I get a LOT of questions from my readers about basic shower construction. I understand that my readers don’t consider this stuff basic and there’s no problem with that. The problem is that I end up answering the same questions over and over and over… So, to save what very little is left of my sanity (which is a number roughly equivalent to absolute zero) I will cover some basic things here so I can simply reply ‘read this’.

If you’ve been channeled to this page by one of my smart-ass comments please take no offense to it, I’m here to help. Please understand that I currently have over 3000 comments (questions) on this site which I’ve answered – every one of them. I’m just trying to make your life (mine) easier.  I will continue to answer every question I’m asked, I’m just super cool like that. If, after reading through this, you still have questions feel free to ask them in the comments below.

You can also download my shower waterproofing manual which should answer a lot of questions and cover basic techniques and methods you may be confused about. Go ahead, it’s free.  So without further ado (doesn’t even look like a word, does it?) let’s get on with it. (For all my readers who feel the need to correct me: I KNOW it’s actually ‘adieu’ – I was being facetious. Thanks. )

Leaks

First and foremost – tile is not waterproof. Grout is not waterproof. Adding sealer to your tile or stone will not make it waterproof. Your shower should be completely waterproof before a box of tile is even opened! No matter which waterproofing method you choose, proper substrate preparation is the only thing that will make your shower waterproof.

If you have a leak in your shower – stop using it immediately if at all possible. If that is not possible (it’s your only shower) have the shower repaired – immediately. If you see water leaking it is likely not nearly as much water as you don’t see leaking into your wall cavity and structural framing. By the time you ‘see’ most leaks the framing is normally already considerably compromised.

No, there is nothing you can put over your tile to make your shower waterproof if you have a leak – not even sealer. A tile or stone sealer is made to make your tile and grout stain-resistant, not waterproof. It does this by sealing the pores of the tile and stone to slow (NOT STOP) the absorption of liquid and prevent staining. It only means you have more time to clean up the spilled red wine cherry kool-aid before it stains anything.

Substrates

Drywall is not an acceptable substrate for your shower unless you are using Schluter Kerdi waterproofing membrane – that’s it. Cement backerboards are the standard and there are also other products such as waterproofed, gypsum based boards like Denshield and waterproofed, foam-based sheets like wedi or kerdi board.

Cement backerboards are not waterproof. They are water stable, which simply means that they will not swell or disintegrate when exposed to moisture or water – they won’t change size. But they are just like your driveway, they will soak in water, hold water, and dry out, just like your driveway when it rains. If using backerboards there needs to be a waterproof membrane utilized as well.

Membranes

If you are using a topical waterproofing membrane such as a liquid like redgard or hydroban, or a sheet like kerdi, do not use a moisture or vapor barrier behind your substrate. If you have a vapor or moisture barrier behind your substrate do not use a topical membrane on the front of it. This combination creates two waterproof barriers with your substrate sandwiched between them. any vapor or moisture trapped between them has absolutely no way to dissipate. This is lovingly referred to as a ‘mold sandwich’. It is not tasty. Use either a moisture or vapor barrier behind your substrate or a topical membrane on the face of it. One or the other – never both.

With that said, if you want to use a topical liquid such as redgard on the seams of your backerboard, after you tape and mud them, you can do so without problems. If your moisture barrier and backerboards are properly installed there is no real reason to do so – but if it will help you sleep at night go ahead and do it.

If you are using a topical membrane and you have an exterior wall with either plastic facing or kraft paper facing you need to cut slits into that facing before installing your substrate. If you do not it will create the aforementioned mold sandwich. Give moisture or vapor somewhere to dissipate.

Shower-tub transitions

There should be a gap between your tub or acrylic shower base and the bottom of your backerboard. If you are using a traditional barrier waterproofing method you do not need to do anything with this gap. Do not fill it with silicone! This will trap moisture running down your barrier and it will have nowhere to go. If you are using a topical method you can fill it with silicone if you want. If you are using liquid you should fill it with silicone. This creates a waterproof plane between your membrane and the tub or base so water or moisture ends up in the drain rather than in your wall.

When you tile you can tile right over that gap. You should not fill this gap with thinset behind the tile – it will crack due to movement. Your wall and tub or base will expand and contract at different rates – it will crack any cement-based product you place between the two. This includes thinset as well as grout. You do not need a solid backing behind your tile over this gap – it should be less than 1″ wide. You shouldn’t normally be walking on that tile in that particular spot. Yes, it can just hang there.

Grout

If your grout is cracking it is due to movement 99.9% of the time. Type ‘cracking’ into the search box up there and you’ll find in-depth explanations for your viewing pleasure.

