One of the problems with waterproofing a shower is the fact that you NEED to have holes in it. The cutouts for the shower head, shower or bath controls and any other fancy stuff you saw in that magazine. The problem with holes in a waterproof shower is that they make it not so waterproof.

So how do you waterproof a hole? (Please DO NOT email me with the punchline to that joke!)

Whether you have utilized a topical waterproofing like Hydroban or Redgard (liquid) or Kerdi (sheet), or you’re using the traditional method with a membrane behind your substrate, the answer is silicone. You need to use 100% silicone, none of that acrylic silicone or any of that stuff that sounds fancy (but doesn’t work long-term).

First a little about silicone. A lot of people ask me which silicone is best. For the purposes of most shower applications silicone is silicone. If it’s 100% silicone there isn’t (for all intents and purposes) any difference at all. They are all the same. Just grab a tube of silicone and stop overthinking it! :D

Back of tile with holes cut out

Picture 1

Now once you get your hole cut out in your tile flip it over so you’re staring at the back of it. Have a beer Pepsi to congratulate yourself for such a fine looking circle! (Picture 1)

If your hole spans two or more tiles then the technique is the same, but you should have two beers Pepsis.

Bead of silicone around hole perimeter

Picture 2

Now all you need to do is shoot a large bead of silicone all the way around the perimeter of the hole. (Picture 2)

You can click on any of these photos to view a full-size version.

When you comb thinset onto the substrate you want to scrape away the area around where the hole in the tile is. (Picture 3)

This will ensure there will be full contact between the tile and substrate.

Hole cutout in shower substrate

Picture 3

Then just slam your tile up there.

Okay, don’t slam it up there, place it up there carefully and press firmly to ensure full contact.

What this does is create a dam of silicone around the perimeter of your cutout. When water gets behind your tile (and water WILL get behind your tile!) and runs down the wall, it will run around the bead of silicone and continue down the wall into the tub or shower base and into the drain.

Ensuring full contact between tile and substrate

Picture 4

If you want to, pull the top of the tile back off and check to make sure you have complete contact with the silicone bead and the shower substrate. (Picture 4)

If you get enough silicone on there you’ll be able to run your finger along the perimeter of the cutout after you install your tile to smooth the silicone. It’ll be a mess – just like picture 5.

Tile installed with waterproofed cutout

Picture 5

Once you get your escutcheon (the metal cover plate) on there no water will enter through the front of the tile, then any water behind your tile will run around the dam.

You can also do this with the cutout for the shower head if you want to, but it’s not as imperative up there. It never hurts, though.

If you are using the traditional method and have your waterproof barrier behind your substrate (like in these pictures) you’ll need to silicone the perimeter of the barrier to the back of your backerboard. This creates the same waterproof dam on the backside of your substrate as well.

I do not have a picture of that. Because I’m a slacker. Get off my ass about it. :D

I will call him George...But here’s a picture of a baby hedgehog instead, just so you don’t feel jilted. And an apple. Hedgehogs like apples.

{ 107 comments… add one }

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  • Mat

    Hi Roger,

    Sharing a virtual beer with you…Maybe I should wait till the job is finished first, but since most of my project was done in this matter, I figured I’d have one last one before epoxy grouting my shower floor…

    How do I grout around the shower drain? I’ve got one of those Tile Ready pan (heuh!) and the drain is built in and has a ”screw in” type assembly. What is a normal (read better) way of grouting these type of drain? Do I smush the grout in and under the twist in plastic drain making sure the weep holes are not blocked. In this manner I could always take off the drain assembly or do I simply grout under and around it in order to give it a ”permanent” seal?



    • Roger

      Hi Mat,

      You need to just grout around the perimeter the depth of the tile. Once the epoxy cures it’ll stay put and your weep holes will still be open and operational.

  • Matt

    Hello Roger,

    That appears to be a Delta valve in these images. The Delta valve that I installed has a black plastic guard that clips into the deal, I have heard it called the plaster guard. Do you have that installed in these images and just covered it up? Or do I not really need that thing? I would prefer to remove it if possible, but currently have my tile cut to fit around this “plaster guard”.

