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.
I’m looking to do a tiled shower with a high window and have plenty of time to let it cure between steps.
this is from scratch (except the window that’s already there).
I plan on using hardwood look 6″x24″ tiles for the Shower walls, Shower floor and bathroom floor. Being on a second floor (2×12 joists, 16″ centers with 2 layers of 1/2 plywood and a layer of 1/4 plywood), I am planning on using Ditra underlay as my floor uncoupling membrane and waterproofing membrane with a 3″ to 4″ curb and for the walls Laticrete Hydrobarrier.
Two of the walls have plywood the third wall is currently just studs on the bathroom side, probably going to put 1/4 cement board on the plywood then the barrier and for the stud wall, put 1/2″ cement board.
Given your vast knowledge and experience does this sound like a good plan or are there issues that I am missing.
Thanks
I am remodeling one of my bathrooms, I have installed a new bathtub and cement board around the tub/shower area. I am not using tile but a standard shower kit not tile to surrounmd the bathtub. My question can you use liquid nail or whatever is needed to install the shower kit on top of red guard vapor barrier.
Hi David,
I really don’t know. I believe it would bond just fine, but I have no experience with it or proof of it. Sorry.
I am planning on using a concrete grinder to create the slope into the drain on a concrete slab for a shower. I want to achieve more of a “walk in” feel rather than having divisions in this toilet/shower area. Can i use thin set to patch areas that might need it before i apply redgard?
Also. Before I attach the cement boards is it a good idea to use a waterproofer on the the wood two by fours that create the walls of this showers?
Hi Rik,
Yes, you can use thinset. Not necessary on the waterproofer over the studs. Won’t hurt anything, but not needed.
I came to your blog to determine if I could paint over regard, I know now you can’t. However, was reading about the mud pan. I am concerned now that with the initial base mudpan we painted over with regard due to few cracks, this was suggested. Worked as planned, however, we still used roof paper and the rubber liner and another mortar layer to finish pan. The result looks fabulous, no cracks and slope perfect. Is the Redgard and liner going to be a major problem down the road? It is on the second floor… We were trying to be overly cautious?
Hi Arhoden,
No, it won’t be a problem.
Hello Roger, I have an urgent question. I applied the RedGuard all over the walls of a shower I’m re doing, this is on top of Durock. I read the instructions and it says to use a polymer mortified mortar after, so I bought the Custom brand Porcelain Tile Fortified Thin-Set Mortar. When I applied a coat of this to glue the tiles, the tiles started to slide down, they did not stay put. The mortar mix was not too wet nor did I apply too much. I had to remove everything and wash the mortar off from the wall. Now I’m stuck not knowing what to do. I’m inclined to use the adhesive mortar even though the instructions on RedGuard says no to. Please help! !
Hi Caesar,
It will do that with anything. You need to support from the bottom up as you stack the tile. Gravity works against you. The ‘adhesive mortar’, which is simply mastic will do the same thing.
I’m remodeling our upstairs bathroom and would like to apply Redgard and tile on all the drywall about 1/2 from floor up. Shower/ tub area will be cement board and Redgard. The previous homeowner had glued panels up on the drywall. Once I removed the panels most of the top layer of the drywall came off as well. Now I’m left with 1/2 of the wall with brown paper. Should I seal the brown paper with Drywall Primer and skim coat, redgard, and tile?
Hi Barb,
You can just go straight over the drywall with redgard.
how long can redguard sit before tile is applied? We want to apply the redguard then travel north but our contractor won’t be tiling for a few weeks after we leave. Thanks
Hi Anne,
Provided it isn’t subjected to direct sunlight it will be just fine for several weeks (like 8).
I’m building a large tiled 8’x3.5′ shower with a single layer base. The drain will be 1.5′ from the right side of the shower, glass, with a doorless entry on the left.
