Now that you have your curb built and your pre-slope done (if you haven’t done this yet check out How to create a shower floor, Part 1) you are ready to install your waterproof liner.

Purchasing a waterproof liner

When you order or buy your liner you need to get one large enough for your shower. The liner you get has to be at least one additional foot larger than each of your measurements. For instance, if your shower floor is three feet by five feet your liner needs to be four feet by six feet. This allows enough to run the liner up the wall behind your backerboard six inches each way. You also want to purchase two “outside” corners for your curb. These are pre-formed corner pieces to waterproof the ends of your curb after you cut the liner.

I usually order mine two feet larger in each direction. Six inches is the minimum. Specifications state that your liner must run up the wall at least three inches above your curb. So if your curb is three inches high your liner needs to run at least six inches up each wall. I usually go a foot above the curb – overbuilding your shower is rarely a bad thing.

Preparing your shower floor for a waterproof liner

Image of a sandy shower mud deck

It's supposed to be sandy!

Before you install your liner I need to say type this: your preslope will be sandy, it’s suppose to be sandy – it’s normal, don’t panic. If you have any high areas in your preslope you may want to scrape or sand it down so it runs in a flat, straight line from the wall to the drain. Notice I said typed “flat, straight” and not level – if it’s level water won’t drain.

You can scrape it down with a regular razor scraper or sandpaper – yes, sandpaper.  If there is a significantly large dip in your pre-slope you can fill it with more deck mud. You’ll need to coat the pre-slope with thinset under the patch to ensure it will stay put. Don’t get all OCD about this, it doesn’t have to be perfect. Just make sure there are no major humps or dips and water will run from the wall to the drain without problems.

The next thing to do is take a chisel to your wall studs. You weren’t expecting that, were you? You want to notch out your studs about 1/8″ up to the height of the top of your liner. This is so you can place your backerboard over the front of your liner on the wall without them jutting out at the bottom. It allows your walls to remain flat all the way down to the shower floor. You will create “cavities” in your wall studs for the liner. 1/8″ is a bit larger than the thickness of your liner but it’s better to be larger than smaller.

When you place your liner in the shower you will be folding the corners so you want to allow enough room on one of the corner studs for three layers of the liner. I usually notch my corner studs out 1/4″. This allows enough to keep your corner square after the walls are up.

Placing the liner in your shower

Image of a shower liner placed on pre-slope

Liner placed over pre-slope

Now it’s time to lay your liner in the shower and get it all lined up. DO NOT cut anything until you have the liner exactly where you want it. Make sure you have the top half of the drain flange removed before you place your liner over it. I’m not talking typing about the round part that unscrews, I mean the top half of the lower part which bolts onto the lower half. After removing the top half of the flange replace the bolts, this will serve as a guide when you cut the liner.

Center your liner in the shower with the ends running up the walls evenly. Also make certain you have enough of the liner draped over your curb so that you can attach it on the outside of the curb. I will usually place it so that the liner drapes up and over the curb all the way to the floor on the outside of the shower.

Cutting the hole for the drain out of  your shower liner

Image of the drain cut out of a shower liner

Drain hole cut out of liner

After you have it properly positioned you can cut out the hole for your drain. Do this very carefully – there is no second chance. Take your utility knife and poke a hole through the liner directly in the center of the drain. From there cut in a circular motion toward the outside of the drain in a spiral. Only cut it  out to the outside of the four bolts which attach the top half of the flange to the bottom.

Image of silicone under liner around the drain flange

Silicone under the liner around the drain

Remove the bolts from the flange. Now you need to place a bead of silicone under the liner around the perimeter of the lower flange. The easiest way to do this is to place the nozzle of the tube of silicone into the hole you just cut for the drain. Place a good size bead around the lower flange outside of the bolt holes, don’t get any in the bolt holes. This prevents any minute amount of moisture from getting under you waterproof liner. Press the liner into the bead of silicone all the way around the drain to ensure full contact.

