Elastomeric or liquid waterproofing membranes are one of the most convenient methods of waterproofing shower walls before installing tile. These membranes consist of products such as Custom Building Products’ Redgard and Laticrete’s Hydrobarrier and Hydroban and Mapei’s Aquadefense. I will refer to all the membranes as Redgard for the purposes of this post, but they all work nearly the same way.
These materials can be installed with a regular paint brush, paint roller, trowel, or even sprayed on. They are applied to your shower walls then tile is installed directly onto it. When I use these products I always use a cement-based backerboard as the wall substrate without a plastic vapor barrier.
It is imperative that you do not install plastic behind your walls since this would create two waterproof membranes with your substrate between them. Having two barriers this close together leaves open the chance of trapping moisture between them with no way for it to evaporate. This may lead to mold.You must also tape the backerboard seams with fiberglass mesh drywall tape.
The easiest way I have found to install Redgard is, after the walls are prepped properly, start with a paint brush and thoroughly coat all the corners and angles. The membranes are more the consistancy of pudding than paint so don’t be afraid to scoop it out to spread it. You should be used to it after a few minutes.
After all the corners are coated I use a paint roller and pan to cover the walls. Redgard is bright pink – I mean pepto-bismol pink, it almost glows in the dark. This is useful in that when it is dry it turns dark red. The other membranes are similar. Laticrete’s Hydroban, for instance, goes on light green and dries forest green.
Just thoroughly coat the entire inside of your shower until the whole thing is bright pink – enough so it can be seen from space. That’s it – go have an adult beverage until it dries. You must then do a whole second coat the same way. Make sure the first coat has fully changed color before applying the second coat. If you are using a roller Custom (the company that makes redgard) recommends that you roll on the first coat horizontally and the second coat vertically to ensure full coverage. (Thanks for that Davis)
Most of the product specifications for these materials state two coats to be sufficient, and it probably is. I normally use three coats. I’m weird like that. Unless you have a steam shower or something similar, two coats would probably be enough. It’s up to you.
These products shrink a bit as they dry so you must make sure that it has not shrunk enough to create holes or voids in places such as corners and seams. You need a full coating for the product to be effective. When you are finished you should let the walls completely dry for a day before tiling.
Your tile can then be installed directly onto your walls over the membrane with a proper thinset mortar. When these products set they will create a rubber-like coating on your walls that is waterproof. When used on shower walls it is a (relatively) quick, effective water barrier for your installation.
These products can also be used as waterproofing on your shower pans in leiu of a regular pan membrane. Make sure your specific product includes specifications for this application if you choose to do that. Check the respective website for your particular product. I do know you can do this with Redgard, Aquadefense, and Hydroban.
I also use these products for main or additional waterproofing on things like shower niches and concrete wall in basements, places where it is difficult to have a plastic vapor membrane behind the backerboards. Basically any place that does not have waterproofing between the tile and shower framing. I always have Redgard with me. The versatility of these products make them a integral part of my shower waterproofing toolbox.
The only drawback for these products, if you choose to look at it that way, would be the price. They are a bit expensive. You may be able to get better prices by ordering online but make sure you take shipping costs into consideration. You can get a gallon of Redgard online for about $45.00 plus shipping. That should be enough to do a regular tub surround. That is a five foot back wall with two 3 foot side walls. For larger showers you can also get a 3.5 gallon bucket.
Make sure to check the website for your product, they have a load of information for them. As always, if you have any questions feel free to leave a comment for me.
Need More Information?
I now have manuals describing the complete process for you from bare wall studs all the way up to a completely waterproof shower substrate for your tile. If you are tiling your floor and walls and using a liquid membrane you can find that one here: Liquid Topical Waterproofing Membranes for Floors and Walls.
If you are just tiling around your tub or pre-formed shower base you can find that manual here: Liquid Topical Waterproofing Membranes for Shower Walls.
Please advise, my contractor has installed greenboard for my tub/shower in my ground floor condo (concrete under), i was a little curious, did some research and found cement board is the correct product to use now. the greenboard goes from ceiling to tub lip. since all the mudding and sanding has been done, prepped ready for tile. i was wondering is it ok to put some laticrete hydroban on before i tile to make it waterproof or should i rip down the greenboard and re-install cementboard instead.
Hi Atu,
You should have cement board there with either a vapor barrier behind it or a membrane over it. It still needs to be waterproofed. While hydroban will waterproof it, greenboard is not an approved substrate for it. If you want to leave the greenboard your only viable choice over it is kerdi.
