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.

As some of you may know (or simply don’t care about – but know anyway) I actually do reply to every question I’m asked on this site. It may take a while for me to sober up enough get enough time away from work to answer it – but I do. As such I am frequently asked the same or similar questions a lot. I’m going to start turning these questions and answers into blog posts to leave myself more beer drinking time to help people with the same problems. So here’s my first one. If you have a suggestion for future posts like these just let me know and I’ll be more than happy to cobble together some similarly ridiculous advice for your problem. I will not share any names or other information with anyone else because – well, it’s none of their damn business – so no homeowners were harmed during the writing of this post.

Here’s the question:

My husband and I have recently tiled our kitchen and laundry room. It is a 35 year old house that had kitchen carpet in both areas. We removed the carpet and old linoleum was underneath. We installed backerboard thinset extra like you suggested on this site, which i read just now to make sure. Now we have something like a fault line running through our grout. We did remove the grout down to the thinset and cleaned out as much as we could then regrouted. Of course it cracked again within 2 weeks of the repair. I do suspect a tile is moving but is there any sure way to know if it is just that tile or more and if so what is the best way to fix it. Also I am not sure why it would move with backerboard under it could it be the floor itself?

My response to this all-too-common question is a bit complicated since it is rarely one specific reason and could be a number of things.

Hi (Name removed to protect people who actually ask me for advice),

The best way to determine what is moving (something is moving) is to go by layers. One of them is moving in an unusual manner or has not been properly addressed while preparing the floor for tile. We’ll start with the tile itself.

You stated that it appears to be a ‘fault line’ which says to me that it runs the length of several tiles in a row and down one grout joint. Is this correct? If so it means that your actual tile layer is more than likely not the problem – it’s below that. If a tile (or tiles) were moving the grout would be cracked along at least two sides of an individual tile and would not create the line you’ve described. UNLESS (you knew that was coming, right?) that line is the one you snapped a chalk line on or drew on the floor as a reference and did not get thinset completely up to it on the edges of the tile. This would cause voids (conveniently enough) under one edge of every one of those tiles in a straight line. That’s doubtful, though, and would also cause cracking in the grout joints running away from that line.

Your backerboard. Unfortunately this is where I believe the problem may be. You stated that you installed thinset beneath the backerboard – correct? You did not state that you taped the seams of the backerboard with thinset and an alkali-resistant mesh tape. I would be willing to bet (my wife doesn’t let me do that, by the way, so it isn’t binding) that the fault line you’ve described is either directly over or within about three inches of a seam in your backerboards. If they are not taped but are thinsetted down they are fully supported beneath but still move independently of one another. Simple things like walking on one side of the backerboard seam more than the other (completely normal with room layouts) will cause more stress on one sheet than the one next to it. If these two are not tied together with mesh tape and thinset they will move independently and crack your grout. The only remedy for this is to pull out enough tile to tape those joints.

Screwing the backerboard into the joists – this will cause uneven movement in your substrate layers as the area directly above the joist will move differently than the rest of your substrate. The joist will expand and contract moving the layers directly above it more than any areas between the joists. The area above it has direct pressure pushing up on it while the areas between the joist have no pressure below them but, instead, are simply being pulled along for the ride – at different speeds.

The linoleum – I doubt that is the problem but even with thinset beneath your backerboards it can still cause movement depending on the type of linoleum. You stated that your house was 35 years old so it’s possible that it was ‘cushioned’ linoleum. If so there is no way short of tearing it out that will eliminate all movement beneath your backerboards.

Your subfloor – another possibility beneath the linoleum. Since you did not remove the linoleum you do not know what shape the subfloor is in (unless you can see it between the joists from below) nor how the joints in the subfloor are staggered. You also do not know whether or not the linoleum has full contact with the subfloor or if there are voids. Another strong possibility is that the linoleum is installed to ‘luan’ which is a very thin laminated plywood commonly used beneath linoleum. If this is the case it is very likely that there are voids between the luan and the subfloor allowing movement of everything above it.

A joist – You did not state whether the area of the fault line is one on which you walk quite a bit or one that sees very little foot traffic. If the latter it may be a joist directly beneath that fault line which is expanding and contracting an unusual amount. It’s very rare but I have seen it. If this is the case (you’ve eliminated the above possibilities) you can ‘sister’ that joist with another joist screwed directly to it on either one or both sides of it. This will help stabilize that joist and possibly eliminate the problem.

The most likely cause (with walls as well as floors) is not taping the backerboard seams. This would require tearing out at least one or two rows of tile along that line (depending on where the seam is). The next strongest possibility is the layer of luan beneath your linoleum with voids beneath it. A fault line of cracking grout is a very distinctive problem with only a handful of causes and it’s usually the backerboard seams – in floors as well as walls.

Unfortunately anything other than the seams will require tearing out the installation at least down to the problem layer.

There you have it – quite anti-climactic, yes? That’s why I attempt to inject extremely bad humor in my posts – I don’t want you falling asleep on me .  As I’ve stated before the only reason your grout would crack is due to movement (unless it is brand new, incorrectly mixed grout). The trick is to find what movement is causing the cracking. The best (only) way to prevent it is to make certain that your tile installation is properly constructed from the joists up or wall studs out. There will always be movement, the purpose of your preparation is to eliminate as much of that as possible and allowing for what is left.

If you have an idea or question which you feel may help out other people just let me know. You can simply leave in in the comments with something like ‘hey jackass, make this a post, willya…?’ or similar. Or you can shoot me an email at Roger@FloorElf.com – I’ll answer you, I’m pretty friendly. No, really…

Besides, I need all the help I can get.