Image of prepared liner

Prepared liner ready for top slope

Now you can bolt the upper half of the flange to the lower. Do not overtighten the bolts. You want to squeeze the liner between the two but not so much as to crack the flange – they are only plastic, after all. That’s it, the drain is finished.

Now take your liner and place it up the walls into the notches you cut out of the studs. You can nail or tape the top of them to hold them in place. Only place one nail into the very top of the liner, never lower. In the corner you will fold the liner over on itself, never cut it. Place the folded part into the larger notches. There should be enough room in the notches so your backerboard will set flush onto the studs.

In my next post I will cover how to cut the liner for your curb and make sure it’s waterproofed properly.

{ 275 comments… add one }

Leave a Comment

  • John

    Sorry, another question. If I notch the studs for liner, how far down? to top of bottom plate?

    Reply
    • Roger

      To the height that your mudbed will be or the height your substrate will go to.

      Reply
  • John

    Another question. My shower is sn odd shaped corner shower. Curb is at a 45 degree angle. Do I fold and glue the liner at curb corners?

    Reply
    • Roger

      Yes.

      Reply
      • John

        what about the wall ends? I will tile the end walls at each end of curb. Should I redguard the outside of the hardibacker? The glass door frame will attach to end walls. One wall is 5′ pony wall and will have glass panel on top. Same question. I bought redguard fot niches already.

        Reply
        • Roger

          They are folded and stuffed into the wall cavity. You can redgard over the hardi in those areas, it won’t hurt anything at all.

          Reply
  • John

    I had to buy 100 wall board shims to get the few I need. Can I use the shims instead of notching studs for liner?

    Reply
    • Roger

      Hi John,

      Yes you can.

      Reply
  • David

    Dear Elf,
    I have a beautiful new pre-slope curing and in a day or so it will be time for the liner. I think it turned out perfectly. I also think I’ve run out of free articles regarding the construction of a shower though. Is this the last freebee currently posted on this subject, and can you recommend which books I’m going to buy from you? A couple of details on this project. I’m doing a traditional floor. The pre-slope tapers radially to the round drain. I’m doing a very tiny bathroom for entertainment sakes, kind of “boat (or RV) like”. The shower and sink occupy the same space, the toilet is very close by. No curb, but the floor height is challenging me a little bit … The entire space is tiled. The tiled floor will be bubble mosaic and the drain is linear. The pan will slope to the linear drain in a non-radial fashion (yeah primarily flat like). The linear drain is near the center-line (shower/sink to the west, toilet on the east side). The floor will slope, but the footprint of the toilet will be flat. Due to the detail of the tiny room (nooks, shelves, window, etc) I’m going with Hardiboard everywhere (Hardi not touching the pan). No visqueen behind. Glass tape, all joints etc. Redgard the entire Hardiboard shower/bathroom. I’ve read the two shower articles, downloaded the waterproofing article (and kinda read it…) and read the article on deck mud.
    Arrgh, so back to the question… Traditional pan and preslope (kinda sorta), and Redgard sealed walls. Which books do you recommend, or can I continue to scam additional free articles on shower construction? Pretty picture attached if you want to see how many rules I’ve broken already. I have a Dropbox full of pictures if you want a link and you come down with the Flu and you want to kill your brain. Thanks Awesome Floor Elf Dude. Great Web Site.
    Best Regards, David

    Reply
    • Roger

      Hi David,

      Part three is here. Or you can just hit the ‘next post’ link at the end of a post. I believe I have four on this subject.

      As far as the manuals, since you’re using a traditional floor with redgard on the walls, the liquid topical walls manual would probably be your best bet.