We’re doing a full master bath remodel and the shower is our last bit. We’ve installed durock and my husband (because I read it here) used silicone on all of the changes of plane. My question is that he did it on our new shower niche corners (I noticed that you didn’t mention doing it to the niche when someone else asked a question that kind of addressed it). Did we screw up! Should we pick out the silicone from the corners of the niche? From how it looks to me, the tape (and thinset) wouldn’t stick here at all. Are we screwed?
Hi Shannon,
Nope, you’re fine. You can do it either way in a niche.
Thanks for your response, I picked most of it out anyway because he had done a few of the seams and done it too thick so nothing would stick. Anyway, I have another question. My husband wormed into doing the tape and “mud” but on one of the sides of the shower where the durock meets the drywall, he taped and “mudded” on the edge of the durock, but didn’t join the drywall with the mesh. Basically, there’s still a gap between the two. I explained that you’re supposed to tape and mud it like you would with regular tape and mud (but with the thin set/mesh tape) but he’s going on about how he has a plan and how the tile will make it level, etc. I think he’s smoking crack and it will look terrible. Should I do it like i think it should be done while he’s at work today (he’s gone until the morning)? Here’s how it looks now:
My link didn’t work let me try this:
http://s91.photobucket.com/user/mrowmrow/media/Public%20Pictures/5488A29A-7B3B-43D2-99D9-CC5F33ADE2C0_zpsttun8onv.jpg.html
The problem with that is the cement board and drywall will move differently. If the tile is spanning that gap it may end up cracking grout and/or tile. The tape needs to span both of them and be mudded.
That’s what I’ve been trying to tell him. He’s high.
Thanks for your help.
I have laid a preslope, and I have 2×6’s between the joists, and a curb made out of treated lumber.
Now, I need to redgard. Do I need to cover the 2×6’s and 2×4’s at the base of the wall with thinset, and then apply redgard, or do I apply redgard directly to the wood.
Or
Optionally, do I just extend the wallboard down in front of the 2×6’s and 2×4 base, and then redgard that, and put wallboard over the curb, and then redgard that?
Part of the confusion I’m having comes from a TDS-104 “RedGard Crack Prevention and Waterproofing Membrane” document from Custom Builders. It shows a picture where the RedGard is behind the wonderboard, so I am thinking that the RedGard shower pan is supposed to extend up and behind the wallboard, as well as be applied to the exposed side?
Thanks
Hi Bill,
There are two methods to use redgard. One is in place of a normal liner and the other is as a topical membrane. The first, in my opinion, defeats the purpose of using a topical liner, as it no longer would be one. Install your backer down to the mud and over the curb, then redgard everything.
This is where this should be!
That is exactly what I have decided to do.
Normally, when you would make your slope you would put a liner on that, and then mud over the liner. If I wonderboard everything (except the slope) and then redgard it all, do I still need to add a second layer of mud over the redgard, and then tile on that? Does that provide some sort of protection for the redgard base? Or can I just tile on top of the redgard? I was still thinking I need this extra mud.
No, you don’t need an additional layer of mud. Tile is bonded directly to the redgard.
Hello,
I am remodeling one of our showers and have a question.
A worker at a local hardware store told me that if I clean and dry the existing 4×4 white tiles that I could apply Redgard right over the top. Then once that drys that I can apply the thinset to the redgard and start with the new tile.
Does anyone see a problem with this?
Thanks
Bill
Hi Bill,
Custom (the manufacturer of redgard) may have a problem with it. I honestly don’t know. Give them a call and they can tell you whether this is a viable installation method or not.
That is exactly what I have decided to do.
Normally, when you would make your slope you would put a liner on that, and then mud over the liner. If I wonderboard everything (except the slope) and then redgard it all, do I still need to add a second layer of mud over the redgard, and then tile on that? Does that provide some sort of protection for the redgard base? Or can I just tile on top of the redgard? I was still thinking I need this extra mud.
Thank you for the answer, that eases my mind considerably. I also did find a video that showed a similar procedure. Youtube is both my friend, and my enemy.
oops, wrong spot.
No, you don’t need an additional layer of mud. Tile is bonded directly to the redgard.
Good Afternoon Roger,
Remodeling an upstairs bath with two exterior wall on the shower/ jetted tub, I’ve used Durock as my surround 3’/5’6″/3′ by ~7′ tall and I’m about ready to apply the Redguard. (Would like to get started tomorrow morning but I’m thinking I’ll wait till I hear back from you.) After reading several of the posts here, I figured you’d be the one to ask about this one; I’m going to thinset/mortar and tape my seams and then apply the Redguard but I remember somewhere reading that you either needed to mud your surrounding drywall seams and prime them first or apply the Redguard and then finish your drywall. I can’t remember and can’t find the website again. Suggestions? Basically going along a flat wall transitioning from Durock to gypsum and there will be a little overlap of the shower tile onto the drywall, just a 3″x12″ bullnose.
