If you need to decide which method is best for you I have a free shower waterproofing manual that you can download here. Shower waterproofing manual. Go get it – it’s free! And I’m not gonna use one of those damn annoying pop-ups! I hate those things…
There are several ways to prepare the wall of a shower for tile. Depending upon what was originally there, what stage the shower rebuild is currently in, and what type of tile you plan to install plays a minor part in choosing which method to use.
The most critical aspects of which product to choose are: how much work you’re willing to put in and how much money you’re willing to spend. The end result should be the same – a waterproof box. The methods used to accomplish that vary in effectiveness and cost. So we’ll start with what I consider the most bullet-proof method.
Kerdi Shower System
A company called Schluter makes a shower system called Kerdi. The entire system, which can include everything from the wall membrane down to the entire shower base, is considered by many professionals to currently be the top of the line in shower substrates and waterproofing membranes. And no, I don’t work for them. I don’t owe them money. And they don’t take me on those all expense paid vacations to Bermuda – bastards. I like their products anyway.
The waterproof membrane made by Schluter is called . . . well, Kerdi. It’s bright orange and you can see it from space. It is installed over regular drywall or cement backerboard with regular thinset. It makes your shower a big bright orange waterproof box that glows in the dark. Okay, it doesn’t glow in the dark.
The material is difficult to describe with words, it’s kind of like a fleece-lined rubber(ish) membrane. I like it for two reasons: It is the best available and it happens to be the easiest, least work intensive option (once you are used to working with it). While there is a fairly large learning curve to effectively work with it, Kerdi is fairly easy and very well documented. There is a wealth of infomation on the internet about it. Just Google Kerdi. Go ahead, I dare ya. Noble company also makes a similar membrane called NobleSeal, but it isn’t pretty bright orange.
Liquid Membranes
After Kerdi, a brush or roller applied liquid membrane such as RedGard works very well. It is applied with a brush or roller like a thick paint. It’s bright pink. You coat it once, after it changes to red, coat it again. Usually two coats is sufficient for any shower (except steam showers). After is sets overnight just go in and stick the tile to the membrane itself. It is a bit expensive, but they are also simple and quick to install.
There are several of these membranes on the market, the most common being Redgard. My favorite is Laticrete Hydroban. Laticrete also makes Hydrobarrier and Mapei has Aquadefense. They are all pretty much comparable.
Preparing shower walls with RedGard
If you are building a shower and want a manual describing the entire process you can find it here: Liquid waterproofing membranes for shower floors and walls
Cement or Fiber Based Backerboard
If you don’t want to spend the money for Kerdi or RedGard, this is your next best option. These are products such as Durock, Hardiebacker, and Fiberboard. While the product itself is not waterproof, it is water-resistant. The backerboard will actually hold water, as in water will soak through it. There needs to be a vapor barrier put up between the wall studs and the backerboard.
The unique thing about these products is that, although they are not waterproof, they will not become unstable with moisture. (That just means water doesn’t make it swell up.) To use these you must first install some type of moisture barrier over the wall framing. Get a 4 mil or thicker plastic (mil is just the thickness of the plastic) which can be purchased at places like Home Depot, and staple it to the studs of the wall framing. You can also adhere it to the studs using silicone. Completely cover all areas from the tub to the ceiling. The backerboard is then screwed onto the studs to make your shower walls. Then you just stick the tiles to the wall and shower away.
I also have a couple of manuals describing the entire process from the wall studs all the way up to a completely waterproofed shower substrate ready for tile. You can find them here:
Waterproof shower floor and walls manual
If you have a tub or pre-formed shower base and need to only do the walls you need this manual:
Waterproof tub and shower walls
Denshield
Denshield (and others like it) are similar to drywall in that they are lightweight and easy to install. It is a waterproof core laminated on each side with a fiberglass based face. It is installed like drywall except you need to run a bead of silicone between the sheets to waterproof the seams. You then need to use fiberglass mesh tape over the seams. It does not require a moisture or vapor barrier behind the sheets. When properly installed Denshield is an adequate tile substrate for shower walls and relatively affordable compared to alternative methods.
If you are building a shower and want to use a topically-faced wall substrate you can find that manual here: Building a shower with a traditional floor and topically-faced wall substrates
If you are just tiling around a tub or pre-formed shower pan you can find that manual here: Topically-faced wall substrates for tubs and shower walls
Plain Drywall *DO NOT DO THIS!!!
Yes, you can do it if you must. I absolutely do not recommend this! But I’m also realistic enough to know that if you decide this is what you’re going to do, I’m not gonna be able to stop you from here. You can not just go up to your drywall and start sticking tile to it – ever. There needs to be a moisture barrier between the drywall and the framing. At least then when water gets behind your tile and grout and disintegrates the drywall it won’t disintegrate your wall framing as well. Remember, if water gets to one of the studs not only will you be replacing the shower, you will need to do some serious repair work to your wall framing and possible structural work. Please also note that using this method runs the risk of parts of your wall literally falling apart if it gets wet – drywall disintegrates in water.
And it will. So don’t do this!
Unsuitable substrates for shower walls – no matter what you’ve been told
- GreenBoard, also known as green drywall. Never use this or you’ll get a lot of practice replacing showers.
- Backerboard without a moisture barrier.
- Drywall without a moisture barrier. (I do not recommend drywall as your substrate at all.)
- Any type of plain wood or plywood. Ever. No, painting it makes no difference.
I’m certain there are a lot of things I’m not thinking of that someone else will. If you wouldn’t let it set in a swimming pool for a week, don’t use it for your shower walls. That should clear it up.
The golden rule
Although there are many products that can be used for your shower wall, many should not be. Regardless of which method you choose one thing to keep in mind is that you need to have some type of waterproof membrane between your tile and your wall framing. Kerdi membranes and RedGard are both waterproof membranes that go directly on the wall. Plastic stapled to the frame before installing your substrate is also acceptable.
The main thing you need to ensure is that no water reach your wall studs – ever. Wood swells with moisture and the only place that excess swelling is going to go is right into the back of your tile. Remember, your tile is not waterproof so you want to adhere your tile to a substrate that is as waterproof as you can make it.
If you need to decide which method is best for you I have a free shower waterproofing manual that you can download here. Shower waterproofing manual. Go get it – it’s free!
Hi Rodger:
Thanks for clearing up the insulation covering issue.