      Reply
      • David

        Thanks bunches for the immediate reply. Reading the spiffy new manual now. REALLY well written, good info. My crew (son) shows up in about a half hour. I guess now I’ll need to pay him to read the manual too. I think that will be a good investment. I do have one concern though, it’s a little too early for beer. I hope this all works just as well with coffee. thx David

        Reply
  • Alissa

    Hello floor elf,

    Your site has been helpful and you are correct there is so much conflicting information out there. My brother told me about your site after already starting my shower. So here is where I am at. I’ve building 2 showers on a concrete floor. We have built the curbs out of brick, I’ve done the thin set 1st and then the deck mud pre slope with the 1/4″ for every inch from the farthest wall to the drain,we have completed our shower liners with silicon at the drain,notched out 2x4s so there is room in the corners for the folded liner and dam corner over the corners at the curb. Sounds all great Right ? Here’s where I start to have troubles. First… in one of my corners the liner isn’t sitting down into the corner very tight I’m worried I can proceed with my final slope. The 2nd problem is my curb isn’t tall enough and my liner is already on. I didn’t take into consideration that I needed an 1 1/4″ on my final slope. So can I build my curb higher with the wire mesh over my brick curb 1st then do my final layer of deck mud slope? Help! I really am trying to not have to pull up my liner to make my curb taller

    Reply
    • Roger

      Hi Alissa,

      As far as that corner is concerned you can simply pack the deck mud on the top slope against it to get it tight. With your curb unfortunately you have to remove at least some of the work to get it higher. Your liner has to be AT LEAST 1″ above the finished height of your floor – that is the minimum realistic height. By rule, per the TCNA, it should be a minimum of 3″ above your curb. So you have a couple of options:

      1. Remove your dam corners, stack another layer of bricks on your base layer and reinstall the corners/patch whatever is needed.

      2. You can also cut the liner along the top inside corner of your curb, from wall to wall, and remove that. Stack another layer of bricks on top, then use the adhesive you used for your dam corners (provided it’s the correct adhesive) and glue the strip you cut off to the liner beginning at the bottom inside corner of your curb, where the top of the pre-slope meets the curb. Then wrap it up and over the new bricks. Does that make sense?

      Everything else sounds good. :D

      Reply
      • Alissa

        Yikes! the thought of cutting the liner and then patching it scares the crap out of me since I worked so hard not to cut the liner anywhere. If you think that is OK 😬to do that sounds better then replacing the entire liner. Thank you so much for your help!

        Reply
        • Alissa

          Hi Rodger the floor elf ,

          I need some more of your advise please. I’ve removed my dam corners and pulled back my liner cuz you advised me that my curb must be a minimum of 1 inch above my liner. I don’t want to make my curb to high and I can’t find a half brick the same width of the existing curb brick. The half brick I found is slightly wider. (1/4″) I’m thinking I may be able to get away with it because I will be going over it with the wire lath and more mortar. I’m hoping you think the same. Figured I could either center the brick and have it slightly larger on each side or make it even on one side and only have only one side to even up. What do you think?

          Reply
          • Roger

            Hi Alissa,

            Actually, I would cut strips of backerboard the width of the brick and thinset it to the top. Keep doing layers until you get it to the height you need. If you do stick with the brick I would make one edge flush and just worry about the other side. You can cut bricks on a wet saw – just like tile.

            Just for clarification for anyone else reading this: The curb must be one inch above (higher) than the finished shower floor – not higher than the liner. :D

            Reply
            • Alissa

              Thanks again we did go with cutting the bricks to match the width of our existing curb. I wasn’t sure my husband could do that but he did! God bless him! My new dam corners came in so now it’s time to patch my liner 😬 And finish the liner over the curb. Then we need to do the leak test. My question is if it doesn’t hold water how do I know where it is leaking or if my ballon is in tight enough? Do I need a heavy duty ballon?

              Reply
              • Roger

                You don’t need a heavy duty balloon, just make sure it’s down into the drain far enough. If you blow it up and stuff it down into there so it is at least two or three inches into the drain it’ll be fine. IF you have a leak, peel back your liner and look, it’ll be very obvious where the leak occurred.

