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.
Hi Roger,
I came across this website through google. I’m installing ditra over concrete on my basement floor. The directions say to use un-modified thin set for application. The only un-modified thin set I could find was at lowes. The brand is Tec skill set un modified thin set mortar. I’m worried about this because of the price. It’s $5.47 for a 50lb bag. It seems a little cheap to use with ditra. I called Schluter Systems and the person I talked to said the Tec Skill set would be fine to use. What would you recommend? Thanks for your time
Hey Drew,
I don’t know that I would use that. Never seen it nor used it for anything. See if you can order an unmodified through lowes. If you go up to the pro desk they’ll usually order whatever you need and just have it shipped to the store. I would probably use a modified, but you’ll lose your warranty if you do that.
Thanks. I will check and see if there is something else I can order
my wall are painted ,I whont to install Tiles over.Wich mortar is best over painted wall.
Thanks!
Steven
Hi Steven,
If you rough up the paint with sandpaper any modified thinset will work fine.
I want to retile my fireplace surround and hearth-area. The hearth was ripped out and is concrete floor. The surround still has tiles. I don’t want to demo/drywall around the fireplace so I plan to tile over the existing tiles. I’m using 12″ x 12″ porcelain mosaic sheets (the individual tiles are about 2″) and the manufacturer says to use a latex-modified thinset. My questions: what thinset and grout are safe to use around a fireplace? Can I use the same thinset and grout on the concrete floor as I do on the existing tiles on the surround?
Hi Lucy,
Any thinset and grout are fine around a fireplace, but you need to find one that is appropriate for tile installation over tile. Any regular modified thinset IS NOT it. It must be manufactured with that particular application in mind. Ultraflex 3 from Mapei is one, there are others. Yes, you can use the same thinset on the concrete floor as well.
Hi Roger I am going to install 3×6 porcelain tile on a back splash. Is it okay to us mastic?
Jerry
Yes.
Roger,
I’m wrapping up a bathroom in Travertine 12X12 and will be adding a pencil border around the entire perimeter. I know the grout line is 1/16th but I’m curious if I should use the same thinset I’ve been using for the tiles and at what thickness.
Respectfully,
Jason in GA.
Hey Jason,
Yes, same thinset. Thick enough to stick it to the wall.
Once the pencil is up it should have about 1/16″ or so of thinset behind it. Tilt it so the outside edge is directly against the wall for a cleaner look.
You helped me with tiling a kitchen/family room floor using ditra. Now my next job is to replace tile in a beautiful custom made cherry wood table that had tile inlaid with a cherry border. We have taken out the old 4X4 tiles that were 1/4 in thick. It seemed to be attached to the wood surface with something that was rubbery. Not familiar with mastic??? There is no room for cement board without taking the whole table apart. The new tile is porcelain 6X6 and 3/8 in thick. We have routered out the surface so that the thicker tile will be flush to the cherry border.
I have to attach the tiles with something that does not take up much room. Read about sealing the wood base with polyurethane first and then using thinset if cement board was not an option. Any suggestions??
Hi Karen,
It likely was mastic. Your best option is epoxy setting material. It’s expensive, though. A type 1 mastic should work fine for you provided the table does not spend time outside in freeze-thaw cycles. Do not seal the wood with urethane first, it limits the bond by closing up pores in the wood.
dayum…i sure wish i had known about this website before i tackled my bro’s baffroom…cordially, hanklyn, future floor elf…
Hi Roger,
I’m putting down Durock on my bathroom floor. I was told I could use Mapei ultracontact full contact tile mortar with polymer to put under the Durock and also use the same material to set the tile. Will this work ok? Is there another product I should use?
Hey Steve,
That will work just fine. You can, if you want to, use a cheaper thinset beneath the durock. It’s only there to support it, doesn’t need to be expensive stuff.
Help Roger,
I ran into that black mastic in my basement when trying to re-model my game room. Was laying vinyl self stick but doesn’t stick. So went to HD and they sold me glue, won’t stick. I need to find the best way to get a floor down so i can enjoy my game room?