I was buying some hardieboard today and I asked about installation and the sales guy said the top and bottom edges of the backer board should be supported by a wood support, ie a horizontal 2×4. I’m using 1/2″ backer board is this really necessary? Do I need to attach the 2×4’s to the studs or can I just screw it to the lower board and then screw into it with the upper board and not have it connected to the studs?
The sales guy also suggested I cut the board with a diamond blade since I’m going to be cutting a bunch of boards to fit 3 sides of a tub and around a window. Does this make sense or is a Hardie blade or a carbide blade just as good for a circular saw? Or should I forget the saw and plan to score/break the boards?
Dee
Hey Dee,
It is always a good idea to support all the edges although it is not absolutely necessary – it does add a great deal of stiffness to the walls. It is also always better to screw them to the studs but, if your wall studs are 16″ apart (which they should be) simply screwing to the top and bottom board will give it more than enough support.
DO NOT cut your cement backerboard, Hardi, durock, or any other, with a diamond blade on a circular saw! The blade will cut it – very, very well. That, however, is not the problem. The problem is the concrete dust which will be generated from doing so – it will look like someone put a stick of dynamite in a bag of powdered concrete and lit it. This is not good for your lungs, eyes, or general overall attitude. Any blade you use on a saw will do the same. They will all cut but dust collection and control is the issue.
There are saws made specifically for this which hook up directly to a vacuum and cut the dust down considerably. If you don’t want to score and snap it this may be the way to go. You can also just score and snap the straight cuts and get a carbide blade for a jigsaw which will cut any inside corners, etc. This does not generate nearly as much dust and if you keep a vacuum hose as you cut it will nearly eliminate it.
Yeah a bag of concrete dust and dynamite. Too funny. Reminds me of an ocean side community that had a dead beached whale. They decided to blow it up. Blubber everywhere!
I understand that concrete dust in California is hazardous to one’s health, so I was considering making the cuts outside on the driveway with a fan and a dust mask. Will this work?
The Hardieboard I bought has a small bow in it (1″ to 2″ in 5′) is this a big deal or will the fasteners fix it?
Hey Dee,
The bow will not be a problem, the fasteners will fix it. If you have a fan and dust mask it can work, just a matter of how much you’re willing to deal with. For you doing one shower it shouldn’t be much of a problem. Me doing it every day, though…not so much.
Hi Rodger:
I didn’t understand your answer, so I read the posts in your answer. I didn’t find what I was looking for, plus I came up with another question. Go figure.
Insulation
From you June post “If you are using kerdi use unfaced insulation.” I’m not sure what is unfaced insulation. The insulation that I installed has a paper backing, is this ok or should I cut slits in the paper or fully remove the paper?
Hey Dee,
Unfaced insulation is simply insulation without a water or vapor barrier on it. The paper-faced insulation is fine to leave as-is. That’s not the stuff you need to worry about. It’s the plastic coated or covered stuff I was referring to.
Hi Roger, I’ve been reading all of these comments about showers and tile, and now I’m really worried. We have a total bath remodel happening. I noticed tonight when I got home that the builder was halfway through tiling the new shower, and that he just put the tile right over the hardie board.I don’t see anything applied to the board and I don’t remember any membrane going up between the studs and the board. I see here that that isn’t the best idea. Also, he has begun the process of tiling the shower niches and he is tiling over straight drywall at the back of the niche and 2 x 4’s on the sides. Not even hardie board! He has been doing this for 30 years and we are paying a lot for this bathroom. I think I should have him rip it all out and start over now that I’ve read all of your comments. What do you think?? Thanks so much!
Hi Jennifer,
You can simply ask him how the shower walls are waterproofed. He may have installed a moisture barrier behind the board. If not, ask him how the drywall, raw 2 x 4’s and the entire shower are supposed to remain intact. Regardless of whether or not he has the moisture barrier that niche absolutely needs to be waterproofed.
As I tell everyone – just because someone has done it for thirty years doesn’t mean they’ve done it correctly for thirty years, eh?
I would have him stop and answer those questions before continuing to install all your tile incorrectly.
Hi, Roger – I just found your very useful site – thanks!
I’m completely redoing a bathroom – new tub and tub surround, as well as new flooring. I’ve purchased but not yet installed 1/2″ PermaBoard backerboard for the walls (I plan to use porcelain tile). For vapor control, I plan to either install a 4 mil vapor barrier or use RedGard on the CBU, but I’m not sure which makes more sense. I suspect the vapor barrier will be cheaper, but it seems like it’d be less effective. Won’t I have to puncture it to attach it to the wall studs, and then cut through it for the faucet, tub spout and showerhead (all of which are braced on wood)? Can I just seal all of those cuts with silicone? How far beyond the edge of the shower stall should I hang the barrier (and is it okay to cover this non-shower area with drywall)? Do I attach the barrier to the tub flange, or the lip of the tub? If I use RedGard instead, how do I seal the cuts around the fixtures?
I also have some questions about where the tub meets the walls and floor. Is it acceptable to use drywall, rather than CBU, for the walls just on the outside of the tub, and do I seal the contact between tub (I mean the outside vertical surface of the tub) and wall with caulk? Do I have to worry about moisture on the contact between drywall and tub exterior? Similarly, do I caulk the seam between finished flooring (tile) and the tub bottom?
Hi Nicole,
The 4 mil plastic is considerably cheaper. Yes, you will need to puncture it to attach the substrate and your waterproofing will be behind your substrate rather than directly behind your tile. Redgard is a much better, more effective and efficient method. You can seal the cuts for the fixtures with silicone. I usually go about two or three inches outside of the shower itself with the backerboard. Yes, you can cover the rest with regular drywall. You do attach the barrier to the tub flange with silicone on the backside of the barrier (between the plastic and the flange).
If your shower is built correctly you do not need to worry about moisture outside of the tub. Yes, caulk between the finished tile flooring and the tub bottom. Caulk around all edges where your tile ends (outside vertical, top horizontal), around the tub perimeter where it meets tile, and all corners in the shower.
Did I get everything?
You did – thanks! Next question – I noticed on another post of yours that you said you do the taping/floating of CBU joints as you tile (the post in question was about floors). I assume that I’ll need to do this in advance and let the thinset cure before using RedGard. If I go with 4 mil plastic, though, can I tape, thinset and tile all at once?
Hey Nicole,
Yes on both.
