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Waterproof Bathtub Walls with RedGard

Water can find the smallest space in a bathtub or shower space and create a big stinky problem over time.

Unfortunately, I’ve been the recipient of many aspirins because of water leaks not only in our own houses but in multiple rental homes.

But it doesn’t have to be this way, especially if you’re thinking of remodeling your bathroom.

If you’ve been reading my blog you know that I’ve been helping my brother-in-law install a new bathroom. He decided to completely remove the existing blue bathtub (this blue must have been a popular color in 1975!) in favor of a tiled space.

The last post we put up about this project dealt with how we installed cement board.

Today I’m going to share how I made the cement panels completely waterproof using RedGard (1 gallon costs $50).

I’ve discussed RedGard before because it prevents water from seeping into walls & serves as a crack prevention membrane for the tiles.

I’m sharing this experience so that either you can waterproof your cement board or instruct your contractor to do what I did. Like I’ve said before, even if you don’t do this type of work it’s always a good idea to familiarize yourself with the process so that you know a good job is being performed on your behalf.

Being your own advocate is a smart thing in any endeavor and especially so in home remodeling.

I know this post will guide your bathroom renovation project in the right direction. If at any point you have a question or tip of your own, please type it in the comment section below. I love hearing about your projects!


Add Cement Board Tape to All Seams

The last few posts about this bathroom remodeling project discussed hanging cement boards to the bathtub wood studs. Cement board is the cheapest backer board for showers.

I also like KERDI-BOARD because it’s faster to install. Whether you’re doing a small bathroom remodel or a large project, the tips in this tutorial are great.

Adding self-adhesive alkali-resistant fiberglass tape to all the cement board seams is a really important step. This tape needs to be applied to every area where the cement board panels butt against each other or other sections of drywall/plaster.

I added tape to all the seams and then used a thin layer of thin-set to embed it onto the cement board.

The thin-set was the same kind used to adhere the tiles to the cement board panels and the consistency should allow it to just barely hang off a margin trowel or putty knife.

Smooth out the thin-set before it dries. Use a damp spong to feather the thin-set because any ridges or bumps will cause the tile to lay unevenly. Use a level to check and fix any peaks or valleys.

I also applied a thin layer of thin-set to all the screw heads in the cement board. By the time you’re done with doing all this, your bathtub space will look like the following picture.

The thin-set will need to dry for about a day. Once it’s rock solid take a level and make sure all areas where the tile will be placed on the cement board don’t have any peaks or valleys.

This is especially important if you’re installing subway tile showers. The smaller the tile the flatter the backer board has to be. Otherwise, the tile will be wonky and look super unprofessional.

Prep Work for RedGard

The prep work for RedGard is straightforward. Since it does have a thick texture, RedGard should be applied only to the areas where there will be tile.

Also, don’t get RedGard on the tub. I used blue tape along the edge of the tub where it met up with a cement board.

Then, I placed a piece of cardboard on top of the tub to further protect it from any RedGard drips.

The last step for RedGard prep is to dampen the area where it will be applied. I used a bucket of water and a sponge. Take special care to get the corners of the cement board damp as this is the location where you want the RedGard to really adhere.

Now the RedGard is ready to be applied. It’s actually a pretty fun process, but make sure to wear a respirator because it’s stinky.

RedGard Creates a Waterproof and Crack Resistant Membrane

Applying RedGard to any surface is super easy. If you can paint a wall you can use RedGard. And for this shower, we only needed one gallon.

There are two ways to get RedGard on cement board panels:

  1. Roll it on the wall with a 3/4 inch nap roller
  2. Trowel it on the wall

Use a good roller that won’t shed into the RedGard. I really like Purdy rollers and used a 3/4″ nap roller for this project.

The first application was put on vertically.

Use a paintbrush for areas that are unreachable with the roller. I paid close attention to applying a good coat of RedGard to all the corners and spaces adjacent to the tub since these are the areas that water likes to penetrate the most.

How long does it take for RedGard to dry?

I let this first coat of RedGard dry until the panels appear red in color. This took about 1 to 1.5 hours.

Drying time depends mostly on temperature & humidity.

And the surface will appear pink until the RedGard has completely dried.

When the RedGard appeared red and wasn’t tacky I applied a second coat horizontal to the first.

Again, as you roll it on the walls check to make sure there are no bumps or small lint boogers in the coating.

The end result should be a bathtub surround that is red in color.

The bathtub walls are now completely waterproof and the RedGard also serves as a crack isolation membrane. This means RedGard will expand and contract ever so slightly to prevent cracks from forming in the shower tile.

Keep in mind, that the thickness of RedGard should factor into how far to set a shower valve like the Delta R10000.

What’s Next

There are many ways to waterproof a shower, so pick the one that works best for you.

If you’re doing a bathroom remodel and need help, join one of Home Repair Tutor’s online courses and make your project easier.

Let me know if you have any questions and I’ll do my best to help.



RedGard Waterproofing

  1. SheilaG @ Plum Doodles says:

    Great info, Jeff! The guy who did our shower used red guard, but only on the seams. It was the first time I had heard of the product. Now I’m wishing he had done the whole thing like you did. Hmmm.

