Now that I do understand. When I wanted power for my then brand new shop, what I had to do was run the 220 direct from the house board, but not through it, back out the wall and into the ground in a trench I hand dug for that specific purpose. The only question the inspector asked was how I got the trench walls and floor so square to each other, LOL. So what showed up in the shop was pure 220, that got put into a sub box on the wall in there, and then broken out at that point into breakers for both 110 and 220. The way it is actually set up is that all the 220 draw in on one side/column, and the 110 is all on the other. Right now I only pull for two 220 plug ins but that may go up to four as the in house A/C and a second welding plug are on the "to be considered" list.
As for your house box, being full is not a good thing from an electrical inspector point of view. When the time does come for the house to be sold, any house inspector that is hired to visit the premises and evaluate the state/status of things is going to tag that situation because it will affect any renovation plans the new owners might have; which in turn would effect the amount they would offer for the property. It could even be a deal breaker because electrical upgrades tend to become a "while you're there" project because, while they just tend to start as a box swap, there is almost always that one circuit that has bad wiring or too light a gauge or wire for what is on it.
Nick