    Thank you

    • Roger

      Hi Matt,

      They do have it, I just remove it before tiling. Take it off before you install the escutcheon. They don’t remain in there, they are only for the construction portion. If your tile is cut around it you’re fine, the cover will – cover – it. :D

  • Julie

    Hi Roger,

    I have your Traditional Waterproofing Manual and I really appreciate the wealth of information you share here on your website.

    We are building a tub with surround on the outside wall of some new construction and chose the traditional waterproofing method. The moisture barrier (6ml plastic sheeting) overlaps the flange of the tub, but the silicone caulk does not seem to be bonding properly. It sticks to the tub just fine, but adheres poorly to the plastic sheeting. What do you advise?

    Thanks so much!

    • Roger

      Hi Julie,

      If the silicone isn’t sticking well enough you can use sika-flex (it’s in the concrete section) or urethane sealant like liquid nails.

  • Tim

    Well its all roughed in. Looks like its gonna work. Not sure why the escutcheon would not have fit?

    Thanks Roger!

  • Tim

    Here is my small dilemma. I am installing Kerdi complete shower system with valve seal and shower head seal. During my research I realized that the Schluter valve seal is approx 4 1/2″ round and my Danze shower valve plaster guard is 5 3/4″ round. I would really like to use the Schluter valve seal as I am using drywall as my backer.
    1.Do I have to use the Danze plaster guard or is it possible to just mount the valve as usual and just make my cutout 4 1/2″ round so i can use my kerdi seal?
    2.If I cant use the kerdi seal and must go with the 5 3/4″ plaster guard what is the best worry free alternative?

    • Roger

      Hey Tim,

      Provided you can get the escutcheon to fit on there correctly with just a 4 1/2″ hole then you can go ahead and use the valve seal and do that. Plaster guards are normally larger than they need to be to ensure that once plaster or mud cures there is plenty of room for everything to fit correctly.

      The alternative is the above method with the silicone. If you have dryall in there you also want to smear silicone on the inside of the cutout to protect the core of the drywall.

  • sam

    I need to fix the tip of a paver that is broken. It comes to an angle on a corner of a walkway (paver is grouted in). What adhesive would be good to use?

    • Roger

      Hi Sam,

      A putty epoxy would be your best bet for something like that.

  • walter

    Hey Roger,
    Greetings from the craft beer capital of the world! Just downloaded your shower waterproofing book; I was hoping that it addressed how to go about building and waterproofing a bench and niche but alas, (dammit; you made me say “alas”) there is no chapter on them thar topics. Do you have any archival how-to’s on such an endeavor in your site?


    • Roger

      Hi Walter,

      I do not yet have anything about benches – it’s on the list (it’s a big-ass list :D ). I do have a niche tutorial here: Building a niche and I’m putting up another method for it this week.

  • Dave

    “Just the place for a Snark!” the Bellman cried,
    As he landed his crew with care;
    Supporting each man on the top of the tide
    By a finger entwined in his hair.

    Fit the First (First Stanza)
    The Hunting of The Snark, by Lewis Carroll

  • Todd

    Hi Roger,
    I am extending a schluter tray with deck mud as my shower base and have a few questions:
    1. Should I leave expansion room between the schluter tray and the wall or between the mud extension and the wall?
    2. Will the mud base bond to the schluter tray or should I worry about stress where they connect?


    • Roger

      Hi Todd,

      1. Provided you are using a correct mud mix (4-6 to 1) then no need for expansion in those areas.

      2. It will not bond to it. I usually use thinset against the tray before installing the mud to it stays put.

  • Nick

    Although I used the “traditional” membrane set-up, I went and bought Kerdi’s pipe seal and valve seal and installed these on my backerboard. Would I still need to do this silicone trick on my tiles or am I “good”. Also, having used sanded grout on the floor, how important is sealing it? At this point will that even matter if the shower has been waterproofed underneath? Thanks again for your help!

