And in Wikipedia I found:
"Jettying (jetty, jutty, getee (obsolete) from Old French getee, jette) is a building technique used in medieval timber framed buildings in which an upper floor projects beyond the dimensions of the floor below. This has the advantage of increasing the available space in the building without obstructing the street. In the U.S. this style house became called a garrison house."
(I guess modern French 'jeter = to throw' comes from this root too.)
Mmm I did think of it.................