We work where the buildings are: one of the simple truths of a practice based on existing structures is that we can’t jet-set around the world like the skyscraper designers do.
Our projects are predominately in New York City and its immediate surroundings, but we also work on designs across the northeast and as consultants around the country. Today, the entire United States use variations on a single building code, the International Building Code, and building materials are sold in a nationwide – and to some extent worldwide – market, but this was not always true. Before the IBC, there were three national model codes and multiple local ones (including the old NYC and NYS codes); before the national model codes there was an anarchy of local codes.
The further back in time you look, the less national coordination of codes there is, with individual building codes for major cities and each state common in the 1910s and 20s. Before the 1924, there was not even a national steel code, as the American Institute of Steel Construction had not yet published the first edition of the steel manual.
Any design practice is based on experience, and our experience is concentrated in the New York area. Of course, engineering principles are the same everywhere, which is why we can work elsewhere. The same is true for anyone involved in conservation work: the principles are universal, but the experience is concentrated on the building types, history, materials, and systems used in a specific location.