The window installation has been one of the more difficult issues to deal with. The first part of that issue was deciding which product/method to use to flash the windows and achieve the necessary level of air-tightness.
We tested three products/methods on the basement windows. The first was Tremco’s ExoAir Duo Membrane. This is basically a flashing tape that is applied to both the inside and outside of the window jamb gap. Half adheres to the window, and half adheres to the jamb, thereby completing the seal. Spray foam is applied in between the two (before the second side is applied. This product seemed to be the least favorable. First, it was difficult to get the tape to seal to both surfaces without undesirable waves. But the bigger issue was that it seemed almost impossible to get the spray foam to fill the gap without pushing the tape outward. It was obvious that this would make it difficult to properly trim out the window box; at least not without significant difficulty. We estimated that it would have cost approximately $750 for enough of this product to do all 19 windows in the house. Here’s the best and worst of what it looked like:
The second product that we considered is also made by Tremco. It’s called the Exo Air Trio, and seemed to be a much more effective product. It basically consisted of a a compressed foam band with adhesive on one side. It is applied to either the window or the jamb. Once unrolled, it begins to expand, so you have to plan out the installation a bit. But the expansion rate is rather slow, so it’s not a mad rush. Once fully expanded, the foam completely seals all of the gaps between the window and the jamb. It looked pretty effective, if not a bit amazing. The biggest downside was the estimated $1800 price tag to do all of the windows. Here’s what the installed product looked like:
The third option (the option that we went with) uses a three-part solution by Prosoco. Unlike the other two products, the Prosoco solution seals the gap and flashes the window. The first part of the process involves the application of Prosoco R-Guard Joint and Seam Filler, which is described as “a fiber reinforced fill coat and seam treatment.” It basically appears to be a pink, fibrous, rubber caulk. It’s applied to all of the seams in the rough opening. After that, the R-Guard Fast Flash was applied to the entire opening (and the exterior of the opening). Like the Joint and Seam Filler, it’s applied with a caulk gun. But then it’s smoothed out with a spatula to create a consistent rubber-like covering over the entire area. Once dry, it really leaves one with the impression that the opening will be impervious to water and moisture:
Then the window is installed, and an appropriately sized backer rod is installed in the gap surrounding the window on the interior surface. The final step is the application of the R-Guard Air Dam product to the face of the backer rod:
All in all, it appears to be a pretty bullet proof system that interplays well with the Zip System sheathing, and should serve us well. On top of it all, we estimate that it will cost us somewhere around $500 to cover the installation of all of the windows.