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

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

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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Mike

Hey Roger,
Thanks for the response, but I was feeling a little leery about the whole thing, so I went in & pulled all of the tiles, cleaned them, and re-installed, using mortar (the right stuff). It was tedious, lengthy, & labor-some, but I feel a lot better. I’ll be grouting today. When I pulled the tiles, after 40 hrs, the Simple Set product was just as moist as when I applied it. It may have taken weeks, if ever, to cure properly. I wouldn’t recommend Simple Set for any project, especially floors. I’m out about $100 for 2 buckets, but lesson learned.
Mike

Reply

Roger

I’m very happy you decided to do that Mike. :)

I know I’m the only freak on the planet who takes pictures of tile, but if you have any pictures of that after you tore it out I would love to have copies of them. People don’t believe me when I tell them it’s just like putting the lid back on the bucket.

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Mike

Sorry Roger,
I wish I would have taken some pics, if nothing else but to show them to the Home Depot people who backed this product. You’re exactly right though, it’s like putting the lid back on. If you know anyone thinking of using that CRAP, feel free to share my email or my story with them.

MikeP

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Mike

Roger,
I just finished laying a tile floor in my kitchen, 12″ porcelain tiles over a concrete slab (about 60 s/f), part of it Monday night and the rest on Tuesday. I used the powder mix mortar on Monday, and on Tuesday, after burning up a drill mixing the mortar, went to a product called “Simple Set”, recommended by a Home Depot employee. After the fact, something didn’t seem right & I started reading some reviews on this product, mostly negative. Here’s my spot now. All tiles are laid, and have been for about 36 hours. I don’t want to tear out & redo unless absolutely necessary. If I have to wait a few more days, I’m thinking that would be better than tearing out & starting over. I’m alone on this job, so tearing out, trying to clean tiles, and reworking will be a nightmare. I would appreciate your thoughts.

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Roger

Hi Mike,

It’s not ideal, but if you leave it for a few days before grouting it MAY be fine. There’s just no real way to tell. Just keep an eye out for cracking grout, that will be your first sign that it’s not holding up.

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curt

Roger:
I am planning to install 12″ polished marble in my foyer. Its is going over 1/2″ durock which was set in thinset and screwed per manufacturers recommendation. The floor appears rock solid however there are some high / low spots (yes, I know I should have addressed that when I installed the backer board, but it is what it is). The tile is about 3/8″ thick and does not have any mesh on the back.

My question is what type of mortar should be used? Thinset or medium bed? Other characteristics of mortar material that should be used for this marble. Thank you again for all of you expertise

Reply

Roger

Hi Curt,

With marble you normally want a medium-bed mortar, especially when you don’t have a completely flat substrate. Custom’s marble and granite mortar available at home depot is a good one, as is Laticrete’s 4xlt.

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COMike

Roger,

We have an existing fireplace surround that is tiled. We would like to install stacked stone travertine tile that have travertine blocks that are appox 2″ x 4″ on a 12″ x 12″ mat. Is there way we can just install the travertine over the existing tiles versus taking out the existing tile?

I have read a few posts online and it sounds like this can be done if you clean, sand and level (with mortar) the existing tiles and then use Epoxy or Thin-Set Mortar to set the travertine. What is your recommendation? MY challenge is that removing the tile looks precarious as I have an outside edge to an alcove on one side. This could cause significant trouble (read re-drywalling) if that is messed up.

Thank you for any response. Your blog is excellent.

Mike

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Roger

Hi COMike,

Yes, you can. I would rough up the face of the existing tile, install redgard over it and install the new stuff with a good modified thinset.

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Dan Canyon

I want to tile over exiting 4×4 porcelain tiles on a bathroom backsplash around a whirlpool tube using12x12 cersmic tile. MussellBound thinset mat can be used in this applicatin. Reviews vary greatly on the thinset mat. Should I use this or the dreaded Epoxy? No issues with clearances and the tub is seldom if ever used.

