Accessory Structures in Smithtown, NY (2026)
4 verified accessory structures rules for Smithtown, New York, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Smithtown's zoning code permits accessory apartment dwelling units only as a Board of Appeals special exception, and only above certain commercial ground-floor uses, not as a standalone backyard cottage on a house lot. Units cannot sit on the first floor, cannot exceed two bedrooms, and must include a smoke detector or sprinkler system.
Smithtown Accessory Apartment Dwelling Standards
Significant RestrictionsSmithtown Code § 322-82C(23)(a)-(e)
Accessory apartment dwelling units. The following requirements shall be met: (a) The apartment dwelling units shall not be located on the first floor of the building. (b) No apartment dwelling shall consist of more than two bedrooms. (c) A suitable means of access to the dwelling unit shall be provided, which shall be sufficiently safe and attractive for pedestrian use. (d) A smoke detector, fi...
ADU Rental Restrictions
Smithtown limits accessory apartment dwelling units to premises with a qualifying commercial use, such as a retail store, office, or restaurant, and issues the special exception permit for only three years at a time. Owners who miss the 60-day renewal window automatically lose the right to rent the unit.
Smithtown Accessory Apartment Permit Term Limits
Significant RestrictionsSmithtown Code § 322-82C(23)(f)-(g)
(f) Accessory apartment dwelling units shall only be permitted on premises containing only the following uses: a retail store or shop, personal shop, office, bank, funeral home, restaurant, tavern, bar, inn or shop for custom work and making articles sold on the premises. (g) Permission for the proposed accessory use shall be for an initial three-year period, renewable every three years by the ...
Shed & Carport Rules
Smithtown lets homeowners skip a building permit for a small detached tool or storage shed, but only if it stays under 144 square feet, tops out at 12 feet, and sits in a conforming location. Bigger or nonconforming sheds need a full building permit and a $115 flat fee.
Smithtown Accessory Shed Permit Exemption
Some RestrictionsSmithtown Code § 112-10(A)
...except that no building permit shall be required for: 1) the performance of ordinary repairs which are not structural in nature and 2) a detached residential storage or tool shed that is an accessory structure to a one- and two-family dwelling, provided gross floor area of the shed does not exceed 144 square feet, the shed does not exceed 12 feet in height, and the shed is located in a confo...
Garage Conversions
Converting a Smithtown garage into living space requires a building permit under the Town's general construction-permit rule, and the code names the work specifically in its fee schedule: a $305 base fee plus $0.45 per square foot of proposed work, the same rate charged for additions, alterations and detached-garage projects.
Smithtown Garage Conversion Permit Fee
Some RestrictionsSmithtown Code § 112-11(1)(b)
Permit for additions, alterations, fire repair, garage conversions, detached garage, decks or construction of accessory structures: base fee of $305 and $0.45 per square foot of proposed work.
Looking for Suffolk County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Smithtown city rules.
Accessory Structures in Suffolk County →