info@joneshollowrealty.com or (631) 650-3977 for personalized advice.

What is an Accessory Apartment?

An accessory apartment is a separate living area with a kitchen located within the principal single-family dwelling in designated residence districts (A, A-1, A-2, A-5, B, B-1, and C). It is intended to provide small rental housing units for single persons, couples, or relatives of low to moderate income, while supporting resident families economically and preserving neighborhood character and property values. Accessory apartments are not permitted in detached structures or multifamily buildings.

Key Eligibility and Requirements

To create or maintain a legal accessory apartment, your property must meet these criteria:

Property and Lot Requirements

  • Zoning Districts: Allowed in A Residence, A-1, A-2, A-5, B Residence, B-1, and C Residence Districts.
  • Location: Must be within the principal dwelling; only one per lot.
  • Density Limit: No license if 5% or more of lots within a 1/2-mile radius already have accessory apartments (waivable in sparse areas or for pre-existing units).
  • Water and Sewer: Must have Town Engineer approval for supply and disposal.

Design and Size Limits

  • Bedrooms and Occupancy: Maximum of 1 bedroom.
  • Floor Area: Minimum 300 square feet; maximum 650 square feet (not exceeding 40% of the dwelling’s habitable area). Up to 850 square feet may be allowed with Chief Building Inspector discretion (651-750 sq ft ≤35%; 751-850 sq ft ≤30%).
  • Exterior Appearance: Design and entry must maintain the appearance of a single-family residence as much as possible.
  • Health and Safety: Must comply with New York State Uniform Fire Prevention and Building Code for two-family dwellings, Suffolk County regulations, and Town codes.

Owner and Occupancy Rules

  • Owner Occupancy: The owner (with the largest ownership interest) must reside in the dwelling (either the main unit or apartment). Only one apartment per homeowner. Properties owned by LLCs, corporations, or partnerships are ineligible.
  • Rental Restrictions: Intended for long-term rentals; short-term (e.g., seasonal or vacation) prohibited under program guidelines. No discrimination in renting.
  • Prohibitions: Automatic revocation if owner or occupant registers as a sex offender.

Parking and Maintenance

  • Off-Street Parking: At least 2 spaces for the owner; 1 designated space for the apartment (tandem parking counts as one). Must be paved (asphalt, concrete, etc.; no gravel). Submit a parking plan.
  • Upkeep: Property must be maintained neatly (structures, landscaping, etc.) per New York State Property Maintenance Code and Town Code Chapter 82. Violations prevent issuance or renewal.

Violations can lead to fines, revocation, and legal action under Town Code penalties.

The Permitting Process

Obtaining a legal accessory apartment requires a Provisional Accessory Apartment License from the Chief Building Inspector via the Building Division:

  1. Application: Submit to the Building Division: License application, building permit applications, floor plans, photos, renderings (if required).
  2. Completeness and Notice: After notification of completeness, post public notices along road frontages for 10 days. Submit proof (photos, affidavit).
  3. Approvals: Building permits first; license issued upon completion and safety inspection. Comply with codes within 6 months (extendable).
  4. Timeline: Obtain permits within 6 months of approval or it lapses. Construction per building permit timelines.
  5. Duration: Initial license up to 3 years; renewals up to 5 years (at discretion).
  6. Renewal: Submit renewal application; no new notices unless required. Affidavit of compliance needed.
  7. Revocation: For violations, after hearing; automatic for certain offenses.
  8. Fees: Set by Town Board resolution (initial, renewal, transfer, reapplication penalties for failures).

For electronic submissions, use the Town’s online portal: https://brookhaven-public.app.transform.civicplus.com/forms/29953 for renewals or https://www.brookhavenny.gov/NewApplication for new applications.

Buying a Home with an Existing Accessory Apartment

If you’re purchasing a property in Brookhaven with an already-set-up apartment, check its legal status during due diligence:

If It’s Already Legal

  • The license ties to the owner and isn’t automatically transferred.
  • Apply to the Building Division for a transfer to the new owner (no public notice/hearing typically; fee applies). Provide proof of ownership and confirm compliance.
  • Renew every 3-5 years or with title transfer.
  • Search Town records: Contact the Building Division for permit status or use online lookup at https://www.brookhavenny.gov/1245/Lookup-Building-Permit-Status.

If It’s Illegal or Unpermitted

  • Common issue; purchase doesn’t legalize it—you’re liable for violations.
  • To legalize: Apply for a new license and building permits to bring it into compliance. Pre-existing units may qualify for waivers on density limits if applied within specified periods.
  • Costs can be significant; negotiate seller concessions. A home inspection can identify illegal features (e.g., unauthorized kitchens).

At Jones Hollow Realty Group, we recommend a real estate attorney and thorough title search to avoid surprises.

Incentives: The Plus One Accessory Apartment Program

Launched in December 2023, this state-funded program (administered by the Long Island Housing Partnership—LIHP) offers grants up to $125,000 to create new ADUs or legalize/upgrade existing ones for low- to middle-income homeowners. Eligibility includes:

  • Owner-occupants of pre-existing single-family homes in Brookhaven.
  • Household income ≤100% of area median income (e.g., $109,400 for 1 person; $156,300 for 4; based on 2023 HUD limits—verify current).
  • Property taxes, insurance, and mortgages current; all COs in place (or obtained via program).
  • Compliance with Town zoning, building codes, and Suffolk County Health Department rules.
  • ADU for permanent tenants (no short-term rentals); good-faith marketing if vacant.
  • Improvements address health/safety, code violations, energy efficiency, accessibility, etc.

Applications are first-come, first-served via LIHP, with prioritization for low-income owners, affordable units, transit proximity, and easy permitting. Review guidelines and apply at https://www.lihp.org/adu.html. For assistance, call LIHP at (631) 435-4710.

Resources and Contacts

Disclaimer

This guide is for informational purposes only and is not legal advice. Rules are subject to change; consult the Town of Brookhaven, a qualified attorney, or a licensed professional for your specific situation. Jones Hollow Realty Group is not responsible for any actions taken based on this information. Updated as of January 2026.

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