Hopefully the last question – I decided to use the liquid membrane, and this weekend I installed the Permabase. I bought Mapei’s Aquadefense (because I was at Lowes, not Home Depot at the time). Its instructions state that concrete must be cured for 28 days or skim coats for 3 days before applying the Aquadefense – which one makes sense for the taped/thinset-coated seams? Do I really need to wait a month (!) before coating? If so, can I use RedGard sooner?
Hey Nicole,
Nope, you don’t need to wait a month. The 28 day requirement is due to the bulk of the concrete curing process being complete (essentially) after that time frame. The three day requirement is the same reason. However, you can use thinset and apply the Aquadefense after 24 hours. The hydration process in thinset does not take more than that to complete. Redgard and Aquadefense are essentially the same in that regard – the requirements for cure time are reliant on the hydration process of portland cement, not necessarily thinsets.
Dear Roger,
What great information you have here! My question….I live in a manufactured home. We have tiled the floors with no problems. Our (Mobile home) bathtubs have to be replaced at this time. I am wondering, as long as we take the proper steps above, will it be ok to tile our shower walls? (I know we can the floor, as we have already done that in the kitchen and bathrooms). If so, are there any extra steps that need to be taken for the mobile home walls in preperation for the tile? Thanks for your insight ahead of time.
Sincerely,
Pam
Hi Pam,
Yes, you can tile the walls in manufactured homes exactly the same as normal. You absolutely must remove the current walls down to the studs and install the proper substrate. Whether or not you use a topical membrane such as kerdi is completely up to you but you can not install that over any existing walls in your shower. Manufactured homes are notorious for having multiple thin layers of some foreign wooden-like substance that I’m fairly certain is made from pressed unicorn droppings or something. Whatever it is it gets wet, bows out, and tile falls off the walls. (I’m not gonna tell you how I know that, just trust me on this one.
)
So as long as you remove all the current walls and build from the studs out you’re good to go!
Thanks Roger! I will strip the walls down to studs!
I hope to get back to you with good news of my fabulous new tiled shower 
and not feeling like this 
. Thanks again!!
Hey Roger,
OK, I’m knee deep in this now. I was told greenboard was fine to go around a tub and everything is installed and I am ready to tile. I can’t rip it out and replace it, time is of the essence and I need to just go with it. There is no plastic barrier behind the wall as I was told the greenboard was a vapor barrier by itself and it wasn’t needed. Questions:
1. RedGard – should I use it? If not, is there anything else I can use to improve the situation? Kerdi?
2. If I use RedGard, can I use a premixed thinset to tile?
3. There is a gap between the edge of the tub and the greenboard (again, probably got faulty advice, but I was told not to put the wall over the tub lip), is there a product that is used to fill the gap? I’ve read about foams, ropes, silicone, or just tiling over the gap (really?) but I’m a little confused about the whole thing.
Thanks so much, I really bit off more than I can chew here…
Hi Julie,
1) Redgard is an option but not really the best one as drywall of any type (including greenboard) is not a suitable substrate for that product or (and I’m almost positive about this) any liquid membrane. Kerdi would absolutely be your best option at this point.
2) Nope, absolutely not, huh-uh.
‘Premixed thinset’ is simply mastic with sand in it and not suitable for a proper shower installation.
3) How big is the gap? If less than 1/4″ or so and you use Kerdi you can simply install the kerdi to the bottom of the greenboard, span that gap, then use kerdi-fix (or silicone) to adhere the backside of the kerdi to the tub – another reason it is your best option. If it is larger than that you can fill it with a ‘backer rod’ which is a flexible rope-type of thingy (real technical, huh?) that is usually used to fill in space behind a caulk joint in structures. And no – do not just tile over the gap.
Your biggest issue is the waterproofness of your shower. At this point you are essentially stuck with a topical membrane and, as I’ve stated, kerdi would be your best option given the current substrate, the gap, and the timeline. Using kerdi you can run the waterproofing all the way around the walls and over that gap to contain all moisture inside the shower and away from the greenboard. You want a solid waterproof substrate from above the shower head all the way down to the tub – but you already knew that.
Thanks Roger. I will go with the Kerdi. The gap is about 1/2 inch, so I will fill in and Kerdi over it. Thanks so much for all of the advice!
One last question for you – do I need to use Kerdi fix or will any sealant/silicone do? Thanks.
If at all possible – at all – use kerdi-fix. It is chemically manufactured to work with kerdi. As an absolute last resort you can use a 100% silicone and make certain you get total coverage on the back of the kerdi as well as the tub.
Roger –
Great site with good information & humor.
We are installing recycled glass tile in a shower on denshield backer. I’ve seen recommendation to use a crack reducing membrane to guard against shrinkage /shifting of the substrate. Are backer boards going to really shrink /expand in a house? (trying to avoid dumbassery)
Hi Patrick,
The backer boards themselves will rarely shrink or expand. The wall studs behind them or the floor joists beneath them, however, always will. Backerboards by their nature are dimensionally stable but are at the mercy of the movement of whatever they are installed to. (Wow- that was really horrible sentence structure) The best you can do is minimize the effects of that movement whenever you can.
As far as crack reducing membranes if you want to use them you would only use them over the seams between the individual sheets of backerboard. This has the same basic effect of mesh tape over the seams in that it will tie the sheets all together as one large, monolithic structure. If one part of it moves it will all move the same amount in the same direction. Individual and opposite movements are what may cause problems.
With glass tile the individual manufacturers will usually have specific installation methods. Follow those as much as you can and your installation will last – the manufacturers want their products to last and they’ll tell you how to make that happen.
Dumbassery – nice!
Hey Roger, thanks for all the info, I’ve already found a lot of the answers I was looking for, but I now have a couple of questions about some things you’ve mentioned. I have my plastic sheeting moisture barrier behind my durock, but my tub is really old and doesn’t have a flange (I think that’s what it’s called), so I have no way to bring the plastic sheeting over that flange and attach it with silicone. Is there a plan B for this situation? And I’m also curious about the ‘weep holes’… where you mentioned leaving 1 inch gaps in the silicone between the tile and tub… on the wall opposite the shower head i can maybe see it, but the wall that the shower head is on… seems like it would just allow tons of water to run through the weep hole and into the wall. Am I missing something? Thanks!
Hi Keith,
Some older tubs do not have flanges or weep holes. You can place a bead of silicone along the back edge of the plastic barrier and fold it at a 90 degree angle toward the inside of the tub and install your backerboard. Then you can simply cut off the excess at the bottom of the backerboard.