                Reply
  • Tony

    Hello Roger,
    Firstly, thank you for your site. It has been a huge help. I’ve just put in my pre slope into my shower with a 4:1 sand concrete pre mix I got at the tile store. IT’s been a week since I installed. I went to go put in the liner and I noticed that the mud bed had slightly risen. Like when I stand on it, it feels like the whole pan is a separate piece from the concrete. I guess I figured that the mud bed would cure and bind to the concrete beneath. Have you experienced this before? Do you think it is okay to go ahead and install the rest of the shower or do I need to redo the pre sloped mud bed?

    Any help.would be appreciated. Thank you!

    Reply
    • Roger

      Hi Tony,

      Deck mud doesn’t bond to anything but itself. It’s just fine, carry on. :D

      Reply
      • Tony

        Roger,

        Thank you very much!

        Tony

        Reply
  • Alex

    Hello, the cut through my foundation for the shower drain is now empty after changing the drain. Do I fill this void with cement or the bed mud? Thanks!

    Reply
    • Roger

      Hi Alex,

      Either one. I normally just pack it with deck mud.

      Reply
  • Eric

    I’m just curious – why can’t you use pressure-treated lumber for your curb? I had some contractors put in a barebones shower that I’ll be tiling and they used pressure treated for the curb. Now I’m worried I may have to rip it up?

    Reply
    • Roger

      Hey Eric,

      Because pressure treated wood is made to see constant moisture and water exposure, when it doesn’t get that it begins to dry out, which causes it to shrink and twist. It would be best to remove it and replace it with regular kiln dried lumber.

      Reply
  • Scot

    Roger,

    I’m glad there are few folks out there so helpful as yourself. You were a huge help to me working on my project. So many so called pros out there ruining one home at a time. As an electrical contractor that takes pride I can appreciate your knowledge in your field. You are a true craftsman. Thank you!

    Reply
    • Roger

      Thanks Scot!

      Reply
  • Tom

    Hi Roger,
    Can I use a combination of completely redguarded backerboard walls and a shower pan with a liner. How would i make the transition to the shower floor if I was to do this? Should I tape the seem between the top mud deck and the backerbords and then red guard just a couple inches of the top mud deck to cover the tape and some thinset? If the backerboards are in contact with the top mud deck, would water leach up through the backerboards and get to the studs that they are screwed to? I almost made a mold sandwich before I red the above comments about redgaurd on the top mud deck with a pvc liner underneath.

    Reply
    • Roger

      Hi Tom,

      The backer should not be touching the deck mud. It should be about 1/4″ above it, then it is painted with the redgard all the way to the bottom. The liner runs up behind the backer just as it would in a regular traditionally waterproofed shower. If your backer is already embedded into the deck mud you can paint the redgard out onto the floor around the perimeter about six inches. Gravity keeps it from leaching up through the deck mud to the backer. Ideally you don’t want the backer touching.

      Reply
  • Tara

    We want to install this type of shower in an older home and we are a little worried about the weight of all the cement and tile. Do you think that is something that we should be concerned about?

    Reply
    • Roger

      Hi Tara,

      The dead load of a properly built shower floor is approximately 10lbs/square foot. Most structure requirements are a MINIMUM of over 100lbs. So no, it won’t be an issue.

      Reply
  • Brian

    Hello Roger –

    I’m working with a tile contractor to replace a walk-in shower. The contractor installed a proper (in my opinion) pre-slope. However, when he put the pan liner in, he attached lathe to the liner with staples into the wall studs inside the shower itself (not on the outside of the curb). When I questioned him (because he has now created myriad staple holes in the pan below the height of the curb) he replied that a water test would only need to be .5″ deep (curb is 6″ tall) and he did not put any staples that low. He also claims that he cannot apply the mud directly to the PVC liner w/out the lathe. By the way…he also installed the backer boards on the walls before putting in the pan (in other words, the pan does not extend behind and above the bottom of the backer boards). I am thinking that everything but the pre-slope should be pulled out and redone. Am I off my rocker?

    Reply
    • Roger

      Hi Brian,

      You are absolutely correct. He obviously doesn’t have any idea how to properly prepare a shower.

      Reply
      • Roger

        And a flood test requires water to just below the top of the curb, just fyi.

