Preparing a Shower Wall for Tile

by Roger

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.

How to install backerboards

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!

Previous post:

Next post:

Bill

Roger,
Our shower, when originally built about 25 years ago, consisted of a fake marble pan, drywall that extended from the top of the pan to the ceiling, and then large, solid fake marble panels extending above the shower head adhered over the drywall and sealed.

Now we are redoing the shower and want to use tile. All of the panels and pan have been removed exposing the studs up to 9″ above the subfloor. The drywall remains from that point to the ceiling. My question is: Once the new pan is built and waterproofed, can we just place a vapor barrier over the existing drywall and then place a proper backer board directly onto the drywall or does the drywall need to be removed down to the studs?

Thanks!

Reply

Roger

Hi Bill,

The drywall needs to be removed. There is no reason to build up your shower walls like that, it may actually trap moisture in the drywall (it’s like a sponge) and you will have an uneven transition to any point where the shower walls meet the regular bathroom walls.

Reply

Daniel

Replacing a fiberglass tub/shower that ended up with a cracked tub…I am not going to get going on the original plumbing subcontractors.

I have put in a cast-iron/porcelain shower pan. Traditional waterproofing method (purchased your book). However I also have a Redi Niche inset shelf/soap holder. When I stick that in between the studs, how does it interact with the Cement board/vaper barrier etc. etc. etc.?

Do I need to leave lots of slack in the plastic sheating or what? Does the Redi Niche get installed on top of the cement board or between the cement board and the studs? Help!

Reply

Roger

Hi Daniel,

It’s been YEARS since I’ve used one, but if it still has the really thin outer lip on the flange of the niche it goes over the top of the backer. Cut a hole in your barrier and silicone the barrier to the BACK of the substrate around the niche cutout. This creates a dam around the niche hole and keeps everything waterproof.

Reply

Daniel

Thanks for the reply! After re-looking at the instructions that came with the redi niche, it seems to say that you cut the cement board around the niche, then silicone between the 2. So for the vapor barrier, I silcone that to the edge of the niche…OUTSIDE the screws that hold the niche to the studs, correct? Similar to what is happening where I overlap the vapor barrier and the shower base flange.

Reply

Daniel

Also, similar logic to putting holes in the tile, I will put silicone in the screw holes of the redi niche itself….maybe?

Reply

Roger

Yes, to both of your questions.

Reply

Derek

Rodger,

I installed tile over green drywall (was told it would work just fine) prior to finding this site. The tile I installed is a high gloss subway-style tile, so in terms of permeability it should be pretty good provided I really seal the grout something fierce. I also live in Colorado, so I don’t have to worry about ambient moisture from humidity in the air.

My questions are these:

1. Do you have a grout sealer you especially recommend?
2. I don’t have the option of demoing the work and starting over (ultimately, my finances at this point are spent) so I’m going to have to seal this as well as I can and see how long she can last. What should I be looking for as signs that this might be failing, or is this just going to be a case of “well, the tile fell off and/or your wall has developed the structural consistency/feel of an American beer belly”?

Thanks for all your info!

Reply

Roger

Hi Derek,

Sealer DOES NOT waterproof your tile in any form. Your best bet at this point is to use an epoxy grout. Water will still get behind your tile – that’s normal, but using epoxy will slow it tremendously.

Provided you haven’t grouted it yet. :D If you have it’s pretty much cross your fingers and hope. First signs of failure will be at the bottom of the wall where the water will collect, it may start to get squishy.

Yes, squishy is a technical term.

Reply

Matt

Can’t edit my post to spell your name correctly…my bad…

Reply

Roger

No worries Matt, I’ve been called worse. :D

Reply

Matt

Rodger,
Like your site, just bought one of your manuals. About to rough in plumbing, what is the expected thickness of hardiebacker + liquid waterproofing + thin set+ tile? Or how do you decide how far out to set the rough in valves?

Reply

Roger

Hi Matt,

It’s about 3/4″ plus the thickness of your tile. The valves don’t need to be exact, but working with the 3/4 + tile gets it where it needs to be.

