I'm trying to come up with a good detail at the doorway of an industrial building. I'd planned on having the perimeter grade beam come up about 6" above the slab on grade and leave the slab on grade 'floating'. But at the doorway, throw a couple of dowels in and notch the gradebeam down 6", or would you notch it further and run the slab over top at the doorway. It's been a while since I've designed a concrete foundation and I can't remember what is (or if there is a) standard way to detail the door openings.