Blue seal (waterproof rubber membrane) over durock, overkill?

[newbieonhomes]

I am back to the bath project again. I am ready to installing the shower walls over an acrylic shower base. This is a shower stall, separated from the tub. I'll be putting durock on all walls. I have read the blue seal thread and have used blue seal on the surrounding green boards for the soaking tub with success. The question is it overkill to use blue seal on durock before tiling? Or the seal would hinder the performance (mold, water resistance, adhesion) of durock?

I hope some may offer some experience with it. Thanks.

Tom.

[Trask]

HeyThomas,



No such thing as overkill when it comes to water
I'm a sheet membrane guy for the most part. I use trowel on membranes from time to time..but feel sheet goods like Kerdi by Schluter in your application are far superior.

[jdm]

If you use the Blue Seal, you should not have a vapor barrier behind the CBU.

[newbieonhomes]

Thanks for the reply. I have thought of using kerdi, but I did not want to waste the left over blue seal (more than half a gallon).

jmd, I have dutifully put on vapor barrier all around the room! So, is blue seal out of the options? Why should I not have a vapor barrier behind the CBU? I called Use Hickson (maker of blue seal) support line and they said (understandably) it's ok even the barrier is behind the durock. Of course, real life experience may differ from manufacturer's claims. That is why I am looking for second opinions. Thanks.

(try to attach a picture but can't)

[jdm]

Problems can arise if water gets trapped between two waterproof layers in a wall. Nasty stuff can grow.

Besides, if Blue Seal is anything like RedGard, you'll need way more than a half gallon to waterproof a typical shower.