Reply

LaNell

A question concerning the stucco mesh recommended / mentioned in you book. How important is that to my over a concrete slab shower to be HYDROBAN’ed? If so, lots of it or just in place of the tape? Oh…. I have given up on having a bench anyway but with three concrete blocks thinset and mudded into pan. Then thinset together the ones with holes to 4″ solid ones every other one. Set on end that will be 16″ plus thinset then Durock then more t.s. then tile. A few other waterproofimg steps of course. Are you screaming yet? Any comments appreciated.

Reply

Roger

Hi LaNell,

It is important, just use it in place of the tape. Nope, not screaming yet. :D There are countless ways to do stuff like that – yours is just one of them.

Reply

Jim

Is grace ice and water shield a good option to use as a traditional waterproofing method (over studs and behind a hardi-backer)? I was going to use that and have it flow on top of my waterproofed pan at the bottom.

Reply

Roger

Hi Jim,

Yes, that is an acceptable barrier. (Not by standards, but by reality). You’ll be fine using that.

Reply

In Lanai Land

Oops… forgot the hole in floor. Was filled with sand (and a few stringy dead roots). I cleaned that out. If I go with a preformed tileable base or slope in my own pan, pea gravel the hole? Sand it again? Put sand cement mixture in when sloping over that 4″ concrete slab? It is 12″x14″.
Any other advice you can throw in about sloping in over a concrete slap would help bunches.

Reply

Roger

It can be filled nearly full with sand and/or pea gravel, then concrete or deck mud. Sloping deck mud over anything is the same. Just take your time and have everything ready to go before you mix up your deck mud.

I don’t understand your statement about not receiving email notes?

Reply

In Lanai Land

Thanks for your time Roger. Wish I knew how to download your book set into my phone or tablet (I will work on that today).
I have a gutted metal stud wall and concrete floor with large weep hole (weep well) . I am frantic as to perfectly straight walls and had to put 3/4″ X 2″ strips screwed to metal studs. Have plastic shim material handy. Will have to check corners to be sure studs are there or will be adding those.
Big question as to best and or easiest way to be SURE I have a nice straight / square box before I put up Durock.
And that 1/8″ left between planes (corners silicone? And no tape/thinset/extra HYDROBAN? )
Should I worry as much about out of square walls before or after Durock is up, making shim adjustments, or after?
I am not getting mail notes either.

Reply

Roger

It is always best to ensure flat, square and plumb walls before you put the backer up. The gap in your corners get silicone (to keep thinset out of that gap), then tape and mud (thinset). If you are using hydroban that goes up with the rest after it cures.

Reply

renee parks

It’s approximately 100 sq. ft.

Reply

renee parks

Also, what’s the best way to get excess thinset out of the grout joints once it’s already dried.

Reply

Roger

Sandpaper.

Reply

renee parks

Hi Roger!

As always, thanks for your excellent advice. Not sure what happened to my original question about using tec power grout quickly before it dries out, but I did get your response about dividing it into smaller batches. I thought you could do that, but then on the bag, it says they recommend mixing the whole bag at once. Anyway, I’ve since read some not so good reviews on that product on the John Bridge forum, and decided to go with something else.

Also, I might be retarded, but about your suggestion to use sandpaper on the dried thinset, would you just fold a piece of sandpaper and stick it in the grout joint and sand? I am using 1/16″ joints. I just haven’t seen this suggested as a solution anywhere, and was wondering about the exact way to do it.

Reply

Roger

That’s exactly how to do it. I actually use drywall sanding sponges. As far as I know that was my idea – I have one every ten years or so. :D

Reply

Steve_in_denver

Another good tip! I have been scared to use a grout file or anything that might damage the waterproofing underneath, and I have been struggling with all sorts of methods…sandpaper sounds awesome. just gotta be careful to not scratch the tile up…

Reply

Roger

You won’t scratch your tile Steve. Especially if you use the drywall sponge, they work really well.

Reply

renee parks

Hi Roger!

Once again, you are correct about the sandpaper. I tried a grout removal bit on my dremel, and the bit just broke off after awhile.

Anyway, we have a few tiles showing some lippage, due to my husband installing the backer board to hang over the tub flange (which I tried to tell him you said not to do). Is there anyway to disguise the lippage with grout? If so, how?