On tubs without weep holes you can leave about a 1 inch gap without silicone along the bottom edge of the tub-tile junction about an inch from each inside corner. Anywhere you want to put them would be fine as long as any moisture has someplace to drain after it runs down your moisture barrier to the top of the tub. You don’t want that water to sit back in the wall behind the tile. The water is not going to run into the wall through that space unless your tub is angled back toward the wall (which it should not).
Well, what can I say I came home to visit my Mom, I found my brother put a tile shower with no shower pan in her basement. So I ripped out the tile floor, but not the walls. I am ready to put down the first layer of the shower pan. But I was wondering if I should pull the first layer of wall tile down, so I could put the membrane behind the tile. Or could I do a short cut and layer in up the wall and samwich/ layer with tile, cap and silcone.
Hey Brandy, oops.
You need to tear the walls out to at least a foot above the height of the curb – you need three inches above it for the liner (the minimum height of the liner) and the balance to secure the backerboard over the liner. You do not want to nail through the liner so it needs to be secured above it. You could short cut it but it won’t last. Eventually the seal of the silicone will be compromised – it is not permanent – and allow water behind it. That will lead to a lot of very bad problems.
Greetings,
I jumped to this thread for a moment because I have a related question about cement board.
From the outside in, my house is stucco, Thermoply, studs, and, not yet completed, insullation, cement board, tile. My question is: Because I have the Thermoply, do I still use a moisture barrier between the studs and the cement board? Won’t that create a moisture sandwich? (……………mmmm, sandwich… I digress) The cement board should take care of the moisture from the shower and the Thermoply should take care of the outside moisture coming through the stucco. Correct?
I’m learning so much. Be careful, I’m blonde; the absorption rate is different. Ha!
Susan
Howdy,
The thing you need to allow is vapor to be dissipated. The cavity between the thermoply and the vapor barrier is wide enough for any moisture to dissipate. You need the moisture barrier between the studs and the cement board to prevent the studs from getting wet. The thermoply does take care of the outside moisture and the moisture barrier deals with water from the shower. The inside of your shower will see more moisture than the outside of your house – I guarantee it. You need to prevent that water from touching the studs.
Absorption rate, huh? I’m … not even gonna go there.
Sounds like someone’s been reading. You Rock! 
Okay, I have now read too much and am throughly confused. Here is the stage of my project,
walls are framed, one exterior wall with window, shower floor is concrete and level, plan to install mudbed, have purchased Schluter Drain and kerdi for shower walls and mudbed and detra for balance of bathroom floor.
Thinset between concrete floor and mudbed? If so modified or unmodified?
Wall Insluation- faced or unfaced?
Vapor barrier between studs and sheetrock?
Sheetrock on shower walls or cement board or ?????
Have a soapdish and washcloth bar made of resin, much heavier than tile counterparts, wife insist both be installed on wall inside shower, would you use a special adhesive to set these?
Once again, please offer answers to the questions you think I should have asked.
Thank you again, Ron
Hey Ron,
You can use either modified or unmodified thinset for your mud bed – doesn’t matter. It’s only there to hold it in one place.
If you are using kerdi use unfaced insulation. You always only want only one moisture barrier or waterproof barrier behind your tile, in this case it would be the kerdi. If you have more than one there is a possibility of trapping moisture between the two with no way for it to dissipate.
No vapor barrier between the studs and sheetrock when you use kerdi – same reason as above.
When using kerdi use sheetrock or drywall for the wall substrate. You can use cement board if you want but no real reason to unless you’re building a steam shower.
The same thinset you are using for the tile should be more than sufficient to hold those resin fixtures in place. Just make sure you ‘backbutter’ them before installing. This just means put thinset on the back of them as well as on the wall.
With kerdi your layers of substrate and tile are in this order:
Wall studs (with unfaced insulation if needed)
Sheetrock or drywall (or cement board – your choice)
Unmodified thinset
Kerdi
Unmodified thinset (yes you can use modified – I do all the time, but you won’t get Schluter’s warranty)
Tile
Now stop reading so much and confusing yourself and get to work!
I read your reply about a block wall in a shower and wanted a clarification on something. We have one shower wall that is solid brick with plaster applied directly on it. It is an outside wall which is 2 layers of brick with an air-pocket between. We have removed all of the old crumbling plaster, so is it safe to assume that your method of applying a membrane to the brick and then tiling straight on will work in this case as well? PS. Your website is fantastic and I appreciate you taking the time to educate novices like me.
Hi there Shandra!
You are absolutely correct – my website is fantastic.
Umm, I mean thanks.
As long as that brick wall is good and solid you can install the membrane and tile directly to it. (provided you have all the plaster removed, of course)
Would it be over kill to put up Hardibacker and then coat it with Redguard?
Hey Cooper,
That wouldn’t be overkill at all. Even with Hardi you need to waterproof it in some manner. Either a moisture barrier behind it or a topical waterproofing on top like kerdi or Redgard.
Keep in mind that Hardi is ‘thirsty’, it will suck the moisture out of everything usually too quickly for anything to cure properly. You want to mix up a primer of redgard and water, do one coat with that, then after that dries you can coat it with redgard as normal. The primer will allow the hardi to suck the water out of it and seal the pores so the subsequent coats cure normally.
I moved into a newly built home a few days ago and I noticed these gaps on the base of the shower, I hadnt noticed before. After doing some research, I think they are weep channels. Can you confirm this and do they look fine to you?
Picture from each corner of the shower closest to the door.
http://i40.tinypic.com/2meqyb5.jpg
http://i43.tinypic.com/27ystft.jpg
Hi Nadel, if that is your real name.
Those are in fact weep channels. They are correctly NOT caulked and are in place to assist your shower in drying out. You can scrape out any excess grout in there to clean them up a bit if you’d like. There should be nothing in those channels – it’s perfectly normal.
HI, I just had a jacuzzi drop in tub with marble surround put in. The contractor did not use a moisture barrier. The tiles are 18 in 5/8 of an inch thick) with little grout but my plumber says there is trouble down the road. What kind of sealer should I use on marble? I asked the contractor about the moisture barrier and he mumbled something about not having enough room. How much trouble am I in? Thanks, Nancy
Hi Nancy,
Didn’t have enough room in his knowledge base? Not enough room for a piece of plastic the thickness of a garbage bag? Not enough room my ass!
Sorry, my rant doesn’t help, does it?
