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 building a custom 6 foot by 6 foot walk in shower. I have all of my Durock up with no Vapor Barrier behind all my seanne are taped and I use thinset to seal my seams. Do I apply redgard over all of my Durock? Two coats throughout the whole shower?
Hi Jamie,
Yes. But you need to be more concerned with the overall thickness rather than number of coats. You want the cured product to be about as thick as a credit card (the one that burst into flames about halfway through this project…).
Roger,
Basement shower in lake cabin. Walls are cement board. Used alkaline resistant mesh at seems using modified thin set. Applied a thin skim coat of thin set all over walls to obtain a uniform concrete look. Applied 3 coats of Redgard over floor and walls. Now I just want to paint the floor/walls with 1 part epoxy garage floor paint as the final finish ( no tile). Question: Do I need to use a primer on the Redgard before painting and if so what type of primer?
Hi Ron,
You shouldn’t need to. The epoxy should bond to the redgard extremely well.
We are building a new shower in our 1926 house. One shower wall will be on an exterior wall. This is a brick wall on the outside then there are 6 inch timbers which are covered with tar paper followed by 2 inch studs or space and then plaster and lath. My question is for the shower can I redguard over the plaster or should I remove the plaster and install a cement board or use kerdi? Also is the tar paper a second vapor barrier, should I slit this?
Thanks
Hi Martin,
I would use kerdi. Redgard is not approved for use over plaster (although I think it would work just fine). And tearing out lath and plaster walls SUCKS. Do not slit the tar paper, it’ll be fine behind plaster and kerdi (or redgard…)
(If you use redgard make sure to create a primer layer first – mix one part redgard with three parts water and paint it onto the plaster. This fills the pores and gives a solid layer for the redgard to bond to.)
I used RedGuard , 2 coats over a sloped concrete pad for a shower. Waited 35 days (took images to see the time line) before coating the concrete. Longer than the instructions say to wait for. After the walls were completed, a few spots of thin set had stuck to the floor. Normally if I noticed any mud getting on the floor I would wipe it off while wet. But when I removed the few spots, the RedGuard came up with the thin set. The cured thin set was not that big. 1″ ish. With a hole in the ReGuard now it left a flap, so I gave it a pull and was able to easily pull and peel the entire coating of ReGuard off. Disappointed to say the least in it’s bonding to concrete. I did install a typical barrier below the concrete, so its not a complete failure, I preffered the moister layer to be next to the tiles.
Hi Dave,
You have a pvc membrane below regular concrete???
A PVC liner was installed so good to go with tile over the concrete.
My husband just finished red guard on our shower, we have put the membrane with mortar on concrete floor, I heard you say don’t put red guard on the floor. WE DID, why is that not a good thing to do?
Hi Cynthia,
You put the membrane on the floor with mortar? Do you mean a pvc or cpe (rubber) membrane with deck mud? If so, the reason you don’t want to do that is because it creates a layer of substrate (deck mud) that sits between two impervious waterproof layers, it may begin to grow mold and mildew when moisture running down the drain (it sits in the p-trap) dissipates up through the weep holes. This leads to moisture between the two layers, allowing mold and mildew to form. This takes YEARS, but it can happen.
I have a cinder block wall in a shower that we just built. Do I redguard directly on the cinder block before I apply the thinset?
Hi Julie,
Yes.
hello,
I have the green drywall in my basement shower. my installer is recommending using redgard over the drywall. what are your thoughts? Wold you recommend something else instead, like kerdi?
Hi Rey,
I would recommend kerdi, since it is the ONLY product approved for use over any type of drywall. Redgard is NOT.
Roger, I have followed your instructions on building a new shower all the down to the pan and liner. However, I feel like I may have made a mistake when installing the concrete board on the walls. I left a 1/4″ gap at the bottom between my pan surface and concrete board. This is well below the pvc liner so am I okay or do I need to seal it up some way? Thanks man!!
Hi Justin,
You’re fine.
Hi,
I installed at mortar bed atop a pvc liner with a cement sub-base. Mortar bed went in beautifully, pebbles put around drain for the
weepholes. Now before I totally screw this project up, should I
use red guard on the mortar bed or just use it in the corners, seams, and walls? Thanks
Hi heinz,
Just on the corner seams (if you want to) and the walls, not over the top of the mud.
Thank you Sir
ok i am a tile installer that has been using the pvc membrane for years with no problems
i decided to stop using said membrane and go with gator gold topical membrane’s, started using it and loved it!now i can not find it anywhere!
now i have four custom shower floors to do on my schedule,i have completed one using the kerdi/ditra type,used non modified glue,did a flood test la la.every thing is/was fine,the question i have is on the first one i did i also used redguard on top of the kedi liner,is this a NO-NO OR CAN IT BE DONE,said job has been done for three months and no problems!!! i have no care if it costs more just care that the job is done right and want to get over being afraid of using this now again new method,i use laticrete 317(fyi)thanks
Hi Jas,
Yes, you it can be done. I seal my kerdi and kerdi-board penetrations with hydroban – on every job. It’s not an issue at all.
I am planning to coat the vynel pan liner with redguard because i had to seam it, and cut for corners that would not cooperate. Is this effective and/or recommended? Pan is glued with oaty x-15 adhesive with 2” overlap.
Hi Rjm,
Not really recommended, but it is effective as far as I know.
What kind of thinset should be used over the red guard? We are tiling a shower using 13 x 13″ porcelain tile.
Hi Shannon,
Modified thinset.