Also, I’m using non-sanded grout with a 1/16″ joint, and when I sponge the excess grout off the tile, the grout seems to get pulled out of the joint, and it ends up concave. Is there a way to get the joints to stay fuller (is that a word?)? Would I just let the grout harden a little longer before wiping? And how long is too long to wait?

Reply

Roger

Unfortunately there is no real way to hide lippage with grout, especially with grout lines that small.

Just let the grout set up longer before washing it.

Reply

Steve

Just double checking before I go to town with the drywall sandpaper sponge…

My tile is marble…sanding sponge no scratchy?

I’m also preparing to set my curb sills (marble, 5/8″ if it matters). What should I use to set the sills and vertical piece. For the vertical “sill” I will need to build up about 3/16″ on the top section to make it plumb and square with the opening (a door will be mounted there, so I need it to be perfect – I think).

I have whatever Lowe’s and HD have, and I also have some extra Tec uncoupling membrane mortar (though it is grey) if that matters. The sills are all being installed on top of Kerdi.

One more (ha!): How much lippage do you consider acceptable on marble 4×8 subways with 1/16″ grout lines? I started out trying to make them absolutely perfect, but that wasn’t really practical. I relaxed my standards to about 1/64″…I’m OK with the results, but it is taking me a really long time. Am I being too anal?

Eskerrik asko!

Reply

Steve

And while I’m at it…am I right to think that it is easier / better to set the curb sill first, and then the tile pieces on the side?

Reply

Roger

Yes.

Roger

Hi Steve,

Test the sponge on a spare piece first, but you should be fine provided you stick to the grout. Those marble sills are set with whatever thinset you choose, just like tile. If you want your warranty it needs to be the unmodified. Zero lippage is acceptable to me, but I’m an ass like that. 1/64″ is perfectly fine. You can only do so much with man-made tile.

Reply

Steve

Thanks.

Once again, you really came through with the drywall sponge idea – it works quite well. I’m elated. (I just won’t think about how much time I spent prior)

I ended up using medium bed mortar for the sills…seemed to work fine – well in fact. I hope I didn’t screw up. (if I did, please tell me how to fix it…:) )

Jackie

Hi Roger,
I have a very heavy 9″ by 18″ tile. It is 1/2 inch thick and some sort of natural stone. (honed limestone I was told but not really sure). I bought it at a close-out store and it came with no manufacturers information. My question to you is, will this tile be OK on my bathroom walls. I checked that it would not stain or absorb water by putting it under my cat fountain for a month, so that is not the problem but it is so darn heavy I am afraid it may fall off the wall. Do I need a special thinset? Anything else?? Oh, another thing, my ex-husband is doing the work for me, so I need to be able to tell him exactly what to do. Thank you sooooo much for any help you can give me. Jackie

Reply

Roger

Hi Jackie,

Any good modified thinset will work just fine. Sheer strength is what you need to worry about, any decent thinset will have more than sufficient sheer capability for nearly any tile.

Reply

renee parks

Awesome site! I think you have saved us from wasting a lot of time and money! Wish I would’ve read it before we started putting up the green board and cement board! My husband has already put up a layer of green board and then a layer of durock on top of that for the shower wall over a tub. We plan to use a topical liquid membrane (points for reading your manual!) on top of the durock.
1. Since I just read that you said don’t use green board on a shower wall, is it ok to use it behind a layer of durock?

2. Also, we used drywall screws to put them up. Do we need to totally remove the screws and put in corrosion resistant screws, or can we just add the existing screws to the durock?

3. Also, we didn’t know to leave a 1/8th” gap between the durock panels. Do we need to take them down and put them back up with a gap?

4. Lastly (for now!), my husband installed the durock panels horizontally (and didn’t want to have to cut off the excess), so it sticks out beyond the shower way more than I wanted to put tile. Can durock be painted? If so, can paint be applied on top of the liquid membrane, or should the membrane stop at the point we want to paint?

Thank you so much for your awesome advice!