    • Roger

      Hey Nick,

      You don’t need to do anything else with the valves. Sealer has absolutely nothing at all to do with waterproofing. Whether or not to seal it is entirely up to you. Basic sealer information

      • Nick

        Great info. After reading it I feel as though I don’t need any sealer. I’m using dark grey porcelain with a black sanded grout on the floor. The only thing that may cause an issue is mold growth, however since we are not pigs, reg. cleaning of the shower should work just fine. Thoughts?
        Any chance you have a link to an article on how to replace 1 tile? I got a loose one on my stairs that’s making a terrible popping noise and keeping me up at night, LOL.
        Thanks again

        • Roger

          As long as you have some semblance of normal maintenance you won’t have a problem with mold. I do not have anything to replace one tile. Just scrape out the grout between it and the tiles next to it, pry it off of there (should be easy), scrape the substrate and install your new tile with thinset. Grout and get some sleep. :D

  • Fred

    I am using traditional waterproofing (see I learned something from your book) on my shower surround. The book was worth ten times the price, but as I read I noticed my dog starting to smoke and thought I better ask you an additional question. You silicone the vapor barrier to the shower base to allow the water to escape to the drain (which makes sense). You then silicone the tile to base. So how does the water escape? Or did I miss something?

  • Nick


    I imagine you may get somewhat used to the accolades for this website, but let me say very enthusiastically THANK YOU! Your web site has proven to be a fantastic resource for a novice DIY tiler like myself. I am about to embark on my first tile shower project, and have ordered the Kerdi shower kit. Your articles have done such a good job of preparing me to tackle this job (or making me feel as if I am prepared) that my only questions (for now) are regarding some simple items.

    1. Your photo at the top of this page has inspired me to try something similar (run accent tile as essentially a vertical stripe behind the valve and shower head). Is there an elf trick to cutting the accent tile around the mixing valve and shower head?

    2. To expand on the inspiration that you have given me, I plan to run the “accent stripe” vertically behind the valve and shower head, then over the ceiling, back down the back wall and….. along the floor??? Is it a bad idea to use accent tiles on the floor of the shower?

    P.S. I get quite a chuckle out of you writing style, so if you have time an extra witty response would be more than appropriate and appreciated! :D

    • Roger

      Hiya Nick,

      The photos at the top of the page cycle randomly, so I have no idea what photo you may be speaking of. When I looked at the page it was a picture of an outdoor bbq – I have to say it’s an extremely poorly thought-out plan to have both propane and fire in your shower. It makes your burgers soggy and may blow when you’re not looking (I would insert an extra witty part here about my ex-wife having that problem – but I try to keep it family friendly…). Also: Not OSHA approved (although that may have changed in the last week or so…)

      1. Actually I do know what photo it is, there is no real secret, just remove the mosaic around the fixture cutout on your substrate. You rarely even have to cut one because the escutcheon normally covers the entire cutout and about 1″ or more around it. You can usually just remove tiles where the fixture is.

      2. Hey, if you want a racing stripe in your shower more power to you! It makes the water come out faster. I installed a racing stripe in my kids’ bathroom in hopes that showers would take less than 3.7 hours.

      That didn’t work.

      So if that’s why you’re doing it, rethink that. The suitability of the mosaic on the floor depends on the particular tile you choose. If glass, it needs to be approved for use in a flooring application. Not all glass tiles are created equally, and glass for use on floors is expensive as hell. It’s also never a great idea to install glass on a floor in a wet area – it’ll be slippery.

      Try this: Get a block of ice and place it on the second step of a stairway, then run down the stairway. Slippery, huh? Yeah, like that. That, by the way, was a thought experiment. If, by chance, you actually just did that please send me the address of your hospital room and I’ll send you a get well card. Or at least a letter mocking you for actually doing that.

  • Ben


    In this article, you mention that “When water gets behind your tile (and water WILL get behind your tile!) and runs down the wall, it will run around the bead of silicone [around the shower controls] the and continue down the wall into the tub or shower base and into the drain.”

    Assuming one has sealed the gap between the bottom row of tiles and the bathtub, how exactly is the water (from behind the tiles) supposed to “continue down the wall into the tub”?


  • Ed

    Hi Roger,

    I’m in mid-process of tiling and looking for a caulk to match the grout color. All I’m finding around me from HD and Lowes is “siliconized acrylic” which I know you are not a huge fan of but will they work ok? I did use 100% silicone for the backerboard corners and fixture cutouts (in white) but still looking for 100% silicone in colors for the finished tile. Do they exist? I used SpectraLOCK epoxy grout but they don’t carry any Laticrete caulks.

