Tile FAQ’s

The list below contains some of the most commonly asked questions I get about tile and installation methods. For each one I have included a (very) short answer.  I already have, or will have in the future, a post about every one of these. If that post already exists there will be a link at the end of the answer.

I will continue to add to this page as the questions come up. If you have a question just leave a comment at the bottom and I’ll include it on this page.

Just click on the question to view the answer.

Grout

What type of grout should I use for my tile?

It depends on the tile and the size of the grout lines. Read this: Using the correct type of grout

How large should my grout lines be?

It depends on the tile size and the look you want. Read this: How large should grout lines be?

Can I fill my cracking grout with more grout?

Maybe. Read this article for a more complete answer: Filling grout lines with more grout

Are there any “magic” products available to remove stains from your grout and tile?

No there are not. One of the closest things to magic that you can buy is oxygen bleach. It is not bleach! It's a slight misnomer. This is the main ingredient in products like oxyclean. It works very, very well to clean grout. More information: How to clean grout

Does grout help stabilize tile, hold them in place, or make them stick better?

No it does not. (Epoxy grout is different) Read this: Does grout stabilize tile?

Are tile, stone or grout waterproof?

No they are not. Read this: Is tile waterproof?

Can I install my tile without grout lines?

No, you should not. Read this: Tile with no grout

Miscellaneous

Can I install floor tiles on my shower walls?

Yes you can. Read this: Floor tiles on a wall

Sealers

Will sealing your tile and grout make it waterproof?

No! It absolutely will not.

Should I seal (or re-seal) my tile and grout?

If you would like it to be easier to clean then yes, you should.

Setting Materials

What should I use to set my tile?

It depends on where you are installing the tile. Read this: Proper setting materials for tile

Are mastic and pre-mixed “mortar” acceptable to install tile on a floor or in a shower?

No they are not. Read this: Proper setting materials for tile

Substrates

Does my floor have to be level before I install tile?

No it does not. Read this: Does my floor have to be level for tile?

Do I need a waterproof membrane for my shower walls?

Yes, a membrane of some sort is required. Read the article for the different types. Read this: Preparing a shower wall for tile

Can I simply stick tile to the drywall in my shower or the plywood on my floor?

You can but it won’t last – so no. Read this: Preparing a shower wall for tile or this: Installing backerboard for floor tile

Transitions

Should I use grout or caulk in the corners of my shower?

Technically? Caulk. Realistically? It depends. Read this: Caulk or grout in corners?

If you have any suggestions or questions please feel free to leave a comment.

mark

Hey Roger
Any thoughts on adjustable tile leveling systems? I.E. Tuscan leveling system or others like it.

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Roger

Hi Mark,

These systems are not to adjust tile in any form. If you think about them as a tool to hold the tile in place as the thinset cures then you’re using it correctly. If you think about them like a tool that makes a sub-standard or not flat installation perfectly flat, that isn’t what they do.

That said, they work great. I regularly use the mlt, I used to use the tls (tuscan). Excellent tool.

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Chris

Can’t seem to find an answer to my particular question. We are retiling our shower and removing the small bench that was once in the corner. There is a copper shower pan and concrete poured already. We have never had a leaking problem. The seat was inside the pan but the concrete was not poured where it was so now there is part of of the pan that needs to be filled in with concrete. Do I need to tear out the entire concrete floor and redo it or can I just fill in the small part where the seat was? Also where we tore up the existing tile, can I put a smooth layer of concrete to make it smooth before tiling.

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Roger

Hi Chris,

Concrete is not what you want, deck mud is what you want. And yes, you can just fill in the needed area with deck mud. Why do you want to make it smooth? If you need to ‘level’ it out or get it reasonably smooth to get your tile flat you can skim over it with thinset first, then let that cure, then install your tile.

FYI, copper pans will eventually fail – period. While you may not currently have a leak if you think about it they will not leak, until they do. Once they fail you will have a leak. It’s not a built-up process where it doesn’t leak, then it only leaks a drop or two, then it leaks a little, then it leaks a lot – It will go from not leaking to leaking, period. I would highly recommend replacing it with a more modern waterproofing membrane which does not degrade.

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DJ

Roger,
Great site! We had our kitchen floor tiled about 9 months ago and we now have grout cracking in multiple areas, most of which are the heavy traffic areas. The subfloor is 1/2″ plywood over joists set 16″ apart with 1/2″ cement board over the ply. I can feel movement in the floor when someone walks on it. It seems obvious to me that the subfloor is not thick enough however my contractor is saying that if that was the case then tiles would be loose. Isn’t that just a matter of time? Is it possible that this is just a thinset issue? I think my contractor is full of crap.

If I do need more subfloor have you ever heard of someone reinforcing it from below with sections of plywood and braces drilled into the joists? Otherwise it will be a nightmare to remove the cabinets and reinstall them over a higher floor.

