We’ll be framing atop a Superior Walls precast foundation, and from what I have seen in the product out of this franchisee’s plant, and the dealer/installer doing the work, we can expect dead straight and level walls.

You cannot put 2×6 mudsills on these.  The top flanges of the concrete walls have preformed cast holes through which we bolt the 2xs, and the hole placement is about 4″ in from the outboard edge.  We’ll be using 2x8s.  Some guys use 2x10s.

My insulation sub will be using sprayed urethane foam to insulate my rim, and I always have him spray it down, over the mudsill, and a little onto the top of the concrete wall. 

That’s a pretty good barrier to air infiltration under the sill, in my estimation.

So, why put sill seal foam strip under the mudsill, at all?  Particularly so when we have a 2×8 mudsill, sill seal available at 5.5 width max, and a precast straight surface to bolt to?

I was thinking, just as a backup, of running a bead of urethane caulk, one bead only, a couple inches in from the edge, before bolting on the ACQ sills.