    Also making corner shelves today.



    • Roger

      Hey Ed,

      The siliconized acrylics (which is a misnomer in my mind) work fine. You’ll just need to replace them sooner. They tend to dry out more quickly and lose elasticity, silicone doesn’t do that. (I’m talking about years).

      Google either ‘Laticrete latasil’ or ‘TEC silicone’, you should be able to find either online easily.

  • Jim Dare

    Roger, I’ve got my tile layout planned, but was thinking of changing it so the 4 1/2″ hole for my shower control falls completely within a tile (I’m using 12″ x 12″ porcelain tiles). Then I saw your post about putting holes along grout lines when possible to make cutting the hole easier. Can you describe how to get a continuous bead of silicone through the grout line? Making it a little trickier, only about the top 1/4″ of my hole is above the top of the tile, and the tile above that is that little, fussy mosaic accent stuff my wife thinks I can install. Do I just put the caulk on the wall instead of the tiles? Since this is beneath the shower head and will catch the water right at the grout line, I really want to get it right.

    By the way, I’m planning on attempting this fairly large hole with my angle-grinder using a technique I saw on the internet. Keeping the tile from getting too hot, as you’ve noted, appears to be key. An alternative would be to get an X-bit for my Rotozip tool, which they say spins fast enough it doesn’t require water to cool the tile. Any suggestions for making this cut?

    Thanks again for sharing all this information.

    – Jim

    • Roger

      Hey Jim,

      To waterproof it when there is a grout line there simply run your bead of silicone as shown, then after you have the two pieces of tile installed fill the very inside (toward the valve) of the grout line with silicone.;

      I do it with my grinder all the time. A rotozip works, but I prefer the grinder. Just take your time with it. If you have a 4 inch grinder blade it’ll be easier to make a 4 1/2″ cut. Absolutely no need to keep the grinder cut cool either – it spins just as fast (or faster) than the rotozip. If you use a segmented or diamond blade it will be better than one with a continuous rim.

      • Jim Dare

        Got it – thanks Roger. Really. As I’ve been doing the prep for this job (cement board, waterproofing, painting around the stall, etc) I wake up in the middle of the night thinking of the tiling. Really – if I were paid by the hour for sleep-tiling, I could retire. [oh, wait – I AM retired.] Your advice makes this project a lot more fun than it otherwise would be.

        • Al

          Here’s a follow-on quesion about cutting a hole in porcelain tile for the mixing valve. I used Kerdi in my shower and the 4 1/2″ Kerdi mixing valve seal. The valve sits close to the center of a 13″ tile. I don’t have a rotozip and I don’t have a grinder.
          What’s the best tool/method to cut the hole?

          • Roger

            Hi Al,

            A grinder. The fact that you don’t have one doesn’t make it not the best tool. :D

            You can cut it with a wet saw, but you really need to have experience doing that, it isn’t very easy if you’ve never done it. You need to mark the back of the tile and lay it on the tray tilted and lift it up into the blade in small steps around the circle. Is there someone you can borrow a grinder from? Even the little $20 job from harbor freight will more than suffice to take care of that.

  • Jake

    Hey Roger, thanks for sharing your seemingly endless wisdom, I have made a shower and have been following your manual step by step, and all is well…. however reading your site now I realized I totally forgot to create a waterproof dam around the valve cut out by applying silicone on the perimeter of the back of the tile cutout! I dont know how I forgot it was on my to do list I just got carried away I suppose, Do you have any advice to remedy this problem without removing the tile as it has set and otherwise looks great, the shower I am confident is completely and correctly waterproofed otherwise (having followed your instructions.)
    Thanks Rog!

    • Roger

      Hey Jake,

      If you can get the tip of the silicone tube into the gap between the tile and backer just put a good bead in there. If you can’t, grab a roll of paper towels and put a bead between the tile and backer (substrate) by gobbing (technical term) it onto your finger and sticking it through the tile and running it around the perimeter. The paper towels are to clean up your mess, ’cause you’re gonna make a mess. As long as you get that gap sealed you’ll be fine.

      By the way, the ONLY reason my ‘wisdom’ seems endless is because I’ve made every one of these mistakes before and had to figure out how to fix it. :D No extreme wisdom here – just a knack for solving problems (purely out of necessity).