Thanks
Alan
Hey Alan,
You need to mechanically scarify the surface so the cutback is removed. (Cutback is what the black residue it called). It is the only way to get anything other than thinset specifically formulated for use over cutback to bond. The best way to do it is to use a grinder with a diamond cup wheel. It’s messy and hard work, but it’s really the only way to get rid of it.
Hi Roger,
I think that I have seen this question on your website before, but I can’t find it. I’m applying 12X12 ceramic floor tile in our bathroom. Does it matter if I apply the thinset to the underlayment or the back of the tile?
Hi Dan,
Not really, but it’s a hell of a lot faster to install it to the substrate. If you do install it to the tile you’ll still need to burn the thinset into the substrate before placing the tile down, so you’re essentially doubling your time that way with absolutely no benefit and more chances of having a hollow corner under your tile. I’d go for the substrate.
Hi Roger, Great info. Thanks.
I am planning to use Simple Mat backer for installing the Glass tiles as Back splash in the bathroom on the painted drywall (non-wet area) around the Mirror / bath Vanity / sink area. I am just curious to know your opinion on using the Simple Mat. I know Simple Mat is bit expensive, so do you suggest that I should go with Mastic? Also, when installing glass tiles around the vanity & mirror, should lay the glass tiles to line up horizontally or vertically? Thanks.
Hi Sam,
I don’t like it much, but I’m leery of any product that is essentially ‘lick-&-stick’.
The problem I have is the long-term durability of such a product – no one knows for sure. It’s less than three years old and there have been complaints about it. How much of that is the actual product and how much installation error, I have no idea. What I do know is that mastic and thinset both work long-term. If you have glass it needs to be thinset, mastic can not be used.
The glass tile should lay whichever way you think it looks best. Each installation is different and there is usually no right or wrong direction.
Roger, that was a typo, I like to use 1/4×1/4″ trowels for most applications.
Sorry about that.
– Jason Huggett
Hey again, Roger,
Whatever you decide to use to stick your tile with will work to stick your backer board with. I like to use a 1x1 trowel for most applications. I only use the “V” notch trowels for small tiles, such as 1×1 for example. If you are only going tile once or every now and then, no since in buying a collection of trowels. However, spending the extra money on a decent trowel, opposed to the disposable type will be worth the extra money for you.
Tip: the angle which you hold the trowel at will give you either a heavier or lighter bed (thickness). For instance, as you are smearing your thin set or mastic, holding the trowel straight up and down at a 90 degree angle will make a thicker bed than dragging the trowel at a 45 degree angle.
I hope this helps, and you are more than welcome, Roger.
– Jason Huggett
Roger,
I’m installing 12.75″x12.75″ Porcelain floor tile over 1/2″ hardiboard in a bathroom floor rehab. I’ve received conflicting guidance regarding using 1/4″x1/4″ vs 1/4″x3/8″ square notch trowels for the installation. Can you offer advice on which trowel to use?……and thank you for all your great advice throughout this project! My wife and I have been doing this bathroom together and she is very happy with the results (as am I).
Regards
Hi Steve,
The larger the trowel the better. I would opt for the 1/4 x 3/8. You can use the other if your floor is very, very flat, but the larger helps compensate for any adjusting you may need to do as you set the tile.
Hello Roger
I am building dining table and am using 12″ x 24″ floor tile for the top. 2 questions. First, I see you don’t like the use of mastic in this situation because of the curing by evaporation. My thought is that a little less curing could be a good thing for 2 reasons. One, it may allow the tile to “move” a bit and therefore have some flexibility if the base gets torqued a bit and secondly, if I totally screw this up, I can get it wet and reuse the tile. Does this logic make sense? Second, no matter what I use to set the tile, I need to determine what the total height of the bonding agent and the tile will be so I can set the wood border around the edges first before I set the tile. Any idea what that total thickness should be?
Thanks much.
Hello, Roger, (the person tiling a tabletop)
Flexbond and ¼” Hardibacker will do the trick for sure!
I’m not sure if Roger the “Tile Elf” has responded to your question yet (knowing him; he probably has), however, in case he has not; I have an answer for you. I am also a tile man (15 years), whenever I tile something that may have any kind of movement, such as a table top, for instance, I ALWAYS use Flex-Bond; it’s a little pricy but well worth the extra money if you want your project to last for years to come. It is a thinset and not a mastic, though. Mastic will work too, but Roger the Tile Elf is correct that thinset is better. I do personally use mastic often; it certainly is easier than mixing thinset. Plus, like Tile Elf said, when you use mastic, you get a free bucket, who could argue with a free bucket (that’s gotta be worth at least 3 bucks, woo hoo!)?
