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.


Can I use Red Guard over Linoleum?


Leah Haymaker

Hello. We are turning our basement into a bedroom/living suite for my husband and I. There is a 3/4 bathroom down there but we want to change the footprint so the shower, instead of being 3×3 (or whatever a 1971 shower stall is), it will be closer to 6’x6′. We have removed the tile (a day ago, 24 hours BEFORE finding your method on removing tile quickly. But it is okay because the tile pretty much fell off in sections once one or two was removed first.). But, behind the dry-wall is concrete and some type of chicken wire holding it all in. Where the shower is now will become the location for the vanity. Is there an easy way to remove this?! My husband and I are doing the demo ourselves.


Kathleen Gross

We are planning a roll-in shower in new construction with a radiant heated slab on grade floor. Thinking about a curb-less shower with a linear drain. We plan on polished concrete floors in several rooms, including the bath. Would we need a membrane in the shower floor? Would that require a tile floor in the shower?

What about the idea of finishing the shower walls in Hardie-backer without tile?


Dan N

Hello- I just bought two of your books after reading the free one and they are fantastic. I do have an issue I’d like your thoughts on. I have a typical 6″ concrete slab w/rebar between 2″ and 3″ in the middle. I have to put in a no-curb, wheel chair walk in shower where a tub used to be. Some of the rebar was exposed during breaking work. So I will pour and pack some concrete to cover and roughly level that and then I will have about 1 1/2″ left from bottom to level of bare concrete floor. My shower will be 32″ wide with the slope going 32″ down to a linear drain. I have Quick-Pitch strips but I have no room to also do a pre-slope. Can I install the strips on the concrete, pack the mud in, and THEN apply 3 or 4 criss-crossing layers of liquid membrane on the mud slope to the linear drain flange and out onto the concrete level floor? Anything more than that and I’d be adding at least a 1/2 inch above level pre-tile and even if I could raise the rest of the bathroom 1/2 inch, I’d be creating a trip hazard. Thank you!



HELP!!! I need to install tile straight to the subfloor. The problem is that I had a new patio door installed that opens in and there is not enough clearance with carpet to allow the door to open. I have less than 10mm of clearance space between the door and the subfloor.

I hate vinyl flooring, and I need the door to open in. Trying to find a way to successfully install tile next to the patio door. P.S. did I mention that this house was built in 1970? Grrrrrrr! :guedo:



Hi, I’m doing a custom floor for my shower (ocean theme)
the tile pieces will be small 1-2″ with circular tiles that simulate bubbles around the turtle I’ve designed with glass tile and marble onyx tile. What’s the best way to make all these indiv pieces the same height so I get a flat floor. They are going onto a shower pan. Any other tips you have for make this look “spectacular” would help :)


Teresa Aysan

Does this book include the Topical Waterproofing method for shower walls and floor? (I’m asking because the book is called “Traditional”)

How to Build a Traditional Shower for Tile



Hi Teresa,

No, it does not. You need the one titled “Topical Waterproofing for shower floors and walls”. :)



Oh sh*** you have made my f’n day. It’s now 1am and I’m still readying and laughing. I guarantee you I now know way more than my husband. Thanks for the DETAILES, directness, and sarcasm.


Nick Mayfield

Hello. I ordered several of your books last year and my computer died that had the links on them.
Can you resend the links again so I can continue my bathroom remodeling project?
Thank you!
Nick Mayfield



I have seen your recommendations for Unmodified Thinsets; but cannot find a list of your recommendations for Modified Thinsets.
Can you provide a couple so that I can see if they’re available in my area?



Hi there
I bought your Kerdi and tips books and am really looking forward to installing a kerdi shower stall kit. They are seriously good books. But I do have a flooring question. We’re in a new manufactured home where the 30×60 shower is located on the two-foot cantilevered part of our flooring. By that I mean that our floor is 2×6 on 16in centers on top of 2 steel beams that run the length of that side of the house (double wide). The steel beams are about 9-1/2 feet apart and the 2x6s are 13-1/2 feet long. Its a double wide, so the two inside cantilevers are screwed together… but the shower is on the outboard side. The floor is about 3/4 OSB. To that I have to add a sheet of 3/4 plywood to raise the kerdi Styrofoam shower floor up enough to clear a vent pipe that was located “poorly” near the wall. I also want to add some rigidity to the floor area. I intend to put two “pier supports” under the shower floor area, but I’m wondering if I should put two layers of plywood over the OSB instead of one, or do you think one layer will be enough to add the extra rigidity?

Really appreciate your thoughts and advice.

Mike C



For what it’s worth to future readers. Ultimately I decided to lay 2 layers of 3/4 plywood over the 3/4 particle board. I had to cut a 12×16 hole in the PB to reconfig the plumbing. I used 3/4 plywood for the “replacement trapdoor.” The 2 layers of ply over that made the floor extremely rigid, which of course is the goal. It feels like it eliminated all flex in the floor. I’ll still likely install 2 pier supports under the floor there, but it’s probably overkill.



