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 want to put porcelain tile down on an outside deck in SE Arizona that will be 36′ long and 18′ wide and 12′ of the 18′ will be under roof. I am planning on using floor joists with 16″ centers, 3/4″ outdoor plywood, 1/2 inch backerboard, and I need something to put down as a waterproof material over the backerboard. Would you recommend Redgard or some other product? I am looking for the best product for the best price. Winter temps can get into the teens in my local.
Hi Damon,
I prefer hydroban in that scenario. You also need a minimum of 1 1/8″ plywood, so you’ll need an additional 3/8″, I prefer a 3/4″ layer and a 1/2″ layer. The 1/2″ backerboard adds absolutely nothing structurally, it’s simply a proper backing for the tile and/or membrane. Don’t forget your soft joints.
Hi Roger,
We are re-doing a stall shower. Unfortunately, I think that we got some bad advice. Our concrete floor was so uneven after we chipped up the old tiles. We were told to put floor leveler and then Redguard. I’m now concerned because we did not slope the floor yet. Should we slope the floor and then put Redguard again? Thanks so much in advance for your help.
Hi Lourdes,
Yes, your shower floor NEEDS to be sloped 1/4 per foot to the drain. You’ll also need to utilize a topical drain or the divot method, a regular installation up to a three-part drain flange will not drain properly.
Is it okay to redgaurd over drywall instead of replacing it with a backer board?
thank you,
Brian
Hi Brian,
Not in a shower or around a tub. If it’s a wet area it needs to be backerboard. Redgard is not approved for use over drywall in wet areas. If you want to leave the drywall you can use kerdi right over it.
I’m in the middle of redoing a tub/shower and have just got done hanging hardiboard. I was about ready to apply redgard when I gave more thought about the window that’s also in the shower area. It originally had wood trim and was covered with a small shower curtain, of course wasn’t in the best of shape. I did recently replace the whole window with a vinyl window and was going to use vinyl trim. Then it hit me, why not just tile around the window. Where I’m stuck is what to do with the wood framing. I’m not sure if redgard is supposed to go over wood, can I just put thinset over the wood then redgard? It’s only a 3/4 by 1″ strip around the window.
Hey Shane,
Not technically, but a ridge that small should be fine with redgard right over the wood, then tiled.
Great to hear, now I can continue with the bathroom and hopefully get it done soon. The temporary shower in the unfinished basement is starting to get pretty cold.
Hi Roger,
Instead of using lath and mud, I’m wondering if HardieBacker backerboard could be fastened to all sides of the curb with screws, then waterproofed with Redgard? Also, my shower pan liner membrane barely goes over the outside of the curb (the overhang is 1 or maybe even half an inch) – I realize this is terrible. To remedy this issue, can I overlap and glue additional membrane on to the existing membrane using Oatey X-15 Shower Pan Liner Adhesive?
Thanks very much for answering my last question. This should be my last one! Do you have a donation widget on your site? If not, I think you should have one – I, for one, would be very happy to donate!
Thanks again,
Rob
If your liner goes up and over the curb it’s fine. It doesn’t need to be down farther than the top corner. If you want to add more liner you can, no real need to, though. If you penetrate through the liner at the curb you WILL have problems. The water will run down the liner on the wall and onto the curb – under the redgard. Your curb is one of the most vulnerable spots – do it correctly.
No donation spot, I sell the waterproofing manuals and TileTips to keep the lights on.
Thanks, though.
Hi Roger,
My shower pan liner is a little bulky in the corners, and I think this will push my HardieBacker backerboard out slightly, such that it won’t be exactly plumb. As I plan to use Redgard over the HardieBacker, I’m wondering if I can do one of two things: (1) Cut the shower pan liner out, such that it’s pretty much flush with the top of the shower pan. I’m thinking this might be okay since the Redgard should provide all of the water proofing I need. (2) Screw the HardieBacker into the studs through the liner. I’ve read that I shouldn’t screw through the shower pan liner, but I think it might be okay since I’d be putting Redgard over the screw holes. The thought here is that the screws might pull the backerboard tight such that it’s close to plumb.