In price comparison to mastic, Flex-Bond is about $5 more, and you will definitely gain more coverage with it opposed to a bucket of mastic, therefore, it is actually cheaper.
Reusing tile is very difficult, but it can be done, either by scraping/grinding the adhesive off the back (if you can tear it out without breaking it), or by floating the backs of them to make them flat again. A very challenging task, in my opinion, and usually not worth the effort, unless of course, you are in a bind and must reuse a tile or a few.
The concern you have about messing up and therefore, wanting increased time to move tiles around is an easy fix, sir. Simply dry set everything first, including your cuts, and make sure you buy extra tile (trust me on the extras).
If you do want to ensure that your table lasts and lasts, make absolute certain that you use Hardibacker or some other cement backer board before you stick to the table. You should glue the backer- board to the surface as well (not glue like Liquid Nail, thinset or mastic). It is not mandatory to glue the backer boards to the surface, but recommended, and it will give a stronger surface if you “glue” it, for lack of better terms. It is mandatory; however, to screw or nail the backer-board; you can use screws or roofing nails; this is more important than applying a bonding agent underneath it. NOTE: you do NOT have to buy the expensive screws recommended for Hardibacker (I NEVER buy those); you can use regular drywall screws (1 ¼” screws will be fine and generally are not too long so that they stick out on the underneath).
Furthering the installation of backer-boards: just a quick reminder, you do have to nail or screw it while the underneath pooky (glue) is still wet. So only work in areas that are feasible to do so, if you do choose to stick the backer-board to the surface.
If you are nervous about weather conditions, such as a patio, simply upgrade to exterior screws, they are still much cheaper than the “Hardibacker screws.” I believe that Tile Elf uses another backer board (maybe not, I cannot remember), but I prefer using Hardibacker. Use 1/4” for surfaces such as counter tops (tabletops) and floors (pier and beam or second stories, etc.) ½” is for walls.
For your thickness- place a piece of cardboard underneath your tile (before you start sticking) and use this as your gauge for thickness to see where your wood will need to be in order to sit flush with the tile. The cardboard is a very reliable source for the approximate thickness of your thinset (or mastic). Setting a piece of tile without the cardboard added for thickness may give you a scratching your head scenario of “how did that happen” once you finish your project.
Good luck, Roger, it should be a fun project!
-Jason Huggett
The Tile Mechanic
Jason
Thanks for the information. You mention what not to use to glue the cement board. What should I use to glue it to the base?
Roger
What is your base made of?
pressboard or particle board. Looks like ground up sawdust pressed together. A local furniture maker told me it should not “move” like regular wood. I have sealed it on all sides.
Thinset and backerboard screwed to it.
Hi Roger,
The total thickness depends on the size of trowel you use. If you want flexibility then get a thinset with those properties, there are several. Is the chance that you screw it up and use water the only time it will EVER get wet? Because if it isn’t you don’t want to use mastic. If it won’t get wet then use mastic, it may work, it may not. I wouldn’t, but it’s not my table, eh?
Hi Roger,
The owner wants to have a wood tile over the concrete floorr at the living room area. What adhesive materials i will use and also in the wal of of the living room, a wood finish. I already finished it in fine cement finish. Please help me for I don’t want to crack the cement fine finished, so maybe I can use adhesive materials same as using adhesive on floor tile?
Thank You,
Jean C. Evangeliasta
Hi Jean,
Tile made of wood or tile that looks like wood? If it’s ceramic or porcelain then thinset would be best, it will work on the walls as well.
Hi Roger,
I spent a lot of hours searching for a better solution that it will help my project successfully done and give me a good credit to the owner.
I am constructing a General renovation of One story residential building and the owner wants to have the exterior wall into exterior tile wall. I am using 60 cm. x 60 cm. glazed white tile for the wall and I want to be sure if my procedure is correct. After plastering the wall, what will be the most effective adhesive materials I will use to avoid common problems in tiling work for the larger tiles? What about Polyblend Sanded Grout?
