Adjoining property construction has become an increasing concern in New York City as damage claims continue to mount. In 2014 one of the important changes to the NYC Building Code was the new requirement for a pre-construction survey to be performed in certain instances. Pursuant to newly added section 3309.4.3:
No excavation work to a depth of 5 feet to 10 feet (1524 mm to 3048 mm) within 10 feet (3048 mm) of an adjacent building, or an excavation over 10 feet (3048 mm) anywhere on the site shall commence until the person causing an excavation to be made has documented the existing conditions of all adjacent buildings in a preconstruction survey.
The extent of the surveying required is not specified but entry into adjacent structures can sometimes be problematic. Careful attention to code notice requirements is key to avoiding, or at least limiting, future potential liability.