In order to construct an accessory apartment, the applicant shall apply for and receive a building permit from the Town Building Department in the manner of all other applications for building permits.

Where the application entails structural alteration of the dwelling, the applicant shall also pay all other applicable fees as provided under § 123-12 of the Town Code.

In addition to any other standards, codes, rules or regulations which may be applicable to the construction of an accessory apartment, including the New York State Uniform Fire Prevention and Building Code, the Building Inspector shall certify that the special standards of this article have been complied with.

No building permit for the addition of an accessory apartment which requires structural alterations to the exterior of an existing dwelling shall be issued by the Building Inspector until said application has been approved by the full Board of Architectural Review.

A rental permit in accordance with Chapter 270 of the Town Code must be issued prior to the occupancy of an accessory apartment. For those accessory apartments receiving building permit approval after January 1, 2019, at the time of application for a rental permit, or at the time of renewal of the permit, the owner shall provide a fully executed lease agreement or other documentation that demonstrates that the rent does not exceed the annual fair market rent (FMR) for Suffolk County as established by the Department of Housing and Urban Development (HUD) and that the tenant’s income meets the standards established for low-moderate income or middle income as defined under Chapter 216 of the Town Code.

Owner occupancy required. The owner or owners of the lot upon which the accessory apartment is located shall reside within the principal dwelling or the accessory apartment, and said dwelling or apartment shall be considered the owner's domicile or principal place of abode. No other owner or owners shall own a larger percentage, collectively or individually, than the owner-occupant. Nothing within this Subsection A shall be deemed to apply to lots held in ownership by the Southampton Housing Authority or any not-for-profit agency to which the Southampton Housing Authority transfers title. The exemption of such not-for-profit agency must be approved by the Southampton Town Board, and such exemption will be determined on a lot-by-lot basis. Such required approval shall in no way affect the management of the lot by the Southampton Housing Authority.

An accessory apartment shall be permitted in a structure that has been issued a certificate of occupancy or a certificate of compliance, or be entitled to the issuance of a certificate of occupancy by virtue of a preexisting status, or is new construction that complies with Chapter 123, Building Construction; Section 164, Fire Prevention; and § 330-5, Definitions: "dwelling, two-family detached" and "accessory apartment." Notwithstanding the above, no permit shall be processed until the lot has a certificate of occupancy for an existing single-family dwelling.

The lot to which the accessory apartment is to be added shall have only one dwelling unit in existence on the lot at the time of application for an accessory apartment.

No more than one accessory apartment shall be permitted on the lot.

No nonconformities or violations of the Town Code shall exist at the time of application for an accessory apartment, except as provided in Subsection F below. The Building Inspector shall inspect the premises upon receipt of a completed application, and the application shall not be processed until all outstanding violations are corrected.

The lot containing the dwelling to which the accessory apartment is to be added shall comply with the district area and dimensional regulations, but shall not be less than 30,000 square feet unless such accessory apartment is located within a Town boundary area defined as a "census-designated place" (CDP) where the density measures less than 500 people per square mile according to the ten-year data published by the United States Census Bureau; in such case, the lot shall not be less than 20,000 square feet. A nonconforming lot may be eligible for an accessory apartment, provided that the lot area is not less than 80% of the required lot area for the applicable zone district, but in no case less than 30,000 square feet unless the lot is located in a CDP that meets the above-referenced density requirement; then the nonconforming lot shall be not less than 20,000 square feet. All other dimensional nonconformities shall not be less than 70% of the required setback or lot width. A lot with a nonconformity of a greater degree shall not be eligible for an accessory apartment under this article. Any such request shall be prohibited and can only be treated as an area variance by the Board of Zoning Appeals.

Minimum and maximum sizes shall be as follows:

The accessory apartment shall contain no more than two conventional bedrooms.

The bedrooms and bathroom shall not provide the sole access to any other rooms or the sole access to the out-of-doors.

At least one additional off-street parking space shall be provided for an accessory apartment which is a studio or one-bedroom, and two off-street parking spaces for accessory apartments having two bedrooms, on the lot for the accessory apartment, and such space(s) shall not be located in the required minimum front yard and shall be adequately screened with landscape plantings, which shall include evergreen shrubs, not less than three feet in height at the time of installation.

An accessory apartment shall not be permitted on a lot on which exists a bed-and-breakfast, rooming or boarding house, home occupation, home professional office, preexisting accessory apartment, or multiple-family dwelling.

If a second or new entrance to the accessory apartment is constructed, ground-floor outside entrances to the accessory apartment shall be from the side or rear yard. Second-floor outside entrances shall be from the rear yard.

[2]For existing single-family dwellings, only the owner-occupant of the residence may apply for this building permit and shall execute such agreements, contracts, easements, covenants, deed restrictions or other legal instruments running in favor of the Town as, upon recommendation of the Town Attorney, will ensure that:

Upon the issuance of a permit for an accessory apartment, one Town-owned development right will be extinguished by the Town in the school district where the accessory apartment is located. No permit shall be issued without such extinguishment.