If you have white, or lighter than normal grout when you’re finished grouting it may be efflorescence. This is mainly due to minerals in the water being left on the surface of the grout when the water evaporates. It is usually indicative of either incorrectly mixed grout or using too much water while cleaning the grout – not wringing out your sponge enough. This is normally only on the surface of your grout. Scratch the very top layer of your grout in an inconspicuous spot with your fingernail. If you have the correct, or at least a darker, color beneath the surface that is the likely cause. The easiest, quickest fix, provided it is only the very top layer, is to get some drywall sanding sponges and go over the grout lines very lightly. Just like burnt toast – scrape it to the color you like.

Corners and changes-of-plane

Caulk.

Disagree with me?

Like any other website I get my fair share of people who disagree with my methods or techniques – it really doesn’t bother me. I am more than willing to have a civilized, intelligent conversation about anything tile related. If, however, you simply attack me personally and act like an uncivilized ass I will call you on it – and not in a nice way. I write this blog in a particular manner, it does not mean that I take my profession lightly – I most certainly do not. If I wanted to be a pompous bastard I currently have 19 letters I can place after my name – all tile related. But I’m not a pompous bastard – you can just call me Roger.

If you are a contractor with a customer who has come here for information and I’ve told them you’re wrong – realize that the extent of my knowledge of that particular project is limited to what I’m told by your customer. It does not mean that I am ‘out to get you’ or anything of the sort. I normally limit my replies to those situations by stating the current TCNA and/or ANSI standards pertaining to what I’m told. If you disagree – please let me know in a civil manner, If you’re correct I’ll back it up – I do this everyday, too! If you’re an asshole about it expect the same in return – and please have a thesaurus handy to interpret my reply – I’m a very well educated asshole.

That’s it for now. I will likely add to this post on a regular basis. If there is anything I’ve caused confusion with please, for the love of God, let me know. I can change this page since, you know, it’s my website and all. If you have any questions at all please ask them below – I’ll answer, really.

Another request from one of my readers, this time concerning weep holes. As you may know I answer every question I’m asked here on my site when I sober up get home from work. I have tried to explain in the comments section several times where to create weep holes in a tub or shower (acrylic base) tile installation and now realize it’s a difficult thing to do with words.

So when Kurt asked me to clarify exactly where they go a stroke of genius hit me! (Yeah, I’m slow sometimes) I have pictures. Well, not exactly pictures of the weep holes themselves, but I can at least let you know where they are.

When you have a tub which does not have specific spaces for a weep hole you need to ‘create’ them in your caulk line. Let me back up here a second and explain what weep holes are and why you need them.

A weep hole is basically an open space which allows moisture that makes its way behind the tile a space from which to dissipate. This is the spot that moisture can run out. When moisture gets behind your tile it will always end up at the bottom of your wall (tile installation). When it gets there it needs some place to go – to get out from behind the tile and into the tub or shower basin. That’s what the weep hole is.

Some tubs, and most acrylic shower basins, have these built into them. There is a spot about 3/4″ long that dips down from the plane of the edge and back up. It’s a dip in the edge of the tub or shower basin. When equipped with these built-in weep holes – DO NOT FILL THEM WITH CAULK! Everyone does that – they are there for a reason and no one seems to know what it is. They are weep holes. If you caulk them in it defeats the purpose of them – that will seal in the moisture.

If the moisture is sealed in behind the tile it has no place to dissipate and will simply sit there. Beyond that, the level of that moisture will continue to build with every use. The moisture cannot dissipate at the same rate that is gets back there. That’s gonna lead to a problem. You need weep holes to eliminate the moisture.

When you caulk or silicone the change of plane between the tile and tub you should leave an open space – a space without caulk – in each side wall about an inch out from the back wall. If you click on that little bitty picture to the right you will see two pretty pink lines on it – that’s where those spots are.

Each of these spots are about an inch long (this doesn’t need to be exact) and contain no grout, caulk or silicone – they are simply open space. These are your weep holes.

These spaces will allow moisture to dissipate. These do not need to be the lowest spots on the tub. In other words, if your tub is not entirely level and those spots are not the lowest, it doesn’t matter. The water will end up there and run out – it is the only space to release the pressure the water will build up. It’s a whole physics thing and I haven’t had enough beer Pepsi to properly explain it – but that’s what happens. And yes, you can put them wherever you want, that’s simply where I put them.

When you have an acrylic or fiberglass shower basin without built-in weep holes the same technique applies. Depending on how your tile and shower door lay out you may choose to put the weep holes toward the front of the basin, entirely up to you.

