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.


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


Can I install floor tiles on my shower walls?

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


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


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


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.


any good suggestion on how to addresss insulating around a build in shelf in an exterior wall?


lauren manasse

Hi – you were recommended to me to contact re: thinsetting a glass tile insatallation into a subway tile shower that is getting put in. The tiler is saying that he cannot thinset the installation without recessing the installation because it is flimsy and the grout/mortar will bleed through the tiles if he tries to mount it flush to the subway tile. Is there a best way to install something like this? I am not sure I like the way it will look if the installation is slightly recessed…. I can give you more info if it wold be helpful.THANK YOU!




Hi Roger,

So I build a base to attach my island cabinets to out of 2×6, and 1×6 boards. Now that I’ve got the island ontop of that, I was hoping to create a tile mosaic around the bottom of the island to cover up the 2x6s that create the base, as well as a 6″ ‘step’ or footrest that juts out on the ‘bar top’ side of the island which will have the overhanging countertop.

I’ve read everywhere that I can’t tile overtop of this dimensional lumber. I clearly can’t change the base of this island now as i’ve tiled the floor around it, and i’ve got the cabinets installed ontop of it. Do I have any options for creating a tile mosaic (using broken pieces of the ceramic tile I used for the actual flooring)?

Would screwing a very thin (realistically as thin as I can find, as I hadn’t accounted for this extra thickness in my plans, so it sort of throws everything off) piece of OSB/plywood to the dimensional lumber around the base and over the footrest area suffice?

Any help is appreciated. Thanks.


robert larson

what is the minimum size tile that ca wayn be laid down on an entry



Hi Roger,
I purchased your ebooks and have really enjoyed them. Now to the questions.

1. I am an anal-retentive overkill kind of guy. I planned on using 6 mil plastic for waterproofing but also have a full roll of roofing felt. Does it hurt if I do both or is that a total waste of time. I planned on doing the felt first and then covering with plastic.

2. I am joining Hardiebacker to drywall at an outside corner…with tile (bullnose) on the Hardiebacker going to the edge…and painting the drywall. I know I shouldn’t use the metal cornerbead…but not sure what is the best way to treat the outside corner where the 2 different materials meet. Was planning on using the vinyl corner bead.

3. The framing is pretty straight and level (I did the framing)…but I will need to shim the 2x4s as I want the Hardiebacker to run over the shower pan flange to 1/8″ above the pan surface. The flange is about 1/8″ – 3/16″ thick and I can’t find any shims for this other than the cardboard ones made by strait-flex. Are these okay to use? Do you have any other recommendations on what to use. The only other thing I can think of is splitting a 4×8 sheet of 1/8″ ply.

4.. The toilet flange on the 3″ PVC pipe has been removed and I can tile right up and around the pipe…and then put the flange on top of the tile. Do you have any guidance on what type of flange to use (e.g., PVC or metal)? Any suggestions or guidance on flange installation?

5. I don’t want to second guess your advice…especially since it is in red in your book…but I have read that I am supposed to tape and thin set the inside corners of the Hardiebacker 500. I would prefer to use silicone as you recommend….but as I mentioned…I’m anal retentive and worry about things like this.

Thank you.



Re: no threshold/barrier shower with Kerdi
Can I use ditra on the floor or should I use membrane?
I want the linear drain to go wall to wall,can I do that with a Kerdi linear? It will be 58 1/2 inches wall to wall
I bought your creating a shower manual, but you don’t address linear drains



I will be installing travertine tile (filled & honed, Versailles pattern) in several rooms (sun room, kitchen, hallway, 1/2 bathroom and laundry room). In total, it’s about 700 soft. Since I will be doing this project nights and weekends, it will probably take me several months. All the tile be continuous with no travertine thresholds. My plan is to start in the sunroom, then do the kitchen, then work my way through the hallway, then do the powder room and finally the laundry room. I plan to install one area, grout it, seal it, then move on to the next area. My question is fairly simple. What is the shelf life of an unopened package and an opened package of thinset mortar and grout, assuming the products are be stored in a dry place.


Linda Brock

I have bought some very heavy tile for my shower walls. my tile guys are planning to put the tile on the walls with Tile Adhesive.(It comes in 3 gallon buckets. they said it was too heavy for thinset to hold it. what is tile adhesive and how does it work? Will it keep my tile on the wall?
Thanks for Your Help….Linda :lol2: :lol2: Please email me with your great words of :cool: :cool: :guedo: :guedo: :guedo:



Hey Roger, thanks for all the helpful info. Attempting my second bath re-do with schluter products. 1st one was a shower stall now doing a tub surround and the bathtub will be reglazed after I’m done with the tile on walls and floor. Tub refinisher tells me to do everything as usual but don’t caulk the tub flange or the bathroom floor tile where it meets the tub. Can you please tell me what precautions I take in these two spots. I just read your info about extending the kerdi beyond the tub flange, but I can’t put any silicone or kerdifix on until after the tub is reglazed. Thanks for any help!



Hi Roger,
Question about floor warmers. Any that you would recommend?
My project will include two rooms – one is a breakfast room off the kitchen which would need just to take the chill off the floor (which is on a slab), and the other is a laundry room, small room approx 7 by 10, which I’d like to get as much additional heat as I can.



Hey Roger,

Great site. Thank you for all the info. I also purchased your “Waterproofed
Walls Around a Tub or Shower Base with Liquid Topical Products” pdf. Which was great as well. Thank you.

