Home>Discussions>BATHROOMS>When do you use shower membranes?
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Jod
When do you use shower membranes?

I am having a new shower built in my bathroom and my contractor is using Hardie board without a membrane. The shower is going to have tile installed over the Hardie board with thin set. Shouldn't he be using the membrane too to make it water tight?

dj1
Re: When do you use shower membranes?

CBU is not waterproof, I'd stretch 6mm plastic on the walls before I hang it.

Sombreuil_mongrel
Re: When do you use shower membranes?
Jod wrote:

I am having a new shower built in my bathroom and my contractor is using Hardie board without a membrane. The shower is going to have tile installed over the Hardie board with thin set. Shouldn't he be using the membrane too to make it water tight?

A pvc membrane should be used on a shower floor when a mud base is used. For walls, tarpaper or heavy plastic sheeting is fine. It needs to overlap the pan liner. A shower pan can't be made with CBU because there would not be any slope. A special drain fitting with weep holes is also employed to allow water that permeates the mud bed a way to drain.
For reasons like that, we have switched over to Schluter system shower pans, they have built-in slope, and you tile after swaddling the whole shower surround in Kerdi membrane, which is applied right over the drywall using thinset.
Casey

HoustonRemodeler
Re: When do you use shower membranes?

What they said plus,

All ceeement board manufacturers require the seams to be taped and floated.

IMHO a surface membrane such as kerdi is superior to sheeting behind the ceement board especially if there is a bench or niche involved.

Mastercarpentry
Re: When do you use shower membranes?

The way you describe things is a future failure waiting to happen. Tile installations are not waterproof in and of themselves. Thus the use of membranes, being a more modern and better way than using poly to waterproof, is what we do here because done properly they cannot leak ever period.

I like doing jobs that never require warranty work!

Phil

Sombreuil_mongrel
Re: When do you use shower membranes?

I forgot to state that you want a mud pre-slope underneath the PVC liner so the weep holes work and the mud bed stays as dry as possible. Without the pre-slope things tend to get wet and stay wet, which means that a stone tile floor turns darker and looks water-logged, which it is.
Casey

bill
Re: When do you use shower membranes?

don"t let him do it, i have repaired many of these handy man showers. get a license contractor to give a price with a membrane, and a guarantee.

Lazarus
Re: When do you use shower membranes?

You either use a rubber membrane between the preslope and the final tiling slope. (old school) or you use a SAM...Surface Applied Membrane such as Kerdi or Hydroban over ONE slope. The advantage being that water NEVER penetrates beyond the barrier, thus dries out quicker.

Look at it this way~the waterproofing goes on FIRST! The tile and grout are only there to make it look pretty....they have absolutely NOTHING to do with the waterproofing.

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