Shower waterproofing and vapor barriers: Part 5

tile shower waterproofing wrap-up
Wrapping up shower waterproofing. (Image from Google Images)

Part 5: Conclusion

The final post of this series will review the three different methods for waterproofing a residential bathroom shower that have been previously discussed and the whys, or why nots, for each method.

Conventional Shower Construction with Durock cement board and 6 mil plastic
Conventional shower construction using Durock cement board over a plastic vapor barrier. (Image courtesy of Tiger Mountain Tile Inc of Issaquah, WA

Traditional showers

The good:

lowest cost

tried and true


water is allowed to soak into substrate which may lead to mold growth and minerals coming to the surface (efflorescence) through the grout

Liquid surface waterproofing

Hydro Ban tile swimming pool construction
Surface waterproofing is applied over the surface and the tile adheres to it. (Image courtesy of Laticrete International)
The good:

blocks water at the surface, rather than letting it absorb

easy to install


lack of vapor protection

more prone to user error by not getting spots thick enough

Waterproof sheet membranes (and foam board)

Waterproof sheet membranes come in rolls and are applied over the surface for tile waterproof applications. (Image courtesy of Noble Company)
The good:

blocks water at the surface, rather than letting it absorb

excellent vapor protection



sheet overlaps can cause flatness issues

It’s important to remember that all three of these methods are specified by the Tile Council of North America. There’s no right or wrong, it’s up to you to choose the one that works the best for you.

If I had my choice, I would use a sheet membrane on every project. I think it’s the best way of waterproofing a shower. Unfortunately, not every budget allows for it.

Catch the parts of this series here:

Part 1: Waterproofing membranes vs Vapor barriers

Part 2: Conventional Tile Shower Construction and Water Management

Part 3:  Liquid Surface Waterproofing for Tile Shower

Part 4:  Surface waterproof sheet membranes for tile showers


  1. Ok I’ve read your whole piece and now I just want some confirmation about how we are going to proceed. Our home is a Craftsman. All areas of the home have been done very well except the bathroom. Here they scrimped a bit choosing to use sailboats over lathe and a glued on shower surround. We intend to keep the tub but want to use subway tile in the bath area. From your article I have many choices..ultimately if I am going to invest my time and supplies I don’t want to worry about mold etc ruining or making more work for myself as I/we get older. We want to do it right the first/ last time. What would you do?

    • Hi Debra, if you’re keeping the tub and just doing a tile surround the risk of failure is lower than if it were a tile shower floor. Any of the systems will work if they are installed properly.

      Cement board with plastic or felt paper behind is the most economical. Cement board with a product like Redgard or Hydroban wouldn’t cost much more. And if you’re doing the work yourself some Kerdi fabric isn’t a big expense and is probably the best way.

      Sorry for the politician-type answer but all three systems work. Doing things properly and reading the instructions is more important than the products used.

  2. When using a liquid waterproofing membrane is it a waste of time to use durrarock?

    • The problem with liquid waterproofing over green board is the possibility of even a slight comprise. Even a hairline crack would result in total demise of the surround. Green board is still only drywall, exposure to water turns it to mushy goop.

    • It’s not a waste of time. I don’t think you’ll find a liquid that is ok for sheetrock. And you won’t find many sheet membranes that are ok with it either.

  3. My issue involves a recessed shower in Florida. The builders in this state are not required to use any form of liner whatsoever. I have a terrible smell that is located behind the shower wall, in the guest bathroom closet. I don’t have a shower liner. Yet, there is no moisture. What could this be from? No liner and the water seeping down past the floor tiles into the substrate and odor coming back up???

    • It’s hard to say. If you’re not using your shower then it could be sewer smell coming up from the drain. Otherwise, is hard to know. It could even be a mouse died in the wall or something.

