I want to remove a garage door and fill in the opening with a frame wall. It is on a gable end of the detacted garage and not a load bearing wall. The garage has a concrete foundation (36" frost depth), but no slab or structure under the door opening. I intend to have a concrete floor poured as part of the work. How do I best support the new wall section and close off the edge at ground level? Do I need to put a foundation under the opening and new wall section, or can I support the new wall with a beam at the bottom and just have the new slab under it?