# How to waterproof stucco in bathroom/shower?



## Tscarborough (Mar 31, 2006)

I hate to tell you this, but nothing is going to work well in that application.

However, the solution is simple, but too late. On your finish coat, you should have used marble dust as an aggregate, and it would be inherently waterproof.


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## c2g (Apr 10, 2009)

When you say nothing will work well, what do you mean? I actually did this in two bathrooms and I'd hate to think I have to do them both over again.


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## Tscarborough (Mar 31, 2006)

There are no non-surface sealers that I know of that are approved for immersion use, and even most surface sealers will not warrant their product in that application.


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## Tscarborough (Mar 31, 2006)

Also, note that that doesn't mean it won't work, just that if it fails you are on your own.


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## c2g (Apr 10, 2009)

I just spoke to a distributor who says Aquron SPT-1200 would work and that if I have someone certified to do their applications, it would be covered with a 15-yr warranty. I'm probably going to go ahead and try it. It's around $350/5 gal, but anything that might work is fine by me at this point.


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## Tscarborough (Mar 31, 2006)

Excellent! This one looks like a better choice, though:

http://www.aquron.com/our-products/concrete-protection-and-waterproofing/cpsp/


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## ccarlisle (Jul 2, 2008)

A shower is a system, not just a collection of made-for-it elements...stucco on shower walls? sure why not? Even though it's a porous cementitious compound similar to mortar and can be trowelled onto cbu or any other cement base... Trouble is that it's a rough surface and very hard to clean, as you would see when you applied it. 

But, since you built a shower system all by yourself, and apart from being porous and hard to clean, the waterproofing membrane behind it will stop the water and allow the whole shower system to breathe and dry out, so you're good to go!:laughing:

Uh...you _did_ put a membrane there didn't you? oh-no, maybe not...:no:

Well then, you're sorta stuck. Personally, I think you have a mess on your hands. 

Ya know, I don't _assume _anything much in my life anymore because when I do, I mistakenly figure I have all the bases covered and have all the answers. Seems like the more I know, the more I know I haven't got the answers...Having said that, I _do_ assume I have enough food in the fridge to eat a good meal tonight - but thats as much of making an a** of myself as I want to go...

If I'm wrong I'll get hungry; but when I work for others or work on my own house, I certainly *don't assume anything* as I just don't know all the answers - and people pay me to know them. So I research a lot first before I do anything - to put chance on my side.:yes:

Now, and correct me if I'm wrong, first you built a shower assuming that stucco could be waterproofed afterwards. Then you went out looking for an answer and a product.:whistling2:

I don't know of any product (except RedGuard) that trowels onto another surface to make a shower waterproof, even as a first line of defence against water infiltration. No paints, no coatings, nothing. And especially not a cementitious product. I mean, I love thinset - but only for certain things.

On the bright side stucco is cheap and so you can afford to replace the shower in a few months as it starts falling off the wall. So just put up another one...done right this time.

Oh...and since you would _hate_ to have to think about doing it over, you'll probably _hate_ me for saying this: Be warned: you're going to _hate_ your shower soon - and I'd really _hate_ for you to _hate_ me wouldn't I?

Yeah right...

:jester:


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## Tscarborough (Mar 31, 2006)

You raise good points, ccarlise, but you can use stucco in showers, and it can be easy to clean and 100% waterproof, requiring no more than normal underlayment. You have to use the proper stucco and techniques, though.


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## ccarlisle (Jul 2, 2008)

Yes, I know you can...:yes:


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## Lasqueti (May 8, 2009)

*Easy steps to build a stucco shower??*

Hi there - I read through the threads and was hoping someone could outline in 5 or so broad steps how to stucco a shower. I understand that we should use marble dust for the final layer - but any information before that would be much appreciated.

