Updated October 2026. Long Island does not have one building department. Every town runs its own, with its own forms, filing process and review. A contractor who knows the Town of Islip may not know how Babylon, Brookhaven or Huntington want a project submitted, and a homeowner who assumes the rules are the same can lose weeks. Here is how the three differ in practice, based on each Town’s published guidance.
Always confirm with the Town before you file. Procedures, forms and fees change, and the details below reflect public guidance available in 2026.
Town of Babylon
Babylon’s Building Division is located at Town Hall, 200 East Sunrise Highway in Lindenhurst, and you can reach it at (631) 957-3058. According to the Town’s guidance, a building permit is required for projects such as:
- Interior alterations that add or remove walls
- Bathrooms
- Finished basements, meaning drywall on the walls and flooring other than bare concrete
- Garage conversions
- Window and door replacements when the size or location changes
Plans, specifications and any other information needed to understand the project must be filed with every application. In our experience, the basement and garage-conversion rules surprise homeowners most, because work that feels like “just finishing” a room is treated as a permitted alteration.
Town of Brookhaven
Brookhaven is one of Long Island’s largest towns, and it takes new residential permit applications and plan reviews through an online system. Points to know:
- A building permit is required for new homes, additions, alterations and accessory structures.
- A Single Family Residence application is required for a new home, or for an addition that equals 50% or more of the existing structure.
- A building permit is valid for one year from the date it is issued, so projects need to be scheduled with that in mind.
Because Brookhaven stretches from the North Shore to the South Shore, zoning and flood considerations can vary a lot from one property to the next.
Town of Huntington
Huntington’s Building and Housing Division publishes detailed filing requirements. For alterations and additions to an existing dwelling, the Town’s guidelines call for items such as:
- Two completed building permit applications, signed by the property owner and notarized
- Recent surveys by a licensed land surveyor showing the plot and all existing buildings and structures
- Plot plans and construction drawings, with floor plans showing room sizes and uses and the size and location of openings in exterior walls
- For additions, an explanation of how light and ventilation will be supplied to any existing rooms that the addition would cut off
The Town’s guidelines also describe multiple copies of each document and mailing instructions for Town Hall at 100 Main Street, Huntington. Those guidelines were last revised in 2021, so confirm the current copy count and submission method before you file.
How this compares with the Town of Islip
Islip, which covers Islip, East Islip, West Islip and Bay Shore, requires building permit applications to be filed electronically and reviews them against the New York State Uniform Code and the Town of Islip Zoning Code. See our full guide to remodeling permits in the Town of Islip.
What stays the same across towns
- The state building code applies everywhere. Egress, ceiling height, electrical, plumbing and energy requirements come from the New York State Uniform Code.
- Contractors need a Suffolk County Home Improvement license for home improvement work, and plumbing and electrical work require separately licensed trades.
- Flood zones add requirements near the water. See remodeling a waterfront or flood-zone home.
- Inspections and a final sign-off protect you at resale.
Why local experience matters
The permit itself is rarely the hard part. The delays come from missing documents, the wrong form, or plans that conflict with local zoning. A design-build firm that works across towns learns each Town’s habits and prepares the right package the first time. Kuhn Construction is based in Islip and has remodeled homes across Suffolk and Nassau County since 1986. See our pages for Babylon, Brookhaven and Huntington, or contact us to talk through your project.
Frequently asked questions
Are building permit rules the same in every Long Island town?
No. Every town has its own building department, forms, filing method and review process, although all follow the New York State Uniform Code.
Does finishing a basement need a permit in Babylon?
According to the Town of Babylon’s guidance, yes. Finished basements, meaning drywall on the walls and flooring other than concrete, require a building permit.
How long is a Brookhaven building permit valid?
A Town of Brookhaven building permit is valid for one year from the date it is issued.
This article summarizes publicly available Town guidance and is not legal advice. Requirements change. Confirm current rules with the Town’s building department.
