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.
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Help Rodger. I’am redoing the tube/shower walls in my bath room. I didn’t do any research before I started the job. Removed the old wall sections that needed to be replaced and put up green board. NOW I’am online checking out how to tile the walls. Well I should have been ONLINE before I started this job!! My question is can I use Redgard over the green board before tiling the walls or do I have to take the green board out and use cement board with plastic sheeting behind it? Thanks Sam
Hey Sam,
Unfortunately that greenboard needs to come out. You can use cement board with either a barrier behind it or redgard over it.
While redgard is waterproof, it is not entirely vapor proof. Water vapor can still get through it in certain situations and once it gets to the greenboard you may begin to have problems.
Roger,
I’m getting ready to tile my shower for the first time. I’ve got a pre-formed plastic shower pan and the walls are all HardiBacker. I have been planning on putting up RedGuard (as the walls are already up, and I don’t have a membrane of the other side – which I hadn’t planned doing until reading your site and coming to the realization that saving 45 bucks on a gallon of Redguard isn’t worth mold/deterioration issues down the road).
My Question(s) is really about the order or operations… I haven’t taped the seams of the Hardi-Backer yet – should I tape then paint, or paint then tape. Also – I have about a 1/8-1/4″ gap between the plastic base and the hardiboard – should I tape that seam as well?
Thank you for your site, I’ve already learned so much and it has given me the confidence to actually give this a try!
Chris
Hey Chris,
Install silicone in the corners and down where the walls meet the tub, then tape and mud your seams (on the same walls – in the same plane). Once all that cures install your redgard.
My tile installer installed the shower pan liner but cut it short in some crucial area’s in the shower, he covered the corner bench but the liner ended at the back edge of the bench and did not run it 6″ up the wall or sides. He does have Red Guard waterproofing on the quote and assures me that the backer board, taping the seams and using the red guard will make the shower water tight? I feel very uncertain of this and feel that it will leak around the top of and sides of the bench water will run under the liner. I have asked him to patch the floor with additional liner but I am worried about water penetration around the bench.
He also only has 1 gallon for 227 sq ft shower walls and 28 sq ft floor plus a tub deck 74″ x 49″ with oval tub if it needs 2 coats is this enough? should we use Latacret hydorban instead of red guard? thank you for you help
Hi Melanie,
Hydroban is a better product than redgard in my opinion – but either work fine. Why is he installing redgard on the floor as well if he already has a liner in it??? DO NOT DO THAT! It creates a double waterproofing layer which can lead to mold. If there is a liner do not use a topical. If he uses the redgard or whatever on the walls and paints it all the way down to the floor the bench will be fine. The amount needed depends on how thick it is applied.
Roger,
Thank you.
Would you recommend 2 or 3 layers of the waterproofing? I will ask the tiler not to coat the pan liner I do not know if he intended to.
Can you patch pan liners successfully so no leakage occurs? or would it better to have the cut short one replaced entirely?
thanks
It depends on how the installer is applying the membrane. The number of layers are not as important as the proper thickness. You can install three 1/32″ layers and still not be as thick as two 1/16″ layers.
You can patch liners successfully but if you are referring to your bench as long as the redgard is installed over it and down to the shower floor you don’t need to worry about patching it there – the redgard waterproofs it.
Hello,
I have a waterproofing question. I am building a custom tile shower. Do I need to put a vapor barrier behind the durock backer board or can I use something to waterproof the front of the backerboard and then place the tile directly to it. I’ve read mixed reviews, some say you should, others say you don’t have to. I’ve looked into the kerdi membranes, red guard, tar paper etc… which one is the best?!? One guy that works at lowes says the ultraflex 2 (polymer modified) is good enough to create the waterproofing I need.
Thanks
Hi Jarrid,
You need waterproofing of some sort in your shower – ultraflex 2 IS NOT IT! (That guy’s a frickin’ idiot…).
There is no one ‘best’ solution for every shower, it comes down to a lot of different factors. If you go here: and download my free manual it will walk you through each, describe how they work, and help you decide which is best for your shower.
Go back to lowes and smack that guy in the head for me, willya?
I want to put a tile surround in the bathtub. I put up 6mil plastic with staples and also cut out for the niche. On top is hardibacker with the seams sealed with thinset mortar and fiberglass tape. The 6mil platic has a few tears and the cuts I made to fit in the niche. Should I put some red guard in the niche? or anywhere else? Do not want to create mold sandwiches, but do need water tight surround. Thank you
Hey Britt,
You need to cut the plastic around the perimeter of the cutout and silicone the face of the barrier to the back of the backer. Then yes, you need to use redgard or some other type of membrane in the niche to waterproof it.
