# Tiler I respect got me wondering?



## MarcoPollo (Dec 6, 2014)

I met up with a local tiler yesterday that I respect and have learned a lot from. He is employed but he lead of a fairly large outfit here doing primarily large commercial work and they have a good reputation. We were discussing a few things and I asked him two specific things and I thought I would float it to the board here as I like to open myself up to being torn apart 

Scenario 1: 
In regards to tub surrounds we discussed the merits during porcelain installs using type 1 mastic for speed. I will admit I have done this many times before and have had no failures. This will cause outrage here I know but I am having a hard time given the below scenario why this would fail.

My understanding is the first 2' up a shower wall in an all tiled shower is the most susceptible to failure from water vapour. A tub usually covers this. Use Denshield behind with its own coating with a bead of silicone at the joints to complete the waterproofing behind. Tile shower. Wait 48 hours for curing. Power grout the shower.

Argument: We all know thinset is better however with improved grouts these days once the mastic sets before grouting, are you really worried about how moist the mastic is getting from basically splash? You have bigger issues IMO if water is getting to that mastic.

Please note I would never in a full tiled shower use mastic. This is very situation dependant.

Scenario 2:

Thickness at plane changes. I was always taught to match the grout lines up a wall. 1/8" grout lines then at a plane change you measure tight take off 1/4" to match 1/8" both sides. 1/8" off when doing 1/16" grout lines etc.

This tiler recommended basically butting the timer to adjacent plane. This worries me for expansion (tenting). Is the carpenter in me too worried as wood moves more than masonry or is he incorrect? What method do you guys use?

Thanks in advance, sorry for the long post.


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## HS345 (Jan 20, 2008)

MarcoPollo said:


> I met up with a local tiler yesterday that I respect and have learned a lot from. He is employed but he lead of a fairly large outfit here doing primarily large commercial work and they have a good reputation. We were discussing a few things and I asked him two specific things and I thought I would float it to the board here as I like to open myself up to being torn apart
> 
> Scenario 1:
> In regards to tub surrounds we discussed the merits during porcelain installs using type 1 mastic for speed. I will admit I have done this many times before and have had no failures. This will cause outrage here I know but I am having a hard time given the below scenario why this would fail.
> ...


Grout is not a waterproofing, and should never be considered as such. Why would anyone use mastic in a shower? The little bit of "speed" you might gain from not having to mix a bucket of mortar is lost in the higher cost of the mastic. Plus, mastic cannot be built up, so you are limited to notch size. With all of the great non-sag mortars out these days, I never use mastic for anything. 

Plus, how are you going to wait 48 hours before grouting? In your scenario, what size are the tile? If bigger than 6x6 you're going to have to wait a hell of a lot longer than 48 hours, especially over an impervious membrane. In fact, I doubt a 12x12 tile would dry in a month using mastic over denshield. Let alone anything larger.



MarcoPollo said:


> Scenario 2:
> 
> Thickness at plane changes. I was always taught to match the grout lines up a wall. 1/8" grout lines then at a plane change you measure tight take off 1/4" to match 1/8" both sides. 1/8" off when doing 1/16" grout lines etc.
> 
> ...


Are you saying with an 1/8" grout joint you are leaving 1/8" gaps in the corners? Umm, no. :no: I never leave anything bigger than I can silicone in the corners. 1/16" max.


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## TNTRenovate (Aug 19, 2010)

MarcoPollo said:


> I met up with a local tiler yesterday that I respect and have learned a lot from. He is employed but he lead of a fairly large outfit here doing primarily large commercial work and they have a good reputation. We were discussing a few things and I asked him two specific things and I thought I would float it to the board here as I like to open myself up to being torn apart
> 
> Scenario 1:
> In regards to tub surrounds we discussed the merits during porcelain installs using type 1 mastic for speed. I will admit I have done this many times before and have had no failures. This will cause outrage here I know but I am having a hard time given the below scenario why this would fail.
> ...


The biggest reasons not too use mastic have been listed already. I'll add that it will never cure properly if you are tiling as if it were thin set.


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## CarpenterSFO (Dec 12, 2012)

I have taken apart plenty of mortar-based showers that were holding up fine, after many decades of use. I have never taken apart a mastic-based shower that hadn't failed and that wasn't contributing to the failure of the building. Read the data sheets for Type 1 mastics - they generally can't be used over water-proof underlayments, because they will fail if the underlayment doesn't absorb the moisture that gets through the tile and grout. The water that gets absorbed by the underlayment will need to find its way out through the building structure. A wood building will rot.