    1. Jeff says:

      The seams are definitely the weakest point where water can penetrate behind the walls. So I’m sure you’ll be fine. I just like to go overboard sometimes since I’ve seen a lot of circumstances where water has completely destroyed walls or ceilings. Using a product like RedGard allows me to feel a lot better about the remodel lasting a long time 🙂

      1. Jose A. Hernandez says:

        I had a shower remodeled about 1 year ago. The contractor used black roofing paper #30 all around the shower compartment. They started at the bottom and in one piece covered three walls, then, a second layer was placed in the middle with about 4″ over lap, and, thirdly, they covered the upper section with an overlap, covering three walls. Is this O.K.? I am remodeling another bathroom and I plan to use the same technique the contractor used on my other shower, except this one is a bathtub/shower.

        1. Jose A. Hernandez says:

          I forgot to mention, that after the black roofing paper, Durock was installed and then porcelain tile. I did not see or I don’t recall if the seems were covered.

        2. It’s pretty old school Jose. There are much better methods. I’d opt for Wedi or Schluter KERDI-BOARD instead of the cement board and roofing paper. Both are waterproof and provide vapor protection. Plus Wedi and Schluter offer warranties on their products. I doubt the manufacturer of the roofing paper will warranty agains water problems. In addition, Wedi and KERDI-BOARD are way easy to install. Send me an email at [email protected] and we can talk more about your options

    2. Robo Man says:

      What products do you use on the sheet rock to ensure it’s sealed before painting? Any type of special paint you use?

  2. Cathy says:

    Jeff, Would you suggest that we only use RedGuard on the seams and the area of the cement board above the tub flange if we are using Swanstone tub panels (x 3) for the tub surround. We are only going to use tile above the tub surround panels for a decorative look. Our contractor has never used RedGuard but I am wanting to use it for the reasons you indicated. Thanks, Cathy

    1. Hi Cathy,

      Thanks for your question.

      It won’t hurt to use RedGard on all the cement board.

      The contractor will have to buy a 1 gallon bucket and follow the directions for your particular situation.

      But the application is pretty easy. We rolled the RedGard on the cement board in a vertical patter, let it dry, then rolled on a second coat in a horizontal pattern.

      It provides a level comfort in that you know your cement board is absolutely water proof.

      Let me know if you have any questions 🙂

  3. Mark S says:

    Hi Jeff, I enjoy your articles. They are a great help and inspiration:)

    I have a shower that I am building after tearing out the old one. I have the walls installed (Durock) and taped already. I poured my own shower pan as well, which as you know, involves using a shower pan liner sandwiched between two layers of mortar. If I Redgard this seam (where the Durock meets the pan), this means it will be watertight all the way to the drain. In this case, this sort of defeats the purpose of the liner in the pan (which is to catch water that drains through the tiles and grout and channels it to the weep holes in the drain). So, The question I have is: Do you tape, thinset and then redgard where the Durock meets the shower pan?


    1. Thanks Mark for your question, could you send some pictures to [email protected] so that I can see your setup. When in doubt always call the manufacturer of the shower pan because they can tell how to properly install their product.

  4. AceoStar says:

    I noticed you only did the redgard up to about a persons standing height. What should I do at the top few feet to protect the drywall from splashes?

    1. Great question, the best thing you could do is tile the entire way up to the ceiling. You could always use RedGard on the drywall itself. But before doing that call Custom Building Products (the maker of RedGard) and ask for their opinion. Their number is 800-282-8786. Anytime I’ve called their technical service line has been fantastic.

  5. Regina says:

    I need to make a repair to the wall that connects to the tub at the bottom of the wall…could I use Red Gard here?

    1. Regina, if you’re going to tile over this area then go ahead and use RedGard. But it’s not a good idea to paint over RedGard since it will be a rough texture. I hope this helps. Let me know if you have additional questions.

      1. Lenny says:

        We gutted a bathroom installed a shower pan over the plywood floor the red coat was applied .Am I now red to mud the tile or is vinyl also needed

  6. Bill says:

    Hey Jeff! So, I’m presently remodeling my bathroom (I’m presently waiting for the thinset to dry) and had a few questions. What is done with the gap between the pipes and cement board? Do I apply redguard to the pipe? And I plan to silicone the cement board to the bathtub, should I do that before redgard is applied?

    Thanks for the help!

    1. Nice questions Bill, sorry if I got to this after the thin-set dried!! You can add silicone caulk with Microban (DAP is my favorite brand right now) to the space between the cement board and pipes.Then add RedGard.

      Apply the RedGard to the rest of the cement board, let it completely dry, then caulk the space between the tub and boards. Hope this helps. You gotta send me some pictures of the finished project though ([email protected]). I can’t wait to see your finished project 🙂

  7. tom says:

    I’ve learned a great deal from your comments. I have already installed the green board and textured over the screw holes. My question is this: green board, hardi back and then Redgard, or green board, Redgard, and finally hardiback? My contractor says the green board gets the Redgard. What do you recommend? Thank you for your help.

