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.
can you use a drywall compound on top of redgard? If so, which one?
If you are just painting over the drywall compound (outside the shower) you can use any brand you want. Inside the shower it is best to skim-coat the redgard with thinset and paint over that. Thinset isn’t affected by moisture – drywall compound is.
I am tiling a shower and am using regard all around prior to tiling. What do I do where the shower pan and cement board meet?
Hi Peg,
Use silicone in that gap to seal between the tub and redgard.
Roger, loving the site. It’s nice to find people who enjoy doing things right. If I’m building my tub surround with Hardibacker covered with RedGard and I am also installing a Niche. Do I need to tape and mud all the inside and outside corners of the Niches? and then apply the RedGard?
Hey Brad,
It’s not technically required as long as your seams are tight enough to bridge them with the redgard without gaps, but it’s always a good idea. I do it because if I don’t my OCD murders me in my sleep.
Roger, really enjoy your site, it was a great resource for my last tile project and have a couple more questions for new project. I purchased a Noble pro-slope tub replacement kit for a walk in shower install. Unfortunately it does not state whether or not the slope has to be adhered to concrete floor or just floats. Also, I will be putting a membrane on top of slope kit and am wondering if the membrane gets adhered to this slope or just floats on top until final slope are added. Last question, do wall tiles always have to go on before installing floor tiles. If so, what is downside if floor tiles are installed first. Thanks for your help.
Hey Mike,
Noble does not state whether or not to adhere the slope to concrete (I haven’t used it) but I would be inclined to adhere it to a concrete substrate with thinset. The membrane simply sits on top of it – it is not adhered to the slope. You can do floor tiles or wall tiles first – your choice. I actually prefer doing the floor first.
Hay Roger, i live in an old farm house and i want to put tile on the 3 walls around my tub.the walls are just sheets of bordes. can i use the RedGard on it or do i need to put somthing over it,
Thanks for the help,
Bonnie
Hi Bonnie,
You need to replace the boards with an approved substrate for redgard. In most cases that would be cement backerboard like hardibacker or durock.
Hey Rodger
Do the corners in the shower where two cement backerboards meet also have to be meshed and taped over with thin set
Hi Germain,
Yes, anywhere the backerboards meet. The idea is to end up with one large monolithic structure.
Thank you for this write up – I’m diving head first into my first tiling job and getting my hands on as much information as possible.
That being said – I hope you can help me answer some VERY basic questions & confirm that I’m about to do this right
– I ripped out my old shower surround & realized how much a home is just smoke and mirrors
– I will SKIP putting up a vapor barrier (such as roof felt or plastic), because I’ll using RedGard
– Instead, I’ll go directly to putting up Durock (leaving 1/4″ space at the bottom where it meets the shower pan)
– After the Durock is up and screwed into the studs, I have to tape the seams with a 6″ wide alkali-resistant fiberglass drywall mesh tape. Would i be correct to tape ALL seams, or just those in the vertical corners?
– Do I then put thinset over the fiberglass or a type of mortar? If the latter – any suggestions?
– Next, put a bead of silicone into that 1/4″ space at the bottom
– Wait until all of this dries
– Go nuts with the RedGard. Twice. Drink between coats.
– After the membrane drys, “snap” in level guide lines or use a laser level to keep me on track (all those adult beverages between RedGard coats will be in full effect now…)
– Then apply thinset & stick on the tiles in 3′ x 3′ sections
– Grout
– Clean
– Revel in my handiwork
Thanks again for putting up this info – I really appreciate it
Hey James,
Yup, you have it. You want to tape all the seams (leave an 1/8″ gap between sheets so your thinset has space to fill and grab as you are taping) and use just regular thinset over the tape.
See, most people forget to drink. That’s just taking all the fun out of it! Well done!
Ok, this may be a dumb question.
We have redgarded our tub surround walls, siliconed the gap between the redgarded denshield and the tub, and we are ready to tile. All the demos and videos we’ve seen about “how to tile a tub surround” involve screwing a piece of wood around the tub to ensure the 2nd row of tiles is level, and then removing the wood and going back and tiling the first row of tiles after you’ve tiled everything else.