Thanks!
DJ

Reply

Roger

Hi DJ,

Yes, the tiles will eventually be loose as well. Yes, it is only a matter of time. Yes, your contractor is full of crap.

No, I have never heard of anyone doing that. No, I don’t think it would work (even though you didn’t ask :D ). It may, it may not. Impossible to tell. The problem is that you’re attempting to place a band-aid on an installation that is improper. 1/2″ ply over joists isn’t even the normal track housing stability, that is at least 5/8″ – 3/4″ minimum single layer. I don’t even know that your floor would meet the deflection requirements for basic building code.

I know what will work, but it requires a proper installation. I have no idea what fixes may or may not work.

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chris

Hi Roger,

1.) How much added height is caused by thinset between tile and backer board or mastic between plywood layers?

2.) My proposed subfloor is as follows: joists 16″ OC then 3/4′ plywood screwed to joists followed by 1/2″ plywood on top. Last layer is 1/2″ Durock on which the tile will be placed.
a.) I had to cut the 3/4″ ply so that there are some joints that are perpendicular to the joists and unsupported. I don’t need to install blocking at these joists, do I? Will the following layers compensate for the springiness at these points? I will lay subsequent layers perpendicular so as not to overlap joints.
b.) Do i need to snap chalk lines on the SECOND layer of 1/2″ plywood to be sure to screw this layer into the joists or is screwing into the field of the 3/4″ below sufficient? Same question with durock to 1/2″ ply.
c.) The bathroom walls are down to the studs and are being rehung with drywall and durock along with a new door. Should the door frame reveal be brought flush in height with wall tiles that go half way up wall (1/4″ thick tiles) so that the door trim is on top of the tile? In this case I’d use a 1/4″ shim under the trim on the un-tiled drywall above. Seems that this would be a cleaner look than bring the door frame out of the bathroom so that tile would be flush in height with the trim.

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Roger

Hi Chris,

1. It depends on what size trowel you use for your thinset. Absolutely no height is added if you use mastic between plywood layers – BECAUSE YOU SHOULD NEVER USE MASTIC BETWEEN PLYWOOD LAYERS. :D

2. a. No, you don’t need to add blocking, although it won’t hurt. Yes, the layers should compensate for it.
b. If it helps you, yes. Same answer with the durock
c. Tile does not need to be flush with the door trim, especially if you only have tile on half the wall. Is the top half of your door trim going to be shimmed out 1/4″ as well? Just butt the tile up to the door trim.

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Jonathan

I have installed 12×24 tile vertically, brick style offset (1/3′s). What would be the best way to install the 12″ bullnose for the transition from backer to drywall? Center of the 12×24 or on thirds like the rest? I realize I have to make cuts either way. Thanks for your help.

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Roger

Hi Jonathon,

It’s purely a personal choice. I prefer to continue the pattern if you have a 1/3 offset, it just looks better to me.

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Jodi

Ok, it is 6 am and we are supposed to begin installing a mosaic project in less than 2 hours. We just found out the cement wall we are installing on was painted last week to cover graffiti…AHHH. So now what do we do? No time to powerwash the paint off. Can we just sand the paint and use a modified thinset? Fingers crossed that someone sees this post and responds. :( :!:

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Roger

Hi Jodi,

You need some type of waterproofing over that cement wall. You can rough up the paint and use modified, but that doesn’t deal with the waterproofing aspect needed for your shower.

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John

I have an older home (rental) that has concrete/cement interior and exterior walls. In one of the bathrooms there is a shower stall only (no tub) again with concrete/cement walls. Obviously for years the shower walls have only been painted and have SEVERAL layers of paint on them. My question is, does the paint need to be removed before tile installation? If not, is it still advisable to use an elastomeric type sealer prior to installation?

Thanks

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Roger

Hi John,

You should use an elastomeric membrane over the face of the walls. You only need to rough up the paint in order to ensure adhesion of your membrane, it doesn’t necessarily need to be removed.

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Robert

Hi.
I’m in the process of installing porcelain ceramic floor tile over Ditra in a mudroom. The Ditra is down solidly over the concrete slab thanks in great part to all your advice on the site – so thank you! I installed an initial set of tiles yesterday over the ditra, covering about 20% of the floor area. Today I noticed that, adjacent to the last row of tiles installed yesterday, some of the waffle squares (about 3 squares by 15 squares) in the ditra got thin set pressed into them. (I’m Using Custom’s Uncoupling Mat Mortar). My question – do I need to scrape all of that out gently with something before tiling over it with the next portion of the floor? Or will it be ok to just go right over it with new mortar?
FWIW, The area in question had mortar ‘pressed in really well’ – I just overshot the area I needed to cover for that last tile, and then missed it on cleanup until this morning.

Thanks again for all your advice on the site – it’s tremendously helpful!