        Reply
        • Brian

          Thank you, Roger. The contractor has proposed that, after he puts in the dry pack on the liner (and brings it up to slightly above the bottom of the backer boards), that he AquaDefense the whole thing before laying the travertine. Certainly not elegant, but seems like it might work if the AquaDefense is as good as the contractor claims. I’d really appreciate your thoughts on the idea.

          Reply
          • Roger

            No! He is mixing two completely different methods in an attempt to band-aid his screw-up. He lacks the knowledge to properly build it and will continue to install ‘fixes’ until you’re satisfied. You can not paint AD over this and expect it to last. It will trap moisture between the two waterproof layers and begin to grow mold – that’s why we call it a mold sandwich. The liner needs to be the waterproof barrier, or the AD needs to be the waterproof barrier (which requires a different installation method). You can not use one to compensate for screwing up the other.

            Aquadefense is a great product, but it’s being used incorrectly here, which renders it not only useless, but may actually compromise your shower due to the mold sandwich method mentioned above.

            Reply
            • Brian

              Thank you, again, Roger!

              Reply
  • jeff L.

    I was advised to install a ‘dumb corner’ membrane s required by Dallas code. Have you heard of this and, is this to be installed before I put the liner or after?

    Reply
    • Roger

      Hi Jeff,

      Never heard it called that, but I assume it’s a dam corner, not a dumb corner. :D It is sold in big box stores in the same place you picked up the liner.

      Reply
  • Howard

    Roger,

    I’m doing a tile shower on a concrete slab. I am building my curb like yours with blocks. I’m doing a pre-slope with Oatey liner.
    Since I’m using block for my curb and I can tile directly to that, how do I run my Oatey liner over the curb?

    Thank you for your site!!

    Reply
    • Roger

      Hi Howard,

      You run it up over the curb like you normally would, then the wire lath holds it in place. Read through this, it’ll describe it:

      Reply
  • Jason

    Hi Roger, Quick question for you. I have a realized concrete pan that was done with my slab. I was planning to place the backer boards on the walls down to 1/8″ above that and then use the redgard on the walls and the pan then crest my top pan. Is this method a good way to do it? I have an odd shower shape that’s gonna be hard to place vinyl down on and was hoping this method would work for it. Thanks Jason

    Reply
    • Jason

      It should read presloped concrete pan not realized concrete pan lol

      Reply
      • Roger

        Hi Jason,

        You’ll need to create another mud deck above that preslope in order to have a continuous plane from the floor to the wall. You can not waterproof that 1/8″ gap. After you have that slope in full contact with the walls you can use redgard to waterproof the entire thing.

        Reply
  • Ricky Goings

    on a concrete floor do I need the pvc on the walls only Im making a curbless shower. 4′ x 7′. Do I need pvc on the floor. Im using portland to create a slop 4’x4′ on the inner part of the shower?

    Reply
  • Dave

    How flat and smooth does the liner need to be? I bought an Oatey liner from HD and it was folded a hundred times to fit in packaging. Is there a method to smooth it out or no worries?

    Reply
    • mike

      what was the answer to how flatten the liner thanks. great website

      Reply
  • Rusty

    Thank You…I went with your ideas and it came all together so far thanks again Wife is happy

    Reply
  • Fiona

    Hi,

    I am new to this and am trying to work out how to build a mortar shower bed on top of a concrete floor. I can follower the first part I.e. Use a watery this set rather than metal lathe and then lay a preslope, but after that I wondered if I can just use a liquid membrane rather than a waterproof liner? And if I can do I need to do anything special with the wall and floor joins?

    Thanks

    Reply
    • Roger

      Hi Fiona,

      Yes you can, but you need a drain made specifically for topical waterproofing. The wall and floor joints are dependent on your wall waterproofing method.

      Reply
  • john

    do you have a post with photos showing how to fold a liner over a straight curb? my shower is three sided in a niche

    Reply
    • Roger

      Hi John,

      Is this what you’re talking about?