Roger
Just a couple of quick questions
First I am putting a band of mosaic glass tile in the middle of the shower wall and I’m wondering if I should or could use a white thinset (if they make it) for the glass tile instead of the basic gray (gray may show through).
And then do I apply the thinset directly to the Redgard membrane on the shower walls or to the tile (I’m worried about cutting or scarring the membrane with the trowel.
Steve
Hey Steve,
You can – and should – use white thinset. Install it directly onto the redgard on the wall and install tile over it.
Roger,
I will be tiling a bathtub surround that is also a shower area with 3×3 tiles in 12×12 sheets over a tile backerboard, yet to be purchased, coated with redguard (that I already brought) and my question is what is best for sticking the tile to the wall mortar or the premixed paste/adhesive stuff?
Also I will be insulating outside wall using unfaced fiberglass and if I understand correctly I am not to use a vapor barrier behind the tileboard coated with redgard which makes sense, but what about fom the tub lip to the floor where the insulation will be exposed, should I just use plastic/poly vapor barrier from this point down? I live in Wisconsin so you get an idea of temp fluctuations.
Do you have any preference for tileboard/backerboard for walls in this situation?
Thanks in advance!
I really appreciate any advice and help!
Hey Deuce,
Any good modified mortar will work fine. I prefer laticrete product, but versabond from home depot or mapei ultraflex from lowes will work fine as well.
You can (and should) cover the wall cavity from the tub lip down with poly sheeting.
Thank You for your advice and help!
I can get the mapei ultraflex from Menards it looks like, but apparently there is an ultraflex 1 and 2. Is the 2 better for this application? Its about double the price, but that does not matter, I only need 1 bag. Also would I use a V notch trowel to apply this so I dont get mortar oozing through the grout joints or would I use a 1/4×1/4 square trowel like the floor?
Once Again, Thank You!!
I hope I will run out of questions soon and stop bugging you!
I just ordered and downloaded your tile tips ebook, have found some great tips already and have only started reading it.
I may have found some of the answers I need while reaing the ebook and searching your website…
Please correct me if I am wrong!
I do not use a V notch trowel for wall tile, instead I use a 1/4×1/4 with the Mapei Ultraflex 3 I got today. I got white at the advice of sales dude at Menards as that is only color they had on hand plus I will be using light almost white color travertine inserts in the shower and on the floor. I will use same mortar on floor.
I picked up R-13 kraft faced insulation for the 2×4 walls since it was on sale, now all I have to do is either cut slits in paper face behind redguard area and leave paper with no slits in from tub lip down, or just remove paper face all together and just put the poly from tub lip down.
Lots of great tips in your tile ebook, I picked up a grout cutter for any mortar that ends up between the tile joints prior to grouting.
Thank You for taking the time for all of your advice and for this website!!
Hey Deuce,
Sorry, day job and all.
Yes, the 1/4 x 1/4 trowel with white thinset is correct. Cut the insulation and install it backwards from the tub lip up (with the paper in against the outside of the house) and the right way around below the lip of the tub.
You are da man! I know you work a day job also, which amazes me that you have the time to repond to all the questions here! (many from me
)
Roger thanks for the quick response a couple more in your manual you mention only 3/4″ at the drain for the single topical deck and you use backer board on the curb instead of mud I just want to make sure of this as I am a big boy (300+ Lb’s) and want to make sure that I build it to hold up to my big ass.
The compression ratio of deck mud is upwards of ~800 – 1200 psi. So unless the bottom of your foot is only 1/4″ wide (i.e. you are a pirate and do, indeed, have a peg leg) it will handle your ass just fine.
(Thanks for the candor and the laugh!)
In your Topical book you list several different ones in order of your preference. The Lowe’s in Oregon carries a LATICRETE® WaterTight and this doesn’t need fabric do you know this product? http://www.laticrete.com/homeowners/products/waterproofing_anti-fracture.aspx
Hey Gem,
It is *essentially* the retail/consumer version of hydroban. The differences are such that in a regular application such as yours the only real difference you’ll notice is the amount of time needed for a flood test. I can’t remember what it is with watertight but it will say so on the bucket. It’s good stuff – use it if it’s readily available to you.