Hey bud–
Looking to use either hydro-ban or hydro barrier on a new marble shower. Any advice on which one? Looks like main difference is just the ban doesn’t need any fabric to reinforce? Not sure if it is worth the extra cost?
Thanks
I have a mid century house with an aging tiled tub surround. The walls are plaster. I am remodeling the entire bathroom. I would like to know if I can leave the existing plaster walls intact in the tub/shower surround. Also, do I even need to use redgard, as I would assume a traditional vaper barrier was used during initial install?
Hi Luke,
You can leave them if you can get the existing tile off without destroying them. I would highly recommend a barrier of some sort. In my experience there is a barrier behind there about 50% of the time.
I’m retiling my tub surround, and when I took down the old tile l had foil faced insulation on the two exterior walls. Is the faced insulation considered a water vapor? I was going to use Redgard, but I don’t know if I can use it with the insulation I already have? Would I be better off removing the old insulation and using unfaced insulation and Redgard?
Hi Dennis,
You can just cut slits in that facing down the stud bays to allow vapor to dissipate, then use redgard in your shower as normal.
Roger,
Thank you for answering so quickly. I have a follow-up question. Can I just use the kraft face insulation that’s up now? I’m trying to do a quick(I mean cheap) bathroom remodel so I can put my house up for sale. Or is skipping on the better waterproofing (Redgard) an asshole move?
My opinion? Asshole move.
But you can staple plastic or tar paper over the kraft paper that is there, install your cement board and tile away. Completely acceptable.
I have an outside wall as part of my shower. There is a vapor barrier than 1/2 backer board. Should I Red Guard that wall?
Hi Joe,
If you’re waterproofing your shower with redgard then yes, redgard that wall. I normally cut slits in the barrier between the stud bays on exterior walls, but if you already have the backer up don’t worry about it.
Thanks, it’s done. Also I’m a little confused on what tile is better for a “wet area”
Ceramic or poriclan. They say that poriclan is harder but which one do you recommend or does it really matter.
Thanks for all your help.
Over a properly waterproofed substrate it does not matter. The only time it does is in situations like freeze/thaw applications. Porcelain has a lower absorption rate, but it doesn’t really make any difference in a regular shower.
I have a fiberglass shower pan with a flange on 2 walls and no flange on 1 wall. There is backerboard on top of the two flanges and down to the pan on the side with no flange. All 3 sides have silicon across the edge.
Do I redgard down onto the flange on 2 sides and down onto the pan on the side with no flange, or just to the bottom of the backerboard? Does the redgard stick to fiberglass shower pans?
Hi Steve,
Down the flanges on the two sides and down to the tub on the third. Yes, redgard bonds to acrylic and fiberglass.
Help! Okay my first shower build, and already I have a big problem. I have two windows (glass blocks) that I have already installed. I know now I should have wrapped the frames. Any suggestions short of cutting them out? They are siliconed in. Of course inside and outside. Sorry if this is not the right place to be asking this question.
Hi Paul,
Just redgard right up to the silicone. Perhaps I’m not understanding the question?
I applied my red guard and I have a few fishes that I missed and a couple of large gloosnof the stuff that dried on. Do you have any advice for removing high points or ridged in dried redgard?
Hi Blg,
You’ll need to slice them down with a razor blade, then go back over the area to ensure it’s waterproof.
Could I go overboard and coat my pan liner with aquadefense or would it mess up the pan?
Hi Ryan,
It shouldn’t mess up the pan at all, but there’s really no reason at all to do that.
Roger,
Should I use RedGard or any other product on the plywood subfloor around the tub? Or is it unnecessary? Thank you for all the help.
Hi Justin,
You can it you want, but it’s not necessary.
How did people waterproof a shower/tub enclosure tile installation in the past before there was any waterproofing membrane available anywhere? These products are pretty new & expensive. Are they more effective than just running a bead of silicone in all substrate corners/crevices before tiling?
They used plastic or roofing felt behind the backerboard, it’s called a traditional waterproofing method. Maybe read through my free shower waterproofing manual? You can get it in the library. Before that tile was installed over mud walls (wall mud), behind the wall mud was wire lath and roofing felt or tar paper.
Hi Roger
I want to fix my shower area, for the backer board can you use Gypsum (Mold Resistant drywall) with Redgard waterproofing, or are the cement products (Durock / wonderboard my only option? Thanks.
Hi Gilles,
You can use a product like dennshield if you want, but not any type of drywall at all. It’s that or cement board.
I have a PVC pan liner in my walk-in shower under the the pre-slope. I’m red guarding all the cement boards and skipping the tar paper or plastic between the backer boards and the studs. Question is, should I red guard the final slope as well? Heard some talk about that being a bad idea because of a possible mold sandwich developing between the PVC liner and the shower floor.
Hi Dave,
You mean you have a liner OVER your pre-slope? If that is the case then no, do not install redgard on the final slope. If you do in fact mean you have a liner UNDER your preslope I would ask you why.
It will not adhere to redgard. Siliconized caulk, latex caulk, or Lexel will adhere to redgard. Terrastone over redgard will create a moisture trap, so you may be in a bit of a future problem if moisture wicks up the wall behind the Terrastone.
I have a shower constructed of Terestone which calls for a silicon adhesive caulk for securing the wall panels. I am reworking the riser board below the bench seat due to a leak and will install cement board and then Redgard. Will silicon adhesive stick to Redgard? Thanks very much.
Hi Bob,
Yes it will.