Right now the shower pan liner is about 6 inches above the shower pan. Maybe I could cut it down to be an inch or two above the pan, then put screws above the liner?
Thanks for your help!
Rob
Hey Rob,
None of those would be a good idea. Your best bet is to notch out the studs behind the liner corners so you can fold the liner into the space and the backer will sit flush.
Thanks Roger. I actually have some notches in the studs, but apparently they’re not deep enough. I can probably deepen them with a jigsaw. I’ll take your advice, thanks!
Actually, a good ‘ole fashioned hand chisel might do the trick….
A chisel is always my weapon of choice for those studs.
We installed backer board down to the lip of the fiberglass shower base. That lip is 1 inch high. The backer board is 1/2 in thicker than the lip. So when we ran the tile past the bottom of the backer board, past the lip and down to shower base, the tile has no backing for the bottom one inch. This would not matter as we used large tiles (12×24) and installed them with the long side going vertical, however the grout keeps falling out of the bottom inch if the tile where it meets the tub. We need to put some backing in there to support the grout. We also redid this bottom inch and used colored silicone instead of grout. It dried for 2 days but was an inch thick going back into that empty 1 in high space behnd the tile and it fell out also when the shower was used again. I think the answer is some sort of backing to put behind the grout lines before we regrout? Or should I go to shower base seller and ask for their install recommendations? This is a home we built and sold we need to make our buyer happy.
Hi Genevieve,
Am I understanding correctly that you grouted between the bottom of the tile and the tub (as well as the grout lines)? If so, that’s why it ‘fell out’. The tub will move and crack the grout. Silicone will compensate for that movement but will not stay in the grout lines themselves, only between the bottom of the tile and the tub. If putting grout in the grout lines and silicone around the perimeter at the tub does not work you may be able to fill the area behind the tile with spray foam, but don’t use too much – it expands a lot.
Hi Rodger,
I had a question regarding install around a tub surround. Basically, if the cement board is placed 1/8″ above the lip of the tub, how would one waterproof the area between the bottom of the cement board to the top of the tub?
Thanks in Advance!
Aaron
Hi Aaron,
It depends on how you are waterproofing the walls. If you are using the traditional method the back of the barrier is siliconed to the tub flange. If you’re using a topical method the gap is siliconed and your waterproofing is installed right over it.
Hi Roger,
Thanks for your quick reply! I’m still a little confused though. First off, I was planning on using the topical method(Redguard). With that in mind, and just to clarify…you’re saying that a bead of silicone be run between the bottom of the CBU and the flange of the tub(thus bridging that 1/16-1/8″ gap). That would leave a void between the flange and the back of the tile hanging down. Should this be filled with anything?
Thanks again!
Aaron
Nope, the tile simply hangs over that space. Provided the waterproofing is a continuous layer to below the tub flange it won’t be a problem. Anything you put back there will end up cracking.
Roger,
Thanks again for your help. One final question. Assuming nothing is behind the portion of the tile hanging down, what is keeping the grout in place, besides the edges of the tile. In other words, wouldn’t the grout just squeeze out the other side as you are applying it?
Thanks,
Aaron
The sides of the tile are the only things ever keeping grout in place. Yes it will squeeze out the back to an extent, but it won’t hurt anything.
Your advise would be greatly appreciated. My contractor just built my shower and is supposedly ready for tile. He put down felt and hardibacker on the walls and cement/rubber barrier/cement on the floor. He is saying I am ready to tile. Is redgard necessary in this case?
Hi Bobby,
You have a correctly traditionally waterproofed shower. Redgard is a completely different waterproofing method, it’s not needed in your case. It is ready for tile.