Lasqueti


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## Donn2390 (May 7, 2009)

Lasqueti said:


> Hi there - I read through the threads and was hoping someone could outline in 5 or so broad steps how to stucco a shower. I understand that we should use marble dust for the final layer - but any information before that would be much appreciated.
> 
> Lasqueti


 The thought of brushing up against a stuccoed shower wall with my cute nude little body gives me the shivers...!


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## Lasqueti (May 8, 2009)

*Strange*

Really, I personally think of it as exfoliation treatment while getting my hair clean at the same time.


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## yesitsconcrete (May 11, 2008)

we've used our polymer-modified mtls on shower walls & sealed it w/epoxy,,, they are proprietary mtls,,, 1's been in place for 7yrs w/no troubles.


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## 220/221 (Oct 9, 2007)

I have done it in two of my homes. Simply use "synthetic stucco". 

It looks like stucco but acts like paint. It's made for exterior application and works perfectly in my shower/tub surround. Used every day for 5 years and no issues.

I hung Durock on the walls and used a pretty liberal coat over it.


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## yesitsconcrete (May 11, 2008)

you could use thoroseal or drylock, too, but i wouldn't in mine :no:


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## c2g (Apr 10, 2009)

I ended up using Aquron SPT-1200 to waterproof the stucco. I just used a $12 plant sprayer and one coat ($350/5 gal) and the water beads off fine. The surface is still kind of flaky though. It looks great, but I will probably end up tiling it at some point.


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## Rachael (Nov 5, 2009)

I am thinking of doing the same thing. Where did you buy the product Aquron? Do you have any pictures you could post? Why would you tile over it!


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## ccarlisle (Jul 2, 2008)

What "same thing"? making a shower in stucco or using a sealant on top of what you have?

Up here, we see some stucco on the exteriors of residential and commercial properties but the main knock against 'stucco' - or EIFS - is that, in our climate it is really hard to protect the plaster from the elements of rain and snow, and low temperatures. First, we need insulation and air and vapour barriers on the inside and then stucco requires protection on the outside - in effect making a perfect moisture sandwich - where degradation of the wood or mould growth is accelerated due to the inability of that area to dry. Now down south, you have a different set of problems that make EIFS (known as "synthetic stucco") a better choice because of the problems you _don't_ have...but these stuccos are part of an exterior system - not interior.

The same problems we have up here will be experienced on an indoor shower. First you must prevent water and water vapour from the shower from getting to the structure - so most showers have a waterproof membrane in there somewhere. Then the idea of stucco is to put up a plaster-like application of 2-3 coats of a product which you then must seal to prevent moisture from ruining it from the shower side. Ideal moisture sandwich...the moisture that invariably gets behind the roller-applied "sealants" can't escape - and therefore degrades the structure of the wall. Ticking time-bomb IMO...


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## c2g (Apr 10, 2009)

Rachael said:


> I am thinking of doing the same thing. Where did you buy the product Aquron? Do you have any pictures you could post? Why would you tile over it!


I bought the Aquron from a local landscaping-type place. It was about $350 for 5 gal, and I used about half of it over two stucco bathrooms (one coat - pump spray application, as recommended). I'll take some pics and expand on how it's going over the next day or two.


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## Rachael (Nov 5, 2009)

*moisture sandwich*

Thank you for responding. I look forward to the pictures.

To CCarlisyle.....Okay, I see what you mean about the moisture sandwich. But I see a lot of slate showers which I assume have to be sealed also. How do they prevent a moisture sandwich? And tile is glazed which is a seal, right? Maybe I shouldn't use a moisture barrier at all and just plan on resealing the stucco every year?

Thank you for taking your time to reply.


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## ccarlisle (Jul 2, 2008)

"Sealing" of most showers consists mainly of sealing the tile grout to delay dirt and stains from appearing and to some extent to slow down the penetration of smaller water molecules through it. Now many, many showers are made with ceramic or porcelain tiles (these tiles do not need sealing) and many showers nowadays are tiled with natural stone. Most natural stones you'd want in a shower (travertine, some marble, soapstone, some limestone, one or two slates etc) could use a sealer, again to prevent stains. Some natural stone tiles_ do not need_ sealing at all.