    1. Hey Tom,

      Is the green board adjacent to the shower, i.e. next to the cement board? Also, are you saying that you used joint compound to cover the joint between the green board and the cement board and you’d like to know if you should RedGard the joint as well as all the green board & cement board?


  8. Todd says:

    Hey Jeff,

    This is a great site and thanks for providing all the steps to install tile.

    My problem is I have fiber-taped and thinsetted the joints and corners but I have a few peaks and valleys after the thinset has dried. Should I sand these areas down a bit with a coarse grit sandpaper (like 25 to 80 grit) or should I use float these areas with thinset as you mention above:

    “If you encounter a peak/valley problem between cement boards and drywall use lightweight setting-type joint compound to level the transition. If you have a peak/valley issue within the cement board field use thin-set mortar to level the area.”

    I figure as you had mentioned it will take a few passes with joint compound and thinset to have the area flat and prepped to install tile.



    1. Hey Todd, thanks for the question. You could either sand or float the area. But no matter what, make sure it’s as smooth as possible since this will affect the look of your tile.

      And if you’re using small tiles, like 3 x 6 subway tiles, you’ll definitely what these bumps smoothed out because the grout lines and lippage (when two adjacent tiles have different heights) could potentially make you nuts. So the bottom line is this, if you want any AWESOME looking tile job, ensure the substrate (concrete board and surrounding joints) are absolutely as perfect as humanly possible.

      Use a torpedo level or 4 foot level to check for any peaks or valleys before moving onto the tiling or waterproofing step.

      And one more tip, buy an extra blade for your tile saw. It might cost you $30-$40 extra but once you start seeing the cuts looking sloppy change out that blade. This will make your tile job look uber-fantastic.

      Hope all this helps buddy.


      1. Megan says:

        Hi Jeff,
        If we’re using 3×6 subway tiles in our shower, how critical is it to float the surround walls. The dips are at worse, about 1/8″ over the longest vertical height of the walls. We don’t have any sharp, pronounced bumps.

  9. CM says:

    Pretty sure you’re supposed to put the backerboard over the lip of that tub.

    i.e., it should be resting on the deck of the tub, not on the top of the lip.

    Hopefully you did that and it only looks like it’s done the wrong way in the photo.

    1. Yes CM, I agree that the cement board should be over the lip and I’ll add a second tip: ensure the cement board is plumb!!

      Otherwise the tile will look off kilter. The pictures probably don’t show all the well but the cement board is over the lip and not resting directly on top of the tub but about a fraction of an inch off of it. There’s caulk between the cement board and tub. After the tile was installed a second bead of caulk was applied between the tile and tub.

      Water can create quite a mess, and we wanted to ensure the tile would last for a very long time 🙂

  10. Bob says:

    Can Redguard be applied over modified or unmodified thinset? It appears you chose unmodified thinset for the backerboard seams- was this intentional knowing that Redguard would be going overtop?

    1. Fantastic question Bob.

      I actually called Custom Building Products (they make RedGard) before this installation and asked them about which mortar to use. They recommended FlexBond polymer modified mortar. This mortar also meets ANSI A118.4 and ANSI A118.15 standards.

      So, you should be fine using any polymer modified mortar that meets those specific standards.

      Hope this answers your question.

      Are you going to be doing a tile job soon?

  11. Alex says:

    Thanks for this great information.
    My question:
    I have installed a new bathtub, and plan on using Redguard on the Durock around the Bathtub. Now what do you do to the drywall in the rest of the Bathroom (other than the Bathtub area) regarding waterproofing. Do you put plastic foil behind it or just use latex paint? I will tile in the bathtub area, but paint the rest.

    1. Great question Alex.

      I just use latex paint on the rest of the drywall. If it’s new drywall make sure to apply a primer first, like Kilz primer. Then paint.

      Ask the local paint store for their recommendations on paint for bathroom walls and ceilings. A lot of paints have additives that help ward off mold and mildew. I like using a semi-gloss sheen so that if there’s any moisture it will wipe off the wall.

      But you should also have a ventilation fan that will suck out all the moisture and out through the roof or wall to the exterior. This will help a ton.

      Keep me posted on your bathroom project, can’t wait to see the progress 🙂

  12. Glenn says:

    Question regarding vapour barrier. Did you use vapour barrier behind dura roc ? I read somewhere if you apply a membrane or water sealer than you can create a vapour sandwhich. Is this correct? Or is there no requirement for vapour barrier when you use this red guard

    1. Hi Glenn, great question. We read a lot about the vapor barrier issue. For this project the tub was actually in the middle of the house. As such we chose not to add a vapor barrier but rather let the walls breathe naturally. So we added the cement board then RedGard and that was it.

      Now if the tub was on an outside wall it brings up a ton of other questions. Especially if you live in an area that gets extremely cold or hot. And yah, I’d be concerned with the vapor barrier creating a sandwich effect and trapping moisture in the walls if RedGard was used.

      I’m no vapor barrier guru but would think the RedGard acts as a vapor barrier and therefor doesn’t require any additional plastic behind it. This is actually a great question for Custom Building Products, the maker of RedGard.

      If you’re going to do this kind of project give their technical assistance line a call cause they’re pretty darn responsive and give good advice.

      Hope this helps Glenn.