I’m in a pickle and need serious, informative advice. I just had an old fiberglass surround and base replaced by my arrogant contractor who majorly messed up the project. He’s not a tile guy though he’s a brilliant carpenter. Apparently, there’s a big difference. Duh. He tiled the walls and installed a base with a bench ( cause you can’t just build one and tile over it 🙄😳.). The base goes up 18″ then is tiled above but since it extends a half an inch past the tile, doors cannot be installed. The glass people tell me I need a flat surface and to rip out the new $1000 base. My contractor said to just use a shower curtain. I said just bite me. Clearly I’m getting a real tile person and losing big bucks but before I do, any thoughts on how to salvage this situation? I’m plenty pissed, especially since it’s a vacation home and the joker dragged his heels until summer anyway. Guests need to get in the 50 degree lake to get clean–hospitable, eh? Hopefully, this question has enough smart-ass tone to get a reply. Thanks.



That’s a skillful answer to a dicffiult question



Hi Roger,
I’m installing a slate floor over concrete in a basement that had originally been part tile and part carpet. I scraped off the layers of glue leaving me with a nice level surface; however, in some places it is glass smooth and in others there is a haze of glue still adhering. Should I grind the concrete to remove the last traces of glue and scratch up those very polished areas at the same time? Any particular methods you’d suggest? Thanks!



Boy, people have a lot of questions….I bought your tip book in December and I have installed an awesome tile shower (with shelves, thanks). I am grouting and it is looking great until yesterday. It was an unusually hot day and the grout dried before I had time to wipe it off….OMG. I have never had this issue before but this was rapid setting Mapei so maybe that is why. Either way I am stuck with black grout on a bunch of tiles. Scrape Scrape Scrape but not really doing much good. I have a phosphoric acid substitute that seems to make a modicum of difference. Any recommendations (other than not doing this again) as to product to try? Then I can send you a picture of my shower….but for now I am going for a beer ’cause that I can do.



Well, I figured it out. Phosphoric acid sprayed on the walls (wearing mask and goggles and gloves). Paper towel put on to hold acid in place and re-sprayed. Left it for 20 minutes. Used heavy duty scraper to get top stuff off and then green dish scrubby pads to get the rest. Then rinse to see how far I got and repeat. I have porcelain tiles so they put up with the rough treatment. I sure hope this never happens again.



Hi there, I am using your topical manual on a bathroom remodel, and we are going to have to offset the drain because the underlying joists lie where center is. In the ebook you said you would cover offset drains, but I have read through it a couple of times and seem to be missing it… Can give me some more information on working iwth offset drains? Thanks so much.



I am building a 5×6 shower. I’m having a hard time finding PVC shower liners that are big enough to cover the floor, curb, bench etc…without welding two together. I’d prefer to do a traditional waterproofing method on the shower walls. Can I mix methods and do a liquid topical on the floor?


Jane Stewart

Have you installed the European kind of drains in showers that are less visible than the regular ones in the middle? The ones I’ve seen are expensive, but if I lowered the floor of the shower just a little below the floor of the bathroom and put a horizontal drain next to the bathroom floor, then you would not see it. What do you think?

Jane Stewart


Jane Stewart

What do you think of the NEW vinyl tile that is being touted now? I forget the letters that go before it like LVD or something like that. Is it as durable as porcelain? Do you recommend it for any kind of flooring use? Some of the vinyl tiles look more like wood to me than the porcelain tiles that are supposed to mimic wood.

Thank you!

Jane Stewart



PayPal does not work for me. I would like to purchase your books. Is there another way to buy ?



Hi, I brought the Kedi Waterproofing Bundle and the Tile Tips and I didn’t know the Kedi Waterproofing Bundle has the Tile Tips in it. Can I get a refund on the Tile Tips?



Marsha Wani

I need your contact email urgent
My tile project is going on
And o want to make sure why they dif mot use spacer in installing 9×36 tile porcelain
Please help
Do you have phone as i have few questions before its too late



Hello and great site.

I am building an outdoor fire table 47″ diameter with a 19″ donut hole in the middle for the fire pit.

I’ve cut 3/4″ plywood into the donut shape using a router and jig and glued two halves together. Now I have a 1.5″ maple circle and it turned out great.

My plan is to use mosaic glass tiles on the top and sides. My thinking is to use Ditra on the top and cut a 1.5″ strip of ditra for the side. I will have a seam on the top which I will use Kerdi band to seal. Along the edge perimeter I plan to use Kerdi band around the outside and folded over onto the top. This will create some creases but seems like it will work.

I live in chicago so freeze thaw is a reality. Does this installation sound good to you? Do you have any other ideas?

Thanks and great site!



Awesome site Sir Elf, I’ve learned a lot and want to thank you for all the effort you’ve put in.

I’ve bought a Carrera imitation porcelain tile to do the tub surround in my bathroom remodel.
The tile has a thin plastic covering on it, slightly thicker than plastic wrap used in the kitchen.
Is this protective covering only for shipping and should be removed before installation or grouting?
OR is this covering to protect the tile from the sanded epoxy grout I plan on using (Spectralock Pro Premium), and should be left on until the grout is swabbed in?
The plastic in some areas ends exactly on the top edge of the tile and overlaps the sides in some areas.
I was considering that clean up would be a breeze if I could simply lay in the grout, and the pull up the plastic removing any grout from the surface.

Any advice given (while sober or otherwise) will be most appreciated.



Hi. I.m using the Topical method for my shower floor. Could you tell me what the model number of the kerdi drain you recommended.


Joe Jazz

What are your impressions of TEC Power Grout 550?


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