Thank you very much and more power to your site, you help a lots of people, thank you.
Hi Jean,
A good polymer modified thinset is your best option. I’m unsure what you have available around you, but if you have polyblend available you probably have versabond there, that would work just fine. Be sure to get it in the white version. I do not like polyblend grout. In my opinion just about any other brand or type of grout would be better than that. The only exception to that would be if you were using white, unsanded polyblend, in that case it’s just fine. The problem with polyblend is in the colored versions.
Hi Roger,
how to install bigger tiles. May I ask you again, can I use a port land cement for tiling and for water proofing using Sahara cement? In constructing a concrete gutter I practiced this method often, but I want your second opinion so I have alternative or choice if where can I save more for the budget is not sufficient.
Thank you very much. You help me have an
Thank you very much. Happy Holiday and God Bless.
Sincerely yours,
Jean C. Evangelista
Hi Jean,
Yes, Sahara cement can be used for the larger format tiles and for waterproofing aspects.
Hi Roger,
in how I may instruct my men, thank you for I have you 
. You make me happy. Thanks for this site and more power,
H A P P Y
thank you for everything, now I gained lot confidence
H O L I D A Y
Sincerely yours,
Jean C. Evangelista
P/S. THANK YOU FOR THE FREE TILE TIPS BOOK !
Greetings!
I just installed one inch hexoganal tile sheets using a mastic/adhesive. The mastic went down on a well-cleaned, prior tile floor embedded in concrete, circa 1948. The prior floor was relatively flat and the area is only 3′ by 6′. Having zeo experience using mastic on the floor or laying 12″x10″ sheets, I scoured the forums looking for how thick the adhesive needed to be put down. I found NOTHING! So…I spread it reasonably thin and combed it to get ridges, maybe 1/8″ tall…maybe! The thinnest areas — between the ridges — where just barely covering the old tile. In other word, I could hear the metal trowel combs scraping the old surface. It was thick enough, however, in some areas to squeeze up between the tiles and over, which I immediately cleaned up. I’m giving it 24 hours to dry.
1. How must mastic is enough?
2. Is 24 hours enough?
3. Will grouting, which I will certainly do — help strengthen the overall floor?
Bottom line: I’m worried it didn’t apply enough mastic and am dreading hearing crackling sounds when I walk on it. I do realize that it’s counterproductive to apply so much mastic that its squeezing up and over the joints!
Thanks,
Eric
Hey Eric,
No amount of mastic is enough, mastic is not the correct product for your installation. It is not a product which should be used on a floor. 24 hours should allow it to cure (as much as it’s going to, anyway). No, grout adds absolutely no dimensional stability at all. Thinset needs to be used in that application, mastic simply doesn’t have the needed strength for a flooring application.
Roger,
Ok. Is it that the mastic compresses easily or over time and therefore makes the tile loosen when weight is repeatedly applied? (A number of sites state that mastic is fine for small-tile floor applications, however, there’s no accounting for worthless information on the Interent!). Also, is adhesion to the older mable tile underneath an additional problem of mastic versus thinset?
By the way, this 3 by 6 foot room is a powder room, with the foot traffic fairly predictable. Likely 3-4 square feet will get the bulk of the foot traffic. Door –> toilet –> sink –> door.
Unfortunately, the tile was VERY expensive. Is removal and reuse an option?
And thanks for your help!
Regards,
Eric
Removal and reuse may or may not be an option, it depends on the tile, the mastic, the substrate…basically eveything, and it varies. The problem with mastic in a flooring application is the (lack of) compressional stability. It’s exactly what you’ve described – it cannot take the repeated compression. Using smaller tiles may allow the mastic to cure, but also diminishes the footprint of the load and expands (tremendously) the point-load of the individual tiles.
Being a powder bath it may be fine. If you begin to see cracking in the grout then you have a problem. Just keep a close eye on the grout and if it begins to crack you’ll need to begin removing tile.
