Waterproofing and insulating the rest of the foundation.

I was very excited to be done with the concrete work - it was  a big job and I was really looking forward to setting my own pace with the rest of the project. Before I could do that, however, there was one last reason to bring out a couple of the concrete guys again - the "Blueskin". Applying the "Blueskin" waterproofing membrane wasn't terribly difficult, but I wouldn't want to try it single handed - it's too sticky, awkward and expensive.

4" rigid foam around the exterior wall makes a good capillary break but something more is required to fight hydrostatic pressure. We applied the "Blueskin" membrane only to within 12" of the top of the wall to save material - this stuff 'aint cheap. The black line around the top is a mastic "goo" that seals the edge of the membrane to the wall.

During the application of the "Blueskin" particular attention was given to making sure the seam between the bottom of the concrete wall and the top of the slab was well sealed. 

The day after the "Blueskin" was applied, I began insulating the foundation with 4" rigid XPS insulation boards. In preparation for this step, I had done a couple of things in advance. The first bit of prep work was research. I had been concerned about how I would attach my rigid foam boards to the exterior face of the "Blueskin". The facing of "Blueskin" is polyethylene and there are very few adhesives that will stick to poly, but using mechanical fasteners would puncture the membrane. Eventually I tracked down a general purpose adhesive called QB300 that is compatible with rigid foam boards but also sticks to poly. I was glad that I began my research early, as it took about a month to track down a supplier of this adhesive then another few weeks for it to be delivered. The second bit of prep work was to cross-cut the full sized 2'x8' insulation boards down into 18" pieces. These 18" pieces would cover the the footing/slab edge around the entire perimeter of the house while full length boards would be used on the walls above.

Applying the boards to the foundation was relatively easy using spots - "blobs" - of the QB300 adhesive. As the brochure states, it has a very high "initial tack" which gives it relatively good holding power right from the get-go. In a few instances, where the boards gave me a harder time, I used bits of lumber to brace them against the foundation. Once cured the adhesive made a very good bond between the foam boards and the "Blueskin" - there were no instances of boards falling off prior to backfilling.

18" pieces of XPS were glued around the entire slab perimeter. Notice that I only occasionally had to support the foam board with bits of lumber - in this case bits of plywood.

In this photo you can see how the 18" pieces continue all the way around the perimeter of the slab. Stacking full length boards on top of the 18" pieces brought the foam flush with the top of the wall so the only other cutting was at the "steps" at either end of the wall. After the adhesive had cured, I taped all the seams with sheathing tape.

Pretty Little Ditty - Red Hot Chili Peppers