Somerville, MA Fence Regulations: Retaining Walls (2026)

1: any portion of a retaining wall that rises above the ground level of the higher grade side must comply with the fence requirements, meaning that exposed upper portion is treated dimensionally like a fence rather than like a structural retaining wall. 2(b) then sets the wall-specific limit for the frontage area, the zone closest to the street: a retaining wall located there may be up to four feet in height, and if a property needs a series of terraced walls, each successive wall must be built with a minimum horizontal separation distance of four feet between them, preventing a stack of short walls from functioning as one tall wall.

2(c) removes the height cap entirely, allowing retaining walls to be built to any height once they are set back from the street-facing zone. 1(a)(ii), which requires the abutting owner's sign-off before a structure goes directly onto a shared lot line. Somerville's zoning ordinance does not carry a separate engineering-review or structural-permit clause specific to retaining walls in Article 10; taller or structurally significant walls fall instead under the Massachusetts State Building Code's general permitting and engineering requirements administered by the Building Official.