I am really wondering if it would just be better to stick build this shop. My slab is 28' x 40', I didn't have any real constaints on size it just would look better attached to the house. My original thought was to have the shop area 28' x 27' with 2 10' x 10' roll up doors and a 28' x 14' breeze way. What I have is a Manufactured Home, 32' x 86' on 3.5 acres. I the slab is butted up to one end with a 36' x 20' deck across the rear of the house. The steps for the deck land on the slab at the rear corner, thats where the breeze way comes in. I had thought of using a steel I beam to run the length of the building for the shop, that would allow me to have no center post and possibly a trolly and chain fall hoist. Currently I'm working out of a 12' x 24' protable building, as you say it's bursting at the seems. Like many of you I have way to many projects and just no time.