Reply

Roger

Hi Renee,

1. Not really. While it will probably be fine I would definitely remove it.
2. Correct screws need to be used.
3. Yes.
4. Yes, it can. The waterproofing needs to be stopped before the area you plan to paint.

I would remove everything from that shower and begin again. Installing the backer directly to the studs with the proper screws, taping and mudding the joints, then waterproofing it. You guys are working WAY too hard. :D

Reply

renee parks

Thanks for your response! We actually bought the green board to put behind the cement board to double the thickness. The original substrate was double thick, so one 1/2″ board would not come out far enough to meet the ceiling. That was BEFORE I found your blog. It looks like we could have just put some shims on the studs. Anyway, it’s already up and we plan to leave it up.

One more question. I have bought 2 kinds of caulk – DAP 3.0 Kitchen, bath and Plumbing (says it has Microban and 10 year mold resistance) and White Lightning Latex ultra (siliconized acrylic latex. say it has EcoGuard). Are either of these fine to use or would 100 % silicone be better and why?

Reply

Roger

100% silicone is normally better. Any acrylic-based caulk will lose elasticity over time much more quickly than silicone will. Either one of those others will work, though.

Reply

renee parks

Ok. Thanks for your quick response. You are hilarious by the way! Every time I read one of your articles I laugh!

Reply

renee parks

What about the area around the cutout for the shower handle/tub spout/showerhead in the cbu? Do I need to caulk the gap between the cbu and shower handle, etc.? I plan on using a topical membrane, but I don’t know if I need to go anything to the cbu beforehand to fill the gap.

Also, we have a bout a 1/2″ gap between the cbu and ceiling in the shower/tub area. When we removed the old drywall we discovered that it was attached at the ceiling with a metal mesh. Thus we have some of the metal exposed with some missing ceiling sheetrock, which we plan to cover with some trim. But is it crucial to tape and mud between the cbu and the ceiling? If so, how would you suggest handling such a large gap?

Reply

renee parks

Btw, we are tiling all the way to the ceiling.

Reply

Roger

For your first question: Waterproofing cutouts

You need to tape and mud that gap. You can span about 1/2″ if need be. Use mesh tape and thinset.

Reply

renee parks

OK, Thanks!!! I did see your article about waterproofing cutouts, but it only says to use silicone when you’re actually putting up the tile. Do I need to silicone around the gap between the cbu and the shower handle before I redguard?

Reply

Roger

Nope, just between the tile and membrane.

Reply

renee parks

OK. It’s grout time! thinking of using tec power grout, but am scared off by the limited working time of these grouts. This is our first time grouting, and we are doing the half the bathroom walls and the entire shower/tub surrounding walls. Will I be able to finish the whole thing before it gets too hard to use? If so, can I put half of it in the freezer to use later, as you suggested in your article about spectralock?

renee parks

We have FINALLY finished tiling the bathroom walls (over greenboard in the dry areas), and have just laid 1/4″ hardie backer on the floor with thinset. Do I need to silicone the gap between the hardie backer and the green board, or can I just wait until the floor tile is down and silicone that gap from floor tile to wall tile?

Also, one of 2 of the hardie backer panels on the floor is slightly higher at the edge that they meet. I suspect because we had partially dried thinset overlapping from the first panel. Can this be leveled out when putting the tile and thinset on? Also, can I mud and tape the seams AS I lay the tile, or does it have to be done beforehand and left to dry?

Kelli

I’ve installed my vapor barrier (poly sheeting) and I didn’t buy it wide enough so I have seams. How do I handle those seams? Silicone?

Reply

Roger

Hi Kelli,

Yes, silicone, if they run vertically. If horizontally they should be overlapped top to bottom, like roofing shingles, no need for silicone.

Reply

Matt

Hi Roger,

Thanks for all of your great advice and publications.

I am installing a tile shower: Kerdi-Board walls and Quick Drain USA base w/ linear drain and their tile-on membrane (similar to Kerdi). The base membrane runs 6″ up the studs and the Kerdi-Board covers this section of membrane. I posted previously re: use of Kerdi-Board with Quick Drain and your advice was helpful.