Thank you in advance!
V/r
LT
Hey LT,
Tape and mud all your seams first, including the drywall to durock transition, then redgard to within about an inch of where you’ll end the tile. You can then finish that transition before or after you tile, your choice.
Sorry, I don’t have a salute smiley.
I’ll have to add one.
hi Roger,
I want to use redguard for my walkin shower. And also want to use glue instead of thinset to attach my tile. Does redguard obsorb glue?
thanks
KP
Hi KP,
If by ‘glue’ you mean mastic then no, it doesn’t absorb it, but you can’t use it. It will never cure between tile and redgard. If you use redgard you need to use thinset.
Good Morning Roger. I am Redoing the complete bath room and I have shower is good to Install Redgard on shower floor and install tiles on top of Redgard
Hi Luis,
If you’re asking me if it’s all right to do that yes, it is, provided you have a topical drain in your shower floor.
Hi Roger,
I have chosen to use Redgard as a vapor barrier in my basement shower and intend to seal the entire shower (ceiling included). Will Redgard on the ceiling compromise the ability of the thinset to support heavy 20″ porcelain ceiling tiles? Should I forget about vapor barrier on the ceiling to ensure that the thinset is bonding directly to the cement board?
Nathan
Hi Nathan,
Redgard is a waterproofing, not a vapor barrier. But I knew what you meant.
Redgard on the ceiling is just fine. Make sure you do one coat with a watered down primer coat of redgard, then do the regular coats.
I hired a “contractor” to fix walk-in shower floor. Had 3 men working at same time, could not keep track of who was doing what. They brought in a piece of board, asked what it was. Told backerboard . Never saw it used in shower repair. They took out first 2 rows of wall tile in order to fix floor. Saw the can of Redgard & this put on floor. 2 years now the floor has puddles & does not drain, Original man can’t be found. Hired another. Yesterday he took up the 2 inch floor tiles & 2 rows on wall. When he got to corners & tried to remove tiles he went right down to dirt & some slab that condo is built on. He is going to use some gray/black rubber for waterproofing vs. Redgard. Have spent so much money so far & am so confused, please help.
Hi Patricia,
The first ‘contractor, used a topical waterproofing liquid – redgard – but apparently used it incorrectly, and didn’t construct the shower floor properly. The one you have now apparently plans on using the traditional waterproofing method – pvc liner – which is just fine provided the floor is constructed properly. It’s just two different waterproofing methods, either of which work just fine when properly installed. The first obviously was not.
what is the best way to mix cement for a shower floor. do they make a product for just for floors or do you have to mix them yourself.
thanks j. foley
Cement for a shower floor is called deck mud, or floor mud. There are pre-mixed products or you can mix your own.
I’m in the process of applying a deck mud slope on my wood sub-floor, for my shower pan. I read somewhere that I should apply some waterproofing to the sub-floor first so it doesn’t absorb the moisture in the deck mud. Does this sound right and what should I use (redgard, plastic, …)?
Hey Dave,
You need to have a slip sheet in there (it does the same thing), but you don’t want to completely waterproof it. Plastic or roofing felt is what you want.
1. Purple sheet rock/purple board is one kind of faced topical membrane you mentioned in your article. Is a good idea to use purple board for shower room wall and bath tub wall?
2. How to you prevent water leaking from the joint between wall and bathtub that does not have lip around the bathtub? I had water leaking from the joint and damaged floor next the bathroom. The water was going through the caulk in the joint and was not traveling back to the tub but traveling along the frame to hardwood floor next room because there is no lip around the bathtub. Per my potential contractor, there is no permanent fix and I need to re-caulk every 2 years. Is that correct?
Hi Emily,
1. Purple board / sheet rock IS NOT a faced topical membrane. It is no longer approved for use anywhere in a shower or tub.
2. Your waterproof membrane is folded at the bottom of the wall and the back of it is siliconed to the tub arm. If it is covered, which it will be, silicone does not need to be replaced every two years in general. There is no abrasion taking place and it is sealed so it doesn’t lose elasticity.
I’ve probably have made a huge mistake, but here goes. I removed a tub and installed a shower in its place. The shower pan was hot mopped including 12 inches up the wall. I then screwed backerboard over the wall frame down to the pan of the hot mop and then placed tiles directly onto the backerboard via thin set. I laid down a sufficient amount of cement in the pan over the hot mop and applied backerboard over the hotmop on the dam using screws penatrating the hot mop. However I did paint several coats of Redgard over the screwed backerboard on the dam. Do I have a mess? Will the walls end up with mold since there is no coating of anything on the walls except the backerboard and tile?
