edge insulation on slab for radiant heat
OK I screwed up, but so did the contractor too. I have a "engineered floating slab" for my detached garage. It's a 4" floating slab with beveled edge that goes down to 16" wide thickened edge around the perimeter about 12" deep. So kinda like a little footing. I laid 4 loops of pex for radiant heating on top of a 7 layer foil, bubble and aluminum faced insulation blanket before the concrete was poured. The day of the pour (after the pour) the contractor told me that we probably shouldn't have run the tubing down in the thick edge part, only where the floor was 4" thick. The tubing was spaced 6" apart for maybe 24" along the outside edge, then 12-14" spacing along the rest of the slab.
Their is 1 course of block then the walls are set un top of that. Originally the contractor was going to use the split block to match the house, but since the slab was now done and my tubing was "wrong", he suggested that we use smooth block then run foamboard tight against the outside of the block to a depth of 48" around the perimeter, then run a horizontal piece of foam, 10" below grade, kinda like a sideways off set "T". Run some flashing over the exposed foam so it don't look too bad. Alright I says let do that, we'll go with the smooth block then. Well aparently the workers didn't get the message and when I get home from work the next day I have my split face block in place, it looks nice but now how am I going to run my foam board tight against it for insulation?
I need to insulate it somehow cause my block will just radiate the heat off of the tubing, but what I don't get is it would radiate anyhow even if I kept the tubing away from the thick edge. I filled the blocks that weren't core filled with the j bolts with foam beads, but that's not going to do too much.
I'm almost thinking of spray foam and painting it up against the block, and still foam board below grade, Then I have the front side with an apron, anything here would really look like hell. I'm in Minnesota and this garage will have 2 zones for heating, garage space won't be too warm, but there is some office, living quarters that need to be kept warmer thru the winter.