I’ve run into another challenge. The board is attached to the wall and I’m planning my next move which is connection of the board to the base with Kerdi-Band. However, there is a small area (1 1/4″ long) where the edge of the drain is about 5/8″ from the long wall. Obviously this doesn’t allow for the 2″ that Schluter requires for Kerdi-Band overlap. What is the best way to approach this small area re: waterproofing? Based on my read of Kerdi-Board instructions the edges of Kerdi-Board need to be protected from water?

If necessary, I could take the board down to implement a fix since none of the joints are sealed yet.

One idea I had was to take the board down and wrap the bottom edge with Kerdi-Band (i.e., place such that kerdi-band runs from one side over the edge and onto the other side). Put the board back up and then make connections to base for all boards as normal, except skip the 1 1/4″ long area.

Thanks for your help.

Reply

Roger

Hey Matt,

If you bond the kerdi-band to that area with kerdi-fix it will still be waterproof without a 2″ overlap. And the edges of the kerdi-board are waterproof. :)

Reply

Steve

Roger,

I’m putting up my kerdi and I ran into a few potential issues…

As you might imagine, I’m not as fast as you when it comes to getting thinset out of the bucket and onto the wall. I did wet down the hardiebacker before spreading the thinset, but by the time I got to the bottom, the stuff at the top looked to be drying out. (we are talking 10-15 minutes) I globbed some more on top, and did my best to comb it all out as fast as I could. By comparison my test sheet on drywall seemed a lot less dry after a lot longer period of time.

1. Can I get away with doing that, or once the thinset has started to to dry do I need to scrape it off the wall and start over?

2. I sponged the hardiebacker down with enough water that it got uniformly darker…(it quickly returned to normal) I was afraid to add too much water, but now I’m thinking I should be more liberal with it. How wet do you make it before applying thinset?

3. There were a few spots (one in particular) that I apparently didn’t have enough thinset, or maybe it was too dry….It’s a patch that is about 1-1/2″ diameter. You can faintly see the trowel lines, but the “give-away” is the sound it makes when you run your finger over it. Other parts of the kerdi sound more solid..this area sounds hollow like it isn’t adhered…Is this a large enough spot to be a problem (4×8 tiles). How would you suggest I deal with it?

http://duckisabird.smugmug.com/Gaylord/Kerdi/37410572_8CZG82#!i=3102902809&k=9t7VSvm

4. The part of the kerdi that transitions to the floor was a bit difficult to work with, and as I embedded it, the kerdi had a tendency to lift / bunch up a bit. I thought I had dealt with it, but when I went back to look at it later, I noticed this:

http://duckisabird.smugmug.com/Gaylord/Kerdi/37410572_8CZG82#!i=3102893683&k=hjGvKtR

Is this a problem? What would you suggest I do before putting the floor down (note: the floor part is about 3-1/2″, so I could cut out the offending area and still have 2+ inches of overlap with the floor piece)

Am I worrying too much again?

Thank you.

Steve

Reply

Roger

Hi Steve,

1. It depends on how dry it is. If the thinset forming the lines has skimmed over then yes, remove it.
2. You want it SSD – Saturated, surface dry. You want the interior of the board wet so it doesn’t suck moisture out of it. It normally takes three or four passes. It will be that way once you notice it taking a minute or two to return to it’s normal shade.
3. A spot that size is no problem.
4. That will be fine provided you run your floor membrane to the wall. Get thinset under the edge as you install the floor and it will embed as you smooth out the floor piece above it.

Reply

Steve

Thanks, Roger.

It definitely wasn’t SSD, particularly one section where I installed the board backwards (the back side seems more thirsty for sure). I’m pretty sure the thinset was too dry, so I’m going to pull it down and try again.

1. Can I reuse the kerdi, or is that a bad idea?
2. The thinset is now 12 hours in…If I can’t get it all off the wall is that OK or do I need to get out the rubbing stone, or buy some more hardiebacker, or…?

Reply

Roger

It’s normally a bad idea to reuse it. It will likely be compromised once you remove it. An orbital or hand sander will remove your thinset.

Reply

Steve

Roger,

Do you realize how awesome you are? The tip about using a sander just saved my bacon! (whatever that means).