Can I:
1. Install the curb and concrete board first, then form the mud bed (see#2).
2. I am planning on using the Kerdi membrane and drain on the floor. I want to Kerdi the curb, floor and up the wall a few inches and then apply 2 coats of redgard to the walls overlapping the Kerdi at the base of the wall. Will this work?
1.
Hi Darcy,
Yes to both.
Great info Roger. When using redgard on shower wall over hardy board, what type of thinset should i use? I would think the thinset would not stick to well when applied over redgard do to the inability of the hardy board to absorb moisture and help dry the thinset. Thank You
Hi Steve,
Modified thinset. Redgard is chemically designed to allow thinset to bond to it extremely well.
Roger,
I am redoing a stand up corner shower and I have used the schluter kerdi membrane over everything except…I created a curved curb because that is what the wife wanted and I cant put down the kerdi band in the curved corners. Can I redgard over the schluter kerdi install in those curved corners?
thanks,
alex
Hi Alex,
Yes.
Hi Roger,
Wealth of knowledge here, really love your site! Currently renovating a 60’s era corner shower with 3 mud walls (removed tile, keeping old mud and patching uneven areas with mortar before new tile) and 1 tile-over-brick wall (cannot get tile off without damaging old brick, so planning to tile over tile). Few questions:
1) Can / should I Redgard over the tile where it’s remaining on the brick?
2) I plan to pull out enough tile at base of brick wall to uninstall lead liner and liquid nails the new pvc liner to brick. Then lath and mud over pvc in plane with tile above. Does that sound acceptable?
3) Should I Redgard over the entire existing mud walls? Fairly certain there is no tar paper beneath existing mud.
Hi Dan,
1. Yes.
2. Yes
3. Yes.
Have finished bathroom floor with Schluter Kerdi, in-floor heat, and encaustic cement tile. It looks fantastic. Now we come to the shower area floor. Originally set up for setting bed with metal mesh over sound plywood and 4″ curb. Don’t want the curb now and the ply was not recessed, but I’ve got about 1 1/4″. Shower is 5′ x 4′ rectangle with the 5′ edge abutting the encaustic tile. I can add a saddle to get some more height. Because of the low slope I’m planning to use redguard to waterproof the floor, add synthetic mesh to help the mortar bed and then install Schluter system over mortar bed to accept regular floor tile. I know it sounds insane (that’s what the G stands for in my middle name Ginsane, where the G is like P in Pterodactyl). Comments, please, or directions to the nearest in-patient psych unit. Thank you.
Hi Harry,
Provided you get a proper slope on it I don’t see any problem with that at all. I’m no longer allowed to refer people to psych units, I’ve been banned from that. Don’t remember the conversation but there was something about ‘kettle’ and ‘black’…whatever. But I WAS NOT the one who started the fire!
Will Redgard stick to the fiberglass tub where it touches the wall? Thanks!
Hi Karen,
Yes.
Thank you for all you help here. I noted above Redgard can not be painted and to use drywall mud and then repaint. (unfortunately I read that AFTER doing the first coat of Redgard and tape on the top joint of backerboard and newly painted wall board above the tub:( )
My question is.. was I correct in taping and Redgarding that tip joint> If so, am I suppose to apply tile over that area even though 2 ” will be wallboard?
Hi Barbara,
It’s fine.
Hi Roger,
Sometimes when I have an adult beverage, I think about my old upstairs bathroom floor. I don’t know if this is normal for an adult male. Anyway, my old floor has really bad linoleum tiles, and a vintage toilet (and vintage tub, and vintage sink). Here’s what I’m thinking.
Remove the toilet, and the linoleum tiles. The tiles will come up easily in most spots. I do not know what’s below the lino tiles, but I do know that below that layer (if such a layer exists) is tongue and groove old growth redwood subfloor.
Thus after I remove the linoleum, I am thinking of removing whatever the next layer is (or if not, I am looking at raw T&G), and then laying down a precut sheet of OSB or 1/4 inch plywood so as to minimize any movement of the T&G throughout the season and/or house settling. I find wood easier to cut than cement board but if you think cement board is best, I will take your advice.