      Reply
  • Kris

    Hi Roger,

    This site has walked us through the start of our shower stall remodel. The existing walk-in shower has all been taken out, down to the studs, exposing the existing pre-slope underneath. I’m assuming since this existing pre-slope is in perfect condition we do not need to rip this out, too (please say we don’t have to rip this out!). Now here’s the problem. The top half of the drain flange has been removed to prepare for the pan liner. The barrel portion of this flange does NOT unscrew. It’s stuck, bonded by years of calcium or something else. If this barrel won’t unscrew, and we don’t make the new mud bed and tile the exact depth as the previous- how can we continue? We are clueless as to how to get the bottom half of the flange out of the floor to start with a whole new drain assembly. Oh, and we bought a new assembly hoping to use the top flange, but it didn’t fit with the existing bottom flange. Help would be awesome!

    Reply
    • Kris

      I found my comment! Thought I never hit submit, but here it is! Oops!

      Reply
    • Roger

      Hi Kris,

      You’ll need to either make that mud bed the correct height for that drain, or replace the drain. Replacing the drain would be easier. Get an inside-pipe cutter and cut the drain pipe off and remove that drain, then get a coupling and a short length of pipe to install the new drain.

      No, you don’t need to remove that preslope. (You HAVE a preslope??? Wow…) You can chip around the drain if you need to in order to remove the drain, then just fill it back in around the new one, but you don’t need to replace the whole thing.

      Reply
  • Amy

    We just finished the pre-slope and there is a dip that holding the water from running to the drain. According to some sources I found, I can fill that dip by thinset as long as the thickness is less than 1/4″. So my question is would the thinset is good enough or do I need the thinset then deck mud as you state above?

    Reply
    • Roger

      Hi Amy,

      Thinset will be just fine.

      Reply
  • Stephanie

    I’m reading this in a mild state of panic.
    My tile guy has over 25 yrs of experience. He helped me convert a huge walk-in closet and microscopic fiberglass shower prison cell into a 6’x7′ luxury curbless shower with 4’x4′ entry and linear drain.. The plumbing for the body sprays and showerheads is a thing of beauty.
    Now, the scary part. I haven’t seen him for a month or so, he’s been ‘tied up’.
    The liner in my shower is directly on the slab…the flat…flat slab. My top of my linear drain is flush to slab height. How can he possibly mud to the drain still leaving the mud thick enough it won’t crumble? And how is the pebble mosaic going to meet the drain? Thinset+mud+pebble does not equal slab flush drain.
    Maybe he’s planning on a Redguard coat over the mud since that was what we agreed for the walls. Won’t that trap moisture between the Redguard and liner?
    His liner install matches your description well at walls and studs but I’m just feeling a little queasy at it glued flat on my slab.
    I can send pictures…I dread having to peel it off the floor, or having to remove (somehow) my linear drain.
    Should I send pics?
    .
    HELP!

    Reply
    • Roger

      Hi Stephanie,

      He may be using redgard (it would be a better option) but if he does the liner needs to be removed. If he’s using the liner it needs a preslope beneath it to aim water to the drain. The preslope can be very thin at the drain if need be, the strength comes from the top mud deck. Is the liner clamped into the drain?

      Reply
  • Lane

    One more question. The concrete guys left me absolutely no room to work as the lower flange was dead even with the concrete floor. After doing the pre slope that flange sits about 1/4 inch lower that the pre slope. I was informed this would be ok. Is it? I have found many workers at Home Depot and Lowes have given me incorrect information on this project. :censored:

    Reply
    • Roger

      It’s fine.

      Reply
  • Lane

    Roger,

    On question have done the pre-slope is a little rough but no humps or dips. The oatey pan liner is 48″ wide and doesn’t go up and over the curb. My shower bed is 43″x 45 What do I do in this scenario?

    Reply
    • Roger

      Hi Lane,

      You need to get the proper adhesive for your liner material and ‘weld’ two pieces together to make it wider.

      Reply