  4. Issue: building new home with tiled showers. Builder appears to be using a liquid waterproofing method. We have an issue with a decorative insert that has to be removed and reworked. Installer contends that removing will damage not only the waterproofing, but also the drywall underneath. This leaves me to question have they used an inappropriate substrate in the shower walls. From what I have research and from one of your replies says that drywall should not be used as a substrate. Two questions: 1. Is there any type of drywall that works with a liquid waterproofing method or has builder used inappropriate materials if they are contending drywall will be damaged? 2. With appropriate substrate how difficult might it be to remove a section about 2′ x 3′ and rework?

    • There’s at least one waterproofing company that will warranty their product over sheetrock. This product is called Kerdi and is orange in color. There may be some others out there also. The way to know for sure is to look up the specific product instructions. In general, liquid waterproofing products should not be used over sheetrock.

      The waterproofing may be damaged when doing a repair. The wallboard may also be damaged.But repairs are a part of life. If the contractor thinks the entire shower could be ruined by doing a repair then he (or she) shouldn’t have used sheetrock in the first place. But, in general, waterproofing repairs up high on a vertical wall are low risk. Down low near a shower floor are much higher risk. Yours should be doable. Not fun, but doable.

  5. Hi diy tile guy,

    My tile guy is remodeling my shower from the shower bed to ceiling. He conveyed he uses green board and then installs concrete board over that, is this okay? I don’t understand using green board behind the concrete board?? ‘m guessing they do not want to use the liquid waterproofing do to the time it takes to dry, but that’s just a guess. Any recommendation’s would be greatly appreciated….thank you!

    • I have no idea why one would want to install green board behind cement board. Besides not being a good idea it will hold the cement board out past the wall. Cement board is 1/2″ thick so that it will flush out with 1/2″ sheetrock.

      I would advise against this and also advise looking for other tile contractors. That’s just not something that a normal tile guy would think is a good idea.

      • Thank you! He’s been doing this 20+years, he’s an older gentleman so maybe that’s what they used to do . Will take your advise….appreciate your timely response!

  6. Hi,
    I have found your articles very interesting. I do have a question though. I am remodeling an older model Shasta RV. I am looking to renovating the bathroom and putting tile. I have been doing some research and considering doing GoBoard with a liquid barrier then tiling instead of using a fiberglass pan as they used in the original install. Is this a good idea?

    • I’m not familiar with GoBoard’s installation instructions but I would double check using the liquid barrier. I’m not sure how they want the seams and penetrations waterproofed.

      As far as the pan, I’m not sure I understand the question. Would you be using a foam shower base and tiling over it? If so, I would think that’s ok. I understand wanting to cut weight in a recreational vehicle.

  7. Hi. I am having a 4×4 tile shower done. I can’t figure any if this out. Each contractir us telling me something different.

    What is the best wall board to use? Cement sheet?

    What is best waterproofing with it?

    What is best thing to out on floor to ensure even pitch and waterproof seal?


    • This isn’t an easy question because there’s no one answer. Many systems will work well if they are installed correctly. So you need two things: good products installed properly.

      The choice isn’t simply the products but you meet to choose an installer also.

  8. If I go with the Kerdi option would I put felt paper behind the cementboard?

  9. Thank you for all the info, it’s very helpful to me. I’m having 2 shower areas retiled and am keeping the bathtubs, just retiling the area above the tub to the ceiling. From what I gather, to protect against vapor and water damage, it’s best to put up the plastic against the studs, then use cement board and then the Redguard or similar product. Is that correct? BTW….do you have any thoughts on tub reglazing? If so, do you think it’s a good alternative to buying new tubs? I want to keep costs down as I’m using a contractor.

    • If you’re using Redgard on the surface then you don’t want to use the plastic behind. You’ll probably want to reglaze after the tile work is done in case the tub gets damaged during the construction process.

  10. I have Hardiacker installed around the tub and was planning to use Redguard over it until I realized that adheives don’t stick to Redguard. I am installing FRP paneling. Is it okay to use just the Liquid Nails Tub Surround? Will it adhere to joint compound?

    • I don’t know a lot about FRP but I think it’s normally installed with mastic. The liquids nails may be a better solution over waterproofing in a wet area but it’s probably best to check with someone that knows more about it.

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