Shower Waterproofing

So GoBoard is great stuff. Its a lot stiffer than Kerdi board and the compressive strength is quite impressive. The compressive strength for the 1/4" GoBoard is 300psi which is great for floors and on top of curbs where Kerdi board would be terrible because it is so soft. The compressive strength of the 1/2" GoBoard is still 250 psi which makes it quite stiff for spanning stud spacing with little flex where Kerdi board again is pretty bad. GoBoard is basically a textured fiberglass paper on both sides that sandwiches polyisocyanurate foam in the middle. GoBoard is waterproof as stated in their data sheet, but their system has a flaw. Waterproof in this instance means that water will not travel through the board from one side to the other. BUT, water will soak into the fiberglass paper and travel laterally through the board.

I found this out after doing a test on the material (luckily before I covered it up with tile ;) Isaac's testing inspired me to try this out. My test involved constructing a basin out of GoBoard and GoBoard Pro Sealant. I constructed it quickly and probably should have extended the sealant further out as per the data sheet, but I really just wanted to know if water would travel laterally and I got my answer. The water penetration out of the constructed basin occurred within just a couple hours. GoBoard is already on my walls at this point so I think that I will coat all of it in hydroban after sealing the corners with flofx banding. (The pan will be dry pack, flofx drain, and flofx membrane). Thoughts anyone? Isaac...Feel free to make a video doing a similar test on this stuff. I still like this product, but its good to know all the limitations.