  13. John Ballou says:

    Great info on your site!
    I gathered from some sources that you can apply the seam tape with RedGard instead of thin set cement. I wonder if you have objection there?
    Thanks very much! Keep up the good work!

    1. Thanks John for your question.

      Are you saying to apply the RedGard to the corners and seams then embed the alkali resistant mesh tape?

  14. Jeffrey Paton says:

    Hey Jeff,
    Noticed that you filled your cement board corners with tape and thinset. My glass tile supplier recommends filling the corner voids with silicone in order to provide a good expansion joint for the glass. Would taped thinset negate the expansion capability (maybe some tiles do not require protection where the plane changes?)
    At any rate, can I fill the corner gap with silicone and then brush a couple of good coats of Redgard on them?
    Thx, Jeff

  15. Frank says:

    Did you use thinset mortar or joint compound in the transition from Cbu to sheetrock/green board. And did yo use the Cbu joint tape or regular joint tape.
    Also I am doing this on an exterior wall. Since I can use red guard on the green oars above the tile what type of vapor barrier do you recommend. I plan on using a good primer with some vapor barrier components and then laytex pain.

  16. Chris says:

    Hi everyone, I hope some of you can help. I know this is not really the place but I hope someone can advise

    I had two tub with tile surrounds completed, one looks terrible so it neds to be replaced. Their other looks great but I am going with a new contractor and he says we should redo both. We have metal studs – we use hardiboad but I don’t think that the seamed them. The one thing I am wounding is they use this brown fiber like boss for a vapor barrier, it’s sort of like a compressed board but I don’t this its waterproof. How much of a concern is this. Again this shower looks great and we are already having to repay to fix one. Can anyone advise

    1. Thanks for your tub question.

      Have both tubs already been torn out and now you have hardieboard up and are ready to tile?

      I’d probably not use hardieboard in the tub but instead opt for standard cement board like DuRock.

      All seams should be sealed with alkalli resistant mesh and embedded in thinset mortar.

      Then you’ll have waterproof the DuRock with either RedGard or Schluter Kerdi.

      RedGard is cheaper than Kerdi but if you can afford Kerdi do go that route.

      Kerdi serves as a vapor barrier of sorts but no matter what you put up as a vapor barrier there will always be a certain amount of vapor that penetrates the tile and goes into the stud bay.

      The trick is to make the rate of vapor infiltration be lower than the rate of evaporation and Keridi or RedGard will help with this 😀

  17. Jenn Davies says:

    Someone asked about protecting the drywall from splashes. I have tile in the shower and on the floor, but there’s still water damage happening to my trim. Especially right next to the bathtub– it’s noticeably warped. Is there a way to waterproof that?

  18. Zoe says:

    I’m just about to tile two bathtub surrounds all the way to the ceiling. How much red guard do I need? Thanks!

  19. Ward says:


    I have just completed a shower install that replaces a tub in a highrise apartment… The setup is a shower pan for the floor, and the walls are Hardybacker, with Reguard from floor to ceiling – on top of that is ceramic mortar and ceramic tiles.. This is my first shower install and as I sit here I am worried that the 100% covering “layer” of Reguard might actually be a way for my tiles to fall off one day since they are not “directly connected to the Hardybacker… In other words I’m thinking I should have only used Red Guard in the most vulnerable areas and allowed the mortar mix to connect directly with the Hardybacker board for a secure connection – Question is are we sure a “layer” of Red Guard is safe and won’t prevent the motar from setting properly against the wall?

    Believe me I hate posing this question because I just finished ceiling my grout today…

    Thanks in advance for any assurance…


    1. Great question Ward and if you’re concerned I want to reassure you that if you followed the directions you should be good.

      I personally haven’t had any issues with tiles becoming loose. Although I also like to back butter the tiles with thin set and apply thin set to the walls.

      This ensures a good bond as long as the thin set was properly mixed.

      If you’re worried about RedGard here’s a link to their product page along with some videos

      Send me some pictures of your tile job, I’d love to see the final results. I’m sure you did a great job 😀

  20. Tom says:


    Great tips and advice. I am puzzled on one bit. In the post where you had the backer board going up, you stated it should go above the lip of the tub. For expansion and movement. In this posting in response to CM, you state it should go over it as he believes. Which view is correct? Thanks!

  21. Mark Di says:

    I am wondering if you can help me. I’ve installed Durock Cement Board in my shower/tub surround. I’ve taped it, as you’ve shown. However, now that it as set a few days the Durock is cracking in many areas. Is that normal, and will the redgard help make this not be an issue once I lay my tile? Also, is it normal to have the Durock crack? I have not seen that before. Thanks for your help!

  22. Amber says:

    Can you use Red Guard on the floors of a shower stall before laying the tile down?

  23. Carol says:

    Having small shower redone w/Swanstone glue up panels. Can Redguard be applied to the green board underneath? Will glue bond to Redguard? Thanks

  24. Mehtap Baki says:

    Hello Jeff,

    I’m remodeling my guest bathroom, I have questions about it, it is my first project, the contractor that I’ve hired approved by BBB was very bad experience. So I have to be careful now, lost money and time, plus stress. I would like to show you some pictures so you can answer me better, how can I do that?

