I am in the planning stages of building a shop. I know bigger the better, but I am taking in part of my attic, 20' ceilings and virtually unlimited floor space. I am going to include the size in the heating and a/c contract. I am in the deep south and realize that it needs to be cooled and heated. My, our (My wife is watching) house is an old queen anne, with a large attic and tall ceilings. Enough of the rambling, how many square feet should I allow for an amble shop for large scale planes. My wife says I can't have it all (2900 sq ft). If any body has a good idea please send me details. We are in the remodeling stages now and would like to include in the remodel budget.