Islip, NY Accessory Structures: Tiny Homes (2026)

No Islip-specific ordinance authorizes standalone tiny homes; the NY state default applies and the Town's accessory-structure and accessory-apartment rules control. A detached dwelling unit is not a permitted accessory use - an accessory apartment 'shall not be located within an accessory structure' and must instead be created within the principal single-family structure of an owner-occupied home (Town Code Chapter 68, Article XLVII). Residential accessory structures are capped at 14 feet in height in most residential zones and may not be improved for habitation; if an accessory building is improved with plumbing fixtures its gross floor area counts toward Floor Area Ratio regardless of size, signaling that habitable accessory buildings face the full dimensional and FAR limits. Any habitable structure must also comply with the New York State Uniform Fire Prevention and Building Code, which sets minimum room, egress, and sanitation standards that a tiny house on wheels generally cannot meet on a permanent residential lot. The practical result is that a small second dwelling in Islip must take the form of a permitted accessory apartment inside the main house (minimum 300 square feet, maximum the lesser of 50% or 800 square feet of the principal dwelling), not a freestanding tiny home.