# what waterproofing substance on cement board in bathroom(can't find Red Guard)



## Limit54 (Nov 6, 2009)

I live in Canada and I've been to Lowes, HD, and Rona and can't seem to find this Red Guard stuff anywhere....so what the hell can I use to put on my cement board in the shower to waterproof it....but I'll be tiling the walls so I need them to stick..I can't use some crap that isn't going to stick to the cement board good.

What can I use?

Thompson water seal? or that stuff called Ugly(don't remember the name)


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## BJLower (Aug 2, 2008)

I've always just used regular thinset and never had a problem. What you need to do though is wet the cment board down before applying the thinset and tile. If you don't it will draw the moisture out of the thinset before it has time to set properly. If you've heard of people having problems getting thier tile to adhere properly I'm sure that they tried to use the thinset on dry cement board. 

If you haven't put the cement board up yet it's a good idea to put a vapor barrior behind it, but it's not necasary.


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## Termite (Apr 13, 2008)

No offense intended BJlower, but the issue isn't adhesion, it is waterproofing. A properly constructed shower wall must be waterproofed to prevent moisture from permeating the backerboard and entering the wall space. Plastic behind the backerboard is not a great option, although it is better than nothing at all. No matter how well you seal your grout, I guarantee that water will permeate that tile/grout. 

Thinset is of course the only option for adhering wall tiles in wet areas. Preferably not the pre-mixed stuff. Dry mix thinset (in bags) is much, much better. Thinset itself is very permeable and it will not prevent moisture intrusion into the backerboard.

Reference the TCNA (tile council of north America) installation standards for showers.

Limit54, also, be sure you're using mesh tape and thinset on all your backerboard seams.

I've found that the box stores almost always carry RedGuard but nobody at the box stores has ever heard of it and it is commonly not in the tile department...Oddly enough. You can most definitely find it or a comparable product at a tile supply store in your area. 

Thompson's water seal is a joke for its intended application and it certainly will not do the job for this application. DryLok is not a good idea for waterproofing under tile...It is essentially a paint and it won't work. 

Another option is Kerdi, made by Schluter. It is really the very best way to waterproof a shower. It is a bit more expensive though. It is a cloth-like membrane that is applied to the backerboard with thinset almost like wallpaper. Incredible stuff! Youtube has some good videos of it.


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## Blondesense (Sep 23, 2008)

If you are looking online, or if the people at the store are typing it into a computer, be careful of the spelling. Try RedGard, (or Redgard) - one word, no "U".


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## ccarlisle (Jul 2, 2008)

Mapei has a blue waterproofing product that is sold in big box stores up here. Think it's called "Mapeilastic"....we did a shower with that and was fine.


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## Limit54 (Nov 6, 2009)

ok I'll try looking for that stuff. Funny thing is that my shower is probably about 55 years old...the walls are made of drywall and on top of that is lattice and cement(in the shower section). The other surrounding walls are made up of drywall plus sheetrock on top. Its pretty heavy duty. The whole bathroom was tiled only half way up the wall including the shower. I ripped out all the tile in the shower and broke into some of the lattice as i had to do some new plumbing. Most of the cement is still up though...its damn hard to get off and I didn't see any need to do it anyway. So I put cement board up over it....now this is the section I'll be waterproofing...what do you think? is it mandatory? the shower has been ok for 5o years now...but I guess I've opened it up now. I'm also going to waterproof the perimeter of the floor next to the tub.

Any thoughts on this and my shower?

Edit; I did some research on mapelastic and it seems that it will work well, thanks ccarlile. Now I just have to find it.

Thanks again for the help.


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## ccarlisle (Jul 2, 2008)

_My_ shower is still original and built in 1960! No leaks in cement plaster over wire lath. But if you've already taken part of it down and are about to put up a new surface, the cement board only acts as a tile substrate, it doesn't contribute anything towards waterproofing. We strive nowadays to make showers last as long as yours and mine did, and waterproofing the walls with modern materials is the only way we know how.

No, waterproofing is neither code nor mandatory - but the effective lifetime of a non-waterproofed shower is a number of the fingers you have on both hands i.e < 10 yrs. Waterproofed it's more like 30 or 40yrs if done properly. Depends how much you like spending the scratch to redo a leaky shower. 

Having said that, with new construction and the control of humidity, and in our dry winters there is less of a tendency to have mouldy showers unless something else is way wrong. But for my money and time, a coat of Mapelastic, or RedGard or a Kerdi membrane is a good investment, just in case. It's a selling point too. 

We have a big Mapei plant just north of the city, so their products are on our Home Depot shelves. But each market has it's own particularites. If you don't find it at a big box store, then look for a tiling supply company where they sell all the trowels and mortars tilers use. They'll have something there.