Thank you for responding so soon. I have a few other questions. For my own sanity, could I used Redgard in a few of the more water vulnerable areas of my shower (i.e. show niche, and change of plane)? I am using 6″x24″ porcelain tile on the bathroom floor, 1″x1″ honed carrera marble mosiac on the shower floor and oversized subway tile on the shower walls. What trowel size should I use for each tile and what kind of thin set? Is versabond okay for all of them or should I use the special flex bond or marble versbond? Should I run the porcelain tile UP TO the toilet or place the toilet ON TOP of tile? Do I need to seal my honed carrera marble mosiac tile before or is okay to do it after install? You are a champion for answering all of your subscribers questions!!!!
Yes, you can use redgard in those areas. Just be sure not to completely cover any area (like the floor) with redgard that is already waterproofed – it could lead to mold. I normally use a 5/16″ u-notch trowel for nearly every tile. Versabond will be fine for all of it as well, the flexbond and granite and marble are specialized thinset which work better under certain circumstances but not normally necessary. Always remove the toilet, install tile, and place the toilet on top of the tile. If you are using a grout darker than your marble seal it first, if not seal it after.
Evil in the baptistry – Part III:
I built a 6-inch high tripod platform for a laser (threaded bolts for legs) so I could adjust it for any plane/elevation. Placing it on the steps leading to the floor allowed me to shoot the beam at floor level to study various possible planes/slopes. My conclusion from what I saw was to divide this 20-foot hallway into 3 planes roughly equal in area, the high one being the middle one. I’m thinking of hanging 1/8 x 1 angle iron, adjustable, along the walls so I can screed a layer of mud to a flat plane as thin as 1/8 inch in places (thickness of the iron), let it cure, then lay the tile onto the cured mud. I would prep the slab with RedGuard first, of course. If this isn’t completely idiotic (that’s a warm word), I have a question: What product should I use for the mud? Thin set? I’ve read it’s too sticky for good screeding.
Just use regular deck mud – 1 part Portland cement to 4-6 parts sand. That’s it.
Hello Roger!
I put up cbu on the walls and applied redgard before I put the ceiling in. Now that I wired the shower light and I’m ready to put drywall up on the ceiling, I realize I should have waited on the redgard until I taped and finished the drywall ceiling to the cbu walls. Will joint compound stick to the redgard? if not how would you recommend proceeding?
Also, the curb I put in bowed out in the middle. Can I mix up some more fat mud and try to even it out, or will it not adhere well to the old?
If it’s not bowed that much you can do it with thinset. If you need to use mud you’ll need to bond the new to the old with thinset.
Hey Patrick,
It’ll bond just fine.
My tile experience was one room 25 years ago which turned out fine. Now I’ve agreed to lay ceramic on a 30-year-old concrete floor for my church. My path: removed linoleum hoping to scrape off remaining linoleum and old glue using a rented walk-behind floor scraper, that didn’t work, bought a diamond cup wheel, found that to be too slow and dusty for 225 s.f. which includes 3 dressing rooms too small for large machine, M&D thin set rep said if water drops will not absorb, don’t use thin set. In many places, water will not absorb into my floor. So my options now, as I see it, are to install backing board over the concrete (much trouble). Which brings me to my question: Even though this area is not a shower and therefore water is not an issue, why can I not paint it with RedGuard? You say that tile can be placed on RedGuard using thin set. So why would a polymer-based thin set not stick to my floor since tile will stick to it? It’s considerably more porous than a coat of rubber.
Hey Jim,
You can paint it with redgard. Provided it gets a good bond it’ll be just fine. Do not try to use backerboard, it won’t work or last. Redgard isn’t rubber, it just feels like it. It is an elastomeric membrane specifically formulated to allow thinset to bond to it.