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Roger

Hi Dan,

Never heard of it, never used it, never will. I wouldn’t recommend it. This is directly from their website: “When MusselBound’s adhesive combines with grout it creates a lasting bond.” ANY product which relies on grout to form any type of bond to the substrate is not a product that should be used in a bathroom. Google ‘greenskin tile underlayment’ – use that and thinset instead.

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Kara

I have been told by a friend that I should not use 3/8 x 3/8″ mosaic tiles on my shower walls bc the mortar/grout will come out and that I should use a larger tile. Is this true? If I can use them, what products do you recommend I use for applying it?

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Roger

Hi Kara,

No reason at all not to use them provided they aren’t the REALLY thin ones (like 1/8 or 1/16″). Once you comb your thinset on there flip your trowel over and flatten the ridges out. Once you do that it minimizes squeeze-through on the grout lines.

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Cynthia

Hi Roger,
I want to install tile over tile on a7′x15″ area in front of my fireplace. The existing tile is in excellent condition and the surface is level. Can I use simplemat adhesive sheets for this purpose?

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Roger

Hi Cynthia,

Not if you want it to last a significant amount of time. You can use a sheet membrane approved for that application such as greenskin or tavy thin-skin, but I definitely would recommend against using simplemat. To my knowledge it has never been tested in that application nor around a fireplace, the heat may negatively affect it.

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Ryan

Long time listener. First time caller.

I am looking to install some thick (0.315in – 8mm) 12x24inch tiles on a shower wall. Two questions.

1) Do I need to use epoxy for these large heavy glass tiles or will thinset do it?
2) Any advice for cutting these thick big tiles without chipping the painted back? I have tried scribes and saws. Multiple scribes tested don’t follow score (too thick I guess) and saws chip the back paint slightly which is not a clean edge.

Thanks for everything. I’ll hang up now and take my call offline.

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Roger

Hi Ryan,

1. With large format glass tile you NEED to contact the manufacturer and find out what they want you to set them with.

2. Scribe the paint on the back and use a saw to cut just outside that line.

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Scott

Roger

You’re the man when it comes to tiling that’s fr sure!! I just want to say thanks for all the helpful tips!!!

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Jean

Roger, We used cement boards on shower walls, and thanks to your website we will use Versabond thinset on the joint lines and tape with fiberglass tape. After that do I use Redguard waterproofing on the joint lines (on top of the thinset) and on the nitch before installing the porcelain tile? Sure hope you are still available for answers because I really need the answer now. Much thanks!

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Roger

Hi Jean,

I’m always available for answers – after the day job. :) Yes, redgard goes over the seam after the thinset cures. Inside the niche as well.

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Erick Allen

I would like to tile around a gas log insert, 8 inches at the top and bottom, only about 2 and 1/2 inches on this sides. I’ve picked a real stone tile 1″ square attached to a 1 foot square mesh. It has the reds and greens to match our color scheme perfectly. I have measured and can cut rows of 2 tiles side by side to fit on either side of the insert.

The challenge is how to best install it so it overlaps the metal flange on the insert and the wood stud it is attached to. On the outside of this is finished wood pillars of the same wood and finish as the mantel.

What is the best way to install the tile in this situation?

Thanks,
Erick
[email protected]
801-598-4887

Reply

Roger

Hi Erick,

The tile would be bonded directly to the substrate which surrounds your fireplace insert. That is normally drywall or backerboard. It will not bond to the metal of the insert. I don’t understand what you mean by tiling over the ‘metal flange on the insert and the wood stud it is attached to’? You don’t bond to wooden studs, you bond to a suitable substrate over it.