Problem is, I don’t really want to screw into my freshly waterproofed tub surround! I figure I’ll have to go back and waterproof over the screw holes and let that dry before I can finish that row, which is annoying. How do you normally ensure your tiles are level?
Hi Kate,
I don’t do it that way – and I hate it when people suggest it. Find the lowest point of your tub rail and measure up one tile from that. Then draw a level line all the way around the tub at that height and cut your bottom row to that. You can then just stack all the rows on that and everything is level.
Roger, I tore everything down to studs and thought I was doing it “right” but I forgot to silicone the Denshield edges!
I have all the tile up and the shower grouted! I used a premixed thinset and everything is turning out great! The last thing I want to do is rip it out! How bad is it that I fogot the silicone?
Hi Amy,
Well, your shower substrate isn’t totally waterproof, but it’s a hell of lot better than no type of waterproofing at all. It may be fine and it may not, no real way to tell. You may as well leave it and replace it only if you begin to have problems, it’ll be the same amount of work at that time anyway.
Thanks bunches Roger! Confirmed my thoughts and maybe I will be more ready to tackle it again after a long rest!!!
Hello,
I have a bathroom shower that is on a concrete subfloor which I leveled with Level-Quick. The walls are Durarock taped with alkali-resistant glass fiber mesh and the walls and ceiling are covered with a thin coat of Custom Building Products VersaBond Flex thinset. I will slope the floor 1/8″ per foot toward the drain with a moist mixture of one part cement / four parts sand for the shower pan.
I would like to use Red Guard Waterproofing Membrane to cover the ceiling, walls and floor of the shower. I’ll probably use at least two coats, most probably three coats, of Red Guard and I will brushed on.
>>> Do I need to wait 28 days for the one part cement / four parts sand to cure before applying the Red Guard to the shower pan?
>>>Can Red Guard be diluted and applied as a primer coat? If yes, what can be used to dilute it?
>>>Once the Red Guard coats are applied to the shower pan is it necessary to again slope the shower pan with one part cement / four parts sand: a sandwich of the first slope shower pan covered with Red Guard and covered again with the a second slope shower pan?
Thanks for help, ART
Hey Art,
You need 1/4″ / foot for your shower slope, not 1/8″. You do not need to wait 28 days. Each manufacturer has a recommended time to wait before using the product, I THINK redgard is 72 hours, but you may want to call the 800 number and ask. Yes, if you are using durarock a primer coat is a must. Mix the redgard 1:3 ratio with just water. No, the redgard is a topical membrane and does not require a top mud bed over it for the floor. The floor tile is installed directly to the cured redgard.
Hi Roger,
Thank you for your help. You confirmed my thoughts about Red Guard.
I will use 1/4″ per foot for the slope to the drain. I was thinking 1/8″ “pre-slope” and 1/8″ “final slope”. But without the final slope, I will use 1/4″ per foot “slope”.
I will wait at least 72 hours to make certain that the “dry pack” is DRY. Red Guard says “DRY” without a specific time.
I read in the Red Guard instructions after I published my question to the forum that using Red Guard as a primer could be 1 part Red Guard to 4 parts water. Either should work, the point being it can be used as a primer on pourous surfaces.
I will use thinset and attach the tiles directly to the cured Red Guard and not use a final or top slope.
Thanks Roger, your answer have given me more confidence in using Red Guard.
ART
I’m building a recess in the wall for soap, shampoo, etc. I screwed in two pieces of 2×4 horizontally between two studs, about 15 inches apart, with the front edge on the bottom “shelf” just a tad lower than the back (so water will drain out). Do I need to cover all the interior (wood) surfaces of the recess with hardibacker or can I just paint them with redgard and tape the joints before mortaring in some mosaic tile?
Hey Ken,
You need to cover the entire interior with hardi. Redgard isn’t made to go directly to dimensional lumber. It’s about the tendency of the wood to suck moisture out of it as well as the specific dimensional stability of bare wood. It moves – a lot. Hardi, even 1/4″, doesn’t seem like it would make a lot of difference but it really does. All those layer in the hardi move independently in the macro scale, thus stabilizing the substrate.
just want to thank you for all the info you post and the answers for all the questions.
this has been a very helpful site, thanks again
You’re very welcome Rob.
