If the existing slab is reasonably level and stable, perhaps you could deter rot and termites by substituting 4×8 pressure-treated for the existing bottom plates and running exterior flashing as high as necessary to bring the siding up. I did a similar thing years ago, and it seems to have held up ok. I just snapped a chalk line at the proper height on the existing studs, cut them out and slid the 4x into place, toe-nailing the studs to the 4x and then nailing the sheeting and siding on the outside.
You have to drill through the 4x to bolt them down to the slab, but that’s no big deal
perhaps not elegant, but maybe it would work.
Replies
I built a two block high stem wall on one side of my garage slab and have had no problems with any cracks or with the building inspectors. This slab is 20" deep from the top surface and has a 12" wide footer width with two pieces of #5 bar running a few inches off the bottom of the footer. Might want to dig down a bit and find out how your slab edges are configured.
Reply #2 seems simple enough and should get the job done, but I wonder if termites might find their way up behind the flashing thus hide their tunnels from view. That concern might be solved if you used 6" x 8" "el" flashing and nailed the studs through the 6" flange and then bent overhanging 1-1/2" down on the inside. Also a few years back Fine Homebuilding had an article on how to replace the bottom of a wall.