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Patricia

I came across your blog this week, and how I wish I found you sooner. My husband and I are remodeling our bathroom. We installed 8 X 12 marble on the shower walls and 4 X 2 travertine which comes in square feet mesh-backed sheets on the shower floor. We used pre-mixed ready to use mortar that comes in buckets. They have dried for over a week now since we were working only on weekends. both the marble and the travertine in the shower seem to be holding strongly. I then came across your blog and read that ready-made stuff is good for nothing. So we then used thin set mortar (Versabond) that we mixed ourselves to install the rest of the travertine tiles (16 X 16) on the bathroom floor. Everything looks good and even. Now my problem is that we are not sure if we should try to remove the 4X2 travertine tiles off the shower floor and re-install them with thin set mortar that we mix ourselves. Should we take them off or leave them and grout them and seal very thoroughly? The grout lines on everything are 1/16. If you suggest we remove the tiles off the shower floor, how do we go about it? The shower is not very large (5 X 3 feet). my husband built up a shower pan using the 3 step Goof-Proof Shower system with a vinyl liner. The slope is good. We are just not sure if at some point, we will have problems because we did not use thin set mortar on the shower floor. Thank you so much for your expertise and your advice. It is much appreciated.

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Roger

Hi Patricia,

Sealer does absolutely nothing to waterproof your tile. Nothing.

I suggest removing them. Honestly, the easiest way would be to plug your drain and fill the base with water, let it sit for 24 hours then drain it. You should be able to pry them out of there fairly easily at that point.

And yes, I know that isn’t what you wanted to hear.

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Patricia

Thank you so much for your help. Your blog is an incredible resource–I’ve learned so much.

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John

Hi, if I am installing 16 inch x 16 inch stone tiles on my shower room wall which has an exposed wall of hardiflex cement board attached to metal frames, is it ok if I apply the stone with epoxy adhesive to the hardiflex? Is there any reason not to?

And if I want to waterproof the hardiflex board first with something like Laticrete Hydroban, and then use the epoxy to the stone, is that ok?

Does movement in the frames or hardiflex sometimes crack the stone later on if you use epoxy rather than a modified thinset?

Thanks for your help.

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Roger

Hi John,

No reason not to of which I am aware. And if it is in your shower you NEED to waterproof it, it’s not a matter of if you want to. If your wall framing is adequate and your hardi is installed securely then no, it will not crack the stone, no matter what you used to bond it.

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Bob R.

Hi Roger,
My 32 x 60 shower re-do is on concrete slab. The 2″ waste line was excavated and re piped/moved from the tub end to the center of the shower floor but the immediate area around the new 2″ drain location was left sunken; kind of looks like a 3″ deep concrete bowl about 11″ around so I could have plenty of room to cut and glue the new pvc drain on. The concrete is tight around the 2″ pvc drain line holding it nice and plumb but 3″ down at the bottom of the bowl. The lower half of my 3 piece clamping Kohler shower drain is glued on it so the top flat edge is 5/8″ above the slab grade if the bowl was filled flat/flush. I plan to make my finish top mud bed around 7/8″ to get my full 1 1/2″ thickness at the drain area.
1) ? Question – I was planning on coating the sunken bowl area with a loose thin set slurry immediately followed by a small batch of deck mud to finish it off flat up to and around the lower pvc drain flange and then let it set for 24-36 hours to set up hard before I go on with the pre slope job. Will this work OK? Suggestions?
2) ?? I’m a tool hound like most of us males on our planet so I’ve invested in a $100 T-line laser (Johnson) to use here and on future home projects and see by it (and my 4′ I-beam level) that my slab is 1/4″ low at the right end of the existing shower slab. That is also my furthest corner from the drain flange – 39″…….. So the way I see it I need to set it so it shoots a level line 13/16″ HIGHER than the 5/8″ height of my drain flange plus add 3.5″ to that to use the top of a 2 x 4 (with a hole in it of course) for my screed level line….. Sound right? Or is it really necessary to spend the time to get the base leveled out FIRST with some sort of leveling compound?
3) ??? Can you recommend a specific thin set product at HD or Lowes to buy to use for the slurry bonding coat on this and under the pre slope and also for my tile setting on floor tile (12 x 12 x 1/2 thick Stratastone pebble tile square mats) and wall tile (9w x 12h x 1/4 thick porcelain). Or does each application need a different thin set type? Modified or Not?
4) ???? How bout a trowel size for the 2 tile applications? I was going to buy a 1/4 x1/4 square notch to start with on both tiles and have a 1/4 x 3/8 square notch handy if coverage was poor and then try that. Would this be a good starting point for these 2 applications? Or what else size should I get to have available when setting?

