It will all work out. With this type project, especially involving other folks, it never goes along exactly as you expect, but in the end, it will all work out. For the first time ever, though, someone else is building a building FOR us, yea! It's such a luxury, even though we'll have to do the interior and the fencing (unless my sister gets off her duff and gets my dad's house in the market-dream on). We have plenty of paver base still to put inside around that foundation gap and pack it in then we can use concrete on the outside in those areas, at the very least. The vapor barrier will be attached to the foundation inside then the walls will hold it at the bottom. I'll double up on it with the 6 mil we still have here somewhere, too. They got here at 6:38 a.m., pitch black dark, but they're ready to work. I cringe thinking of them sawing metal at this hour and the neighbors.