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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Another question. . . thinset. . .do you use just water or can you use the Keraply that they suggest to use. I noticed you said to stick to the standard 118.1 and if we use the Keraply it will through it into another catagory 118.4 etc. He wants to follow the directions to do the joints etc. Should we do this just for the joints then use another solution for the tiles just using water? I purchased the Mapei thinset because it was unmodified. Won’t mixing it with Keraply modifiy it?
Thanks
Sally
You can use unmodified to do the joints as well. If you add the keraply it will turn it into a modified thinset. Just stick with water only.
Roger. . . OMG this site is a life saver. Although we started our project with little research
I fell upon your website and we decided to back track. Back tracking included switching to porcelin vs ceramic wall tiles for the bathtub wall; unmodified Mapei tile mortor vs some gooy type of adhesive; taking up the backerboard from the floor and redoing it the “proper” way which includes the thin set under it and off setting the boards. We didn’t get a barrier behind our backerboard on the wall so we took your advise on the membrain coating on top of the board and fiberglass tape in the corners. So as you can see we would rather have lost a couple of weekends of hard work than having to redo everything again later. My husband and I have tired eyes reading but it is was all worth it. We will certainly be back to finish!!! 
I’m extremely glad you guys decided to backtrack and build it correctly! You will be happier in the long run.
Hi Roger,
I’m getting ready to have someone install a 6″ x 36″ wood looking tile. These tiles are reletively new but the install seems a little more complicated. What is the preferred method of install for this size porcelain? should it be installed like marble with no grout lines. LMK your thoughts. Much appreciated.
Hey Manny,
Marble is installed with grout lines also. No tile should be installed without grout lines – ever. Depending on the quality and manufacturing of the tile you may be able to have 1/8″ grout lines, but that is the absolute minimum allowed by TCA standards.
Just about done putting up the hardibacker and will be using porcelain tile. I also put in a niche and will be using Schluter-KERDI-BAND roll to water proof it. Can I use Mapei ultra flex 2 thin-set mortar?
Hey Mori,
You can, but you’ll void the warranty from schluter. No big deal, in my opinion, but the mapei will work fine.
What would you suggest? The Mapei is what I saw at Lowes but HD has versabond or flexbond.
Given the choice with kerdi I would use versabond. Mapei works fine, but I’ve used versabond over it A LOT, so I know it works well.
I’m confused by the type of thin-set I should use to install the 10X13 ceramic tile in my shower. I used Hardibacker board and sealed it with the Kerdi membrane. Their directions call for an unmodified thin-set mortar. What exactly should I be looking for?
Hey Dan,
You need unmodified thinset for kerdi. DO NOT use cheap unmodified mortar like the custom blend at Home Depot – it’s garbage. Get mapei’s kera-bond, laticrete 317 or Ditra-set by Bostik (if you can find it). If you look on the bag there is an ANSI spec number on it. The number for unmodified is A118.1 ONLY, if it also has A118.4 and/or A118.11 it is modified.
The tile distributor that I ordered everything from gave me a bucket of Mapie Type 1 tile adhesive. (I assume this has some type of additive.) Will this work with the Kerdi? If not, can this be used for the floor tile? Thank you for your help!
Hey Dan,
No, it won’t work with the kerdi. That’s mastic – it shouldn’t even be used in a shower at all. You need regular unmodified thinset sold in 50lb. bags that you mix with water.
Sorry to bother you with this issue again, but I just had a conversation with my tile distributor about the Mapie Type 1 mastic. He agrees that this should not be used in the shower. He thinks the supplier shipped the wrong product. He recommends using Kerabond for the shower tiles, but he insists that I should mix it with Keralastic instead of water. He says his tile installers use it for all their showers. He says it creates a much stronger bond than a Kerabond/water mixture. I checked out the Mapie website and it says that this mixture will require “extended curing/setting time” if installed over a waterproofing membrane. I’ll trust you on this one. Please help!
Mixing keralastic with kerabond creates a modified thinset – you’ll lose your warranty. You can either use the kerabond with just water and keep the warranty or simply buy a modified mortar. Keralastic adds to an unmodified mortar the products which make the modified mortar modified.
Thank you! I’ll use the Kerabond with water only.
Roger,
I’m going to remodel my bathroom and am concerned about movement that may cause cracking later on in the tile. In your opinion is one method better then another when it comes to “flexiability”? Meaning faced, liquid or membrane? Out here on the west we get a lot of movin and a shaken.
Thanks,
Nick
Hey Nick,
Liquid elastomeric membranes such as hydroban or redgard lend the most flexibility to an installation. They were originally developed as a crack-suppression membrane so it’s just what you’re looking for.
Hi Rodger,
I am getting conflicting information on how to set the tile around my tub and I hope you can help me. I have cultured marble surround that is very very ugly! I first was going to set the tile on it after I used a belt sander with 40 grit paper but now I have decided to remove the surround and do it right! So I was told to cut the old drywall out with the surround attached to it. Put up backer board and tile on it. Now what I am confused about is vapor barriers and membranes. My tub walls are all interior so do I need to put up a vapor barrier? Do I put a membrane in between the rock and the tile or between the studs and the rock as I think was explained above in another comment? I think I am making this harder than it should be but I keep reading things and one person says this and another says that! Just want to do the job right the 1st time!! I have already did the granite tile floors, countertop and glass tiled backsplash and the surround looks really bad with these updates! Any help would be apprecheated!!! Thank you in advance!!