    1. Sorry to hear about your experience. Although I will say that good contractors aren’t going to be cheap. Feel free to post your pictures over on our private Facebook group, you’ll have to join and I’ll approve you.

      Here’s the link

  25. BS says:

    I have started a bathroom remodel. Used 4 coats of Redgard and am now ready to set the wall tile. Modified or Unmodified thinset for wall tile is the question. After much internet research and your suggestion I called Custom Building Products
    1-800-282-8786 Technical Service and they recommend MODIFIED thinset for wall tile installation. Thanks for your time and help, you have a great website. BS

  26. bill says:

    Hi jeff, been following your tutorials lately, top notch stuff. My bath rem. Is going well. First one and lots of questions. But the ones im concerned about are about properly sealing tub to tile. I read a post in your red gaurd tutorial, you mentioned that the cement board SHOULD overlap the tub lip, well unfortunatley I did not do that and Im curious to know how I should aproach this remedy before I tile. My cement board is slightly thicker than the tub lip so im gonna end up with a pretty good size gap behind the bottom inch or so of the tile. Should I pack that void full of silcone adhesive or mortar before I red gaurd. Thanks for all the help jeff.

  27. Jane says:

    I am in the process of redoing my bathtub tiles. I successfully removed the old tiles without causing any damage to the wall behind. I really do not want to go down to the wall studs. How would I properly prep the wall before I put up my new tiles?

  28. Cheryl says:

    Hi, I’m redoing my shower. I purchased purple board forcthe walls, they are cur ant ready, I know I should have used packer board but, too late for me. I pkan on tiling, can I use packer screws to appky the purple board, can I apply a thinset over the purple board and the use a waterproofing membrane??? Thanks

  29. Thanks for this – I’m waiting for my cement floor to cure in my shower. Can’t wait to see the pink-red transition…

    I’m wondering if I need to apply the Redgard all the way to the ceiling, or only to the lower ~3 feet…? (cement board against studs). I can’t find a solid answer online.

    And lastly – the price you quote in the title is only valid for the US… since HD sells 1 Gallon pails of Redgard in Canada for $90 due to the poor exchange… Which makes a bigger impact on the wallet should I need to buy a second pail! (47×33 shower base, suspended ceiling at around 91″).

    1. Thanks Dwayne, yah the title probably depends on how much RedGard you’ll use and which country you live in.

      Send me a picture of your shower and maybe we can figure out what’s best for your waterproofing.

      My email is [email protected]

  30. Hello,
    I planning to remodel my main bathroom in a few months. Thank you for your information regarding Red Guard, l will make sure this process is included for no water damage.
    Thank you,

    1. Glad to help Hermelinda, RedGard is a pretty great product.

      Hydro Ban and Ardex 8+9 are great products as well.

      If you have any questions please let me know.

  31. Paul :Rick" Nason says:

    Hi Jeff

    Too many opinions here at work on my shower install. I will be removing my Kohler tub surround and replacing it with a Kohler shower base with a seat. I will be using DUROCK on the surround. Do I have to go to the ceiling with the DUROCK if I am using 16X16 granite tiles or can I go two levels high at 72″ and still tile to the ceiling. Either way I will REDGARD the area behind the tiles for uniformity and protection.

    1. It’s not a bad idea to use Durock up to the ceiling Paul. Then RedGard all the walls.

      You might also like Wedi or KERDI-BOARDs because you don’t have to use RedGard on them (which can be stinky).

      Both Wedi and KERDI-BOARD are easy to install and provide warranties, which is always a great thing.

      I’ll send you an email to make sure all your questions are answered.

  32. Sharon L. says:

    Thanks for your excellent advice, Jeff. I have a tip that will minimize the ‘red boogers’ left on the surface from using the new paint roller. Before dipping the new roller into your paint, wrap the entire roller in blue painters tape. Then remove the tape, and you’ll also remove most of the lint from the roller and minimize those little red boogers!

    1. Thanks Sharon, great tip

  33. Tom E says:

    I am building a large soaking tub for my daughters family.I have built a 80×48 enclosure out of reinforced wood framing with 1/2″ cement board on outside and inside walls of the tub. The tub is on a concrete slab to support the weight. I want to know if Red Guard
    system or any other waterproofing can be used to waterproof both the tub interion walls and slab before I install tile. Hope you can help
    Thank you
    Tom E

  34. bob d. says:

    Transition between backer board and dry wall. I can’t tell exactly how you handled that. Did you use thin set or drywall compound to fill the gap? I have a flat surface where the tub wall meets the bathroom wall. I also have an outside corner bead for the same transition between materials on the other side of the tub. Since I took the backer board to the ceiling, I guess that is another transition.


  35. Louise says:

    Jeff, thanks so much for all you pictures. I came upon your website after I had rolled the first coat of Redgard on my cement board. I did not dampen the cement board beforehand. Will this ruin the job and cause the tiles (or actually the Redgard membrane) not to adhere and fall down?

