ADU rules in Suffolk County, NY — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Accessory apartments (ADUs) are legal in every Suffolk County town under varying rules. Most towns require owner-occupancy of the primary dwelling, a minimum lot size (often 7,500-20,000 sq ft), a rental permit, and one off-street parking space for the ADU. Internal conversions and attached ADUs are most commonly permitted; detached ADUs are more restricted.
Brookhaven Town Code Chapter 85 allows one accessory apartment per single-family home with owner-occupancy, 300-650 sq ft ADU size, and biennial permit renewal. Islip Chapter 68-20 permits accessory apartments with similar conditions. Huntington, Smithtown, Babylon, and the East End towns have their own programs. Suffolk County Department of Health Services must approve any ADU on septic for added flow capacity, including the new I/A OWTS (nitrogen-reducing) systems required in many areas. New York has not adopted a statewide ADU preemption law.
Illegal accessory apartment: $500-$2,500 first offense, up to $10,000 repeat, plus rent-disgorgement orders. Unpermitted septic increase: Suffolk DHS stop-use order.
Suffolk County, NY
Suffolk County skateboarders are governed mainly by town ordinances regulating sidewalk and street use; New York Vehicle and Traffic Law treats e-skateboards...
Suffolk County, NY
New York courts have struck down most general loitering offenses on constitutional grounds, leaving Suffolk County to rely on narrowly drawn state statutes; ...
Suffolk County, NY
Loud parties on Long Island fall under town noise ordinances and the New York Penal Law disorderly conduct statute, with Hamptons summer rentals drawing inte...
Suffolk County, NY
Suffolk County prohibits smoking in county parks, beaches, and many outdoor public spaces, building on New York's Clean Indoor Air Act with additional county...
Suffolk County, NY
Under New York Cannabis Law and Public Health Law, adults over 21 may smoke or vape cannabis anywhere tobacco smoking is allowed, but Suffolk County parks an...
Suffolk County, NY
New York State Liquor Authority law and local Suffolk County town codes generally prohibit consuming alcoholic beverages or possessing open containers in pub...
See how Suffolk County's adu rules rules stack up against other locations.
Help us keep this page accurate. If you notice an error or outdated information, let us know.