Hi Roger, just remodeled kitchen installed solid surface counters with 4″ attached backsplash the depth is less than 1/2″ (our previous attached bkspl had a depth of 1″ ) The delema is we thought we would have a 1″ depth to put up backer board thinnest and tile…Question: can I use adhesive to ad hear 12″x24″ ceramic tile to painted walls? There will be 1 course “resting” on the 4″ back splash surrounding the room? If adhesive is ok what type? Thank you for any advice.. I looked into bondera …not recommended for tiles larger than 6″
Hi Colette,
You can use thinset to bond tile to drywall, no matter how large your tile. Any pre-mixed adhesive is not going to be approved for use with larger tiles.
Hi Roger,
Just visited your website today. Great info.
My problem is that a few tiles in my sunroom keep coming loose. I’ve had the tile layer repair them and they are loose again. The tiles are in a small sunroom 4′ x 10′ that was built on a wood frame. I had the builder place extra bracing in the floor. But, there is still a slight movement to it. The tiles are about 10″ x 10″. Only 3-4 keep coming loose.
Any idea why this might be occuring? Could it be that the floor section with the problem tiles is moving too much, even if not noticeable when stepping on it? Or, some other problem. The tiler did put down some type of board over the plywood flooring then a thinset (unknown type). Obviously, the grout also cracks in the same places. Some of the problem tiles can be removed fairly easily, others not. Do you have any recommendations on how to fix the tile problem? What type of thinset should be used, etc.? Should I crawl under the sunroom and place more bracing also?
Thanks for your help.
Hey Ray,
It sounds like he put down backerboard (I’m assuming the ‘some type of board’ was gray backerboard) but didn’t place thinset beneath it. In that particular area there is not full contact between the flooring substrate (plywood) and the backerboard beneath your tile. If the backerboard is not fully supported this area will compress and ‘bounce’ when walked upon, leading to grout and tile problems.
The best solution is to remove the tile AND the backerboard in that area (if not the whole thing), place thinset down, then backerboard, then the tile. More bracing below your flooring substrate will not compensate for the space between the substrate and backer.
Thank you for your rapid response and your solution. I thought that might be the problem. Unfortunately, I did not know at the time to make sure he did the work correctly. I have learned alot since then. I have never put tile down. So, this will be interesting.
I don’t know what screws he used to attach the backerboard. He probably used drywall screws. What is the correct type and length of screw that should be used?
Thanks Again
There are backerboard screws that are specific to either hardibacker or durock, whichever specific type of backer is used. I normally use 1 5/8″
You website is awesome and is great resource !!!
I am a weekend DIY and planning to install tile on a small (8×9 feet) concrete area outside the entrance of my house. I am going to clean the concrete with Clorox outdoor bleach. After that should I itch the concrete with something like Seal-Krete Clean N-Etch etching solution? The itching solution will makes the concrete absorb water very aggressively (I think) which is good for paint primer, but is it good for Thinset Mortar.
Any tips on installing tile on concrete will be of great help.
Hi Amol,
You may or may not need the etching solution. If, after you use the bleach, the concrete absorbs water when you splash it on there then you don’t need it. If it beads up and stays on the surface then you will need to etch or scarify it in some manner. It is always best to have a membrane such as ditra over concrete. Make sure you install the required soft joints, especially on exterior installations.
Mr.Roger:
I’ve plan to use 10x13inch wall Tiles in bathroom , will Portland cement mortar (Thinset Mortar) work as setting material? Thank you !!!
Hi Eng,
Yes, regular powdered thinset mixed with water is the proper product.
Thank you very much Sir for the quick post. Thats it.
Hey Roger :
Thank you very much for your advise here to all , It is sound beneficial and Useful for all the concern people. Thank you for the helping folks!!!!…
Roger: Thank you for this site. It is great to be able to have confidence that what I’m doing isn’t totally wrong!
I’m renovating two bathrooms, including tiling a shower, tub and two floors with a mixture of 6″ and 12″ tiles. I purchased from Lowe’s something called Mapei Porcelain Tile Mortar, which the manufacturer describes as “regular-setting, polymer-enriched (“modified”) mortar for installing a wide range of tile and stone over a diverse range of substrates in thin-set applications. ” Is that an acceptable setting material for each (or any) of my needs?
Hey Scott,
Yes, the porcelain tile mortar will work fine for your installation.