    1. You should be okay Louise. Let the RedGard dry and feel around to see if it’s okay and stuck to the cement board. It’s pretty sticky. Keep me posted 🙂

      1. Louise says:

        Jeff, thanks so much for your quick response. I was starting to freak out.

  36. Chuck Uebele says:

    As far as Redguard being put outside the tile area, I do that with a paintbrush. This leaves a smoother surface, which I can paint over. I had a lot of issues with crumbling plaster next to tubs in my rentals, and this helped.

    1. Thanks Chuck for that tip. I’ve had the same problem with plaster and drywall. RedGard is a great product, might have to try that. I’ve also used KERDI-BAND over the drywall and smoothed it out with setting type joint compound.

  37. John Mitch says:

    Jeff – as usual great info – but I share Tom’s question regarding whether cement board should stop just before the lip of the tub or should it go over the lip of the tub by maybe 1/8″ of the top of the tub. I read where you don’t want to go over the tub lip due to expansion and contraction, as well as having an issue with a non-flat surface for the tile. But if you stop above the tub lip, then what do you do to fill the void behind the tiles and the tub lip?


  38. Adam says:

    Nice article. I am finishing up a DIY project and letting a professional Tiler install the backerboard and tile. We have the 5 ft backerboard around the 14″ tub, total height of 74 inches above the floor then transitioning to moisture resistant Drywall. The plan is to float 2-3 rows of tile onto the green board, 3×6 inch subway tile. Tiler has installed the backerboard, drywall, mesh tape and thinset. He is going to use Hydroban to further waterproof the area before tiling. Is it ok to have Drywall compound underneath the tile? Seems odd to me to have a water soluble drywall compound, not thinset, under tile.

    1. Thanks Adam for asking about the tile. Any section of the tile inside the shower should have Hydro Ban underneath it and be set using a thin-set mortar. If you’d like you can send me some pictures via email.

  39. Tori Aaron says:

    We flooded with Hurricane Harvey. We hired (and later fired, but a little too late) a contractor to rebuild, and he used RedGard for our shower walls. However, he didn’t cover the bathtubs or surrounding floor. So now I have it all over my brand new bathtubs and floors. We are able to peel it up in the places that it’s thick, but we can’t seem to get it off in the areas that are thin. Do you have any suggestions on how to get it off?

    1. That stinks Tori and I’m sorry to hear you had a bad experience with a contractor. My best advice is to call Custom Building Products and ask them. They make RedGard and probably have a good answer. Here’s their number 800-272-8786

  40. Divina Martin says:

    Hello Jeff,
    Your videos have been extremely helpful but our back and forth with this bathroom has us wanting to run away from this renovation. Unfortunately, we had someone install our bathtub and they put Wonderboard behind the bathtub, not floating it at all. I know this is completely incorrect but with this being the 3rd attempt at fixing this problem and asbestos being the costly cause of this renovation..we are unsure what to do with out it costing us. Do we need to gut it all over again? Is there an alternative solution?

    1. Thanks Divina, just sent you an email with a good explanation of your options. It’s preferable to have the backer board sit flush or over the lip. The latter is feasible if the studs are bumped out using scrap plywood.

  41. JB KEPPER says:

    I have an existing shower…tile goes all the way up to the ceiling. I want to extend the area ..raise the shower opening to 3′ to make a shower/Roman tub combo…
    Any suggestions.

  42. Gary Rousseau says:

    Morning Jeff,,ty for your time,,,my questions, ,ok doing wife’s bathroom over,,,here is we’re I’m at,,I installed perma base cement board,,my seams ,corners all done with fiba tape for cement,,,I started taking out low spots in my wall ,,before I waterproof, ,,I was using thinset,,,,,,,I ran out in middle of doing this,,I started using mortar mix,,I had left over from my shower pan,,,,,Jeff I leveled 2 walls,,,,,I’m thinking of doing my last wall again in thinset, it’s easier to use,,,question Jeff,,am I going to have issues were I used mortar mix,it’s stil, cement and I’m waterproofing with Lowe’s mapie brand,,,after,,,the whole shower,,and floor,,,,,also cement boards are rough not smooth, I take it ,it’s for bonding better when I tile, ,using mortar mix kept it rough, do I need to shoot this out,or is a little rough better,,,,,ty so much ,,,your help here would ease my mind,

  43. Eve says:

    Hello Jeff. Thanks for all of the instructions. I have a question. Is RedGuard 100% waterproof over cement board no matter what thickness cement board, such as a 1/4 inch cement board for a shower wall, instead of over 1/2 inch thick cement board?

  44. Molly says:

    Hi Jeff,

    We installed .5” HardiBacker around the tub, posted off the top of the tub flange 1/8”. All Hardi seams are tapped with thinset. The first coat of RedGuard is applied.

    What do we do at the transition between the cement board and the tub? Should we tape and mud between the two and cover with redguard? Leave as is? Can we even use (modified) thinset over RedGard?

    I thought we just started tiling now, but this 1/8” gap, which grows much larger at the front left corner of the tub (big gap), is concerning. In your tutorial above you have your HardiBacker in front of your tub flange, not above it. In your Ardex tutorial, you have the cement board above, use caulk in the gap, then Ardex all the way down to the tub flange itself.