  • Jake

    Hey Roger, your site is a lifesaver! Question about the backerboard though: I have cut the hole around where the shower handle valve will be too large about an inch and a half maybe two inches to large around the entire perimeter, aside from removing the 4by 8 piece of dura rock, how can I fix this? Mud and tape? The tile I am using is small so it won’t span the distance of where I have the hole cutout.


    • Roger

      Hey Jake,

      You can use mud and tape or something like kerdi over it. You can also install a piece of 1×2 behind the hole and screw it in through the backer outside the perimeter of the hole. You can then fill in extra backer and screw it to those 1×2’s.

  • Matt

    Roger, what is your opinion about attaching wooden furring strips to 2×4’s, then attaching hardibacker to the strips. This seems to be the only way I can attach the hardi in order make it extend beyond the lip of my swanstone base.

    • Roger

      Hey Matt,

      That’s the proper way to do it.

  • Tom


    Thanks again for your insights for the insightless…

    I am completing my tub surround in subway tile and have a vinyl window that I am keeping in the shower stall. I have applied Red Guard over mudded and taped Hardi-Backer with sealed corners– so feel like I have a good seal all around…thanks to your guidance. I have most of the tile in place and am almost ready to grout…

    1) I want to add a typical Daltile Chair Rail Trim to “picture frame” the window recess… with bullnose tile returning to the vinyl window frame from the edge of the Chair Rail “frame”. I am assuming I would want to caulk he inside joint between window frame and tile as well as possibly at the outside joint between bullnose and Chair Rail Trim… or can I just grout the Outside joint?

    2) Related…Do you run the grout to the corners and to the face of the frame and then seal over the top– or do you rake out the grout at the edges to make room for the caulk– more in the same plane as the tile? This would also apply to the inside corners of the shower stall and possibly at the bottom seal along the tub-which I have left a 1/4″ to 3/8″ gap for sealant…

    3) How do you grout the 3-dimensional chair rail so it looks best? Sharp sponge edge along grooves?

    4) I’d also like your opinion about grout color with white subway tiles with some 1/2″ black “liner” tile bands…I am leaning a grey that splits the difference between white and black–or– go with white to cover up some of my poor spacing work in the tile field?

    Thanks again for your help and humor…

    • Tom

      Follow-up on floor tiling outside of tub…

      I have an existing double 3/4″ ply substrate that I will be laying 1″x2″ mosaic tile over. It does not regularly get I need to apply ditra or 1/4″ backerboard or do you think it is safe to just lay tile in a modified thinset? Thanks…

      • Roger

        Backer or ditra, you still need a proper substrate to bond tile to.

    • Roger

      Hey Tom,

      1. Grout the outside joint.
      2. Rake out all the grout and fill the space with sealant. 1/4″ – 3/8″ is HUGE! Should be 1/8″ or so, if not smaller.
      3. Yes, cut your sponge in half corner to corner – works very well for tricky spaces. And you get twice as many sponges. :D
      4. White. Subway looks best with white and the chair rail will ‘pop’. (my opinion – my designer’s word)

  • Nancy


    I’ve been through your liquid membrane shower installation manual and your web site. I understand to silicone joints where there’s a change in plane and to mud joints in the same plane. Then cover all with the liquid membrane. The hydro ban instructions directs to mud the corners (change in planes). Would there be a reasone to mud over the corners (previously siliconed) then apply the liquid membrane?

    Thanks in advance!


    • Roger

      Hi Nancy,

      You can do it either way. It’s simply two different methods. The silicone method is the way I do it. You can still tape and mud the corners if it would make you feel more comfortable.

  • Garrett Lee

    A question about an alternate method.

    We installed subway tile for a shower surround, and went with the traditional method of waterproofing. We didn’t have silicone caulk handy for sealing the holes in the substrate, so we very thoroughly filled the holes around the pipes/controls with plumbers’ putty. I assume that this is an acceptable (though old-fashioned) way of sealing these? If not, well, I don’t have a dog to combust. Will the cat burn?

