In a message dated 12/27/2005 3:04:26 PM Eastern Standard Time, [log in to unmask] pleads: The purpose of this exercise is to determine when this basement stair enclosure was constructed, with the ultimate goal of determining when the house was converted from single family occupancy to 2 family. The 1930 census is probably no good, since it's too early. But try the criss-cross telephone directories - if actually divided, two phones should show up at time of alteration. Also, I seriously doubt that Zoning Board will respond well to preserv-tech carbon-dating of Beaverboard, unless you have high-priced architectural historian on board. c