I didn’t mention that my intent was to secure the backerboard using screws. But there be worser banshees now: The area in question is a 2nd level T-shaped hallway with dressing rooms serving the baptistry. The final step of the staircase lands you in the hallway. I just discovered the floor at that point is 4 inches lower than the center of the area 8 feet ahead. I had considered self-leveling soup but that’s out now. Even if I poured that thick a layer, it would elevate the entry step 4 inches. Candidates for baptism would trip, then think or say something… ummm… and who knows where that might lead? Anyway, with all the hills, valleys, and slopes – and the project undertaken (root: undertaker) by a retired music teacher – the outcome (if it out comes) might make a good spook house… one of those optical illusion things. We could charge admission.
Hi Jim,
I wanted to waterproof my bathroom subfloor prior to laying down sheet vinyl. The subfloor the plywood stuff looks like wood shavings all glued together. Does Redgard work on wood?
Thanks!
Hi Valeria,
That is particle board. Why would you want to waterproof under vinyl? The vinyl itself is waterproof unless it gets around the edge. I suppose you could use redgard, but I highly doubt that the vinyl glue would cure between the two impervious surfaces.
I’ve just discovered your site. Thank you for your time and help to the rest of us.
My question is about replacing individual tiles when using Redgard. We bought a fixer-upper and our tub surround was beyond dead and moldy, so after a weekend of demo and a lot of bleach, I’m now staring at studs needing a new surround. (fwiw, we had mold people come out and test the area before we bought it; this was “just” garden-variety stuff, thankfully.)
At this point, I’m planning to tile the surround using generic cheapo tile since we need to do something soon but don’t have money to do more than a plain jane look. At some point in the future though, we plan to have more money and will want to install some decorative tiles into the plain jane. If we use Redgard now, can we chip out tiles in the future, re-apply Redgard to the tile-less hole, then toss in fancy-schmancy single tiles? Will it still be an effective membrane or will we need to pull everything down and re-tile at that point?
Thanks!
Hey Ben,
It can be done. You’ll need to scrape out the grout and run a razor knife along the perimeter to separate that area of the membrane because it will be torn out. If you cut the membrane before removing tile you’ll have a nice straight line where you can tie in a new layer of redgard.
What should I do if one of my 3 walls on my tub surround is an exterior one? As in should I take the plastic barrier out and just use redgard on backer or keep plastic and not use redgard on backer? Matter of preference?
Hi Brett,
If you are using redgard use it throughout the shower. You can cut slits into the existing barrier to allow vapor dissipation without removing the entire thing.
Hey Roger,
Came across your site while researching steam showers. I had a couple of questions, but when talking to product reps, they don’t always have an un-biased opinion. My main concern is the waterproofing. I normally use RedGard in my shower applications, but I was told it was not rated for steam and that I should go the kerdi route.
Also, if RedGard is acceptable for a steam shower, can I still use a latex-modified thinset, or would un-modified be better.
One more question – Grout? Would you recommend cementuous grout or epoxy? Or does it even matter with proper sealing?
Thanks for any info you can provide. I get a lot of calls from homeowners who are having bathroom nightmares. Its nice to see another contractor who seems to actually care and does things right.
Hey Jeremy,
Redgard is approved for steam showers, but it (as well as any of the other liquid membranes) is not a vapor barrier. Water vapor still permeates through the membrane. If you use it you must still install a vapor barrier behind the substrate. Modified thinset is acceptable but with certain less dense stones such as travertine you may run into the problem of latex leaching. With porous stones use an unmodified.
Kerdi or any other sheet membrane is a better option, they can be used without a barrier behind the substrate.
Now I’m confused. Plastic and RedGard? RedGard is a “waterproofing” membrane, but it doesn’t classify as a vapor barrier?
I found where RedGard has a water vapor transmission rate of 0.02 perms, whereas 6 mil poly is rated at 0.06 perms (15# felt is 1.0 perm).
I thought the rule is only one vapor barrier – either plastic behind the substrate, or membrane (RedGard or Kerdi) on top. I’m not installing a steam shower – just a regular shower. zIs this where the difference lies?