    • Roger

      Hey Garrett,

      Yes, plumber’s putty will work fine -your cat’s safe. :D

  • Bill


    I have installed wunderboard in a shower and was told that I could use silicone or thinset on the seams. As I had the silicone available, that is what I used. It seems (pun intended) that everything I read leans toward thinset. I plan to redgard over it and then tile. Will the silicone be a problem?

    • Roger

      Hey Bill,

      You need to have thinset and alkali-resistant mesh tape on the seams that are in-plane (on the same wall). In the corners you can have silicone, but they should be taped and mudded with the same.

      • Bill

        Thanks Roger,

        I realized after sending that I actually used Hardyboard – not wunderboard – if that makes a difference. Beer level must have gotten too low. Do I need to remove the silicone and then tape and mud over the seams? The gaps were fairly tight, so the silicone has made a nice seal. Can/should I tape & mud over the silicone since it is, for the most part, flush or below the surface. Out of curiousity, what is it about the silicone that is not right for this. As I mentioned, before finding your site, I was told that it was an acceptable alternative. Not questioning your wisdom…just the engineer in me that tends to want to know why.

        • Roger

          The boards in-plane need to be tied together so they move in the same direction at the same time rather than independently. Taping and mudding them accomplishes this, silicone doesn’t. You should be able to just tape and mud over them as long as you don’t have a large amount on the face of the board.

  • Gene

    Dear Roger,

    I am designing the layout for a bathroom remodel so that almost all dimensions will be on full tile boundaries. Is there any way that I could send you a couple of sketchup drawings for comment?

    What is the best way to mount (substrate) a stone deck for a drop-in tub? I am considering a 1″ thick mortar bed over 3/4″ plywood, kerdi, thinset, stone or 3/4″plywood, Ditra, thinset, stone?

    Is there a standard overhang dimension (the tub will be located in a corner) so it will overhang on two sides.

    Can I use Keri Board on the walls and Hydroban to waterproof the niches?

    The shower area will be located between the drop-in tub and a glass shower wall. Ideally, I would like to install a linear drain between the tub and glass wall 5′ from the shower head wall. The floor is covered with two layers of 5/8″ plywood over sistered joists (it is rock solid). A mortar bed will slope from the showerhead wall to the drain. Is this doable without raising the rest of the floor? Proline Drain has a drain that is recessed into the plywood but it would require a mortar bed that slopes to 0 or the use of a prefab pan.

    Thank you for any advice you can offer.


    • Roger

      Hey Gene,

      You can email me at with the layouts if you want.

      Either the ditra or mud deck will work fine. Standard overhang is four to six inches. Kerdi-board and hydroban work fine.

      If you install a curb in your shower you don’t need to do anything with the rest of the floor. If it’s a curbless shower you’re talking about you need to have the drain across the entrance to the shower and the floor rises to the back. If you have anywhere else you either need a curb or need to raise the rest of the floor to accommodate the slope.

  • Jerry South San Francisco


    I have my hardieboard up but did not apply hydroban yet. I did not have time to build a niche. I thought to install a grab bar with integrated shelf. If I install it after the tile can I diamond drill the holes and fill them with silicone to waterproof or should I make an intervention during the hydroban process?


    • Roger

      Hey Jerry,

      The silicone in the holes will be fine.

  • Eric

    Hypothetically, if one were tiling a new shower, and one were to place the tile with the control cutouts exactly two days before reading this blog entry, and one were to realize they hadn’t done anything to address water running down the surface of the Redgard behind the thinset, what would be the best course of action to remedy this totally hypothetical situation that is in no way related to my current bathroom remodel? :-)

    I have two control knobs penetrating the Durock and Redgard. One is for temperature and volume, the other is a diverter. The diverter rough-in valve is recessed, and fortunately there wasn’t much thinset right up to the hole in the tile, so I was able to squirt a nice bead of silicone around the hole after the fact. Unfortunately, the volume/temp control rough-in valve protrudes through the tile , leaving little room for access, and the thinset is pretty much right up to the hole.

    Is there anything I can do at this point? If not, am I in trouble?

    • Roger

      Hey Eric,

      You can still seal it with silicone. Just make sure you get the bead all the way back to where the redgard is. As long as there’s a good bead in there it’ll be fine.

      Hypothetically, of course… :D