Cast iron columns, commonly used in building construction in the 1800s and early 1900s, possess low tensile capacities and require special attention to detail in building alterations. 315 Hudson Street is a ten-story cast iron column building undergoing such alteration in New York City. Extensive renovations to the building included lowering a portion of the ground floor structure, transferring two off-grid columns at the ground floor via transfer beams at the second floor, and reinforcing columns for new rooftop loads. Each endeavor required novel detailing to brace, support, and reinforce the cast iron columns in a manner that limited tension on the cross-section.