Seriously, I stripped 95% of the wall in about 15 minutes with my new belt sander (bonus points for justifying my recent tool purchase). I tried to use a scraper and hammer at first, but it would have taken hours. The belt sander with a 36 grit belt made quick work of it. I think the extra $ for the premium belt (shop smith brand) was justified.

This tip is a gem! Definitely put it in your tile tips book. In fact, make a Tile Tips Volume 2 and just put this single tip in there – a bargain, I tell you!

Two questions (you should start charging, btw)

1. Do I need to get every bit of the thinset of, or can I leave some on? Particularly around screw, near seams, and near the kerdi corners are what is hardest. Maybe I should give up on trying to save the corners..?

(picture here):
http://duckisabird.smugmug.com/photos/i-vqSQxPX/0/O/i-vqSQxPX.jpg

2. Do you have any ideas for getting all the thinset dust out of the shower drain?

(just kidding) :D

Reply

Bill

Steve, from the image you posted, it looks like you’re using a HansGrohe ibox. Make sure that thing is perfectly level, so the handle is centered when the water is off. Mine is used to divert water between the tub and shower, and when the handle is in the center position the water is off. After installing mine, I did a test fit with the handle and it was slightly off center (you could see it was ever so slightly turned). I know of no way to adjust the handle once the ibox is in place, so I will have to adjust ibox instead.

If anybody knows how to adjust the handle without shifting the ibox, I’d like to hear about it!

Bill

Reply

Steve

Bill,

I don’t know which “trim kit” you are using, but with mine I’m pretty sure the handles are adjustable. There is a set screw (small allen) which I believe can be used to “clock” the handle.

I did run into a similar issue – the trim piece / face plate (escutcheon?) on mine has 2 holes – one for temp control and one for the diverter. This piece didn’t have an adjustment, so the two holes didn’t line up vertically. I did make adjustments to the iBox install to adjust for this.

Reply

Roger

I use a hammer. But then, I’m not a plumber. :D

I’m just kidding, by the way, don’t use a hammer.

Reply

Roger

Hey Steve,

You can leave some on there, not a problem. You just want to get the biggest areas as flat as you can. Best way to get anything out of a shower drain is not to get it in there in the first place. :D

Reply

Chad

Hi Roger,
I plan on using a waterproofing membrane on my shower walls. Someone else has already installed tape and thinset in the corners without using silicone. Should I scrape the thinset out and install silicone and then re-tape and thinset?
Thank you

Reply

Roger

Hi Chad,

Nope, it’s fine. It’s always best practice, but it won’t cause your shower to fail if it isn’t done.

Reply

Graig

Roger,

I have 4 mil sheet hung on shower walls can I use 1/4 inch backer?

Reply

Roger

Hi Graig,

Nope, needs to be 1/2″ on walls. You won’t be able to match it up with existing walls, if you have that transition to make, and it is not sturdy enough between the studs unless you have 6″ on-center.

Reply

Amy

So I read the Traditional Waterproofing for your Tub and Shower and I just have a question about the moisture barrier. I am using a cast iron shower base and tiling 3 interior walls. It all makes sense to me up to this point. Where does the moisture go after it would run down the plastic barrier? It looks like it would get trapped behind the silicone bead at the bottom edge of the tile? Then what? How much moisture really gets back there anyway if the tile job is done right and sealed properly? Thanks for all the information here by the way. Especially explaining the reason behind doing stuff. I like to understand the why before I do something.

Reply

Roger

Hi Amy,

The amount of moisture depends on your particular tile and grout. But there will be water behind there. It should go here: Weep holes in tile installations

Reply

Adam

Roger,

I am currently in the middle of a remodel of a bathroom that had bad tile (learned of this three months after we bought the house). It is a full tub and tile surround and we plan on new tile. We took down old cement board and put up green board. Now I see that green board is not what is recommended. Can I still red guard over this and have a surround that will last, or did I just waste a bunch of time and money.

Thanks,

Adam

Reply

Roger

Hi Adam,

You just wasted a bunch of time and money. You can not redgard over greenboard. The only thing that is approved over greenboard is kerdi, if you want to use that you’re fine. If you want to use the redgard you need to replace it with cement backerboard.