John
Hi John,
Yes, you have a mess. You’ve penetrated your waterproofing, you seem to have straight concrete rather than deck mud in your shower floor (is there a pre-slope beneath the hot-mop? I’m guessing not), redgard or not you CAN NOT penetrate the waterproofing over the curb. Water can wick up the backer behind the redgard and get into your curb materials behind the waterproofing. And you have no type of waterproofing at all on your shower walls.
I can not guarantee that you’ll have mold, I never can. What I can guarantee is that, built correctly you will not have mold. You have everything in place to create a perfect environment for growing mold. It really should be taken out and have a properly built shower put in it’s place.
And yes, I know that’s not what you wanted to hear.
Quick question regarding the preslope…I have down loaded the manual of installing a shower. I followed the directions you gave for mixing the mud deck up….half of the 60 lb sand topping mix and 1/4 bag of sand in each 5 gallon bucket…let it cure overnight…..next day it was set up hard almost like concrete….it’s not sandy on top….should I worry about this? It is solid as hell….
Hi Chris,
Nope, it’s just fine. It means you actually pounded the hell out of it as you should – well done. I just emphasize that because most people don’t, but that doesn’t create problems either.
I saw on tv where they painted a “blue” substance on the existing tile in a shower, then applied mortar and tile/grout directly over the old tile. Is this “blue” stuff a product of yours? Do you know what I’m talking about. Pls email back with your thoughts. Thank you.
Hi Sandy,
I don’t have any products – I’m a tile contractor. The blue stuff was likely hydrobarrier by laticrete. It is a liquid surface applied membrane similar to redgard (red) and hydroban (green).
I found some stuff at Lowes called Mapelastic Aquadefense. It was green. It sounds just like the stuff you are thinking about. You paint it on and then it dries making a waterproof barrier. Pretty easy to use.
Hi Pat,
Yes, it works extremely well also. There are currently about a dozen elastomeric membranes on the market – all work the same with slight variations in installation.
Hi Roger,
Thanks for the tips. I did have a question, however. I had not heard of Red Gard, so was going to go the plastic-behind-hardibacker-route. I did put up plastic, but only about 1/2 way up my wall (on the advice of another tile setter whom I don’t think I will listen to again). Anyway, you suggest never using a plastic/backer/Red Gard setup because it would lead to mold. But would my partial plastic be ok since there would be room for vapor to escape out the top? Or should I take off the backer and remove the plastic?
Thanks for your advice!
-pat-
Hi Patrick,
It should be fine only halfway up the wall.
Hello Elf,
One wall in my tub surround is cinder block. Can I use RedGard under a fleece membrane, and then apply tile directly to that?
Thanks,
Kellie
Hi Lauren,
You can, but there’s really no reason to. You can tile directly to the redgard unless you get moisture on the cinder blocks from water migration through the wall. If that’s the case you have negative hydrostatic pressure and redgard can not be used over them.
Hi Roger,
I have a shower shower pan which was installed incorrectly so it needs to be taken out and redone. The problem is that the shower walls are tiled and waterproofed. Is it possible to cut out the tile and durock for only one or two levels of tile up from the floor and replace it along with the new pan or does the entire tile wall need to be removed and start from scratch? If it’s possible what is the process to re-waterproof the portion of the wall that is being replaced to ensure that the patch is properly waterproofed? Just tape the seam and re-waterproof the seam and new portion?
Hey Brian,
I’ve replaced a couple of those. I had to remove the bottom two feet (two rows) of tile to remove and replace it. Waterproofing depends on the method of waterproofing that is behind the current tile. I don’t know what that is.
It is a liquid waterproofing membrane like your article above about Redguard but its a different product. Just looking for info so I know if the contractor is trying to pull one over on me when I talk to him about it. I appreciate any more detail you might be able to provide.
After the new base goes in the new backerboard should be placed with a bead of silicone between the new and existing backer. The waterproofing is then just painted on the new stuff overlapping the old waterproofing. If possible cut out backerboard 4″-6″ below the existing tile. For instance, if you pull out 24″ of tile only cut out backerboard 18-20 inches high. That way you have a portion of the existing backer showing, makes it easier to tie the waterproofing together.
Roger,
I am doing my first shower installation in my basement. The walls are up, but I only used greenboard. Can I simply apply 1/4″ hardibacker over it and then liquid membrane such as Redguard? Or should I pull the greenboard out and use 1/2″ hardibacker? Thanks for advice to a rookie!