Hey Jon,
Yes, the difference is in the steam shower. While redgard’s literature states a perm rating of .06, both their tech line (twice) as well as my rep state that if used in a steam shower it requires a vapor barrier behind the substrate. Same with hydroban, Aqua-D, all of them. These membranes shed water, hence the ‘waterproof’ label, but in all reality still allow vapor penetration. All elastomeric membranes are vapor-permeable. Every one. Steam showers are a very specialized installation.
And no, it makes no sense to the pros, either. We are, however, required to follow manufacturer’s recommendations over the handbook when they differ. Redgard in their literature makes no mention of proper use in a steam shower, if you call their tech line or speak to a rep it’s quite evident that they REQUIRE a vapor barrier as well, and they’ll tell you that.
You aren’t the John Cox from San Antonio, are you? If so – why in the hell am I explaining this to you?
He knows more about it than I do.
You have me confused with a San Antonian. I’m over by Frog Level. In another state. But if I ever want to build a steam shower I’ll give him a call.
Thanks for all the info.
Hi Roger,
Your site has provided us with soooo much useful tiling information we’re using to remodel the master bath. THANK YOU!! We’re using a ProLine linear drain, QuickSlope (pre-slope installed with thinset) and NobleSeal waterproof membrane for the shower pan. From the installation manuals and info on your site, it looks like we would probalby install backerboard then waterproofing (Redgard) on the shower walls. Can I simply paint the Redgard down to the NobleSeal to waterproof the seam between the walls and floor? Let me know if one of your manuals cover this info and I’ll gladly buy it :-)
Hey Susan,
Yes, you can paint the redgard right down onto the nobleseal to waterproof it. I do not yet have any of the ‘hybrid’ manuals written – I’m workin’ on it.
Hello Roger,
Thanks for the straight on this website. Question: the shower pan already has a membrane installed along with the finish mud and thinset layer AND the Aquadefense has been painted on over that. Is this going to be an issue as you mentioned on your site that these type products should not be used in conjunction with a another waterproof membrane:
“It is imperative that you do not install plastic behind your walls since this would create two waterproof membranes with your substrate between them.”
The walls do not have a vapor or waterproof barrier behind the duraRock, but they do have regular insulation in the walls behind them. The insulation comes covered in a plastic type wrap. Will this be an issue if the duraRock is covered the the Aquadefense?
Thank you very much for your time.
Hi Nini,
My first question is why? Why is there aquadefense over an already waterproofed floor? You have used two products together which should be used separately. But you already knew that.
It may cause problems, it may not. I cannot guarantee a failure, I can only guarantee methods that will not fail. The double membrane may cause a failure but it is less of a concern in the floor provided you have open weep holes in the drain – moisture can dissipate that way. Ideally you should have slits cut in the plastic on the insulation, but it is not *technically* a double barrier on your shower wall, so it should be fine there.
Roger,
I decided to use Redgard to waterproof the shower.
I poured some into a trim bucket, intending to use a brush to paint it into the shower niches first. When I did this, the substance was basically like pink water. This was unexpected, so I went to the web and did a search for a video showing installation, and when it came up, it appeared that it was supposed to be more like really mushy putty, not like water.
So I decided to ask you: is the watery appearance normal, or has something happened to the batch I got? Did I skip some important prep step that makes it thicker?
Never mind.
I opened up the second pail I bought, just to see if both were the same consistency, and the second one had the mushy paste appearance it’s supposed to.
F$*(#$! Home Depot. Add this to the list of reasons I don’t do business with them unless I absolutely have to.
Oh, nevermind my answer then.
Good timing, eh?
Hey Brendan,
When sitting for a while the liquid may separate in the bucket. Did you mix it up well before pouring it out? After mixing it the consistency should be nearly identical to pudding (vanilla, not rice).
If not then your bucket may have hit the expiration date (I believe it’s on the bucket) or you’ve received a bad bucket. If that’s the case take it back to where you got it and get a different bucket.