    Let me know your thoughts – really appreciate it!!

  45. Nate says:

    Hi Jeff, your information has been invaluable. I have a question regarding corners where cement is on one wall and butts up against another wall with drywall, what do you do about the corner? Should I just use cement board tape and thinset on both the drywall and cement board, or should I use a vinyl corner bead and thinset in the CBU and Drywall compound on the drywall side? Thank you so much!

  46. Kevin Butler says:

    You guys provide amazing content. I’m putting in a full bath on a basement. It’s time to finish the shower. I’m using Durock, Redgard, and a Redi Niche. I have 2 quick questions…
    1. What are the acceptable methods to waterproofing the redi niche and Durock edges (basically around the niche)? Because I’m using Redgard, can I use mesh tape and thin-set over the seams and then paint on the redgard?
    2. What is the best way to transition between the green board drywall and Durock? Do I need to use mesh tape for this transition?
    Thanks so much.

  47. James says:

    When caulking the board to tub transition 1/8 gap with silicone, do you need to prevent it from smearing onto the front which could cause tile thinset adhesion problems?

    Also,what’s the lifespan of the silicone and wouldn’t you need to fully demo that wall to replace it?

  48. Eric Spring says:

    I have covered hardie board with Redguard. However the wife wants the walls painted now. She bought an exterior paint for me to paint the walls. Will this work. This is the walls around a bathtub that will receive the paint and should only receive some sp;ashed water occasionally

  49. Kimberly Bufe says:

    Hi Jeff! Good stuff here. I am completely remodeling our bathroom and as of now I’m just finishing up screwing in the last durorock piece. I have already chalked the 5’ piece and end piece. Will be calking the final piece today and finish taping. My question is the transition from the cement board to the green/purple board. I’m stressing out over it! I’d like to post a picture for your opinion. I plan to Redgard every inch of where the tile is going and I’ll snap a few chalk lines. But how should I make the transition seamless and ready for paint? I just can’t grasp the concept no matter what videos I watch! The hubs is assisting me with this but I’m having a hard time figuring out our “places” when it comes to this part of the job! Argh… I’m out of aspirin, lol… Its one of two bathrooms I’m doing, the second one is in dire need, this bathroom just “happened” during a light remodel as I noticed damage… And you know how THAT goes! Yep, complete tear out, walls tile floor etc… 😑

    1. Hey Kim, thanks for your questions. I’d be happy to look at the shower and transition via email. I’ll reach out and we’ll figure out a solution.

  50. Mike black says:

    Are used red guard on my entire shower surround after installing hardy backer did three coats of the red guard and then he used a mastic to me to hear my porcelain tile to the walls and I’ve had no problems whatsoever with the mastic why are people telling me that is not OK to install mastic in showers

  51. Tanner says:

    Love your videos!

    I have a question about putting red guard under the Schluter waterproof membrane. Will the thin set adhere to the red guard properly? I bought both, but I think I am just going to use the Schluter membrane. All the videos I have watched don’t use both, I just was curious if it was a good idea to use to water proof barriers instead of one.



  52. Themusj says:

    You mention “If you have a peak/valley issue within the cement board field use thin-set mortar to level the area.”

    I have a 3/32 valley a few place in my CB installation. By your comment, are you suggesting taking thinset and a wide putty knife and filling those areas?

  53. Cody Donelson says:

    I’m building a Roman Tub in my bathroom (I don’t want to have to knock out the walls surrounding the bathrooms to put in new tubs). Is Red Guard reliable enough to apply really heavily in the areas where there will be the most pressure (the tub area)? Could I negate the use of a waterproofing membrane by substituting it with Red Guard?

  54. Calvin says:

    Hi, Informative thank you!
    If I were to use a shower floor panel pre-fabricated, could I use modified thinset to secure it and then Redguard over it then thinset and tile? Or is the Schluter paper the only way to waterproof a shower floor panel?

  55. Jackie Garvin says:

    If you get RedGuard on the tub while applying it, what is the best way to remove it without damaging the tub?

  56. Matt says:

    Thank you for the write up, it has been VERY helpful. I’m currently finishing up my shower. I used concrete board, I’m doing the seams with tape and thinset today and will be doing redgard tomorrow/this weekend.
    My question, what about the concrete bottom of the shower? Should I redgard where the wall meets the floor? How far into the shower floor should I go? The entire floor?

    Thank you!

  57. Ania says:

    Can you paint over red guard?

  58. Frank says:

    Can you use redgard on shower pan instead of hot mopping

  59. Lenny says:

    We installed a shower pan painted if with red coat ,am I now ready for mud then I can tile or do it still need vinyl .?

  60. Dale M says:

    Ho Jeff ‘
    I’m am completely replacing a shower back to the studs. I have new Hardiboard and have used thin set on the completed parts (seams and screws). I had planned on using Hydro Ban for two reasons. #1; The Big Box building supply said I had to use different tape with Red Guard and I didn’t really need it over this tile backer board. #2; Hydro Ban was far better. Now for the added assurance that I will never have to replace this shower again, I decided to add a man tame layer. I’m finding Hydro Ban Is almost double $$ in my area.
    Can I just use Red Guard this Great article says or do I need to do something different for preparing the surface? What about other products out there like Hydro Barrier; Mapei Mapelastic AquaDefense, Durlock, etc.?? I don’t want to go back to replace seams etc.

