Asked on Dec 06, 2011

I am redoing my shower.

David E
by David E
Someone put in green board, then cement backer board, then tile. What I want to do is copy that, put in green board, (then add a waterproof selfadhesive membrane on top of green board), then the cement backer board, then tile.
Is this a good method or what are potential problems with that. Reason I want to use the green board is to provide support and additional water proofing for the selfadhesive membrane I am going to apply everywhere in the shower.
Can you help me out? Thanks.
  20 answers
  • 3po3 3po3 on Dec 06, 2011
    I believe there is no good reason to use the "green board." Attach a waterproof membrane to the studs, then add the cement backer board.
  • The entire bath needs to be green board. The cost of this material is cheep based on the extra protection you will get by using it behind the shower assembly. I use Dens-Armor Plus sheetrock behind my showers and tubs. Then use Schluter-Kerdi mat as my water proofing membrane. I was turned on to this several years ago after going to the New England JLC show and have never looked at another product or shower/tub system again. Bit on pricey side, but with the labor savings using the fiberglass sheet goods on the wall It always goes up fast and true.
  • David E David E on Dec 07, 2011
    Reason I am using green board, is the membrane I am using is actually a foundation membrane with adhesive backing. I wanted to attached the membrane to the drywall, then attached the cement board over that. Also to give a little more rigidity to the backerboard so it doesn't flex. Is there anything wrong with doing that? Codes, etc. Thanks.
  • Paul M Paul M on Dec 07, 2011
    Green board should never be used. Find a reputable drywall supply company, like Capitol Materials, and get the DensShield material. it is fiberglass, no paper and it is specifically designed for bathroom applications. It is far superior to green board and has fungi inhibitors built in. It doesn't cost a lot more either. Lowes carried it for a while but I guess people couldn't figure out what it was for because the dropped it about a year later and went back to the old green board. You can put any kind of membrane on the Dens material and in the past 15 years I have not seen one commercial job use green board, Do you think there is a reason for that? I do.
  • Paul, I wondered why Lowes stopped selling the stuff. They said it was because the material was being damaged to easily and there were loosing to much inventory. I have to admit I understand this as although it works real well, it does when bumped on edge get crunched pretty fast if your not careful. I had a few sheets of this left over from a job and had it next to my shop for a long time. Over last years winter as matter of fact. Thought it was no good once it got rained on so figured I would get rid of it after the snow melted. Well its in a clients basement now. It did not warp, nor become damaged from all the water. No mold, nothing. Its just hard to find as not to many companies sell it because of how easy it becomes damaged. The only thing I hate about it is you must wear long sleeve shirts when handling it as you end up with tiny welts as though you have been putting in fiberglass insulation all day.
  • David E David E on Dec 07, 2011
    Thanks for the answers, but I'm still hoping for more ideas.
  • I can say this is something new to me,I've done a lot of showers,And have never put up green board behind durarock or wonderboard,I don't see the advantage of doing that,Maybe I'm missing something,I have never had any problem if you install the backer board right.
  • David E David E on Dec 07, 2011
    Well, here is my issue. If you put up membrane on the 2x4 wall, there is nothing to support the membrane, and mine is actually an outdoor self adhesive membrane. So i am putting up green board, then sticking the membrane to that board, then putting up durarock on top of the membrane. The advantage is, you are sticking the membrane to the green board, and supplying an additional layer of protection from allow the membrane to ever be punctured (it is easier to puncture a membrane floating between studs, than attached to a solid surface.) Anyways, another reason I am doing this, is I ordered too much membrane for my outdoors, so I figured I'd use it in my shower, and stick it to the green board, then build my waterproofing layout with durarock from that.
  • David E David E on Dec 07, 2011
    Thanks for the answers, but I'm still hoping for more ideas.
  • Ok I see what your doing now thanks,That's a great way to do it.
  • Paul M Paul M on Dec 07, 2011
    On commercial jobs the DensGlass board is used to give another layer of moisture protection in areas that could be exposed to water and moisture damage. It is the best. Yes it can be damaged on the edges, just like any sheet rock material can. But as you noted, woodbridge, it is impervious to the elements. If I remember correctly it has a five year warranty when it is exposed to the elements against any type of moisture damage or fungi growth. Every commercial building I have been involved with in the past 15 years uses that material for exterior sheathing and interior sheathing in the bathroom areas or any area they believe will be exposed to moisture. Once I found out about it I was done with green board. David, I used the Dens material in my bath with two layers of half inch wonder board. I used two layers to get the face of the second one to overlap the tub lip and create a void making it impossible for water to go up two inches and get behind the wall, and even if it did the floor is sealed and the Dens material is there to greet it in that unlikely possibility. It may not be necessary to take extra precautions but if you want to, and know how to do it, and can afford it, it certainly can't hurt to have as many layers of protection as you feel comfortable with.