Roger –
Found your website and have been finding it extremely helpful. Here is my question:
My drywall installers have installed DensShield in my tub surround, and despite the manufacturer’s instructions not to use paper tape and joint compound, they have sealed all the seams and covered screw heads in this manner. I pointed this out and they basically shrugged their shoulders and said “all we have is joint compound.”
My plan to remedy the situation is to RedGard over the whole mess. I get the impression you don’t think RedGard over DensShield is a good idea. Can you elaborate? Would you try to get the joint compound off? If not, tips on prepping this surface for RedGard? Or other alternatives you would try?
Thanks again for hosting such a helpful site!
Hi Kate,
That’s why drywall installers do not install tile (that lasts, anyway).
I simply do not know how well redgard will stick to denshield. It may be fine, or it may peel off with a slight breeze – I simply don’t know. Short of removing that and replacing it correctly you can probably skim over the entire surface – joint tape and all – with regular thinset. Press it in there hard to get a good grab. Then after that cures paint the whole thing with redgard. I know thinset sticks to denshield very well – and I know redgard sticks to thinset very well. So – there you go. Very well. 
great! thanks for the quick response! we’ll try the “thinset then redgard over the whole mess” method and let you know how it turns out…
I had a plumbing contractor install my mortar bed and liner as well and re-center my P-trap in the now-larger shower area after removing the old corner shower basin. This is all on grade in a basement area. My shower is now 42×36 and square without any of the wasted space of the old corner shower where I had a few inches of silly dead-space behind the shower door and the 3rd wall and a triangular-shaped shower space.
Then I installed the cementboard over that myself and taped and sealed with grout.
Now it is time to seal the cementboard before tiling the walls and I’m unsure of how the moisture barrier works at the bottom. Isn’t it possible for the moisture to work its way into the bottom edge of the cementboard where it sits on the mortar bed and then work its way up the substrate under the Redgard until it gets above the rubberized outer liner that stops 12″ up on the outside?
Should I paint a little bit of Redgard out towards the drain on the floor a few inches to stop this?
I know I don’t want to make a sealed sandwich of the floor mortar but it seems to me there is nothing really sealing the junction other than gravity. Is this right?
Hi James,
You taped and sealed with thinset – not grout – right?
Cement board will wick water (what you are describing). If you do not have a gap there to install silicone then yes, you can paint the redgard 2-3″ onto the floor without creating a moisture sandwich. Ideally there should be about 1/8″ space between the mud bed and backer board and that should be filled with silicone.
I applied Redgard over Durock (smooth side out) on tub/shower walls but forgot to moisten the Durock prior to applying the first coat of Redgard. Now I’m concerned about how well the Redgard is adhered prior to putting on the tile. It seems OK, but I want to be sure. Am I just being paranoid? If I need to start over with the Redgard, how would I even go about doing that?
Thanks in advance,
Erin
Hi Erin,
It may be fine but I really have no way of knowing that. Try to peel away a small portion in a top corner and look at the durock beneath it. If it has a pink ‘hue’ (redgard residue in the pores) then it will likely be fine. Sometimes you won’t even see that, though. I would say it will likely be fine as long as you used a brush or roller to apply the layers and not a trowel. With a trowel it is much easier to get a flat layer without getting a good grab in the pores.
The Laticrete website says the 9235 should be applied over a smooth surface….does that mean Durock would be too rough and need to be smoothed out first. I also seems that is a 2 step process…first the “paint”, then a waterproof membrane, or is the membrane for something else?
The 9235 requires mesh or fabric reinforcement at all plane changes – that’s what the membrane is for. You can apply it to durock but you would need more layers to ensure proper coverage – durock sucks moisture out of everything.
How thick do i put on the redgard? I put the first layer on and it didn’t even cover up the lettering on my hardibacker. Is that too thin?
Also, what do I use to clean up my brushes, clothes, wristwatch, and garage floor? Do I need some kind of solvent or paint thinner?
