Southampton, NY Fence Regulations: Retaining Walls (2026)

Southampton's Zoning Code treats a retaining wall as a species of "wall" under the Chapter 330 definitions, meaning it falls under the same berm rules as ordinary fences and walls unless a specific exception applies. Section 330-109F states plainly that no fence or wall may be built on a berm, but carves out one exception: the Planning Board may allow a retaining wall on the sides of a berm if the Board finds it will promote aesthetic considerations, and only if the wall's height does not exceed the grade of the berm itself.

That approval sits inside the Town's broader berm regulations at §§ 330-110 through 330-112. Berm height is separately capped by § 330-111: no more than four feet in a front yard or six feet in a rear or side yard in residence districts, six feet in any yard in nonresidence districts, and up to 10 feet along a highway if the Planning Board finds the extra height serves noise, light or aesthetic goals. Because a berm-side retaining wall cannot exceed the berm's grade, those same numbers effectively cap how tall the retaining wall can be.

Any berm exceeding four feet, other than one built under an approved subdivision plat or site plan, needs a building permit under § 330-112A, and the application must include a detailed grading plan with contour intervals no greater than five feet existing and two feet proposed, plus a cross section showing the fill and topsoil materials. Berms, and by extension their retaining walls, may only be constructed from March 1 through October 15 under § 330-110D, and must be properly vegetated before erosion occurs. A retaining wall or berm installed without the required Planning Board finding or building permit is a Zoning Code violation.