If you click the photo of the shower to the right, and ignore the fuzzy toilet seat cover,  you will see the two pretty pink lines in the back as well as pretty blue lines toward the front. That’s where I put them when I don’t put them in the back. They sometimes look better toward the front if there is a shower door there – the frame will make the weep holes less noticeable.

That’s it – longer than I expected but much easier than trying to explain with just words. If you have a question or just need something clarified do not hesitate to let me know! My blog is here to help you and the fact that I do this stuff every day will, at times, blind me to certain basic things. I do a lot of this stuff without even thinking about it and don’t realize that what is basic to me is not basic to you. If you want a post about a specific subject just let me know in the comment section of any of my posts or shoot me an email at Roger@FloorElf.com. Or, you know, send up smoke signals from your dogs back – he may have just burst into flames again.

There you go Kurt, tell mom you win this one and she owes you a six-pack.

UPDATE: I finally got off my ass and actually took some photos of weep holes in the silicone bead around a tub. These are what I’ve described above and can be used in either a tub or a shower base. There is one on each side of the tub towards the front.

Waterproofing

Just look at you! Sitting there with a hole in the wall of your shower. What are we gonna do with you? If you do not happen to be sitting there with a hole in the shower of your wall read How to Build a Niche for your Shower – Part 1 and join all the cool kids. We’ll wait…

There, now you’re one of the cool kids. Now take your beer Pepsi off that niche shelf so we can waterproof it. You have a couple of different methods with which you can accomplish this.

Liquid Waterproofing Membranes

These products are usually readily available and fairly simple to use. Products such as Custom’s Redgard and Laticrete’s 9235, Hydroban, Hydrobarrier, etc. are all a thick, paint-like product which is brushed or rolled on to your substrate to waterproof it. You should only use these products if you are using a cementious backerboard as your shower substrate, they should not be used over regular drywall.

If you do have a cementious backerboard and choose to use one of these products for waterproofing simply follow the directions with whichever product you choose. Make absolutely certain that you get enough of the product in your niche to effectively waterproof it. The specifications vary but the best way I can explain it with a general rule would be the thickness of a credit card. Two or three good coats and you should have a layer on your substrate equivalent to the thickness of a credit card – that would be the correct amount.

I use to waterproof niches this way until I started doing them with Kerdi. Unfortunately I don’t have any photos of a niche I’ve waterproofed with a liquid membrane. Just make certain you have every (literally) pinhole and corner covered very well. For the remainder of this post I will describe waterproofing your niche with…

Schluter Kerdi

Kerdi is now my preferred method of waterproofing a niche, bench, floor, wall, beer Pepsi cooler, just about everything. For those unfamiliar with Kerdi it is the orange membrane on the shower walls in all my photos.  It is a thin polyethylene sheet which is installed directly to drywall and/or deck mud as well as other substrates, to make it waterproof. It is easily cut with scissors or a razor blade and can be folded, molded around curves, etc. and is installed directly to your substrate with regular (unmodified) thinset. A very versatile product.

While there are countless ways to utilize Kerdi to make your niche waterproof I am going to walk you through the way to cut and install it using one single sheet cut to size for your niche. I say type there are countless ways because there is really no *particular* way which Kerdi must be installed. As long as every piece is overlapped 2″ your substrate will be waterproof – no matter how many pieces you use. I just prefer a single piece cut to whatever size I need for the particular niche.

So what size do you need for your niche? Here’s how to figure it out. The badly created diagram to the right explains it better than I can with words, you can click on it for a full-size version.

It is basically the width of your niche plus the depth (twice)  plus 2″ (twice). See? I told you the diagram was easier.

For my 13 x 13 x 3 niche the measurement for the piece of Kerdi is 23 x 23. That is 13 + 3 + 3 + 2 + 2 = 23. Width + depth + depth + 2 + 2 = width of kerdi. The two inches (twice) is for the overlap on the outside of the niche. Remember I said kerdi needs to be overlapped 2″ – that’s what that is. 2″ on each side of the niche.

For a square niche both measurements will be the same. If you are creating a rectangular niche the width and height measurements will be different – they need to be figured differently.

Photo 1

So here is my piece of kerdi for the niche. (Photo 1) You can see the measurements marked out. Take a ball-point pen or pencil and mark the measurement lines on the piece of kerdi.

At the bottom right of this piece I have marked the two partial cuts you need to make in every corner as well as the small square piece to remove. (Hold on to that piece – don’t throw it away)

Cutting each corner in this manner will allow you to fold the kerdi into your niche correctly and have an exact fit. Make sure you do not cut the lines too far, it’s always better to cut them a bit short and fine-tune it later.