Hey Ken,
You want it about the thickness of a credit card. Keep putting it on until you can’t read the writing. The first layer normally comes out thinner due to the substrate sucking moisture out of the redgard. After the redgard cures you can normally peel it off of anything it’s not supposed to be on – your wristwatch, garage floor, dog, etc. I’m afraid the clothes are likely now work clothes or rags.
I have just finished putting up my durock and taped and bedded the seams. now i want to make a shower bench out of cement blocks. my question is do i put the redgard on the walls and let dry then construct my bench. Or do i construct my bench then redgard over walls and bench together.
Hi Carolyn,
Technically either one is just fine. I prefer to build it first then redgard everything, that way no water gets beneath or behind your bench at all since it’s all waterproof.
Your website has been an extremely useful resource for my remodeling project. I am confused by all the information out there on liquid waterproofing membranes. I plan to buy either Redgard or Laticrete Watertight simply because they are easily available at the local HD or Lowes. But, I cannot figure out which is better. Is there any difference between the two? If so, which one works better? Thank you in advance for your response.
Hey Rick,
If you ask 100 contractors that question you’ll get 50 of each answer.
I’m in with the guys that think Laticrete is the better product. When it’s all said and done they both work well and do exactly as they state they will do if installed correctly. I simply prefer Laticrete products over any other, even though they ARE NOT readily available in my area – I need to drive 65 miles to buy all my stuff. I do it anyway, that’s how much I prefer it.
While starting to lay tiles on walls around a tub, the general advice I read is to start with the second row supported by a straight edge at the bottom line where the second row begins. I also notice that the straight edge is installed using either screws or nails. Wouldn’t these screws/nails puncture the membrane? Is it okay to fill/cover the hole with 2-3 coats of membrane before the first row of tiles are installed? Thanks for your response.
Hey Rick,
A lot of guys do that. You can fill / cover those holes with more liquid before installing the second row. Filling them with silicone works as well.
I have started installing 10×13 wall tiles over 3 coats of hydroban. One of the corner tiles appears offset, i.e., the tile spacing is wider than the other tiles. It has been about 48 hours since installation, and I have not grouted. If I remove this tile carefully, will I damage the hydroban? If I do damage the waterproofing membrane, can I add a few more coats to patchup? I am tempted to leave it as is assuming that grouting will mask the error – this is the conclusion I came to after several beers. But, your thoughts are appreciated.
Hey Rick,
Beers always get the ideas flowing, don’t they?
Yes, you can remove it. Yes, you will likely damage the waterproofing. And yes, you can simply paint more layers over it to repair the damaged waterproofing.
Have a beer!
if i have a shower liner on my preslope. can i or should i apply redgard to the top of the shower floor.
Hi Carolyn,
Nothing is needed on top of the mud deck if the liner is installed correctly. It will create a ‘mold sandwich’ and render the weep holes useless. Just the deck mud and tile.
Hey I installed one coat of red gard and alkali tape before I skim coated on thinset can I just skim coat thinset on now and reapply the redgard?
Hey! Yup.
Thank you!
I am tiling a kitchen backsplash. I installed Hardibacker and hired someone to mud the drywall in the room. Well he put drywall mud over the Hardibacker too! Can I Redgard over the drywall mud on the Hardibacker and then tile? Is there some way to wash off or sand off the mud so the thin set will adhere correctly? How can I fix this?
Hey Chuck,
On a kitchen backsplash yes, you can apply the redgard over the wall mud. You can sand down the mud if you want, it’ll remove it all except in the seams. Entirely up to you. It will be just fine either way.
Would that be a no for a tub surround? Unfortunately I was not home when the contractor splattered heavy knockdown texture 10″ onto my permabase. He just might have ended up splattered across my front porch. Do I need to scrape it all off before redgard and tile?
The texture needs to be at least scraped off level with the face of the backer, then sponged down to ensure there is no loose powder on there when you install your redgard. Other than that it’ll be fine.
Thanks Roger. Soon as I’m done scraping n sponging I’m gonna try your bullseye method. My first time to tile a shower ceiling.
