TDR

TDR is the family of mechanisms by which unused development rights — floor area a lot could carry but has not built — move from one lot to another. The general-purpose mechanism is the zoning-lot merger, which combines adjacent lots on a block into one zoning lot whose floor-area budget the owners allocate by recorded agreement. Designated landmarks have a path of their own: under § 75-42 of the Zoning Resolution, a landmark's unused development rights may be transferred, by certification, to a lot on its block or across a street or intersection from it, raising that lot's maximum floor area by up to 20 percent; § 74-79 is the special permit for larger transfers in the densest districts.

Some special purpose districts operate their own transfer mechanisms with their own geographies. In every variant, the transfer is documentary and lot-specific — recorded instruments bind identified lots — and the receiving site must still fit the acquired floor area within its own envelope rules.