Photo 2 - Kerdi cut for niche

In photo 2 the kerdi is cut to fit into the niche. After you get it all cut you should place it into your niche to ensure that it fits correctly. Just take the piece of kerdi and place it into your niche like photo 3 here:

Photo 3 - Dry-fitting the kerdi

Take the inside corners – the ones that go into the back corners of your niche, and push them tightly into each corner. If measured correctly the corner marks on the inside square should fit perfectly. Wrap the top and bottom flaps over the niche and onto the wall outside.

The side flaps then get smoothed onto the sides and all the strange corner pieces you cut out will fold over the top and bottom flaps and outside to the wall with a 2″ overlap. If fitted properly it should look like photo 4 here:

Photo 4 - Correctly cut and fitted

At this point make any minor adjustments in the cuts or remove any excess you may have and make all the folds over all the corners to make sure they fit tightly.

After you ensure that the fit is correct its time to actually install it. Make sure you are comfortable with the way it fits and how it folds into there. Remove it and replace it a couple of times until you are sure you know how to do it. Once you start playing with the thinset it gets really messy very quickly if you need to make adjustments. I became a tile guy because I like playing in the mud – you may not.

Pull the piece out of there and comb your thinset into every corner and part of the niche and about 2 1/2″ around the outside of the opening. You need to make sure you get every little bit covered. There must be full coverage behind the kerdi to make everything waterproof.

Photo 5 - Combing thinset into and around niche for kerdi

Photo 6 - Placing the kerdi into the niche

When you go to place the kerdi into the niche you should fold in the sides as it will be placed into the wall. By folding the flaps over and in before placing the kerdi in it will help get it in the right place with a minimum of mess.

Start with the upper two corners in the back of the niche and press them in there very firmly. Make sure the line between those two corners follows the corner of the wall in the upper back of the niche. This is why you want to draw all the lines onto the kerdi – it will assist in getting the piece all lines up and in the space straight and square.

When you get those corners and the line between them pressed in firmly run your fingers down each side of the back of the niche to make sure the lines follow the niche. The lines you drew on your kerdi should follow the lines of the niche exactly.

Smooth out the entire interior of your niche starting with the center of the back wall and working outward. You need to make certain there are no air pockets behind your kerdi. Once the back wall is firmly in place start with the sides of the niche working from the back to the front wall again ensuring no air pockets remain.

Once the entire inside of the niche is smoothed down and flat start with the main flaps by using your index finger and thumb along the outside edge of the niche to get a nice, square transition around the corner like this:

Photo 7 - Smoothing outside edges of niche

If you look closely (or click on it for a full-size view) you will notice that only the first inch or so around the outside edges are completely smoothed down. You want to get that nice and tight before worrying about the remainder of those flaps.

After you get the large, main flaps installed and smoothed out flat you can start with the inside corner flaps. Just do one or two at a time and don’t rush through these – they are the point where your overlaps create the waterproof aspects. I do the two opposite corners at a time.

Photo 8 - Installing two of the corner flaps

Photo 9 - Finish installing the remaining flaps

You want to take considerable time and great attention to detail while installing these flaps. The tighter the seams are together where they overlap the more dependable they will be. Kerdi is made waterproof by the overlapping and attaching of the seams – the tighter the better. Get it all smoothed out and tucked in and you will have an absolutely waterproofed hole in your shower wall. That is, after all, what you are building – a hole in the wall.

Now, if you are anal retentive attentive to detail like I am there will probably be one or two spots which may concern you for one reason or another. Remember those 2″ square pieces you cut out of the corners that I told you not to throw away? There’s your patch. Just comb thinset over the spot that’ll keep you awake tonight and install the patch over it. The outside corners of your niche may be one of those areas.

See photo 9? It’s a frickin’ mess. If you aren’t making a bit of a mess you aren’t doing it correctly. Yours should be a bigger mess than mine. Don’t be afraid of it – thinset is your friend. Besides it looks better after is sets – see:

Finished

If you do it the right way you will never have to worry about leaks, standing water or any other fun problems associated with an improperly built hole in the wall. When done correctly you will end up with an absolutely waterproof niche in which to store your rubber ducky! See:

Thought I was joking, huh?

You thought I was joking about the rubber ducky, didn’t you? I wasn’t. I build showers – I like rubber duckies.

In my next post I will describe various ways you can place tile in your waterproofed niche for maximum rubber ducky storage.