I wouldn't worry about shimming issues as much as something else I see. The one big mistake I see is that you cut the siding off too short. You stopped it at the TOP of the footer/ 2X4s. You should have run the siding clear down about 2 inches past the top of the cement. That way when it rains, the water would go down the side past the top of the cement and into the ground. The way you have it now, when it rains, you'll have water getting inside- on top of and under the 2X4s and eventually it will rot. Not to mention water will getting inside. Even if you put trim around it, you'll have to caulk down each of those little groves in the siding to keep the water out. But other than that it looks pretty nice. Have fun.
Yeah that was one of the design compromises I had to make without laying a row of block or something - the detail at the bottom is not finished and will have trim closer to the slab.
The slab is slightly out of square and beyond the 8' dimension by about 1/2" in some places, so it would have been difficult to overhang the siding. LP Smartpanel also has a 6" above grade requirement, and I'm already breaking that rule by about 1". It would've been way too close to the ground if I brought it down past the slab, so I'd be fighting rotten siding in that case.
The only sill plate you see on the outside at this point is a ground contact rated 2x4 that has seam seal between it and the slab - the 2nd upper sill plate is above the siding, and a trim board on the outside of the siding will go down slightly closer to the slab.
I know it's not ideal and I'll be relying on OSI Quad and paint for protection to an extent, but hopefully my eave/rake overhangs will help shield some of it too.
