With New York City’s constantly evolving built landscape (particularly in Manhattan and Brooklyn), old buildings are being demolished and new (and bigger) ones are being constructed in their place. Often, the new buildings are infill projects replacing brownstones and townhomes previously sharing party walls with adjoining neighbors. In this article, we will address the issues raised with demolition and new construction on sites previously occupied by a building sharing a party wall with its neighbor.

Party Walls in General

In urban neighborhoods, buildings of all types were traditionally built adjacent to each other with a separating wall that, under certain circumstances, was considered a “party wall” forming a common wall for the two adjoining structures. A party wall is unique because it is an adjoining wall and also carries with it legal principles that embody certain rights and duties of the adjoining owners. Generally, a party wall may stand directly on the dividing line between two parcels of land.1 As such, the co-owners own so much of the wall as stands on their land, subject to the easement of the other owner in their share for the support and the equal use as an exterior wall of his or her building.2 Similarly subject to the easement belonging to an adjoining owner, a party wall may stand entirely on the land of one owner. A party wall easement may be acquired by grant, prescription, or by agreement between the adjoining owners.

Adjoining Structures