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## Limit54 (Nov 6, 2009)

ok makes sense to me. Just a point of interest is why don't people just use the same materials as our old showers now a days?? to expensive and to time consuming?

I'm going in about an hour to go find some mapelastic. I'm pretty sure i've seen mapei products at one of the box stores around here.

Thanks a lot. I;ll let you know how it turns out.


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## ccarlisle (Jul 2, 2008)

Well because of manpower costs. We've been asked by an insurance company to replaster a ceiling of a 1920s era house. Now the choices were the old style,3-coat-plaster-and-lath - or put in new gyproc over the damage but to keep with the rest of the house, the old method was chosen. Now to do that we had to find a certified plasterer and one old enough tobe able to do a plaster-and-lath job well enough to satify the HO. They're booked two weeks out...

According to the 'bible' we use in damage restoration, we charged something like $8.50 per square foot to replace that ceiling, for a total of something around $1200, over three days. 

Compare that to putting up new drywall, around 5 sheets by two guys, taped and primed for $225...and done in an hour.


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## Limit54 (Nov 6, 2009)

i guess I should get into the oldshool plastering business. Anybody know anybody in Toronto that I could get a job with?


anyway, I've been everywhere today looking for maplastic and can't get the stuff anywhere. The only thing I could come close to finding is this stuff called "Blue Seal" waterproofing rubber membrane. I don't know if it will be good to tile over??

I went to a tile store for contractors or whatever and they had all mapei products but not maplastic. I don't think anyone uses this stuff here?? Anyway he said he is going to talk to his sales rep today and see if he can bring me in some.

I'll see how much he tries to rip me off on the price.



Thanks, I'll let you know what happens next. I'm going to be days behind now...oh well.

Thanks,
Steve


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## ccarlisle (Jul 2, 2008)

A big tile supplier here has a place in the GTA area: Ciot...they carry it. Mapei have 3 different distributors, one for tiles one for concrete etc and although they represent Mapei, they don't all have the same product lines. Go to their website, punch in your postal code and they'll tell you where to go.


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## Quickdraw (Nov 18, 2008)

Limit54 said:


> i guess I should get into the oldshool plastering business. Anybody know anybody in Toronto that I could get a job with?
> 
> 
> anyway, I've been everywhere today looking for maplastic and can't get the stuff anywhere. The only thing I could come close to finding is this stuff called "Blue Seal" waterproofing rubber membrane. I don't know if it will be good to tile over??
> ...


FYI: Laticrete also makes a great waterproofing product called *HydroBan*. Laticrete also makes a rubber water proofing product called "*WaterTight*" that is sold at Lowes. The Lowes product is $44US a gallon in the Chicago area. Home Depot has Redgard in the bagged concrete & mortor section of the store for about $48US a gallon.


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## Limit54 (Nov 6, 2009)

@quickdraw

Here in the GTA(Toronto, Canada) Redgard is not available. trust me I've been around. If the tile supplier can't get it for me then I'll head over to Ciot...

Thanks for the info. Help a lot.


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## Limit54 (Nov 6, 2009)

ccarlisle said:


> Compare that to putting up new drywall, around 5 sheets by two guys, taped and primed for $225...and done in an hour.


I have a question about this. How can you possibly tape and prime drywall in an hour? what is your secret? I have to tape and use compound...wait to let it set then do a little bit of sanding...i'm an amature i know but i would like to know how to do it your way and not see any tape lines?

Thanks,
Steve


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## ccarlisle (Jul 2, 2008)

Two guys come in, place the 12' board, both screw it in, then the next, then cut the next and place, approx 100 sq ft in about 25 minutes, then both apply compound, paper and fibre tape. No Finishing. What they call a Level 1 finish. Done in 85 minutes.

Next!

Couldn't believe it myself either...


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## Limit54 (Nov 6, 2009)

ok so its been a pain in the ass to find this waterproofing stuff but I have finally found something that just might do the trick. The stiff is called Blue Seal Waterproofing membrane. I'm gonna use it on the floors and shower walls.

I found a way to get the mapelasic but the guy at the tile store was going to charge me some rediculous price like $130 for a 1 gallon. I hate how these guys treat you when your not a contractor(pisses me off so much). anyway I'll post back after I use the stuff.

Thanks for the help.

Also my boss is a pro tiler and I asked him about what he uses for waterproofing and he said they don't use anything?? He says that he just makes sure he fills the gaps in the cement board with the tile adhesive. He said teh showers last a very long time....20 or 30 years(i'm not sure about that though...but who keeps a shower around for that long anyway right!)I'm just glad that my bathroom was done right adn with indistructable material. Now I want to keep that going for the next guy.


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