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## MarcoPollo (Dec 6, 2014)

I didn't present this correctly I guess -

I have used Mastic in the past primarily on 6x6 and subway tiles. Now I am not getting into a debate about merits of Mastic.

I made a mistake based on ignorance and have long since changed that approach.

Thee point was to ask people thinking about the actual water penetration that goes through a tub surround. 

A tiled shower is one thing as we have seen all the horror stories of tiled showers with improper waterproofing.

Tub surrounds are very different IMO.

To touch on the grout joints at plane changes, I do 1/16" as well, I did a few 1/8" When i first started and the silicone joint looked hod awful. My question was whether or not butting tiles at the corners is acceptible. I was concerned about tenting.


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## TNTRenovate (Aug 19, 2010)

MarcoPollo said:


> Scenario 1:
> In regards to tub surrounds we discussed the merits during porcelain installs using type 1 mastic for speed. I will admit I have done this many times before and have had no failures. This will cause outrage here I know but I am having a hard time given the below scenario why this would fail.
> 
> My understanding is the first 2' up a shower wall in an all tiled shower is the most susceptible to failure from water vapour. A tub usually covers this. Use Denshield behind with its own coating with a bead of silicone at the joints to complete the waterproofing behind. Tile shower. Wait 48 hours for curing. Power grout the shower.
> ...










MarcoPollo said:


> I didn't present this correctly I guess -
> 
> I have used Mastic in the past primarily on 6x6 and subway tiles. Now I am not getting into a debate about merits of Mastic.
> 
> ...


Tub and showers are only different in the fact that the base is higher in a tub versus shower. Everything else should be handled in the same manner. 

You never said that you don't use mastic. In fact you said that you were discussing the possible benefit of it speeding up installs.

Can you explain how tub surrounds are different?


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## MarcoPollo (Dec 6, 2014)

Upon rereading the original post I still don't see how I say I DO use mastic, we discussed merits of a scenario. I believe that the science behind all construction is important and why while apprenticing I always asked why as opposed to how.

Based on above scenario, the difference would be height. The higher you go the less direct water hitting your application.

So based on this, what amount of vapour will permeate a wall 18-24" above a floor if grouted with higher end grout When gravity will draw 90% of the water's vapour downhill.

So if a 10% perm rating is absorbed into the substrate with the denshield coating shouldnt affect mastic the way people react to it.

I have seen tests on here where mastic is submerged for long periods and not fallen off the tile. If this is the case i understand that grout is not waterproof however if you use power grout, urethane or somehing with far less permeance and with porcelain which has a low perm rating it shouldnt matter.

Again i reiterate that I am not telling anyone to use mastic but I found it an interesting discussion that in theory, if you were using mastic on a tub surround your failure rate may not be very high.

As mentioned before on the tiling forum here tile is percentages but I thought it was an interesting theoretical discussion.


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## MarkJames (Nov 25, 2012)

MarcoPollo said:


> I met up with a local tiler yesterday that I respect and have learned a lot from. He is employed but he lead of a fairly large outfit here doing primarily large commercial work and they have a good reputation. We were discussing a few things and I asked him two specific things and I thought I would float it to the board here as I like to open myself up to being torn apart
> 
> Scenario 1:
> In regards to tub surrounds we discussed the merits during porcelain installs using type 1 mastic for speed. I will admit I have done this many times before and have had no failures. This will cause outrage here I know but I am having a hard time given the below scenario why this would fail.
> ...


You can get failure/seepage at either floor-wall joint (showers) or tub-wall joint (tubs). One could say there's the added security of the tub flange, but that doesn't mean much if the joint isn't sealed and the substrate isn't overlapping the flange.

Other problem areas are the top outside corners of the tub when there's a gap behind the tile (common problem, letting water behind the wall that migrates down within the grout), water getting behind the mixer plate, and water getting through the grout and into non-waterproofed walls like cement board.

I ripped out a shower done with mastic walls for 4x4's and those things peeled off way too easy. I don't know if that's normal, but it made tear out easier. It was raining tile as I scraped.


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## CarpenterSFO (Dec 12, 2012)

MarcoPollo said:


> ..., I will admit I have done this many times before ....


Clear.


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## MarcoPollo (Dec 6, 2014)

CarpenterSFO said:


> Clear.


Yes, I freely admit was wrong, was corrected and put in my place. This was a learning curve for me. I was taught incorrectly, thought I was doing something correctly. No longer do this after educating myself for the benefit of my clients.


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## MarcoPollo (Dec 6, 2014)

Wow, you guys really are a pack of rabid dogs looking to pick off a member of the herd.

