Islip, NY Building Safety: Building Permits (2026)

2's setback table (added 2020, amended 2021) ties both the permit requirement and the required setbacks for a roofless deck or patio to how high it sits above grade, treating the mainland, Fire Island and pool decks as three separate schedules. On the mainland (all districts except Fire Island), a deck or patio 0 to 18 inches above grade needs no permit and can sit at the street property line, but must keep a 4-foot rear setback and 4-foot side setbacks. Once the structure rises above 18 inches, a permit is required, the rear setback jumps to 10 feet and the side setback to 6 feet; above 48 inches, both setbacks match whatever is required for the main house on that lot (the code's 'M/H' shorthand).

Fire Island is treated far more strictly: because it's a narrow barrier-island community, any deck or patio wider than 4 feet needs a permit at every height tier, with a 15-foot setback from walks/streets and the rear line, and a 5-foot side setback that tightens to 15 feet, matching the main house, once the deck exceeds 48 inches. Pool decks and patios follow a third schedule, needing a permit and handrail once they exceed 18 inches, with rear and side setbacks of 6 feet at the lowest tier rising to 10 feet or main-house setbacks above that.

The code notes handrails and guards must independently conform to the New York State Building Code, and a narrow exception lets a side setback be waived for zero-lot-line homes if a 6-foot opaque fence already screens the deck.