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Roger

Hi Bob,

1. You can actually just pack deck mud in there while you do the preslope. No need for thinset or anything else, deck mud has plenty of compression strength to stand on it’s own.

2. No need to level it first. As long as you have the level line at the top of the 2×4 it can be built to varying thicknesses to compensate for any uneven flooring. Deck mud is magic! And the hole in the 2×4 joke just made me literally laugh out loud!

3. Versabond from HD or Mapei ultraflex 2 from lowes will both work just fine. They are both modified.

4. I would use the 1/4 x 1/4 on the shower floor tile and the 1/4 x 3/8 on the walls and bathroom floor if you’re doing that. If you need more than that just comb it onto the back of the tile as well.

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Pratap Bhatnagar

Namaskar Roger !

Happy Christmas and New Year !!

Thank you

Pratap

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Guy

Is this thinset mortar good for shower wall tile installation?
there are so many different ones to choose..(CustomBlend 50 lb. Gray Standard Thin-Set Mortar $5.87)
Thanks

Reply

Guy

P.S Installing tile shower wall on cement board

Thanks

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Roger

Hi Guy,

No, that thinset isn’t even good to use as sandbags! :D Get the versabond which should be somewhere next to it.

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Carmen

Hello,

Our foundation is a concrete slab. I’m being stubborn, I know. Would thin set mortar seal well over short ply carpet. I think that is what it is called. It is that very thin carpet used back in the 70′s or before. It is on my kitchen floor. I like the warmth it gives but I cannot sweep or mop it. I’ve decided to put ceramic tile in the kitchen so I can sweep and mop. The reason I want to put the tile over the carpet is because of the warmth. My laundry room and bathrooms have tile but they are very cold even through socks and even some house shoes. We cannot afford other floor warming alternatives. Thank you for your help in answering my stubborn question.

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Roger

Hi Stubborn, er…Carmen,

No, it won’t last any amount of time at all. Sorry.

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Pratap Bhatnagar

Namaskar,

Questions for about mosaic tiles ( back splash purpose or kitchen ) …
one made up of steel, stone, glass, marble pieces ( sometimes most of these on single tile ) …
(1) how to cut them for end pieces ?
(2) how to set them … use mastic, PL Premium or thin set ?

I request … about my last quiry :
” One more question please … how is a carpet installed over a carpet ? … should the new one be over a plywood … how thick ? ”

If carpet is to be installed over a carpet … can it be by laying / fixing 3/4″ or 1″ plywood over the existing carpet … the subfloor could be concrete or
wooden ?

Thank you ( and apology for pestering )

Hv a nice day !

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Roger

1. They are normally either just placed full along the edges and the back corner of them are siliconed, or a bullnose or trim piece is placed along the edge to cover the edge of the mosaics.

2. Thinset

I’ve already answered this question for you – carpet is NEVER installed over existing carpet. The existing carpet is always removed first, then the new carpet is installed over whichever substrate you have.

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Pratap Bhatnagar

Namaskar,

One more question please … how is a carpet installed over a carpet ? … should the new one be over a plywood … how thick ?

Thank you and hv a nice day

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Roger

Carpet is not installed over carpet.

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Pratap Bhatnagar

Namaskar,

Questions for you please …

tiles for around the fireplace … what is good … PL Premium, mastic or modified / unmodified thinset

what is premixed grout essentially good for ?

Thank you and hv a nice day !

Reply

Roger

Hi Pratap,

Mastic or modified thinset will work. Unlesss you’re installing natural stone, in that case you need modified thinset.

In my opinion premixed grout is good for nothing. It can be used on whatever the bucket says it can be used on. I have no idea if any of them are approved for fireplaces, I don’t know how heat affects them.

Reply

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