It was trying to talk about an interesting discussion further but you guys clearly are not interested in that, more in attacking me.

So here's the cole's notes:
Great company, apprenticed to be high end carpenter.

Sick of doing just carpentry (they subbed all tile paint roofing drywall etc) so I moved on after completing wanting new challenges. 

Found gentleman who seemed legit and ticketed carpenter who's father was tiler. Was him and me 2 man show he taught me to tile. He used densshield and mastic siliconed the joints behind as waterproofing similar to a vinyl surround application. Tile in front. Didn't get us called back and the manufacturer stated this could be used on tiled walls in shower. Seemed legit.

Went out on own first tiled shower I used mastic and was discussing with a tiler I had met he tore me a new *******. Researched and alas I was wrong.

Have at it guys, tear me a new a-hole now too.

But may I suggest we get past this and move on since the idea behind this clearly isn't leading to anything productive minus a witch hunt.


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## angus242 (Oct 20, 2007)

The guys are not so much "attacking" you but what you're trying to get someone to say OK to.

My guess is that you were hoping someone "experienced" would come along and say "sure, today's mastic is OK to use in a tub surround and _will_ help you speed up production."

Problem is, the brunt of experience here tells us something else. Also, don't take it so personal. You realize some people have been here for years and it does get a bit old answering the same basic questions over and over. You are not the first to ask about this and you won't be the last.

The best advice I could give is try to separate yourself from your competition by being BETTER not worry about faster. See how easy it was for a few people here to knock your technique? Well, if you step up your materials and procedures you could do the same to the lazy competition. 

Of course, you need to be able to sell the whole package. That's not something you can really teach. I'm a terrible seller and even though I have no problem saying I can construct a shower that will last a lifetime, sometimes I simply can't sell the point. 

And try to have a little thicker skin. You asked a question and when you don't get the answer you're expecting, you need to be able to process that and turn it into something positive. I mean would it have been better if no one replied at all?


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## CarpenterSFO (Dec 12, 2012)

It's not a witch hunt, or some sort of snobbishness or elitism. It's just attention to the trade.


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## CarpenterSFO (Dec 12, 2012)

MarcoPollo said:


> Wow, you guys really are a pack of rabid dogs looking to pick off a member of the herd....


Exactly the opposite, actually. Every better-educated contractor out there, selling the right thing to property owners, makes it easier for the rest of us to do the same.


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## HS345 (Jan 20, 2008)

MarkJames said:


> You can get failure/seepage at either floor-wall joint (showers) or tub-wall joint (tubs). One could say there's the added security of the tub flange, but that doesn't mean much if the joint isn't sealed and the substrate isn't overlapping the flange.
> 
> Other problem areas are the top outside corners of the tub when there's a gap behind the tile (common problem, letting water behind the wall that migrates down within the grout), water getting behind the mixer plate, and water getting through the grout and into non-waterproofed walls like cement board.
> 
> I ripped out a shower done with mastic walls for 4x4's and those things peeled off way too easy. I don't know if that's normal, but it made tear out easier. It was raining tile as I scraped.


Are you talking about a failure of the tile joint at the floor wall of a tile shower, or a failure of the waterproofing membrane or pan liner? Because the tile joint of a tiled shower has nothing to do with the failure of a tiled shower.


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## HS345 (Jan 20, 2008)

MarcoPollo said:


> Wow, you guys really are a pack of rabid dogs looking to pick off a member of the herd.
> 
> It was trying to talk about an interesting discussion further but you guys clearly are not interested in that, more in attacking me.
> 
> ...


Holy crap, I hope you aren't referring to my comments, because I certainly wasn't looking to attack you. Just a friendly discussion, if you took it any other way, that's on you. And you did ask.


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## CarpenterSFO (Dec 12, 2012)

HS345 said:


> Holy crap, I hope you aren't referring to my comments, because I certainly wasn't looking to attack you. Just a friendly discussion, if you took it any other way, that's on you. And you did ask.


If you're a contractor, you better be able to put up with some candid talk.


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## jaydee (Mar 20, 2014)

*Ya, can't we all get along*...

Wow, I used to think that also, when I was a newbie.

Now, Well, I go with the flow..

You'll see..


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## MarkJames (Nov 25, 2012)

HS345 said:


> Are you talking about a failure of the tile joint at the floor wall of a tile shower, or a failure of the waterproofing membrane or pan liner? Because the tile joint of a tiled shower has nothing to do with the failure of a tiled shower.


The method behind the tile, not the tile. Frankly, I regret wading in on this one. :drink:


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## TNTRenovate (Aug 19, 2010)

I'll go back and actually address your OP. It'll be hard to refute or dismiss my answers.



