ProShield HPG Over Shower Floor Base

thekctermite

I'm in the process of building a tile walk-in shower. I did a sloped pre-pan, applied a thick vinyl membrane, and then the final mud base. As it is, it should perform great. However, I want it to be bulletproof. So, I'd like to apply ProShield HPG (a lot like RedGuard) over the concrete base before I tile it.

The base and concrete curb have been curing for two days now, and have hardened up nicely. I'm walking on it with no problem. I know that the first several days are the majority of the curing, and it will have reached the bulk of its strength by 28 days.

My question pertains to a warning on the instructions of the ProShield HPG that states that it shouldn't be applied to concrete that hasn't cured for 28 days. Well, I don't have 28 days. I have a few days before I'll be tiling. Are they just covering their backside or is there a valid reason for this warning? Concrete will cure without being exposed to any air, so all I can figure is that the curing might somehow effect the coating???

(I've applied ProShield HPG to all the wonderboard already.)

Bud Cline

Do you have a vapor barrier behind the wallboard?
Are you a concrete chemist and engineer?
If you have the vinyl membrane installed why would you need a topical waterproofing product?

Sportbilly

Does 'crete out-gas as it cures maybe? I bet there's a reason for it to be specified on the wrapper...

Bud Cline

Ya think..................................?

thekctermite

Yes, there's a vapor/moisture barrier behind the cement backerboard on the walls.

The shower floor is slate tile, and I'd like to have the base as impervious as possible. I know the membrane under the mud base will take care of any moisture that gets past, but my thinking was to prevent moisture from ever getting to it! Is that flawed thinking?

nwtile guy

I think the general thought about that is to pick one form of waterproofing or the other. If you constructed the shower pan correctly with the liner and didn't block any weep holes, then you should be fine with that method. If you want to go without the liner and use a topical waterproofer, then just use that route. Either one will work fine on their own. From what I understand, it is not a good idea to use both because of the fear of creating a moisture sandwich and tying the topical waterproofer in with your pan liner. I have been only using topical waterproofers on my shower pans and no liner. When applied correctly, you should have no problems.

__________________
Chad

Bud Cline

Wall installations require either a moisture barrier behind the wallboard or a waterproofing product on the surface of the the wallboard (or a waterproof wallboard.) But not both. Condensation can occur between the barriers with no way for it to dissipate properly. Mold mildew and moisture erosion can result. Shower walls located on a structures exterior walls only compounds the problems.

In the case of the shower floor. If a vinyl shower pan liner was used then a clamping drain was also used. The clamping drains contain weep holes for the water that eventually wicks its way into the concrete from above and collects on the surface of the pan liner to escape. Evaporation is also an important part of the concept.

It is conceivable that those weep holes could also work in reverse allowing water to wick into the concrete as it drains on its normal course. If the floor has both a pan liner AND a topical waterproofing then there exists a possibility that moisture wicking into the concrete would have no way to evaporate.

So.....as nw says. It should be one or the other but not both. Using both systems isn't bulletproofing anything it is simply creating new problems.

thekctermite

Thanks for the info Bud and NW TileGuy. That clears up a lot for me, and it makes sense. I'll leave the floor as it is and install my tile!