If you have read anything on either of my websites you should know that I tell everyone on the face of the planet who will listen (all three of them) that Laticrete’s SpectraLOCK is the only epoxy grout I will use – period. So rather than just talk smack I’m gonna show you why.

You see the bottom of that logo up there? The part that says ‘Grout that Locks in Color and Blocks Out Stains’? I’m going to put that to the test. And being the kind of warped individual I am – I’m gonna do it in the most ridiculous, convincing way I know how.

Since I have kids I happen to know what the most vile, dangerous, and toxic staining substance on the face of the planet actually is. It is not red wine, a sharpie, or grape juice. Not even close.

It’s cherry kool-aid.

If you have kids you know exactly what I’m talking typing about. If I even set my beer Pepsi near a cup of cherry kool-aid it turns pink through either osmosis or sheer fright, I’m not sure which. This stuff is brutal. I’m fairly certain kool-aid consists of toxic radiation and sugar. The toxic radiation is purchased in powdered form and my kids add about 3 lbs. of sugar per quart.

They like their radiation sweet.

After grouting one of my showers with SpectraLOCK’s #89 ‘Smoke Grey’ grout I created little grout cakes. Since I wasn’t hungry I decided to test the stain resistance of SpectraLOCK, just because I can. And, because I tell all of my customers that they should choose SpectraLOCK, I should have something to back up my preference rather than the ease of installation – that simply makes my job easier.

To the right you will see a photo of two of my grout cakes (I’m gonna copyright that term) and a small bowl of toxic radiation cherry kool-aid. Normally when I place something light colored like that next to a bowl of cherry kool-aid it starts to tremble with fear. SpectraLOCK grout cakes do not tremble – ever. They just sat there with a smirk as if to say ‘yeah, so…?’

Fine – in you go!

Now, normally it takes about .0314159 seconds for just about anything to permanently stain when placed anywhere in the vicinity of cherry kool-aid, let alone actually soaking in it.

So I carefully calculated the ideal amount of time to leave the grout cake soaking and after a lot of beer thought I decided that to get an overly-realistic sense of how stain-resistant SpectraLOCK actually is I would leave it in there for … two weeks.

Hey, I have a job. I don’t have a lot of time to watch grout soak in kool-aid.

In all of the photos below the cake that was soaked in kool-aid is the one on the left. It’s fairly obvious but I don’t want to be vague.

So, after two weeks … I’ve done it! I’ve actually stained SpectraLOCK! Well, I’ve colored it anyway. So to see whether or not it actually stained I needed to try to un-color it. (You can go ahead and copyright that term if you wanna)

To get rid of the pretty pink color I decided to use Oxy-clean, which is available just about everywhere. The active ingredient in Oxy-clean is oxygen bleach and it is great for getting most stains out of most things provided it is only dirty or ‘colored’ like our grout cake up there.

I did not scrub, brush, or otherwise attempt manual cleaning of the grout cake during any of this. I simply mixed some Oxy-clean and water and let the grout cake soak in it for three hours then rinsed it off. After about three hours oxygen bleach basically loses its effectiveness since most of the extra oxygen molecules (which is how it works) are gone. It’s simply water and soda ash at that point.

After one soak and rinse

So after one soaking and rinse …

Not quite as red but still a pretty pink hue to the SpectraLOCK. Given that all I did was let it soak for a while and rinse it I find that to be fairly impressive nonetheless.

After the second soak and rinse

So I did it again…

That is impressive to me! It tells me that the coloring of the cherry kool-aid (I’m still convinced its toxic radiation) did not actually stain the grout but rather was only sitting on the surface in the pits and dips of the ‘cake’.

SpectraLOCK after three soakings and rinses

So I did it one more time…

Yeah, that’s nearly the same color as it started. If you look closely you can still see a very slight pink tinge to the grout cake on the left but for all intents and purposes I believe it to be the original color. And that could probably be eliminated by another one or two soakings or, you know, actually scrubbing it.

Now, in the interest of full disclosure some may think that this is a post about the effectiveness of oxygen bleach. Well, it is that too. But, I will tell you that it does not get cherry kool-aid out of everything – that’s how I know cherry kool-aid is actually toxic radiation. Once something is actually stained the color becomes a part of whatever it has stained – chemically. Oxygen bleach will not remove that. Believe me, I’ve tried.

And before I start getting all the ‘well oxygen bleach IS bleach – duh!’ hate mail – it actually isn’t (bleach). It will not ‘bleach’ the color out of anything, it simply removes dirt and surface stains from stuff. It does this by releasing oxygen molecules when mixed with water which then attach to the stain and released it from whatever you are attempting to clean. It will only do this if it is not actually ‘stained’ but rather only has the stain on the surface. Bleach actually removes the color, oxygen bleach does not. You can use it on your dainty red unmentionables if you want.

So it is my conclusion that yes, SpectraLOCK grout is actually stain resistant – and then some. The claim that SpectraLOCK ‘locks in color and blocks out stains’ isn’t just hype. I’m absolutely certain that if cherry kool-aid will not permanently discolor it after two weeks fully submerged that your kitchen backsplash, entry floor, and shower tile will be nearly bulletproof. I’m absolutely confident that if you clean your tile with any regularity it will continue to look brand new for a very long time.

So now when you see the Laticrete SpectraLOCK advertisement of a tiled floor with a glass of wine spilled on it you now know it isn’t just a marketing ploy – they really did that. And I really did this – with cherry kool-aid.

Because wine isn’t made with toxic radiation.