I’m not sure how to affix the ply to the T&G. What’s best here … screws or liquid nails? I’m leaning toward 5/8 inch screws.
Next I would paint the plywood with Redgard. Once dry, tile the floor, grout, and last, replace the toilet.
I’d appreciate advice on how to affix the substrate to the T&G, if 1/4 inch ply sounds OK, and whether or not the rest of my idea makes sense. If it does, it will give me more to think about as I consume additional beverages. Thank you!
Hi Lee,
Sorry for the delay, you got lost in the mix somewhere. I would go with a minimum of 3/8″, 1/2″ would be better. Attach it to the t&g with screws, only into the subfloor, not the joists.
If you are going to use redgard directly over what you install you need to install cement board instead, you can not go over the ply directly with redgard then tile – it won’t last. You can put 1/4″ backer over ply, then use redgard if you want.
My house was built in 1989 and I have a shower stall for my bathroom. The shower stall is 68 1/2″ tall leaving 25 1/2″ of wall to ceiling. That rest of the wall constantly gets wet since there are 6 people using the shower and all are close to 6ft. tall. Is it ok to use RedGard on the wall and then paint over it when it dries? The wall was starting to get a hole where the seam was.
Hi Vicky,
No, because paint won’t bond to redgard. You can redgard it and tile over it. You can put cement backerboard up there and paint or tile over it.
Hi Elf,
You say not to use a plastic vapor barrier on the shower walls if you are planning on using Red Guard. What about using roofing paper under the durock?
I tore out my old (pink!) tile as it had failed and the shower was leaking into the closet on the other side of the shower wall. I’ve installed roofing paper behind the 3 walls of the tub/shower, which are a durock like product called Permabase. I was planning on using Red Guard to seal the walls, but your comment has me concerned.
Is the roofing paper (15# felt) enough of a water barrier? Can I still use the Red Guard? Whata do you think? Your expoertise is deeply appreciated.
Hi TMac,
Roofing paper is a more than adequate moisture barrier for your shower. I would not still use the redgard unless you remove the roofing paper. You normally want one or the other – not both.
Do you ever have issues with redguard red color bleeding through and showing behind glass tile? Just wondering since I saw that posted somewhere as a negative to using the product….and it is so very red!
Hi Amy,
Absolutely not. Once cured it is inert, if someone had that problem they likely didn’t wait for full cure before installing over it.
You say to use fiberglass mesh drywall tape. The only fiberglass tape I can find is the kind with the little tiny square holes in it, but the videos I’ve seen their mesh tape is solid with no holes. Can I use either??
Hi Lisa,
You want the kind with the little square holes in it.
Very helpful post. Consider myself pretty handy but was gunna make the mistake of using redgardin over the shower floor concrete base which already had the pvc membrane. Sometimes being overly protective and over thinking can cause more problems.
Can you paint over redgard? like touching up the wall where your tile stops? and can you use drywall mud over redgard?
Hi Josh,
You can not paint over redgard. But you can use drywall mud over it and paint that.
I have gutted out a two piece tub and shower and have installed concrete board to replace it. I only have one bathroom and I am having to do this project after work so my question is…..Once the Red Guard is applied and dried, how much do I have to worry about getting the Red Guard wet (taking a bath) before the ceramic tile goes on.
Hi Charlie,
Provided it’s cured you don’t have to worry about it at all. It will turn pink when wet, don’t panic, it’s normal.
Roger
This site is great. Used it with my last project. Using it with this one as well.
I have a shower project and would like your advice. In my 2nd bathroom I have removed the existing tub/shower combo and replacing it with just a shower (3′ x 5′). The shower enclosure has three walls all cement boarded (durock) the fourth wall is a pony wall, curb and door (all glass). I had a mortar shower pan installed (a little wavy but sloped correctly. A couple of questions.
1. Waterproofing
Should I redguard the entire surface of the cement board including shower pan? I also read that you silicone corners. Do you suggest this?