Is this a surround on a tub/shower combo or is it just the tub? If just a tub the potential for problems rely entirely upon the type of substrate used for the tub deck.
If it is a tub/shower combo it also relies on the substrate used BUT does not excuse the fact that there is no moisture barrier present. If it is a cementious backerboard such as hardiebacker or durock you may be fine. If it is drywall then he’s simply done everything incorrectly.
You should use a penetrating sealer rather than a topical sealer for marble. That will not solve your problem, though. Sealer does not make tile or grout waterproof. It simply SLOWS the absorption rate of things like water and cherry kool-aid.
To be specific about how much you really need to worry I would need specifics about the installation. Which substrate? What was the tile set with? Was it pre-mixed in a bucket (mastic) or something he mixed with water (thinset)? Did he use minimal size grout lines (1/16″ or 1/32″)? What type of grout (sanded, unsanded, epoxy, what brand)?
The more information I have the more likely I will be able to help.
The 1/8″ gap left at the bottom of the hardieboard where is meets the tub, do you seal that gap? If you seal it, how does the moisture between the hardieboard and the moisture barrier escape (If any where to get between them). I know the tile is the next layer and I’m guessing you leave a gap between it and the tub, do you grout or silicone that gap? Then you have two sealed layers holding in moisture. Or do you leave the first gap open and It will drain through the grout? I’m confused. Please help.
Hey Stephen –
Congratulations! You have just hit on one of the biggest problems most professionals have with properly waterproofing a tub surround. Well done (and I’m not being a sarcastic asshole – this time)
Your moisture barrier comes down the wall behind your hardie and over the tub flange (there should be a flange that goes up the wall about an inch or so on the tub itself) You need to silicone the barrier – plastic or whatever you used – to the tub flange. The silicone will be on the back side of your barrier. Then install your hardie.
Now the fun part. After you set your tile (yes, leave a gap between the bottom row of your tile and the tub 1/16″ – 1/8″) you need to run silicone around the perimeter into that gap. There are two ways we deal with it:
1. Some tubs actually have ‘weep channels’ similar to a fiberglass shower basin. On the top outside corner (the horizontal part) of the tub these will be small channels that dip down about 1/4″ from the top and back up. Do not silicone these. Just leave the bottom of the tile open above those channels.
2. If your tub does not have weep channels (and most do not) you need to leave a gap on each end of the tub about an inch long where the tile will be left without silicone. This creates a ‘weep channel’ of sorts for you. The placement of these is entirely up to you. I place mine on the short wall of each side about an inch from the corner.
So from each corner of the tub to the outside of the tub you would have a 1 inch long bead of silicone, a 1 inch space where the tile simply meets the tub (1/16″ above it) then silicone to the outside corner.
This creates a release channel for any moisture getting behind your tile and does not trap it.
Another way to deal with it is simply to grout the tub-tile connection. But that goes against standards which state caulk or silicone at any change of plane. You know, the same standards that have that particular flaw in them. I will sometimes do this if I build the shower and reasonably believe that the grout will withstand any movement in the structure. Sometimes I do, sometimes I don’t.
BUT! – I am the one that accepts every ounce of responsibility for that decision. If I’m wrong I fix it. Plain and simple. Also, if you do grout it and seal your grout – do not seal that portion.
Easy, right? Outstanding job on thinking things through! I really wish more people would. Then again, if they did I’d have to start a blog about the care and upkeep of a pet platypus, or something else people don’t care about.
Thanks Roger. I weep hole sounds like a good option. Kind of like a weep hole in a brick wall of a house I guess. Next question, how much water actually gets passed the tile, sealed grout, and thinset to penetrate the hardiebaker? I mean does the hardiebaker get soaked every shower or is every waterproofing measure just a precaution? Will water be pouring from the weep hole? If it’s a lot, will using porcelain and small grout lines with non-sanded help? I was planning on using 12×12 ceramic (less grout lines to leak) with maybe 1/8″ grout lines with sanded grout. I hate to hit you with a lot of questions at once but you are very knowledgeable. Thanks in advance.
Hey Stephen, never apologize for asking questions, that’s why I started this whole mess call FloorElf.
Not much moisture gets behind there at all. Not during each shower anyway. But think about it like this: If you take a ten minute shower each day for a year it is exactly like leaving the water running constantly for 60 hours. If there were no precautions there would you leave your shower running for 2 1/2 days straight?
And that is just over the period of a year. A properly built shower should last AT LEAST 25 years or more, or until your wife gets sick of the tile. (Think 1970’s lime green).
The moisture will eventually build up. The precautions you take now will ensure that any moisture that does get back there has a specific way to escape properly. This means keeping it away from the wall studs and out of your floor. Channeling everything into the tub – even moisture behind the wall – ensures a well-built, long-lasting shower installation.
One of the main issues you face is ‘static pressure’ Think of a straw full of water with your finger on the end. The water will remain there until you let go. The backerboard is like that straw. Taking a shower is almost like letting go of the straw because it will ‘flush’ the water through the backerboard. This is completely normal as long as there is a barrier between your backerboard and wall framing as well as a proper ‘escape route’ for the water that flushes through.
As long as you take proper steps to ensure those two things your shower will last. If water gets to the framing it will ‘wick’ into it – just like a candle wick. This becomes the new escape route for your water. You are simply taking away that possibility.
When people think that there is no way enough moisture can get through they are right – as long as you are speaking of one or two showers. No one thinks of the sixty hours a year.
Sealing your tile will help tremendously but does not make anything ‘waterproof’. It simply slows the absorption rate of things like water and cherry kool-aid. Porcelain will help as well as it has a lower absorption rate than ceramic.
But neither are necessary. If you build your shower properly it is waterproof before you open a box of tile. As it should be. The places with which to be concerned about absorption rate and such things are porches, freeze/thaw climates, and the like. Travertine is one of the most porous stones but I install it in showers all the time. That’s not the issue – waterproofing your shower is.
A lot of water does not pour out of your weep holes/channels, but they need to be there. By ensuring that any water getting into your backerboard has a proper escape route you are golden. After all you are dumping 1.5 to 2.5 gallons per minute into your shower as you use it. Even a low-flow head throws 7 – 8 gallons every five minutes at your shower tile. Envision a full five gallon bucket being thrown at your shower wall – that’s what I’m talking about.
Built properly it works well. Built poorly it keeps me in business. Know what I mean?
If you have any more questions please do not hesitate to ask.