RJ

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Roger

Hi Robert,

It’s just fine, go right over it. I pre-fill them sometimes and go over the whole thing the next day.

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bonnie

I need your help ! How do I make my husband understand he shouldn’t use mastic to do our new shower! He told me he knows what he is doing. Any suggestions since your a Guy! I have already told him what will happen after reading your info.

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Roger

Hi Bonnie,

If you’ve told him what will happen that’s about all you can do. If you can get him to read instructions have him read the back of the bucket, it is not suitable for use in wet areas with tile larger than 8″ square. It’s right there. If he has to learn things the hard way just let him do it and start saving up for the replacement. :D

Or you can send him over here, I’ll learn him…

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John

I’m going to tile above a one-piece tub-shower surround (the 21″ gap between that and the ceiling) and have to replace the drywall up there anyway because it wasn’t properly prepared before painting back when it was installed.

Do I need to install concrete backer board before tiling, or can I just use green board as that area does not get direct water spray as a shower wall would?

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Roger

Hi John,

You can use cement board, greenboard or regular drywall.

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Mike

Roger, I flip houses in San Diego. I’ve done several showers myself, but I prefer to hire it out to save time. My tile guy likes to use Denshield in place of greenboard, and of course charges me for it. Is he wasting my money? It seems to me that if the shower is correctly built, water should never get to the drywall. He Redgard’s the Denshield seams. Is this essentially a topical shower waterproofing? Thanks.

Reply

Roger

Hi Mike,

NO! He is not wasting your time. You need some sort of waterproofing behind your tile. As of 2009 greenboard is not acceptable in any wet area. Furthermore, your assumption about tile and grout preventing water from getting to the drywall is incorrect. Tile and grout ARE NOT waterproof. You will always have water behind your tile, it’s completely normal. A correctly built shower is a waterproof box before a box of tile is even opened. Densshield is a type of topical waterproofing, yes, and he is sealing the seams and penetrations with redgard. He is doing it correctly. Be happy you have a tile guy who knows what he’s doing. :D

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John

Hello,
Really enjoy your blend of knowledge and humor!
I have an enamel shower pan setting on the slab with an irregular gap (1/2 to 3/4 inch) between the pan and the edge of the brick floor in the bathroom. I was planning to fill the gap with thinset, and then transition over the gap from the pan to the brick floor with bullnose set in thinset. I will use SpectraLock grout between the bullnose ends to match the grout lines in the shower, and use silicone where the bullnose meets the shower pan (plane change). Does this make sense, or do you have an alternate suggestion?
Many Thanks

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Roger

Hi John,

That sounds fine, but the more I think about it the more I’m confused about what you have there. You have a brick floor in the bathroom (I’m assuming) and an enamel pan? Never seen an enamel pan, is it acrylic-like? Is it a tiled pan or are you bridging the bullnose from a pan that is not tiled to the brick floor? If you could upload a photo of it here for me I could probably help more than just asking questions you’re probably rolling your eyes at. :D

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james

What about effervescence on dark-colored grout after curung? I’ve read in 100 uses for coca cola that sodas with phosphoric acid are among the best grout cleaners. Will this work on effervescence?

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Roger

I have no idea, never wanted to soak fresh grout in coke. :D Pretty sure it would compromise your grout, discolor it and make it sticky.

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Brian

Ummmm……do ya mean “efflorescence”?

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Roger
james

Why don’t they make grout you can jus pourb between the tiles rather than wipe. Would be easier, cleaner, faster. What happens if you keep the sanded grout just thin enough to pour?

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Roger

Hey James,

It uses as much water as the cement particles will allow (the exact amount, by the way, that the bag states to mix it with), the rest evaporates, it shrinks and turns to dust when you touch it.

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Sean

Hello,

I am replacing the walls in my shower. Previous owner used greenboard which got wet and crumbled. I’ve got the area down to the studs. For the walls I am using next gen durarock and then coating it with the paintable redgard. My plan is to use the existing shower base. My concern is that the existing shower base has 1 inch high and1/4 inch deep lip. The base was not notched into the studs, so it sits 1/4 outside the studs. If I use the 1/2 inch durarock in the shower area so that it is flush with the existing walls, it will sit 1/4 inch past the shower lip, creating a gap that I am not sure what to do with. The plan is to use 12 x 24 porcelain tile. Do I need to fill this gap or can I attach the tile to the durarock so it sits just above the base of the shower? (leaving a gap between the back of the tile and the shower lip).

Your advice is appreciated. Thank you

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Roger

Hi Sean,

You don’t need to do anything with it. Bond the tile to the durock (I know it’s durarock, I’m a stubborn ass…) and let it overhang the lip. Take it down to within about 1/16″ – 1/8″ of the vertical arm of the base and silicone that gap, leaving the weep holes open.

Reply

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