Hi Kay,
You shouldn’t, you should remove it and use 1/2″. That said, I know people don’t always do what they should do, so it will work provided you get good coverage with your redgard.
Can you use redgard as an outer covering?
See, the lady we are living with is on a fixed income and there some major issues with our shower in the basement.
The shower has no drain pan or water barrier, it is just tiled on the concrete right up to the floor drain with melamine on the walls. I have tried to contain it with some new caulk, but the melamine is warped, from age and damage.
So I am trying to do this as cheap as possible. I am hoping she will sell us the home, and then I would do it correctly, but right now I need a cheap job that can just contain the problem.
Can i just coat the floor tiles, and corners, and make a waterproof floor pan with the redgard?
Hi Cody,
Redgard can not be used as a wear layer, it must be covered with something (tile). Perhaps you can go to a tile store – they usually have several boxes of older tile in the back which they’ll NEVER use or sell, they’ll usually let it go very cheaply. Call around, it’s easy to find cheap tile.
I’ve installed a new fiberglass tub and wall surround. I plan on tiling the 20″ or so above the surround and plan on bringing the tile outside of the tub/surround about 6″. I’ve installed HardiBacker above the surround and outside the tub/surround where I then transition to drywall. Would it be necessary to Redgard the HardiBacker since it’s theorectically above and outside the wet area of the shower? Or would treating the seams with mesh tape and thin-set be sufficient before installing the tile?
Hi Alan
With the surround taping and mudding the seams should be sufficient.
Hi Roger,
I purchased your e-book regarding liquid waterproofing membranes and I can’t find an answer to this question: Which side of the Durock sheet do I put on the outside (the side which will be coated with Redgard), the smooth or the rough.
Thank you for your book, it’s very helpful.
John
Hi John,
Either one works. I prefer the smooth side for liquid waterproofers.
I’m curious if using Redgard or something similar is OK to use and will have the longevity of moisture protection in any/all types of shower wall applications?
I’ve noticed just about every builder in Arizona has their tile installers just slap this Redgard stuff on all the shower drywall walls prior to tiling directly over the Redgard painted drywall.
Being born & raised in the Northeast I’m still a little leery of Arizona’s termites holding hands construction & the lack of common sense amongst millions out here.
Hey Mike,
Drywall is not an approved (nor intelligent) substrate for redgard. It needs to be backerboard. Provided it is properly built it will last just as long as nearly any other waterproofing method.
Thanks Roger,
I kinda thought so.
The furthest I’ve ever gone from the old fashioned way of mud set was by using HardiBacker, although the Arizona Registrar of Contractors has been letting all the prehistoric contractors out here get away with splashing RedGard on just about anything possible for many years out here. Pretty much all the workmanship on this Western side of the country would’ve gotten any contractor a nice bullet in the head as payment in New York back in the 80’s & 90’s.
Just a note:
If you watch the regard company video on applying the membrane
over cement boards – such as Hardie Backer, they clearly demonstrate
that you should not apply too little – or too much.
they actually stick a little metal ruler gauge into the surface.
If I recall correctly, 3 mils is desired…
I’ve seen several DIY Videos applying these products abundantly…
I always call the manufacturer when using new products…, their
tech,. staff are usually friendly and very knowledgeable.
It’s called a wet film gauge.
I have a block window over my tub which I want to replace with a glass shower. One contractor who seems to know what he’s doing said he would install Hardie board and then put a coat of Redguard and it would be waterproof. He will also tile the window frame.
Another contractor told me this couldn’t be done and I would eventually have moisture problems.
I’m hoping you say the first man is right as I want to hire him. Thanks.
Hi Rachela,
The first guy is right. Hire him. I have no idea what the second guy is talking about – maybe he tried it and didn’t do it correctly.
It works just fine.
I love your site, has helped a lot as I tackle a bathroom remodel. I am tiling a tub/shower surround, and am planning to use redgard on top of hardie backer or durock. My question is about what I should put behind (if anything) the cement board. I need to put insulation in the wall because it is an exterior wall, but should I use insulation with a vapor barrier on it? If so should it face the shower wall or the exterior wall. The exterior wall has plywood – felt – siding. Also, the inspector told me he will be looking for paper behind the cement board, but I have read in many different places not to put multiple water vapor barriers because it can cause problems. Advise would be appreciated.
Hey Kevin,
Unless you’re in Canada, where it is REQUIRED to have a vapor barrier, you do not need any type of barrier there. If you get the faced batts for insulation and put them in (with the paper on the shower side) it will both be fine with the redgard and with the inspector.