Hey Roger, which grout size do you prefer for a 12×12 ceramic tile? Sanded or non-sanded and why?
Hey Stephen,
On 12 x 12’s I will always use sanded. In fact unless I am installing tile with ‘nubs’, which are self-spacing tiles that butt together and leave a little less than 1/16″ grout line’ I will always use sanded.
On walls I use a 1/16″ grout line and on floors I use 1/8″. I use sanded in everything because it does not shrink significantly after it is installed while it cures. non-sanded does. I just prefer to have the piece of mind with it. You can always use non-sanded in grout lines 1/8″ (although that is pushing it in my opinion) and smaller.
Hi Roger,
Have you had any experience with (name removed to protect the innocent – but it starts with ‘P’*) for a shower/tub tile install? They claim to perform the same as Kerdi and a bit cheaper. Also, do you install the Kerdi right on top of regular drywall?
Thanks,
Bob
*I have removed the name of the product because this page was showing up in search results for it. People were coming here looking for information about it and not getting what they want. All of a sudden I’m an asshole (ok, maybe not all of a sudden). I want to help and don’t want people wasting their time reading through my rants without at least receiving the help they need.
Hi Bob,
Sorry, I have not used that particular product. I use Kerdi exclusively as my waterproofing sheet membrane. My feeling is that if someone claims it performs the same as Kerdi – I’d rather have the Kerdi. Price point may be a selling point if it is, in fact, comparable to Kerdi. I just don’t know.
Yes, Kerdi is installed directly over regular drywall. That is actually their recommended method. I do install it over hardiebacker or another cement board if I am installing a steam shower. The vapor properties of Kerdi are actually fine for most steam showers but I prefer to have the cement board behind it in those applications.
i got a lot of 1/4 inch durock for free. can i just put it over the drywall then tile on it? If so would i need to seal it first with redgard? this is for a shower/tub surround. thx.
Hi RB,
You can if you want to – not the best solution, however. What will you do with the edge of the shower where the durock ends? It will be sticking out 1/4″ from the rest of the wall.
If you do put the 1/4″ durock right over the drywall you will need to use Redgard or another topical waterproofing membrane over the top of it. Since durock is not waterproof you need something to stop moisture from reaching your drywall, if it gets wet it explodes! Ok, maybe it doesn’t explode but you get the point.
When you say ‘a lot’ of durock do you have enough to double up the walls? That is enough for two layers so it would be the same thickness as your drywall – 1/2″? If so you would be better off removing the drywall around the shower or tub and replacing it with two layers of the durock. You will still need either a moisture barrier behind it or Redgard on the face but that would provide a better solution for you.
Hello Roger, happy new year! Thanks so much for your earlier advice- I decided to sand/cement render the walls myself in the end, using a 5:1 sharpsand:cement mix. It was backbreaking work that I wouldn’t recommmend to the typical DIYer, but I’ve learnt a new skill and saved some money so I’m really happy. The new wall is actually straighter than the plaster it replaced!
However, I’ve just started tiling and I’ve got a problem. I’ve put about 30 of my slate tiles (400x400x10mm) already around my shower area, but I’ve found today that 6 of them that I stuck on earlier this week don’t seem properly stuck to the wall. I hink they seemed fine when I stuck them on (I think), but now they sound hollower at the top edge and can be seen to flex very slightly when pushed at the top. The bottoms feel as solid as the other tiles.
I pulled one of them off today that I had applied yesterday and found it easily came straight off, with all the adhesive staying on the wall and none on the tile. As an experiment with this one tile, I spread a thin layer of new adhesive over the old adhesive and spread a thin layer on the tile too, then pushed the tile back on. Is this an ok thing to do?
Here’s my thoughts on what could have gone wrong:
1. Maybe the tiles were put up too late when the adhesive had lost stick? 4 of the faulty tiles were all done at the same time, so maybe I spent too long applying the adhesive that time? However, I only did 4 tiles at a time, mixing enough adhesive for 4 tiles each time in a clean container… and the other ones that don’t seem stuck properly are all from different batches… so I don’t understand how this could happen.
2. Maybe the tiles have a thin layer of quarry dust on their keyed back? However, nothing seems to come off when I wipe my hand across the back.
3. Maybe the adhesive I was sold is out of date? It says 28.05.09 on the pack, but that might be the date the batch was made which would mean it would be good for a year after, or maybe it’s not even a date or relates to something else. I bought two packs from a reputable big company (Kirkstone) and they both have this number on them.
4. Maybe I should be back buttering the tiles? I’m pretty sure I wasn’t told to do so in the supplier’s instructions. I back buttered the row of 4 tiles I did today to see if it helps.
5. Maybe I squished these tiles too much all over such that they lost contact with the adhesive in places? I was pressing them all over and in corners to get them level with neighbouring tiles, maybe I shouldn’t’ve done that? However, then wouldn’t the tile that I took off have had some adhesive attached where contact hadn’t been lost?
-The tiles are Kirkstone Rio Neblina Cleft and the adhesive is the PCI Tilefast 6 Flex that they sell to go with them. Please help!
Hey Al,
The biggest problem that leads to tile not having full coverage is lack of back-buttering. With any type of natural stone at all, especially slate since it is rarely perfectly gauged, you need to back butter it as well as combing the thinset on the wall.
Any adhesive when properly mixed, unless it is a fast setting product, has a pot life (workable time) of at least 1 hour so I doubt not setting them fast enough was the problem.
You stated you did not back butter the slate so I’m sure that’s what the problem is. The ones that you reset and backbuttered should have not problems at all.
The reason for this is you want (ideally) 100% coverage of thinset on the back of the tile when set. 95% is the industry accepted amount. By backbuttering you will guarantee this.
FYI, the date on any bag of thingset is the manufacturing date of the product.
It is also good to sponge the back of slate tile off and let them dry to ensure there is no residue on the tile which will lead to non-adhesion. It will not always come off by rubbing your hand across it. Sponging it off will ensure you get off whatever happens to be there.
Thanks, that’s a great help. Should I take them all off, or just the few I identified?
You should be fine just pulling and reinstalling the ones that sound like they have hollow spots.
Phew, I was hoping you’d say that! I have one final question that I’d be grateful to hear your view on: ‘to seal or not to seal’?
I was thinking of not sealing the slate to be as green as possible (stone is left unsealed in eco-homes, to minimise use of manufactured chemicals).
