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Waterproofing shower: Membrane applied?

Rick Evans | Posted in General Questions on

Came across an interesting water sealant/vapor barrier product while exploring a new home construction project.  The owner/builder is a highly regarded drywall contractor in the area.

Anybody ever seen anything like this?  Cheaper/easier alternative to Schluter and or cement board?

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  1. Ethan Foley | | #1

    Looks like RedGard, used around here occasionally. Never used it myself.

  2. Expert Member
    Rick Evans | | #2

    That's the stuff!

    Thanks, Yupster. I couldn't find it despite my Google searches...

  3. Expert Member
    Malcolm Taylor | | #3

    RedGard is a great way to add protection to an already water-resistant substrate. If he is installing it as backup over something like Denshield, that's a good idea. If he is relying on it to waterproof water-resistant drywall like Green Board, he is going to have problems down the road.

    Either way, it still doesn't deal with the main problem area of the base, and the intersection between it and the walls.

  4. Expert Member
    Rick Evans | | #4

    Thanks, as always, Malcolm.

  5. Alan Lehman | | #5

    My tile guy likes RedGaurd for non wet areas as a crack isolation membrane. It is not liquid Kerdi.

    1. Expert Member
      Rick Evans | | #6

      Thanks Alan, Kerdi and it's components are so expensive, I was hoping for a faster, cheaper alternative.

      1. Expert Member
        Malcolm Taylor | | #7

        It really depends on the location of the shower. If possible I like use either pre-formed finished or preformed tile-ready bases.
        That deals with the most potentially difficult part. The walls can then be either DensShield or Cement Board board with RedGard on the seams and penetrations.

        It makes things pretty DIY friendly and fairly worry-free. Of course the easiest of all options is a one piece acrylic or fiberglass shower unit.

  6. AR T | | #8


    A traditional thick mortar bed with a CPE or PVC liner is also a great system. From your picture, the waterproofing looks sparsely applied. Why do you want a highly regarded drywall contractor doing what a highly skilled tile setter would do? If your using nice expensive tile, why cheap out on the substrate or the installation. Tile pans are also required to be inspected for leaks, in many jurisdictions, using a water test before the bed, walls or tiling can be completed. In other words, the pan has to hold water. Good Luck.

  7. Keith Gustafson | | #9

    The wall on my curbless shower were done with red guard over cement board 9 years ago, floor with schluter.

    Talk to me in another 9.....

  8. Nathan Scaglione | | #10

    There's nothing wrong with liquid applied membranes. The real genius of all these products is the integrated drain flange which makes these systems face sealed rather than water managed.

    Redgard, unless something changed recently, does not have a face sealed drain flange in their system, which is a weakness. The TCNA handbook does detail a method for face sealing everything except for the old school PVC drain area.. not worth the effort IMO.

    Laticrete is one company that offers a liquid applied membrane with integrated drain flange. These products install a lot faster and are significantly less work than schluter IMO.

    Also IMO redgard is just as good as laticrete or any other liquid applied membrane, the reason some pro's don't like to mix and match is because it will mess up the warranty. If using schluter, it makes more sense to liquid apply a custom niche than to spend a lot of time trying to oragami your way through it, it's just that you could theoretically run into warranty issues if there is a failure.

    Only thing watch for is in the old school PVC liner pans is that you need to make a pre-slope mortar bed before putting down the PVC. Then you put down another mortar bed on top of the PVC. It's a lot of extra work.

    Next shower I do will be Laticrete or something liquid applied with integrated drain flange. Corners can be reinforced with fiberglass mesh.

  9. Alex P | | #11

    I've been looking in to this a lot for my own house. There's several good youtube channels that go in to the pros and cons of various systems and products. What I've gathered is the main advantage On of the foam board system is the integrated shower pan/drains and the lighter weight of the material for the installer. One point of note is that the Kerdi system is just highly water resistant, not waterproof as many seem to think. The modified thinset used to set the Kerdi band allows water penetration. Now the conditions for that to occur would be unusual (prolonged wetting, poor sloping) or installer error so it may never be an issue, but it's worth considering if the expectation si a completely waterproof set up. In Europe Schluter sells a separate waterproof product for setting the Kerdi Band because the modified thinset sold in North America would not pass. The top channel goes in to this.

    1. AlexPoi | | #12

      Kerdi is waterproof up to a certain water pressure. If you respect the kerdi band overlap specification, you won't have any problem. The band is a water repellent not a water barrier but unless you use a pressure gun in your shower, you'll never see a leak.

      There are two things I don't like about liquid barrier.
      1) You must ensure you have applied the required thickness everywhere. This means taking a thickness gauge and checking you have the right thickness at regular points. Otherwise, you risk having problems. Foam boards are much faster to install because of that. And you still need a good backing board when applying a liquid membrane which mean using cement board and not drywall (Tile Ansi standards). So I much rather pay a little more and deal with foam than have to mess and cut heavy cement boards that create a ton of dust and than meticulously applying a liquid membrane that smells really badly.

      2) You have to fill the seams before applying the liquid membrane otherwise the membrane will crack. This means using fiberglass mesh. Some people skip it but I think it a disaster waiting to happen. So if you are applying tape on the seams, why not go all the way and use the Schutler or Wedi board system?

      1. Alex P | | #13

        Watch the videos on the testing of Kerdi. I'm not saying it would cause a problem in a normal use domestic shower but the limits are lower than you are stating.

        I agree, for a DIY shower installation Wedi seems like the most idiot proof.

  10. Roger Berry | | #14

    Something I have not seen mentioned so far is a warranty requirement that annoyed the tile setter I had on a bath job. Nine years ago when we specced Kerdi for a steam shower, the warranty called for non-latex fortified thinset materials to be used. The setter much preferred the ease of using latex fortified, but I believe the issue would be long term saturation of the thinset, especially in a steam shower. The latex component can apparently absorb and hold water sufficiently to cause debonding. Be sure to check with Schluter about this.

    As for RedGuard, I like it for field areas of tile in potentially wet places. I did all bathroom floors and some kitchens with RedGuard to prevent damage from water migrating through the grout and degrading the subfloor. (Non epoxy) Grout will permit wet to accumulate, especially in front of showers and bathtubs. Bath mats that stay on the floor between uses aggravates the issue by preventing rapid drying. Mosaic tiles have a much higher grout area relative to large tiles. I mention this because too many tile people will still set direct to subfloor. Hopefully, yours doesn't. Even certain cement boards will transmit moisture if saturated from one side. The damage then takes longer and is more diffuse than what one sees from mosaic directly on subfloor.

    I haven't been brave enough to do an entire shower stall with RedGuard, but others I worked with did many that way. Don't know about their call back rates.

    1. AlexPoi | | #15

      Modified thinset is not recommended because it relies on air to cure properly. Since the tiles and Kerdi Board are air and vapour impermeable, drying could only take place through the grout lines. It would take lot of time.

  11. Roger Berry | | #16

    Good to know. Hopefully the Schluter rep I spoke with is reading this too. I will stop repeating what I was told. Meantime, seems like the need for non-fortified material is required to ensure warranty claims, which was the main reason I brought it up.

    Just realized this could be read as snarky... its not.

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