Reply

Judi

hello. We are in the middle of the project and thought we had to use the vapor barrier, hardibacker board, then red guard. I am now reading that we do not need all that. The plastic vapor barrier and cement board are already up. We have purchased redguard but haven’t used yet. Should we not use it and tile over cement board? After seams are sealed….

Reply

Roger

Hi Judi,

As long as the plastic overlaps the floor liner or base correctly then you can just tile right over the board as it is. It’s waterproof right now.

Reply

Steve

Roger,

1. I understand that drywall is the recommended substrate for Kerdi, but I’m concerned about the integrity of the walls if the drywall gets wet (there are pipes in 3 of the shower walls as well as the ceiling above the shower). Am I overthinking it? Any reason to not use Hardiebacker instead?

2. I had to sister some studs to get my walls flat, which creates an overhang at the bottom. Do I run the substrate down to the floor leaving a void behind it, or fill the void with deck mud when forming the pan and run the substrate down to the deck mud.

Reply

Roger

Hi Steve,

1. No reason at all not to use hardi. Backer can be used just as well as drywall.

2. Fill it and run the backer down to the floor.

Reply

Carlo

Excellent Blog Roger! Great info. We do lots of shower installations and have had great results with all the bonded membranes like Kerdi and Prova but we are now using one called Trugard which is green. I can’t tell the difference between them except that Trugard costs 40% less.

Keep up the good work

Reply

Roger

Hi Carlo,

Probably isn’t much difference at all other than the color.

Reply

Ron

Hi Roger,
I’m looking to replace the tile around the faucet and shower handle down to the top of the tub. Just replaced the showerbody to make 4 handles into 1. The issue is there are no studs in the building. Instead the construction is “structural terracotta” (basically hollow ciderblocks made of really hard clay with steal support beams). In the shower mud was applied directly over the terracotta and tile over that. Now the terracotta had to be cut away to replace the shower body so I’m left with two open holes into a plumbing wall. Just wondering how you think I should “fill” the holes. I was thinking mesh with cement/mud filled in, then laticrete painted over that, then the mastic and tile. Any advice?

Reply

Roger

Hi Ron,

I think that would likely be your best bet. I’ve never run into a situation where I couldn’t shore up a stud of some kind behind where the hole was.

Reply

Larry

Hi Rodger,

I was reading your post and I want to be honest with you. I rip out a fiberglass tile surround that had a connecting tub to it. I keep the tub portion to it and decided to tile the front side and back wall of the tub/shower area. At the time I was not aware of a barrier needed to be put up before the cement board. It has been (7) years since I did this project and just recently had a unusual weather day of -10 below one night that caused our Shower pipes and drain to freeze. So, it looks like we have to remove part of the front shower wall to replace the shower faucet which got damaged. Thankfully no pipes had burst and we used a space heater to thaw the faucet out to get water and we used a warm water and salt solution the thaw out the tub drain. My concern is, now that I have to remove a few tiles in the front to repair the faucet do I have to consider tearing all the tiled walls down and start over using a moisture barrier in order for it to be correct or just let it be.

Larry

Reply

Roger

Hi Larry,

I would just let it be if there is absolutely no damage behind it at all. Sometimes they last just fine, most times they don’t. I would just examine the wall substrate to make sure there is no water getting into the framing.

Reply

Leave a Snarky Remark

***PLEASE READ THIS FIRST!***

If you have already posted a question about your project and you are leaving an additional comment or asking another question - please do so as a reply to my answer to your last question.

Below every comment is the phrase 'Please click here to reply to this comment', just click on that and leave your next question.

If you post an additional question here it will show up as a new topic and thread. I have over 15,000 comments on this site (seriously), I can not go through every one to find the project or question you may be referencing.

HELP ME HELP YOU!

Thanks.

;) :wtf: :wink: :whistle: :twisted: :suspect: :shades: :roll: :rockon: :oops: :lol: :lol2: :lol1: :idea: :guedo: :evilb: :evil: :eek: :dance: :cry: :corn: :cool: :censored: :bonk: :arrow: :D :?: :-| :-o :-P :-D :-? :) :( :!: 8)