MarcoPollo said:


> I met up with a local tiler yesterday that I respect and have learned a lot from. He is employed but he lead of a fairly large outfit here doing primarily large commercial work and they have a good reputation. We were discussing a few things and I asked him two specific things and I thought I would float it to the board here as I like to open myself up to being torn apart
> 
> Scenario 1:
> In regards to tub surrounds we discussed the merits during porcelain installs using type 1 mastic for speed.
> ...


Hopefully this helped.


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## aptpupil (Jun 12, 2010)

Not to hijack the thread, but how is it that the few tub surrounds I've taken out that were done over plaster or drywall have no damage behind them? I can't help but feel like I'm going overboard when I demo that and install kerdiboard in its place when it's done just fine for 20+ years.
Have I just been lucky?


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## angus242 (Oct 20, 2007)

Yes and no.

Luck does come into play but so does amount of use and depending on how old, the mastics of yesteryear were actually a bit better then they are today. Things like asbestos & VOCs made some older materials really good construction materials....well, they _thought_ they were good.

For every one you took out without issue, I bet there's one or two with them.


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## rrk (Apr 22, 2012)

Some of the mastics from yesteryear were actually very flammable and would not be easily dissolved with water. But not so today.


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## MarcoPollo (Dec 6, 2014)

Ok I am going to swallow things here and try and explain.

I felt attacked as it felt you all thought I was backpedaling on what I posted. Let me be clear, this is not the case.

I did stop using mastics when I was first explained and did my research. The comment about the showers vs tub surrounds was meant to describe that I never considered using them for full showers ever. I was using them as surrounds. 
If a call back from a client didn't arise and I did the wrong thing then that's on me, however I have a hard time believing no-one on this forum in any capacity has ever made an error before they didn't realise.

The discussion stemmed from the conversation based on the fact this tiler made the comment "if water is getting behind the tile you have larger issues." It got me wondering if maybe there is merits to his comment which led me to believe maybe this method isn't as taboo as it seems. I as well have torn showers apart that have been tiled with mastic that have no signs of water damage and thus based on this conversation I wondered further if this tiler had a point. 

I don't like the mould idea though as I do agree a mould issue where unseen is very dangerous.

Either way I guess where I'm sensitive is I don't want people looking at me like a hack as I take what I do very seriously and pridefully.


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## HS345 (Jan 20, 2008)

MarcoPollo said:


> Ok I am going to swallow things here and try and explain.
> 
> I felt attacked as it felt you all thought I was backpedaling on what I posted. Let me be clear, this is not the case.
> 
> ...


Obviously you're not a hack, or you wouldn't be interested in educating yourself. I have a feeling this "tiler" you speak of doesn't really understand the nature of tile assemblies. If he did, he wouldn't make comments like "if water is getting behind the tile you have larger issues." Water is going to get behind the tile with all cementitious grouts, whether newer technology, or not. The newer cement grouts don't add anything as far as "waterproofing" goes, they only add stain resistance. However, even with less permeable grouts such as epoxy, you never want to rely on grout to stop water. A tiled shower should be completely waterproof before you hang a single tile.


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## illbuildit.dd (Jan 7, 2015)

Makes me think of a guy I know who always grouts his corners in showers. The guy does great work, but i did repairs in a home where he did this about 8 months later and the grout was falling out in all corners. I've always caulked with matching. Anyone ever grout corners with full success?


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## charimon (Nov 24, 2008)

I have been reading this thread for several days and I have to question the basic premise (In regards to tub surrounds we discussed the merits during porcelain installs using type 1 mastic for speed.)

If you have already started the shower with mortar how does switching product speed things up? 

If speeding things up is the driving force. Are you referring to the amount of tile you set in a day? The overall job? What exactly gets sped up?
I realize there is the perception because you do not have to mix.


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## TNTRenovate (Aug 19, 2010)

illbuildit.dd said:


> Makes me think of a guy I know who always grouts his corners in showers. The guy does great work, but i did repairs in a home where he did this about 8 months later and the grout was falling out in all corners. I've always caulked with matching. Anyone ever grout corners with full success?


John Bridge does as well as many on his forum. His belief is if the framing is constructed properly the grout won't fall in the corners.


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## illbuildit.dd (Jan 7, 2015)

TNTSERVICES said:


> John Bridge does as well as many on his forum. His belief is if the framing is constructed properly the grout won't fall in the corners.


I've wondered. Makes me think of all the mortar bedded walls. I knew a guy still did them that way about 15 years ago but haven't seen him in 10


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## angus242 (Oct 20, 2007)

This is a case where the tiler should know best.

