I'm pretty sure that there is a "gotta live in it for x months out of the previous y years" requirement attached to that exclusion, and you obviously didn't (I hope) live on that building plot. However, I'd suggest going directly to the source and calling IRS (1-800-829-1040). I spent about half-an-hour on the phone with them this morning; they were very helpful and explained what seemed to me to be a fairly complicated issue in a way that I could easily grasp.