  • Putting the water proofing membrane behind the wall material is just a waste of time. It will provide you with no prevention of water, in fact it will prevent the green board from every drying out should a minor leak occur. You have a few correct options for doing the tub/shower area. Use cement board over a plastic vapor barrier. Then tile, Or use any kind of wall material green board, or cement board or Dens Armor sheet rock then cover it with a water proofing membrane such as the Kerdi. Any other method is simply a gamble with products that are not typically used for this type of job and its anybodies guess if it will work or fail. And doing this type of job which as you already know is a lot of work only to find out in short order that you may need to tear it all out and start again.
  • Nicholas S Nicholas S on Dec 10, 2011
    I agree some of this sounds like overkill. Green board or cement board and a GOOD tile job would keep it waterproof
  • David E David E on Dec 10, 2011
    I have to say, it seems like there is no 1 way of doing that waterproofing. Everyone has different ideas. Unfortunately, my shower we designed a way where I need green board behind the durarock, for the main reason, that is the gaps they have in there when they designed the walls. For my project the best solution is green board, membrane, durarock, tile. If I had to design the show from scratch, I would probably do membrane only, then durarock. Thanks for the ideas.
  • Paul M Paul M on Dec 10, 2011
    Once again David the Dens fiberglass gypsum product is superior to green board, it works and fits the same way. You don't have to use green board you are choosing to use the green board.
  • Paul, what I think hes doing it packing out the wall with the greenboard, then putting in moisture barrier, then the cement board to bring it out flush with the tub or shower pan. While I would agree with using the dens armor for this construction he should be fine. I just am not sure about the water proofing membrane he is going to be using.
  • David E David E on Dec 10, 2011
    I couldn't find the DENS it at my local lowes. The problem with specialty products is you have to order them, that takes time, of which I don't have. I am trying to do these projects with the products that are available without lead times or replacements. I WISH, that lowes or home depot would carry this stuff, but that is the problem I have always had. Sometimes they carry not so good stuff. Thanks for your input.
  • Paul M Paul M on Dec 10, 2011
    David there is a drywall supplier in your area that carries the Dens product for commercial jobs. You shouldn't have to order it. Capitol Materials, here in Atlanta, stocks that material all the time. Since it is a regular part of commercial construction I find it hard to believe that it is not available in your area, unless there is no construction work going on there. Lowes used to carry the Dens Armor but for some reason they quit about a year later. That was the first time I saw it and then it started popping up on commercial sites. Anyway I did a quick search for you, here are two supply companies that most likely carry something better than green board. All Interior Supply 4000 N. Orange Blossom Tr. Orlando, FL 32804 Phone: 407-291-8024 Fax: 407-299-5734 or Seacoast Supply 3018 Shader Rd. Orlando, FL 32808 Phone: 407-521-7330 Fax: 407-521-7515 I hope this helps. Sometimes you have to get away from Lowes or Home Depot to get something better. Last year we reinsulated our house and I was knocked off my feet at the cost of insulation. I checked with our local supply company, Capitol Materials, and they had the same insulation, brand and all, as Lowes but it was half the cost. A little digging can pay off big when you are doing a project. Good luck.
  • Rebecca Ellis Rebecca Ellis on Jun 30, 2013
    Hi guys, we are using DENS board... after we finished mudding but before we layered the thinset we noticed the "Tile on other side" words printed on the sheets!! How imperative is it that the yellow side is against the studs rather than facing out? eg just under the tile?! It's going to be a lot of work to take it all apart and turn the sheets around the right way but at the same time, we want to do it right the first time... please help!! Thanks Bec
  • Are you talking about Dens Shield? This product requires the yellow side to be away from the tile while the other side is coated with a moisture resistant coating to prevent moisture from wicking into the material. If its the other way it is not installed according to the manufacture and you will not get any benefits to using the product. Click on product diagram on the page. IN essence now all you have installed is mold resistant drywall on the wall. There is a work around however. You need to install Schluter Kirdi mat over the wall to provide the moisture resisitance that the board would have if it was installed correctly. This material is a vapor and moisture barrier that is installed using Unmodified Thin set mortar. NOT Modified. If you use the wrong mortar it will not work and end up failing. There are other membranes such as the Schluter brand but this is considered the leading one in the market.