2. Shower Pan
When tiling, can I just use more thinset under the tile in lower areas to smooth out the tile?
Thanks in advance
Hi Ron,
1. Yes, provided you have a drain in the floor that can be used with a topical membrane and you DO NOT have a rubber membrane in there. If you do then no, do not use redgard on the floor. You can use it on the walls and paint it out onto the floor a couple inches, but you don’t want to go over a base with a membrane already in it.
2. Yes. Or you can simply skim-coat it with thinset first to even it out, then let that cure, then set your tile.
Thanks Roger
Yes I do have the rubber membrane. So I won’t redguard on the floor.
Modified or unmodified thin-set for the skimcoat on the floor? Planning on using marble tile.
I was reading on your blog about vapor barrier (mold sandwich) and using redguard. One of my walls is an exterior wall and has vapor barrier. Should I remove the concrete boards already screwed in to access the vapor barrier to allow the vapor to dissipate? Right now the exterior wall has 6ml poly and cement board (joints not taped yet)
If you only have one wall it’s not necessary. Doesn’t matter what type of thinset you use on the base, either will work just fine.
Thanks Roger. You have been very helpful.
I have one more question for you. Would using the Kerdi membrane on the cement board be a better option than RedGard for waterproofing the shower?
Thanks again
I prefer kerdi because I can begin tiling right away. That said, they both work very well. Completely a personal choice.
We removed an old acrylic tub shower surround in our washroom. Then the sheetrock behind this. The house is almost forty years old. The vapour barrier and insulation behind smelled bad and removed that too. When we removed the vapour barrier and the insulation to the cold wall, we discovered the exterior wall badly water damaged. We wanted to install cement board and Redgard as the waterproofing membrane around our tub. Since it is an exterior wall, wouldn’t we need the vapour barrier and insulation behind the cement board???
Hi Lynn,
Yes, but having in on one outside wall doesn’t create any problems.
we gutted our MBR shower which is back to back with the tub surround of another bathroom. we discovered that the area of sheetrock (yes sheetrock) surrounding the spout and two handles of that tub surround was well on its way to becoming mush. we cut out all the questionable area. the tub surround is fully tiled and the entire rest of the bathroom is tiled to 4′. the tile is 30 years old and we have tried unsuccessfully in the past to match it. at the moment repairing the hole is the only option. current plan is to cut a square of cement backer board to fit, seal it with redguard, and re-tile using the tiles we removed. given the circumstances, what is the best way to seal the cut edges of the existing sheetrock? red guard, silicone, something else?
thanks for a great site!!
irene
Hi Irene,
Redgard is your best option. But the wall around the repair won’t last much longer either, once you waterproof that area that water will simply find somewhere else to go – the nearest un-waterproofed area of your drywall.
But you already knew that.
yup, we do. since our kids are grown and out of the house, once the mbr shower is completed, the other shower will rarely be used. so we can catch our breath a bit before plunging into another gut job.
thanks for the response and for all the info on your site. great info, great ideas.
Hi! Roger my name is michael i am having a question and waiting for your answer before start waterproofing with redgard. so got redgard and backer board tape from homedepot and the shower is complete installing hardie backer board so what should i do first and after for complete waterproofing the shower before tile
Hi Michael,
Get your backer up, tape and mud the seams, let that cure, install your redgard, let that cure, then tile.
How long between dry time for tape mud curing?
We are down to studs / putting in new bathtub and plan to tile walls & floor
Is this correct procedure
Install backer board over walls & tub area
Tale & mud (let cure for ?)
Redguard everything that will be tiled only
Let cure
Install tiles
Is this good?
(When buying backer board is that what its called? What should i be asking for exactly?)
Thanks soooo much!
Hi Lynn,
Normally 24 hours cure time is sufficient. Yes, it is called backerboard, that is what you ask for. More specifically you can get durarock or hardibacker (hardi is easier and less messy to work with). And yes, that is the correct procedure.