New York Construction Report staff writer
When contractors excavate alongside existing buildings in New York City, Chapter 33 and Chapter 17 of the New York City Building Code impose strict engineering, monitoring and third-party inspection mandates designed to prevent lateral soil movement and foundation failure:
- Mandatory plan review (No professional certification): Effective July 1, 2025, under Buildings Bulletin 2025-005, Support of Excavation (SOE) and underpinning applications are no longer eligible for self-certification (“Pro-Cert”). Every SOE filing must undergo full DOB plan examination and approval before work begins.
- Pre-construction surveys and owner notification (BC § 3309): Before digging below the level of an adjacent footing, developers must provide formal advance notice to adjoining property owners and document existing conditions — including cracks, bowing, leaning and masonry deficiencies — via an engineer’s structural evaluation and photographic survey.
- Continuous movement and vibration monitoring (BC § 3309.4.4 & § 3309.16): Any building located within a horizontal distance from the excavation edge equal to or less than the maximum depth of the cut (such as a structure immediately abutting a 14-foot excavation) must be monitored under a design professional’s monitoring plan. The plan must establish specific thresholds for optical, crack and vibration readings, along with mandatory reporting to the Buildings Commissioner if tolerances are exceeded.
- Independent special inspections (BC § 1704.20): Sheeting, shoring, bracing and underpinning installations require continuous or periodic Special Inspections performed by an accredited agency hired directly by the building owner — never by the general or excavation contractor. Unreinforced masonry buildings require additional floor-level bracing evaluations before adjacent foundation or underpinning work proceeds.
