Tiling over bubbles

Andy21

I built a shower enclosure. Over the drywall I applied MAPEI membrane strip in the lower portion of the wall with MAPEI flexible waterproofing membrane as adhersive. You can see the subtle shape of the fabric strips in the photo. And then I applied MAPEI flexible waterproofing membrane everywhere with a roller and trowel. When it all done, I found lots of air bubble under the membrane strip. My question is: If I apply the tile over such a condition, will the weight of the tiles tear down the fabric so the layer of tiles will seperate from the wall? Thanks very much in advance.

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Bud Cline

What is a "membrane strip"? How was it applied to the wall?

Are you talking about the white colored fabric?

What is the orange thing around the valve?

I will tell you that liquid waterproofing (I assume you used Mapei HPG) is vapor transmissive and I personally wouldn't trust it over regular drywall. The only way drywall can be used is if it is covered with a vinyl membrane such as Schluter's KERDI Mat or Noble's CIS Membrane.

Water droplets and water vapor are two different animals.

Does the Mapei product say this can be done? Where does it say that?

Is there gypsum joint compound under the liquid waterproofing? Liquid waterproofing really doesn't want to stick to any gypsum joint compound products.
The blisters should be repaired in my opinion.

Open one of the blisters and tug on it to see if it is in fact bonded to the substrate. My guess is that it is not.
I would be afraid the weight of the tile would continue to separate the waterproofing film from the substrate.

Ron6519

Remove the top bubbled layer and redo it. Tiling on top of this would be a waste of time.
If it pulls off the lower layer, redo all of it.

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"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
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jimmy21

its hard to tell if its really an issue or not. If it didn't adhere its a waste of time to tile, but maybe it did ahear just fine and just a few air bubbles got in there, but there's no way to tell. The smaller the tile, the more chace of problems

Bud Cline

...and the air bubbles came from, where........?

oh'mike

Call the technical help number---Mepei is usually quite helpful.

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Andy21

Thanks everybody for the advices and questions in details. The orange color is the Fabric strip from Mapei. It shows since I did not apply the Mapei HPG around the valve. I could not remove the existing regular drywall in large area expect the cutouts for plumbing, since the drywall is in two layers dividing my suite from the neighbor. Therefore, I cannot apply vapor sheet and then another layer of cement board because the store told me too many layers only cause mold. It is too bad the Mapei HPG won't be as good as its descriptions. I patched the cutouts and used compound and primed the drywall and then used HPG itself applied the Mapei fabric strip for extra protection. I will use 6x6 tiles. The bubbles are small and scattered. Other than those bubbles, everything is stable. So I am tending to take a chance. I will seal the tile carefully.

Bud Cline

Yes you are.

Has nothing to do with the issue at hand.

Andy21

Hi, Bud Cline. thanks so much for warning me and concerning the condition for me. I did so because I went to asked couple sale managers in Rona prior to start. Without the bubbles, I would not even concerned what you told me. I am not sure if you are from the United States or Canada. Rona is a big chain in Canada like Homedepot. Without their confirmation I would not do so. and Mapei HPG also decripts the product as good on drywall. I also show Rona the picture about the bubbles and got a possitive answer after I posted here. I have to think it over again and make a carefully dicision. Thanks!

jimmy21

i have a feeling it will be fine. Its probably like applying vinyl to glass. Your bound to get a few bubbles in there, but it has nothing to do with it not adhering. If the air bubbles formed AFTER the application, you might be screwed

Leah Frances

Seriously? What do you think is happening at the bubbles? Bubbles are, by definition, a location where the coating is NOT adhering to the substrate. Why would you give the OP the go ahead without addressing a problem that will lead to failure??

OP - if you read around on the site you will find lots of people led astray by big retailers. Bottom line, when your project fails the guy at Rona probably won't even offer an apology - nor will they refund your expenses or turn back time so you get back your wasted hours.

Bud is a bit .... straight forward. But he is REALY knowledgable. He's giving you the hard truth. You should listen.

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Ron6519

Yeah, it's just like vinyl over glass.
No, really it is.

__________________
Ron
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
B. Franklin 1759

jimmy21

do you understand what im saying? If the bubbles were there at the time of application, it has nothing to do with whether the membrane adhered. If they formed after the membrane was cured to the wall, then it is a sure sign that its giving way. Only problem is, there is no way to know without ripping it off. I would sure hate to be taking a shower and have tiles start falling off the wall. It usually happens at the most inopportune times

Bud Cline

I am aware of who Rona is. The employees there are no more qualified to give accurate advice than the employees of Home Depot or Lowe's or Menard's or Builder's Warehouse. They lack specific training and only know what they are told by a superior that has a profitable product with a substantial profit margin to move. I'm sure they think they are doing the right thing but most of them were asking you if you wanted your meal super-sized just a few weeks ago. Now they are tile experts at Rona. Mapei HPG is a quality product and for it to do what your photos illustrate would tend to make me believe you have errored in some fashion. My guess is the HPG was either applied over a dusty substrate or over gypsum joint compound.

I don't have a dog in this fight but if you would do what I suggested and simply open up a bubble and try to separate it from the wallboard by tugging on it you will know what you are up against either way.

To keep hashing it back and forth isn't accomplishing anything. If it is, I fail to see how.

Try my suggestion and go from there, then you will know.

That is absurd. A bubble indicates lack of bonding to the substrate. How hard is that to understand? It doesn't matter when the bubble was born, it is not adhered to the substrate now.

Ron6519

The only person who has had success in dealing with bubbles was Lawrence Welk. No matter where they were, he could successfully accomplish his goal.
Many of his bubbles were larger then the ones you have, and he had no problem with the issue.

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"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
B. Franklin 1759