Now most slates are inappropriate for shower environments just because of the way they were made, their chemical composition and the reaction of slate to lots of water. Sealed or not, they are just a sad choice for a shower...they might last 5 years - which is a short time for a shower.

As I said, some tiles don't need sealing: for example all glazed tiles are impervious to water - that's why they are used in showers....ceramic and porcelain don't need sealing. they are already waterproof because of the glazing process the ceramics undergo.

No matter how well you seal, all it takes is a pinhole for water and water vapour to get in and cause mould. And it's not a question of "Sealer A" versus "Sealer B" - no matter what you call it, there are only a finite amount of chemical sealers that will do the job on one or two substrates - not all.

But your idea of sealing just from the outside is closer to what you need that anything else; this is because I trust where you are is humid and therefore the air on the inside of your home is air-conditioned most of the time, right? If so, humid air is trying to get INTO your home from the outside and you are best off to prevent that as much as you can with exterior air barriers. If you do so, then the dehumidification of the air via your AC should reduce the humidity the shower creates. You'll get less of a moisture sandwich if your walls are dry right to the outside air barrier. 

So look into a good ceiling fan to get rid of the humidity to the outside, make sure your AC is OK and seal the stucco well from the inside...I didn't ask what it is about stucco that you like? texture? why not just put up drywall and put a texture onto _that_? a lot cheaper and replaceable + same effect


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## c2g (Apr 10, 2009)

OK, it's been a year now with the two stucco bathrooms. Looking back, I really do like the look, but I'm going to tile over the tub/shower area and leave the rest. It really is a pain to clean and now we have a baby on the way, and the wife doesn't want them getting scratched up by the stucco in a few years. 

I already picked up the travertine tiles. Never tiled over stucco before so I'm wondering if there's anything different I have to do? I'm guessing give the walls a really good scrub with bleach a few days before I tile and let everything really dry out. The rep at the tile store called his contractor and said we should be fine.

I included a couple of pics from a year ago when we just finished the stucco.


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## nap (Dec 4, 2007)

If you are going to tile over the stucco, that stucco had better be really secure to the backer. If not, it is going to come off and the tile with it.

another problem is going to be the lack of flatness of the walls and such due to the troweled stucco. 



I had considered doing something like you did with the stucco only would never have considered stucco. I was considering Tadelakt plaster. I understand there are some synthetic products out there that might be even better.

did you employ a water proof membrane behind the lathe walls and the shower base?


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## c2g (Apr 10, 2009)

nap said:


> If you are going to tile over the stucco, that stucco had better be really secure to the backer. If not, it is going to come off and the tile with it.


Membrane, wire mesh, scratch coat, top coat with waterproof additive, sealer. Aside from some minor dust if you rub it good, I think it's on there pretty good. I forget the brand, but I got the good thinset (TEC, I think) from the tile store, not the home depot stuff. 



nap said:


> another problem is going to be the lack of flatness of the walls and such due to the troweled stucco.


I went with a small 1" mosaic tile. Should be fine for the wall bends. Hoping I can pull off the recessed soap/shampoo holder areas. Never grouted mosaic before, but I hear it sucks. 



nap said:


> did you employ a water proof membrane behind the lathe walls and the shower base?


I did apply a membrane all around the bath/shower areas. It also has that Aquron SPT-1200 layer of sealant.


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## michaelmarrin (Oct 27, 2010)

*How much Marble Dust ?*

We are getting ready to stucco 2 walls inside a walk in shower and around a soaking tub -- I would like to know -- how much marble dust should be added to the the stucco mix. I am going to use Expo Stucco Shower Coat stucco, -- and I purchased marble dust at NPT National pool tile supply. Any advice befor we start would be apreceated


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