Proper Setting Materials for Tile

by Roger

There are three basic materials used to set tile.

  • Mastic
  • Thinset Mortar
  • Epoxy

For each installation there is a specific material you should be using. Before you start any tile installation you should ensure that the material you choose is suitable for that application.


Mastic is a latex or solvent based adhesive that cures by evaporation. It is sold in airtight containers (buckets) and requires no mixing. It is ready to use immediately. It is suitable only for non-wet applications.

Mastic should never be used for showers or floors! Ever! When mastic gets wet the water will re-emulsify the adhesive base. This means that mastic turns to goo when it gets wet. Goo will not keep your tiles on the wall. Every one of the failed showers that I’ve ever replaced were installed with mastic.

With that said typed, mastic does have its place. It is “stickier” than thinset mortar which is why some prefer to use it – for everything. It should only be used in non-wet areas such as a backsplash, wainscot, or fireplace. An area that is not consistently exposed to water or moisture. It should also only be used on tiles smaller than 6 inches square.

Think about it like this: mastic is stored in a bucket with a lid on it. This keeps it from being exposed to air which would cause it to cure (dry). If you spread it on your wall and place a 12 X 12 inch tile on it, that’s just like putting the lid back on the bucket. It will never fully cure. If any moisture gets behind that tile with the mastic it will eventually re-emulsify and lose adhesion. That means is that your tile is going to fall off the wall.

There is also a product called “premixed thinset adhesive”. This product is pushed as a suitable material with which to set tile – it is not. It is only mastic with sand added to it. While sand does help materials from shrinking as it sets, it does not make mastic suitable for showers or floors.

Thinset Mortar

Thinset mortar is what you need to use for shower walls and floors of any type. It is sold in bags and needs to be mixed with water. Sound simple? It is. Referred to as thinset, mud, mortar, or a number of other things, it is a combination of sand, portland cement, lime, and other stuff that makes it the preferred setting material for elves everywhere.

When mixed properly (read the directions, no, really, read the directions) it is stable,  not compromised by water or moisture, and rock solid. Thinset must be mixed with water, allowed to slake, then remixed before use. Slaking refers to letting it set for a specific amount of time to allow the chemicals to interact and become workable.

Thinset cures through a chemical process, not by evaporation. Air is not required for it to set. It will cure in the bottom of a bucket of water, really. This means that no matter the density or type of tile you use it for, it will fully cure. No worries there. The tile will stay where you put it.

Unlike mastic, thinset will not be compromised by water or moisture. If it gets wets the thinset will remain cured and will not be reactivated. It’s similar to your driveway. The concrete on your driveway was mixed with water but it doesn’t turn to mush when it rains. It’s the same stuff.

Thinset mortar will be the correct setting material for nearly every application.


Epoxy is a chemical based glue that cures through chemical interaction. It is almost bulletproof and not user-friendly. To be frank, it’s a pain in the ass. It is usually a two or three part product which, when mixed together, form a very stiff, very thick putty-like substance. When cured it becomes a permanant part of whatever is attached to it. That’s great on the back of the tile, not so much if you get it on the front. Use with care, it is nearly impossible to get off of anything once it’s set.

There are not many applications which require the use of epoxy setting materials. Certain exterior applications need it, swimming pools, certain types of stone and glass tiles. While epoxy can be used for any application, only specific jobs actually require it. It’s expensive. I mean really expensive. If you don’t need to use it, don’t.

If you are unsure whether or not your product or application requires epoxy, just check the manufacturer’s recommendations. If it is required, they will make sure you know about it. You can also ask me, just leave a question in the comments. I’ll reply, I’m a fairly sociable guy when I’m not crawling around on a floor.

Which to use

The general rule of thumb is to use thinset mortar. Unless your specific application requires epoxy, thinset can be used. Anywhere you can use mastic you can use thinset instead. It is more durable, water resistant, and cheaper than mastic anyway. As far as I’m concerned, the only thing mastic is good for is a free bucket.

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Roger, I want to install 1″x1″ travertine over existing man made fake marble shower floor. Will mortar work? Do I need to sand ( etch fake marble)



We are putting quartzite tile for the coping of our pool. The tiles are 12″x12″ and about 3/4-1″deep. We live in Michigan so it will need to handle freeze thaw. Wondering what you suggest to use for thinset? Any certain brand? Any certain additives? Also wondering what to use for the grout inbetween the tiles? Mortar? Any certain brand/additives to help hold up to freeze/thaw? shoukd we seal the tiles before laying? Will they still bond to mortar and thinset? Is there a temperature below which we shouldn’t do the work? Any advice would be awesome? Thanks



How thick should the mortar be for a shower wall using 13×13 tile :?:



How thick should the mortar be on 13 x 13 tile for a shower wall


Polly Briley

Floor Elf,

I am hoping you can tell me definitively whether I must use the Laticrete 333 with my Laticrete 317 for adhering my porcelain 12″ x 24″ tiles on my shower floor, walls and ceiling? I have hardibacker then hydroban and then the 317 for the floor, walls and ceiling. The 317 bag says I must use the 333 for porcelain tiles, but you often say it is not needed. So, please help before I spend $79 and wait another week to receive my 333.

Do I need Laticrete 333 to mix with my Laticrete 317 to place my porcelain 12″x24″ tiles on top of my Hydroban coated Hardibacker walls and ceiling AND my FloorElf directed wood substrate, poured shower mud, topped by hydroban?

Thank you.




Hi Polly,

Technically yes, you do need the 333. Realistically – no, you do not need the 333. It will work either way.



Hello, I have an issue with a shower/tub line. There tiles are going up as a shower liner. I completed putting in the backer board ( Wonderboard) and proceeded to mortar and tape all of the seams and mortared over the screw heads. The mortar I used was specifically recommended by the local hardware big box store, even though I told him I thought it was incorrect and also what I was going to use it for. He said that I should use TEC 369 Polymer Modified Full Contact Mortar. I have been waiting over 7 hours for this stuff to dry, and where it has dried does not seem solid, I can put my thumbnail into it. I started reading the bag to see how long it should take and noticed that it says ” not for wall applications”. Now I am concerned, will it ever dry? And if it does, can I use it as is? Continue using it to lay tiles? Or do I have to start over? Removing all of the Wonderboard or just clean it off?



Hi Guy,

That mortar is just fine. Give it about 12 hours. If you can put your thumbnail through it easily I would contact tec to see what’s up with the bag you have. It shouldn’t do that. On the other hand, your tile doesn’t have thumbnails. :D


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