hey Roger a few more issues bouncing off my thick scull….first of all I called laticrete to ask about the difference between the water tight vs the hydro ban…….not that I didn’t trust you, I just had to know. he said it was a heaver duty and the extra testing it has to go thru for the certifications is a large part of the price not to mention the cure time which is more important to those of you doing this for a living that it is to me. I also mentioned while they say you don’t need fabric I was thinking of just doing the changes in plane and was having a hard time finding the fabric and stucco isn’t that popular in Oregon rain so what about joint tape. he said definitely not to the normal tape but the alkali resistant would be ok but stopped short of a recommendation. I was thinking of doing a corner bench do you have a post on this also I was thinking of getting 16 x16 x 4 blocks and cutting them in half and stacking them (mortar) is this dumb? could I just tile to them or cover with backer board first? thinking about tiling at the curb is driving me nuts I have gone thru numerous scenarios in my head probably all wrong….any thoughts?
Alkali-resistent mesh tape will work fine. I do not yet have a post about benches – cinder blocks work fine. You can install tile directly to them if you want.
Not sure which scenarios or problems with tiling the curb you may be having so it’s difficult to have any thoughts at all about it.
Whattsa problem?
Well I guess I should say the whole door area. the shower rough in is 41″ x 78″ I have two shower heads one on the same wall as the door about 2′ away this head should point away from the door if I can train the wife (hardest part of the project) and one on the far end (not sure my water pressure is good enough for both at once but will deal with that later) I am hoping not to need a door as it is in the far end of one of the long walls and I have blocking in case I end up needing one down the road. (when I give up on training the wife) As for the curb all three sides of 2 x 4s’ with backer board and Topical and I was thinking I would use the same tile as I do on the floor (yet to be determined but am leaning towards the small ones that come on 1×1 mats) wrap up and over (I know I cant wrap those but you get the Idea). I am doing tile in the bathroom with bull nose around the edge on the walls and not sure how to transition to that if the heights are different (I don’t know the curb height yet). As for the door jams, backer board but the outside wall is drywall and I was going to use corner bead there I have metal not plastic before I saw you recommended plastic in another post but as I hope not to need a door don’t expect much water there your thoughts? the wall tile would just wrap onto the jam BUT that leaves an unfinished edge and since this will be 4 3/4″ to 5″ . I thought about bull nose along the outside walls but thought the door might just look like a big picture frame??? Also thought of bull nose flush with outside drywall but 3 1/2 doesn’t cover that so maybe cut tile and bull nose to split the difference so they are even? (2 1/2″ each piece) what is commonly done or your suggestions? Also one a new question I have green board on the ceiling since I wasn’t going to tile it? it is a 9′ ceiling and no drops in the doorway so fan in bath will help clear out steam, hope this is ok and if so how do I finish this seam between backer boare and green board? just caulk both backer board seam and tile at change in plane?
I normally cut the bullnose down to half the width and place them back to back. Be sure to take into consideration the thickness of the jamb with the tile installed on the inside wall – it’ll be more than 5″.
You can either silicone or tape and mud the transition between the backer and the greenboard.
Roger
I’m ready to tile. Should I tile the floor in the shower first and then the walls?
Or does it make any difference? I’m a little worried if I tile the floor first that I will get thinset all over my floor when I do the walls……
Steve
Hey Steve,
It makes no difference at all. I prefer the floor first, then the walls. But it’s a personal opinion. You can always cover up the tile on the floor if you do it first – or work cleaner.
It doesn’t matter, though.
Roger
I’m back on my project again
I’m curious if I could or should put Redguard on the ceiling of my shower – it is sheetrock that I’ve already painted with Kiltz, but I’m wondering if a coat of Redguard would benefit me?
Also, I have a beadboard around my bathroom and I want to know if I can put Redguard about an inch up the beadboard to sort of put a waterproof membrane all around. I guess my main question is can you put Redguard on sheetrock, beadboard, etc? And finally I have a half wall of glass block that I am installing – I have hardiboard as the base – can I put Redguard down before I set my first row of glass block with glass block mortar?
Hey Steve,
Yes, you can redgard the ceiling. The top of your shower gets a lot of water vapor so waterproofing it never hurts. You can install redgard on nearly anything and tile over it provided it is not inside the shower or other wet area. I would skim-coat the redgard beneath the block with white thinset before installing the block over it just to ensure that the red does not show through.
Hello Roger,
I created a mud pan with a pvc liner with the specifications you provided in your posts. I have a question regarding whether I can redgard the top mud layer of the pan for extra protection. Would that be a good idea or will I be creating a mold sandwich?
Hey Mo,
You have the possibility of a mold sandwich. Provided your deck is correctly built you don’t need any extra protection. It often creates more problems and solves none.
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