However, as this is a shower area I am concerned that if left unsealed the stone will absorb limescale in a way that will not be completely removable, or even worse absorb shampoo etc, particularly the coal tar shampoo I have to use. If the slatebecomes ugly through staining, then it would have been more ecological to seal it in the first place, because the slate will get replaced anyway. Sealing is I’m sure more sustainable than replacement. Would my slate shower get ruined, or need much more frequent care and cleaning, if not sealed?
Hey Al,
You absolutely need to seal slate, especially in a shower. The minerals from the water alone can, over time, discolor your slate not to mention the soap and shampoo build up in a shower. Slate is a porous stone and tends to absorb most things it comes in contact with to some extent. If you need to replace all that slate it kind of defeats the purpose of eco-friendly.
The downside to most sealers is their relatively high VOC (volatile organic compounds). However, Aqua Mix makes a sealer called ‘Sealer’s Choice Gold’ which contains less than 0.01% VOC. It’s the sealer I use for eco-conscious installations. You should be able to find it online if your local big box doesn’t carry it.
To answer your last question – yes, your slate shower will at least need a lot more frequent care and cleaning if not sealed. And it will be harder to clean. And it may be impossible to clean. And it will stain easily. And it may get ruined. And . . . well, you get the point.
You need to seal it.
You owe me pictures when you’re finished.
Hello,
I took off my old shower tiles to put up some slate, but found that it was plaster underneath. I have been told I have to rip the plaster off and that I can’t just put backer board over the top and screw through to the blockwork. I have been told I have to either cement/sand render onto the block, or adhere and screw backer board onto it.
Is this true? And if so, which do you recommend and what mix or method of fixing should I use? There isn’t room for a stud wall.
If using board, I was thinking hardibacker. I could also get Marmox if that’s better but I’d prefer hardibacker as there’s no plastic in it. Also, would it be possible to just remove the plaster in the shower area, but then board over the plaster on the wall that is the other end of the bath away from the shower?
I’m having to do this all myself to save money, I didn’t realise the job would escalate and just assumed the flat would have been built properly. I have ripped off a third of the plaster so far, the neighbours are annoyed about the noise and I feel like I’ve been hit by a truck! Please help!
Hey Al,
Are you speaking of a block wall in your shower covered with plaster? I assume so. There are two ways that I have dealt with this. With either the plaster will have to come out. You should be fine leaving it on the other walls and going over it as long as you have something to screw the backerboard to.
You can install a topical membrane directly to the blocks. These include either kerdi membrane or a liquid waterproofing membrane such as redgard or hydroban. Apply that directly to the block wall and tile directly to it.
As far as installing a backerboard to the blocks if you chose to do so, you may be able to simply use thinset to adhere the hardi to it and tile to that. Maybe use some anchors for the backerboard as well. To be honest though, I don’t think I would do that and I don’t know how long it would last.
Hope that helps.
Thank you for the swift reply, Roger. I’m not sure if I can tile straight onto the blocks, because they’re rather uneven. The plaster that I’ve taken off so far varies in depth between something like 10mm and 25mm+! Blocks are out of line by up to 5mm of their neighbours, and there is a cut off metal pipe jutting out and a long bit of render, as well as joint mortar protruding and smeared down the sides.
That’s why I was thinking of using backer board, because I’m guessing it would be a lot easier for me to get a straight finish with that rather than attempting to apply a sand/cement render (which I’m told is not easy to get level and slow work too). Could you elaborate on your doubts about backer board please? I have similar suspicions, because I’d like my work to last.
Al,
The sand/cement render to which you refer is known here as “mudding a wall”, just so everyone here knows what you’re talking about. The method would be the best for your situation but it does take considerable skill by someone trained in the method – absolutely not for a novice.
I think about the only reservation I would have with the backerboard would be the durability of the installation.
If you could use a mortar (regular medium-bed tile mortar) beneath it to ensure there are no unsupported spots and to level it out and use a mechanical fastener of some sort (lag bolts, perhaps?) to make certain they stay where they are put there would probably be no problem with it.
At that point I think the only reservation I would have would be the amount of movement in the block itself. That, however, would be prevalent with any method. I don’t see why it wouldn’t work. I just tend to stay with what I do but no reason not to try it this way. Seems it would be the best option with what you’ve described.
Thanks Roger. I feel confident in getting on with it now. I’ll look into how much paying someone to render it will cost, and put up backerboard myself only if it’s significantly cheaper.
Please could you just clarify one point: when you say ‘ no unsupported spots’, does that mean that the entire board must be adhered to a relatively flat surface, or could I just fix it to levelled mortar dabs placed wherever the screws will be (12 inch centres, or 8?)?
What I mean by no unsupported spots is absolutely no space between the backerboard and the wall. I would skim coat the entire wall to get it flat (or at least get it close) let that cure then use regular thinset or a medium-bed mortar with a 3/8″ (9.5mm) v-notch trowel and put your backerboard up.
The whole idea is to have the entire board supported on the block so that if you lean or push on any particular point on that wall there is mortar behind it and it will not move. I wouldn’t want any movement in that backerboard at all. Any movement at all will end up with your tile installation moving, grout cracking, etc.
You want 100% support.
Thanks Roger! Much appreciated.
I have metal studs with 2×12 blocking around all walls to support the shower liner. Do I still need a vapor barrier behind the backerboard? Thanks for your service, you have an outstanding website!
Greg
Hi Greg,
With the metal studs the vapor barrier is not as important but I would use one anyway. What is on the other side of those wall? If they are other interior walls then the vapor barrier will protect them from moisture. But, I tend to overbuild and err on the side of caution so it probably isn’t really necessary. Couldn’t hurt though, right?
That’s a great question, though. I’m going to get some further input from other professionals and find out what they do. I’ll let you know what I find.
EDIT: Okay, according to TCNA standards handbook method #W244C a membrane is required over metal studs behind CBU in wet areas. So yes, it is required according to the standards and, like I said, couldn’t hurt. Thanks for helping me learn something today!
Thanks for the kind words. Glad I could help.
My husband put durarock up before learning that he needed to put a membrane between the studs and the durarock. Without taking it all down, can I seal the seams with caulk or thinset, then paint on redgard?
Hi Candyce,
Absolutely you can. You want to get some fiberglass tape that is alkali resistant (Regular fiberglass drywall tape) and tape your seams with it. Then just go over that with regular thinset.
That will lock it all together so you have one big monolithic structure. Then you can redgard the entire thing.
Hope that helps.