I am about ready to start my tub/tile project and I came across this post: http://www.johnbridge.com/vbulletin/showthread.php?t=29633

These guys have me a little worried. I am using 1/2″ HardiBacker and AquaDefense… did the guy who had the Redgard peel off just not have his HardiBacker clean enough… or might it have been something else? They also mention diluting the first layer… do you recommend this? I understand this post was 10+ years ago and specs may have changed too.

Thanks for any info your can provide.



Gerard Maryak

Had a frameless glass shower installed three years ago. Water always made its way out of the shower because no seal on the bottom of the door. Figured a few drips here and there wouldn’t matter. I guess over three years they added up and the flooring outside the shower softened. So I am gutting the bathroom and want to install a slightly modified layout. What I had before was an enclosed shower and Jacuzzi tub on a platform. I want to relace the jacuzzi with a standing tub and create a shower that has just one glass wall with direct entry in the now larger space between the tub and the shower. (Not quite a roll in shower but along those lines.) I have looked at the Kerdi shower method and think, wow that is what I need to do to ensure a complete sealed system, but I am not a huge fan of their pan. I would like to use an Onyx low profile shower pan instead of mud and tile.

But I really would like to put a Kerdi like seal around as much of the shower and floors as possible. I could do the whole bathroom that way but is there an alternative, like lets say using the kerdi system several feet out from the primary wet zone and then just stopping? If I am getting tons of water further out than that, then I am having real problems.

The one issue I see is that the Kerdi system puts their waterproof covering on the inside of their pan and my pan would be above the water proofing. I suppose that is still possible if I used the Kerdi system on the flooring below the pan and just installed the pan over top of that, or is that crazy?

Any thoughts would be appreciated.


Ken M

I got your Kerdi manual and its got a lot of great info but I wanted to get some clarification on the using the Kerdi shower tray (KERDI-SHOWER-ST shower tray) that’s included in the kits.
Does the change the install any?
Are there any quirks when using/installing it?
Do I install it before the walls or after?




Great Site! I am building my shower using deck mud for the base. I will be using Kerdi for waterproofing. When I make the curb, can I use the Wet Mud mix for the entire curb to minimize any expansion issues? Would you recommend embedding rebar or lathe for additional strength?
Thanks for your time.



I purchased the Schluter Kerdi Shower kit 32×60. The kit came with the shower curb do you recommend using this or building your own with wood? The shower will have a full glass panel across the front (60 inch side)with a door. With the curb have you ever worked one piece threshold/silestone (not sure what is the right terminology) which would allow a seamless top to the shower curb? Any downfalls to the one piece top?

Thank you for your help.


Robb Johnsrud

I had a dryer fire recently – laundry is in my second floor bathroom – and the grout took on quite a lot of smoke. It shades from dark grey-brown at the tub junction to black at the top. The more important issue to me is that it’s taken on the odor and is releasing it. I’m doubtful about trying to seal it; I anticipate that, while the sealer will probably help it will continue to off-gas. I usually use Miracle 511 Impregnator, though I haven’t used that on this bathroom. I believe I last used Gold Seal.
I’m expecting that I really should remove the grout and regrout, but…well, I’m getting lazy.
Any opinions?
I want to say that I really appreciate your website and expertise. It’s somewhat unusual on the Internet, and has been quite useful a number of times. Thanks!
Finally, you being in Fort Collins and in the trade for quite awhile, I think it conceivable you might know one of my old building partners, Alex Blackmer. He used to run Enersol, and is now working full time on solar advocacy. Well, you might…
Thanks in advance for your opinions.



Hey Rodger, I’ve been reading that professionals aren’t using green board any longer in bathrooms. I’m building the shower inclosure with a roman tub drop-in included. I don’t want to tile to the ceiling so I’ll be running the backer board up to where it just clears the shower head. From the point on and including the ceiling i’ll be covering the studs with Greenboard. I planned to run 6mil poly moisture barrier behind the backer board and not behind the green board. I have read discussions about how its not a good idea to put moisture barrier behind mold resistant drywall. What do you think and does the plan work? Thanks, Geo.



loved your sense of humor and tips for removing old floor tile grout and replacing it. Know my back and bent knees can’t do the job, but have a much better idea of how it is going to be done correctly, cost of items, and now to find someone to trust doing it. Thanks again, may be purchasing entire e-book soon



Hi Roger,

What could cause for tile grout breaking up in certain areas in a shower stall shortly after a DIY installation?


Christina Kreinbring

Help! We had an area of tile removed, about 10×10 at the top of our open stairway (smack dab in the middle of our house). Its a common area where the 3 bedroom doors and 1 bathroom door opens into. The one side of the space over looks the family room. The guys that did it did not seal up the area at all, simply a matter of putting up one piece of plastic across the 10′ area that is open to the family room below). They didn’t even close my sons bedroom doors. As a result, we have a thick layer of grout dust through out my entire house. Its crazy where that stuff gets into….closets, kitchen cabinets & drawers, even the frig! My sons bedrooms and our living room furniture (including blankets and throw pills) has an extremely thick layer of this dust as it was right below where they were working. My question is, being tile removal guys shouldn’t they have know what a mess this would make and partition off the area? Or atleast make the suggestion to give us the chance to partition it off or cover our furniture? It took 2 of us 10+ hours to clean up a mess the could’ve been, even partially, contained with a little preparation. And if this is a reasonable request, who dropped the ball? The flooring store or the guys they hired?


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