How can I ensure that red gard will not dry out if used over days?
Hi Jaye,
Put the lid tightly back on the bucket between uses. Is that what you mean?
Hi Roger,
Thanks for all your time and expertise. I am tackling a big project (new home with tiled entry, kitchen and two bathroom floors, tiled tub and shower surrounds, and tiled countertops). I have tiled before, but it has been a while. Anyway, our sheetrockers sheetrocked our tub/shower surround and our shower surround while I was out of town and unable to stop them. I was planning to use the traditional method of vapor barrier, backerboard, tile, but now I don’t know what to do. I don’t really want to tile over sheetrock, but can I? Is Redgard the way to go if I choose to do this?
Thanks,
Margie
Hi Margie,
Redgard is not approved for use over drywall in a wet area. The only product that is would be Schluter kerdi. You can install the kerdi right to the drywall with thinset then the tile is installed directly to the kerdi membrane.
Should fiberglass tape/fabric be added in corners and seams with the first coat of RedGard or can it be added with the second coat?
Hi Sherry,
Ideally with the first coat, but you can add them on subsequent coats if need be.
Will thinset stick to vinyl patching? I was going to use thinset over the existing vinyl patching, and then redguard over the thinset.
Hi Jim,
Yes, it will. No need to ask your question multiple times. I can only give you one answer.
I answer questions when I get home from work. I always get them, but I really am a tile contractor so it may take a little bit before I get home.
I’ve used Quikrete vinyl concrete patcher on part of a new vertical shower seam to level it prior to using Redguard, but still need to level it some more. Will redguard stick to the vinyl patching? When I then use the fiberglass tape on the seams, should I use redguard or the vinyl patching with the tape?
Hi Jim,
Yes, redgard will stick to it just fine. If you did not install the tape over the seam as you installed the initial layer of patch then it won’t do any good installing it now. Just float it out with the patch, let it cure then install your redgard.
Hello Roger,
Ok a few questions here:
1. I have a 5′ long niche running the length of my shower, can or should I redguard just this but use 6 mil plastic behind the rest of the CB.
2. For my tiled floor, it looks like a pain in the butt to use a rubber membrane between two slopes of mud, so can I redguard the floor. (is redguard rated for water proofing floors).
3. If i do decide to go with #2 how do i prep the floor for redguard, does it still have to be rolled on over CB over a sloped mortar base. or can i roll the redguard directly onto the sloped mortar base. (how is this properly installed at the drain, would i still need a double drain with weep holes).
4. I thought that thinset in order to adhere properly needed to adhere directly to CB. does thinset adhere as well to red guard (in the post you describe it as a rubbery finish once the redguard dries) i am just a little indifferent about trying to adhere ceiling, wall and floor tile to a rubbery backing, because of expansion and contraction between the two different substrates. have you ever had any problems with this?
5. this isnt a question, its a thank you for the vat of information you provide on this website, you sound like you know your stuff.
thanks,
Colin
Hey Colin,
1. Yes, it is always best to use a topical membrane (redgard) on a niche. It would be best to use it on the entire shower as well, but at least the niche.
2. Yes, redgard is approved for shower floors.
3. With a topical membrane on the floor you need to use a topical drain. Shluter’s kerdi drain as well as Laticrete’s hydroban drains work well. They do not have weep holes. You simply fabricate a single mud deck with the drain in it then install your membrane right over the top of everything once it’s cured.
4. Redgard, as well as all of the elastomeric membranes, are formulated to cure with microscopic pores large enough to allow cementious crystals to grow into them and small enough to prevent water from doing the same. So yes, thinset adheres to it as well as it does backerboard. I know it sounds counter-intuitive, but I’ve actually TRIED to pry tiles off a cured lamination (backer, redgard, thinset, tile) and it was just as difficult as the one on plain backer next to it – both tiles came off in pieces and the redgard was still partially bonded to the backer.
5. This isn’t an answer – just a thanks.