My husband converted a bath tub to a shower tub combo by using a shower wall kit (several years ago). The walls are not a solid piece and always look nasty. Is there any type of tiles that stick on to what is already there? The tub is in great shape – it’s the shower and the walls that drive me crazy. Any suggestions or help would be greatly appreciated.
Hi Chanda,
If you’re talking about a fiberglass surround kit being what your husband installed I’m afraid there isn’t really anything that will adhere tiles to it and last any significant amount of time. Epoxy would actually stick the tiles to it, but cost-wise you would spend about three times what it would cost to replace it all properly and have no assurance it would last.
My suggestion would be to take out the shower kit and install a vapor barrier and backerboard on the walls and tile it. Cost wise to prepare the walls for tile yourself you are probably looking at less than $100 plus the cost of tile.
Doing it this way would ensure it is done properly and will last. You also get a brand new shower.
Roger, Thanks for your reply.
I talked to the guy that did the work and he assured me he has done this a million times and never had an issue. He came by while i was not home to make the repairs. When i got home looked like he took clear silicon and caulked all corners and all along the seam where the wall meets the floor. This seemed to stop the leak. When questioned what he used he told me it was a grout sealer. To make sure there was no leak for a week I used only that shower. After about the 4th shower I noticed that that the grout on the out side of the shower where the threshold is ( the step you step over to get in the shower) was gone. I continued to take a shower and then while in side i noticed the grout in the same place was gone and then i saw that the tiles were cracked and that the only thing holding them on was the strip of the bottom of the shower door. He did not use backer board all all around the door. He just secured the tile to the wood 2×4. So as I am writing to you tonight I have a friend ripping my bathroom shower to pieces. Worse part is I no longer have enough tile to replace all the ones we have to rip off to fix the issue. As you said rip out is the only choice i have to fix it for good. So any help you can give us would be great , tips and products we should look for.
Hey Karrie,
I was afraid this was going to happen. All he did with the silicone is prevent the water from running out beneath the walls. Since it was trapped the only place it had to go was up into the wood. As the wood swelled the tiles moved, grout cracked, and eventually tile cracked. All the sealer did was prevent the tiles from being stained, as I stated before it does not waterproof tile. I’m not sure where this guy has been doing this for 25 years but I’m pretty sure it wasn’t from anywhere anyone can get a hold of him.
But none of that fixes your problem, does it?
As I stated before the best way would be to tear out everything from the floor to about a foot up the walls. We can create a dry pack shower floor and RedGard it. Then we’ll just tile over that and you’ll be good to go.
Start looking around for some tile either on sale or talk to some tile shops and see what kind of deal they’ll make you. Like I said, a few would probably even give it to you to get rid of it. In the next couple of days I’ll put up a post about creating a shower floor.
If you decide to go in a different direction let me know. As always feel free to ask any questions you may have.
Sorry about the problems, we’ll get it done correctly. It’ll just take a bit of work on your part (or any real good friends you can scrounge up.)
Ok you have great information but I really need some help. Single no money $$$$ mom here. I had a tile shower installed in the basement since the builder left me rough in plumbing and had about 10 box of un used -non returnable tile from 10 yrs ago taking up space in my garage. Was done by a father of a friend of a friend … you know how that goes. Well he did not use a liner or a pan for the floor, Think he used backer board on top of some ripped 2×4 (to slope it towards the drain) and then filled it in with some kind of quick set concrete. First shower was very short and if it was there didn’t notice a leak. Second shower ( the wash and condition hair) was much longer and on the outside of the wall (the one facing the room not inside the bathroom) could see water on the floor due to no floor being laid yet. so OMG is there anything that can be applied at this time to stop this. I can not rip this out and start over. We have not put any sealer on the grout or tile yet. Please help let me know what can be done. This father said he has done it this way many time and never had an issue till mine ( go figure) Thank you in advance for your information.
Karrie
Hi there Karrie,
Sorry to hear about the problems. Just promise me you won’t shoot the messenger, ok?
If there was no membrane used on the shower floor it will not last. Quite simply – it is a shower floor and needs to be waterproof. The advantages of backerboards are that they do not swell when they get wet, but they are by no means waterproof.
If he did, in fact, install the backerboard “floor” over ripped 2 x 4’s, the 2 x 4’s will eventually get wet (If you had water running from under a wall they most likely already are) and they will start to swell. Once that happens it will push up into the backerboard and into the bottom of your floor tile. Tile and grout will start cracking.
The bad news (like you needed any more) is that it will not last. The worse news is that unless it is solved it may lead to more serious problems. That water has to go somewhere. If it gets into your wall framing you will have to replace more than your shower floor.
There is nothing that can be applied to the top of the tile that will waterproof it. Sealers do not waterproof tile, they simply make them water resistant and prevent things like kool-aid from staining your tile and grout.
The simplest way to fix it is to tear out (I know you don’t want to) the tile on the floor and about a foot up the walls. You can then use a product like redgard or Laticrete’s 9235 and brush or roll on three layers to waterproof your base. This is assuming that the “base” that was built is solid and sound although I don’t think the type of base you’ve described is nearly solid enough to serve as a shower floor.
The solution that would be best and would last would be to do all of the above but also tear out the “floor” that was built and replace it with a mud base. You would basically have the same size and shape as what is presently there but rather than the backerboard and 2 x 4’s it would be entirely made of concrete. You could then coat that with the redgard or 9235 and replace the tile.
I know you’ve stated that you can’t tear it out and replace it but without replacing at least the bottom foot of your shower it will not last and will lead to bigger, more costly problems. Sorry. If you choose to do this let me know and I’ll post up a step by step to walk you through it. I’m sure you aren’t the only one with a shower base that needs replaced.
I also understand that money is an issue. For a regular 3 foot by 4 foot shower you would need about 10-12 40lb. bags of quikrete’s concrete for your base. They run about $3.00/bag around here. The redgard or 9235 can be purchased in gallons. That may be around $40, I’m not certain, you would have to call around. Find a flooring supplier – they should be cheaper than a big box store. If you need more tile you can always get cheaper sales at places like Home Depot. A lot of flooring stores that do tile also usually have extra stock they will let you have for next to nothing, sometimes they’ll even give it to you to get rid of it.
Let me know what you want to do and we’ll get it worked out for you. In the meantime I would strongly suggest not using that shower. It will lead to problems that you really don’t want to pay for later.
Sorry to be the bearer of bad news.