  61. Dennis skorupa says:

    Can you use polymer modified speed set on red gard in a shower

  62. Caitlin Heckathorn says:

    Two questions…
    1. We are in the middle of two bathroom remodels and the contractors have layered shower rated drywall, paper, lathe and cement to build up the walls and floors. Should Redguard be used over the cement before lying the tile? Or will that create a vapor/moister barrier issue? Both bathrooms have 1 or two exterior walls.

    2. What would be the proper way to install tile on walls in the bathroom that aren’t the shower? The walls are all painted with eggshell paint. So can we just Redguard over that and install tile from there?


  63. Jeff says:

    I’ve tiled over 1000 apartments tub walls applying redgard straight to standard 5/8″ drywall. Works great. Not a call back 1.

  64. Rod says:

    Hi there about Red guard not sticking to my dry pack floor. Saw video some guy used acrylic latex primer before applying says works better. Is this good idea? I decided on to use hydro ban instead basically the same stuff but should I use the latter primer first? Thanks , Rod

  65. Cyndiloo says:

    Great article,
    However, I’m wondering why you didn’t mention priming the cement board? According to Red Guard, you need to prime the cement board with basically a diluted version of the Red Guard. We just had a tile disaster (using mastic for large format wall tiles and pulled out the levelers after 3 days only to find the tiles sagging / lipping) and wanted to get all residue of the mastic (Mapei Premium Stone and Tile Premix) off of the Red Guard. Turns out the Red Guard coating peeled off pretty easily which leads me to believe the cement board really needs to be primed first.

  66. Joseph says:

    I’m redoing my shower, and put a vapor barrier behind the cement boards on the walls> I was going to do the shower pan with slightly sloped mortar base and then water proof it with Red Gard and bring the Red Gard up about on foot on to the cement board walls, would that be ok, or do I have to be concerned about mold where I basically have a vapor barrier sandwiched cement board, or should I just Re Gard the bottom of the shower and the seams between bottom and walls?

  67. Mike says:

    I have an old house, 100+ years. The (original) tile in the bathrooms only goes up about 5 feet. The rest of the wall is the original plaster wall and is painted. Is there a way to waterproofing the plaster wall with out having to replace it or tilling over it? I really want to keep the bathrooms original.

  68. Dan says:

    Hello –
    Thanks for this information. Great to see pictures of what Red Guard will look like when I put it on walls. I just recently build my home and had the builder finish the drywall in the basement. We have a full bath and plan to tile the shower on our own. After researching, I noticed that the cement backer board is the preferred method, however, the builder put up blue board sheetrock. Can I simply put up the Red Guard to put that waterproof membrane between the blue board and the tile?

  69. Glenn says:

    I am thinking about converting a school bus into an RV and I’m interested in your opinion about using red guard then gluing cedar tongue and groove to the walls. I assume you do not want to nail the cedar. would that work or is there a better option? I am trying to limit weight and also worry that tile may crack due to Road vibration. For the floor I was thinking building some type of cedar floor mat that can be lifted out. Any insight you would like to share I would very much appreciate.

  70. Rick in MI says:

    I am building a basement bathroom. The goal is to have it handicapped accessible. The bathroom is about 8 x 9 ft.. The shower will be about 4 x 6 ft. My plan is to lower the cement floor to have a curbless gently-sloped entry into the shower area with a glass door system enclosing. With this in mind, 2 of the showers 3 tiled walls will all be inside walls (the furnace and water heater are on the other side of the main back wall), and the end wall near the shower entry will be an outside wall. I have insulated this single outside (below grade) wall with Owens Corning 2″ XPS and 8″ of XPS in the rim joist — but this is far away from the shower. My plan was to build a traditional cement pan and use Durock from the cement floor all the way to and including the ceiling over the shower. I will then tile the floor, walls, and ceiling. My dilemma is whether I should use Redguard everywhere and if I should have any sort of additional thermal barrier under the cement floor? I have not yet begun to cut out the floor, but I presume there is currently plastic under the cement on top of pea gravel (or similar) to keep water out of the basemen floor. (I know a thermal barrier is generally not a good idea for internal walls under Durock.) I also wonder if I need some sort of extra water/vapor protection in the shower corners where the walls meet the cement floor. THANK YOU!

  71. Thomas O'Meara says:

    I applied durock to bear studs on shower wall five feet high above is regular Sheetrock
    The Sheetrock is thicker than durock
    Applied mesh tape and thin set
    I’m going to put another coat or two
    of thin set to feather the seamst
    How wide do I need to feather th join

  72. Ramy says:

    Does it make sense to Red Gard the floor of my bathroom as well (to prevent leakage into the floor below) in addition to the shower area or are there better options for the floor?

  73. Diane says:

    Can you tell me which backer board you’d suggest for Swan Veritek by swanstone it is a fiberglass tub walls. Can Wedi be used? And if so no sealing other than using their seam sealer ? I was told you cannot use Kerdi board.

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