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.

Steve Johnson

Roger, prepping to tile a shower wall above tub. I’ve read your traditional waterproofing manual and topical. I’m going to do topical, but the manual does not explain how to seal around pipes sticking through the hardiboard. Traditional method says head of silicone around the pipe, but how to on topical.

Also, for transition to drywall, my drywall is finished and wall painted. Do I need to tape and mortar from the backer or can I stop it at the edge and use silicone so that I do not have to redo the drywall? Again, I’m using the topical method.




I am going to put wood look tile in a bathroom. The tile are 6×24. We have some samples and looking at them the edges are straight but tapered a little from the base of the tile to the top. How will this affect the spacing of the joints?
Also when I laid the tile on a flat surface I noticed some cupping in the tile. I could push down at the center of the tile. I have not bought any tile yet. Just want to know if I am worrying about nothing.



I’ve purchased your e-book on how to build a shower using the topical method for both the walls and floor. I have two questions:
1. Can a ‘Quick Pitch’ be used for the floor? I’m not great at working with mud but I’m concerned the combination of mud, plastic and the mortar slurry topcoat won’t go well together due to differing expansion/contraction.
2. Your e-book shows the cement board above the shower floor. Can the backer board be installed first?

Looking forward to your answers so I can keep from screwing up any more than I need to.



I’m starting a tub alcove remodel and studied your books and have one question. What is the proper way to transition from durock to dryall? Use the tape and mortar from the backer board, bead of silicone, other? Thanks!



Hi Andy,

Yes, tape and mortar from the backer.



I recently bought your 3-book set – Kerdi waterproofing walls, Tile Tips, and Tile & Stone Installation. I planned to use a pre-formed base but, due to layout problems, I will probably have to make my own base. I see you have a book covering that and traditional wall waterproofing. Do I now have to purchase it to learn about making my own base?



Hi Steve,

You can if you want. :D Or you can read How to create a shower floor.


Lois Meyer

Can sanded/unsanded grouts be made to be water proof?



Hi Lois,

No. And you wouldn’t want them to be. Tile is not waterproof anyway. :D


Jean Vallee

I have used Bostic urethane (premixed) grout before for my shower floor (and loved it).
Now I’m getting ready to tile my screen porch.
Any thoughts on using it again?



Hi Jean,

I would check with the manufacturer to ensure that the weather you experience wherever you are will be compatible with the grout.


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