For what kinds of wall structure - tile type combinations a waterproof membrane should be used between walls and tiles?

  • 3
    When? Preferably before it leaks. ;) Of course, a contractor we once employed used the alternative sequence, waiting until we found leaks in our house before he tried making it waterproof.
    – user558
    Commented May 9, 2012 at 14:12
  • @woodchips What could be the source of leaks? Where should I preemptively put waterproof membranes?
    – ipavlic
    Commented May 9, 2012 at 14:25
  • The source of leaks is from water egressing through the tile grout(generally water won't go through the tiles). Having said that my 40 year old house has no waterproofing but it has a concrete floor and rendered wall that the tiles are attached to. Because of this the amount of time water is present on the floor / walls isn't enough to let water permeate through, with with wet room plaster or cement sheet this isn't the case and water will leak through onto the frame sub-floor etc.
    – UNECS
    Commented May 10, 2012 at 1:50
  • @UNECS the buildings around here have either concrete or brick walls, which are then additionally prepared (see webgradnja.hr/clanci/unutarnja-zbuka/135 for photos).
    – ipavlic
    Commented May 10, 2012 at 7:02
  • @ipavlic same as my bathroom ( the one that's not wet sealed) really site dependent then...
    – UNECS
    Commented May 10, 2012 at 8:30

3 Answers 3



It's a shower. It needs to be waterproof.

A product I've used and liked is RedGard:

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You install your backer board, then 'paint' this on. It's basically an adhesive roll-on rubber membrane. You then tile right on top of it.

I like this better than the traditional plastic-behind-the-backer-board for two reasons 1) You can easily put holes in the plastic during construction (screw holes, for instance) and 2) the RedGard is closer to the 'wet side' of the wall, reducing the chances of water getting into the wall.

  • Where exactly should the membrane be installed? Behind shower walls, beneath the shower floor (if a shower tub is used), around the shower?
    – ipavlic
    Commented May 9, 2012 at 19:48
  • 1
    Sorry, and what is a backer board?
    – ipavlic
    Commented May 9, 2012 at 19:57
  • 1
    Backer board = what you are sticking the tiles to. In most cases it'll be a cement board of some sorts. You paint this particular type of membrane onto the cement board after you tape and mud the cement board. You then apply tiles on top of that. You'd have to do the same for the shower floor, though for shower floors, I'd recommend Kerdi products: schluter.com/143.aspx
    – DA01
    Commented May 9, 2012 at 21:49
  • I apologize once again for my lack of experience - in my country the walls are most likely either concrete or brick, and they are smoothed with a limestone-cement compound (mortar/plaster?) - see e.g. webgradnja.hr/clanci/unutarnja-zbuka/135
    – ipavlic
    Commented May 10, 2012 at 7:01

As DA01 said Always use wetseal, considering how much it costs it is a worth while investment

  1. Install the wall sheeting (we usually use villa-board which is a cement fibre board)
  2. Set the joints on the wall sheeting, fill any gaps between the wall and floor with silicon
  3. After all the sheets are set and dry
  4. Apply 1 coat of wetseal, for bathrooms in my state we seal the whole bathroom floor and up the wall 150mm where there is no splash areas and up the wall to a min of 2m in the shower
  5. Use a fibre wetseal joint tape in all corners eg where the wall and floor meet and where walls meet, this should be install why wetseal is still wet and then wetseal should be re -applied to just the wetseal tape.
  6. After 24hrs and wetseal is dry reapply another coat over all the area you have already covered

You can also get a professional to do this for you. Having a good wet seal job is very important for the longevity of your bathroom


This YouTube link is pretty good, explaining what can go wrong, as well as how to do it well.

  • While a good video, it's primarily focused on why you shouldn't tile onto sheetrock--though the examples at the end of the water damage are good (as is the Kerdi product)
    – DA01
    Commented May 9, 2012 at 21:51
  • It basically tells you to waterproof the whole thing, andwhere to put that membrane. This is the information you were asking for. So how does that not give you what you need?
    – user558
    Commented May 9, 2012 at 23:46
  • a) I'm not the one asking. b) like I said, the kerdi product example is good.
    – DA01
    Commented May 9, 2012 at 23:51

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