If you construct the framing, you should feel more comfortable with the corners. 

I feel that even though caulk (silicone) is the accepted method, it's a maintenance item. It's going to fail. The problem occurs when the HO doesn't actually maintain and once you start getting some moisture behind, the mildew is a close second. 

I personally grout corners because of how I handle the substrate and the grout I use.


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## illbuildit.dd (Jan 7, 2015)

angus242 said:


> This is a case where the tiler should know best.
> 
> If you construct the framing, you should feel more comfortable with the corners.
> 
> ...


I use to grout only in the corners til they came out with the matching caulk. Then I use to caulk only, but now I grout and put a nice bead of sanded matching caulk on top


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## angus242 (Oct 20, 2007)

illbuildit.dd said:


> I use to grout only in the corners til they came out with the matching caulk. Then I use to caulk only, but now I grout and put a nice bead of sanded matching caulk on top


You should reconsider. When you get moisture behind the grout (doesn't necessarily come directly from the corners) it will have a harder time evaporating out and can get trapped behind the caulk causing mildew.

One or the other, not both.


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## Xtrememtnbiker (Jun 9, 2013)

Angus, care to elaborate on what you mean regarding a proper framed corner and how you do the substrate?

I'm assume expansion and contraction is what we are fighting?


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## angus242 (Oct 20, 2007)

I never mentioned properly framed. But if you lock your corners together, you should have less chance for movement.

I use FibaFuse and AquaDefense in the corners. You'd be amazed at how much movement that combo can absorb.

This stuff was the best. You could thinset it in and the middle was a rubber waterproofing. Mapei discontinued in the States.


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## illbuildit.dd (Jan 7, 2015)

angus242 said:


> You should reconsider. When you get moisture behind the grout (doesn't necessarily come directly from the corners) it will have a harder time evaporating out and can get trapped behind the caulk causing mildew.
> 
> One or the other, not both.


Makes sense. I'm writing a contract for a large shower now. I'll certainly reconsider
But sealing wouldn't do the same?


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## angus242 (Oct 20, 2007)

No, sealers are more advanced. They can handle "breathing" without allowing staining.


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## Philament (Dec 9, 2014)

angus242 said:


> This stuff was the best. You could thinset it in and the middle was a rubber waterproofing. Mapei discontinued in the States.


Interesting because Mapeband is what they sell with the ARC Tuff Form to go with the Mapegum. I was able to get 50' extra from my supplier here for a wet room we're doing, but I'm guess that they must import it with the Mapegum and form. It was spendy for sure. 

I was wondering about the fibafuse with Aqua D, is there any literature on that, or just a combination you came to from experience?


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## Xtrememtnbiker (Jun 9, 2013)

angus242 said:


> I never mentioned properly framed. But if you lock your corners together, you should have less chance for movement.
> 
> I use FibaFuse and AquaDefense in the corners. You'd be amazed at how much movement that combo can absorb.
> 
> This stuff was the best. You could thinset it in and the middle was a rubber waterproofing. Mapei discontinued in the States.



You're right. Rob mentioned that about JB. Sorry.

I'm going to try it at my house when I tile my shower (whenever that actually happens...)

The Urethane in the corner idea.


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## angus242 (Oct 20, 2007)

Philament said:


> Interesting because Mapeband is what they sell with the ARC Tuff Form to go with the Mapegum. I was able to get 50' extra from my supplier here for a wet room we're doing, but I'm guess that they must import it with the Mapegum and form. It was spendy for sure.
> 
> I was wondering about the fibafuse with Aqua D, is there any literature on that, or just a combination you came to from experience?


Mapeband is available from the UK where ARC gets their kits from.

No documentation. It's one of those tiler rules. I read once somewhere that FibaFuse was alkali resistant but it really doesn't matter. I embed the FibaFuse with AquaDefense so thinset never touches it. Just make sure to keep the CBU joints to 1/8".


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## GO Remodeling (Apr 5, 2005)

Back in the day of mastic with oil ingredients, you were suppose to skim the wall (usually green board in new construction) with the mastic and let it dry. It was your waterproofing. Then you set over that with tiles under 12"x12" sizing. That's all you had. It worked pretty good if you followed the directions. But new construction was about speed so many went in improperly.

The speed was of mastic vs thinset was in placing the tile without spacers. You set by eye. But when mastic formulas changed and tiles got bigger and heavier there wasn't any advantage to mastic.

In the corners of a shower, I cut strips of membrane like Durock Tile Membrane installed with thinset. Rapid set thinset if I'm in a hurry to start.


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