We have put redguard on cement on walls before tiling, but noticed that contractor left a few small pinholes in redguard before tiling. Will that create a problem, as he did not go back and fill in the small tiny pinholes as prescribed on the spec sheets for redguard. Any advice on how to tell if redguard has been properly applied would be greatly appreciated.
Mirka
Hey Mirka,
The only way really is to simply check closely for pinholes and fill them if found. The possibility of problems relies on the amount of potential damage should water get into the pinholes. Obviously this is diminished when installed over a concrete wall as opposed to a wooden substrate covered by gypsum or cement backerboard. The pinholes should be filled, but it isn’t as dire as it would be over a wood-based stud system of a normal wall.
Hi Roger,
I had left a message in December and am just starting to tackle my steam shower now! Damn I hate this real-life thing!
Anyway, how it sits right now is the shower is framed, insulated and the plumbing is roughed in. My questions are around where to go from here. The plumber did also put black membrane, on the lower portion of the shower stall, with the name “LynCar” stamped on it. It’s a plastic-y, rubber-y texture and seems to be pretty durable. We’ve tested for leaks and all seems good.
Since this is a steam shower, the plumber mentioned that I’ll want to continue up the walls and onto the ceiling with the same membrane, working from the lowest point, up to the ceiling, to maintain a proper overlap. Then put cement board over top to put my tile up.
Now, he’s affixed the membrane he did with a short, wide-head nail, almost like a roofing nail and has the corners folded in very neatly. Can I use the same nails to do the rest of the membrane? Then, do I us Redgard, or similar product, to paint over the nails/screws, and all the corners to get a good seal? Do I need to seal the nails in the membrane AND the screws in the cement board?
Also, I’ve read where some guys are sloping the ceiling to prevent dripping and others say the ceiling will drip no matter what. What’s your school of thought on this?
Lastly, what’s the best method of me doing a couple of shower niches? Just custom frame them and use the same membrane, then cement board, RedGard, Tile? Any suggestions would be greatly appreciated.
Thanks for the time. I look forward to your reply.
Regards,
Barry
Hey Barry,
Lyncar liner is made specifically for shower pans. As far as I can find from their literature and all available info online that’s all it is made for. I see absolutely no reference for the liner to be used as waterproofing behind the wall substrate. The installation literature shows what most liner specs show – tar paper (roofing felt) lapped over the liner with the substrate in front of it, and tile installed. I would not use it for your wall membrane. If the plumber does that – let him do it, and warranty it for you.
You can use a topical membrane rated for use in steam showers, like hydroban, 9235 or redgard. All of which require a vapor barrier behind your substrate in addition to the membrane on the substrate. At the bottom of Laticrete’s technical design manuals page you will find a pdf about steam showers and rooms. Read through that and it’ll give you a load of information about your installation.
Hi there Roger
I’m redoing my bathroom, installed new bathtub and used hardie backer on all the walls and ceiling, I’m going to be tiling the walls. I’ve taped and thin setted all the seems, but I’m not sure if I’m ready to apply the red guard yet. Question 1 How smooth do the walls have to be for the tile? I tried to fan out the thinset over the seems, but there is still a step there appox 1/16″. Do I need to mud the wall to smooth the seems out more? Question 2 I was told that if I’m going to tile over the red guard on the walls that I need to put put horizontal grooves through the red guard for the mastic/thinset to be able to adhere to and not slip downward. Is this correct or do I just paint smooth and tile over it that way? Thanks in advance, and I’m glad I found this web page. Mike
Hey Mike,
Provided you are using a 1/4″ x 1/4″ trowel or larger (which you should) the 1/16″ isn’t gonna make any significant difference, there will simply be a thinner layer of thinset in that area.
And… who in the hell told you that???
That’s a new one on me. Two things wrong with that – first, mastic is never to be used over a topical membrane (or in a shower) and secondly – grooves in your redgard will do nothing but compromise your waterproofing in those areas and make your wall look funny. Grooves in the redgard will not prevent tile from sliding. You can either start at the bottom and stack them up – no sliding. Or you can use a non-sag thinset – no sliding. Just paint it smooth and tile away.