Hi Janet,
You do need a barrier of some sort in your shower – cement backerboard is not waterproof. If you grab my free waterproofing manual here: Waterproofing methods for your shower it will answer every question you’ve asked and a lot more you haven’t (yet).
Thanks Roger!! I will do my homework before I start!! And I am sure I will have more questions, something that started out as a facelift has turned into almost a full remodel! Oh well what we do to make our home pretty!!! LOL!
Roger,
Is there anything special I need to tile on my basement concrete floor? The floor is level and flat.
I was just planning to put down modified thinset and tile on top of that. I just wanted to double check because it seems like it’s too easy ..
Thanks,
Mike
Hi Mike,
You can do it that way provided you use a good modified thinset and (MOST IMPORTANTLY) have soft joints follow up through the tile installation over the expansion joints in the slab. This means that you will need a soft joint directly over the expansion joints in the slab. Slab expansion joints (that’s a general term describing both formed and saw-cut joints in the concrete to dictate where it cracks – yes, it WILL crack) are the areas of movement in your concrete slab, they need to also be the areas of movement in your tile installation.
Utilizing a membrane such as ditra allows you to place theses in areas that may not be exactly over your slab joints – you can move them one way or the other – to actually have it on a grout line. If you do not use a membrane the soft joint will need to be directly over your slab joint and that may require actually cutting a joint through your tile installation.
And yes, you need them. It’s like brakes on a car – brakes aren’t technically need to allow the car to get from one area to another, but if you need to stop when you get there or anywhere in between it’s the only way your car is going to last. KnowWhatIMean?
Thanks for the feedback. After reading your response, I found this article on your site (http://floorelf.com/what-is-a-soft-joint-and-when-to-use-one). It says you need a soft joint for every 20-25′ for any interior installation or over cement control joints or expansion joints. But I didn’t tell you how small the area was that I’m tiling–the area I’m tiling is a small basement bathroom (6′ x 5′). There are no cracks in the cement floor and there are no expansion joints in the cement floor in this area. Since there are no control joints or expansion joints and this is a small area, I should be able to get away with using modified thinset to tile directly on the cement floor?
Thanks again for all your help!
Absolutely. Just be sure to leave about a 1/8″ open space (no grout either) around the perimeter. You’ll be fine installing directly to that.
Roger:
Great site and love your writing style. I’m remodeling a bathroom and installing glass tile. Should I use glass tile adhesive mortar, or will white modified thinset do the job (on the back of the bag there is no mention of glass tile). The local glass tile vendor doesn’t sell a product specific for glass. HD and Lowes do.
Thanks, Pete
Hey Pete,
Glass tile mortar would be ideal, but normally not necessary. White modified thinset will work just fine.
I plan to tile the face of a water feature. Water will come out of the face of the wall and splash down into a trough below. Does it matter what type of tile I use for this? I am looking at Daltile semi-gloss ceramic. I assume the thinset and grout type matter; what should those be?
Thanks for your help.
Jim
Hi Jim,
Any type of tile will work, a porcelain would be a better choice because it absorbs less water. The lower the absorption rate of the tile the better. Any good modified thinset will work also. Once it’s cured it’s like your driveway – water won’t affect it.Regular grout would work fine as well, an epoxy grout would be best.
Thanks, Roger.
I didn’t mention that the water feature is outdoors in Phoenix; lots of direct sun and heat but, fortunately, no freezing and thawing. The tile would go to just below the water line of the trough. I read that a ceramic tile with water absorption of less than 3% is best. The tile I’m looking at is rated at less than 20%. Seems like a big difference. Will it still work okay for this application?
Thanks again for your help.
Jim
Yup, it’ll still work just fine.
Thanks. Any recommendations for keeping mineral scale from forming on the face of the tile? Any concerns about chemicals in the water affecting the tile or grout?
You’ll either need to use only filtered water or keep the tile wiped down. Most chemicals will not affect the tile or grout, but there’s always a chance.
I am going to install porcelain tile on my walls and floor in a bathroom, wand was wondering if I need a special type of thinset for porcelain tile? Also do you recommend Laticrete magabond at Lowes?
Hi Barry,
If you’re using the megabond for porcelain you’ll need to use the additive with it rather than water. It would be easier (and likely less expensive) to get a more expensive modified laticrete thinset for your installation like the 252 silver.
Roger
Thank you for your reply. Which type of versabond do you recommend for the same porcelain tile?
There’s only one type of versabond, in two different colors. (Unless you mean the rapid-set, which isn’t usually available at HD) If you have a lighter tile use white, darker gets gray.
I’m sorry, what I meant to ask is should I use versabond or flex bond for porcelain tile in a bathroom?
Flex bond is a better choice, but the versabond will work also. If the price is not an issue go with the flex bond.
Roger, great site and love your writing style.
I am tiling my basement which at present is asphalt tile over concrete. I removed the same tile in an adjacent bathroom last year and it was a nightmare removing. The fact that there’s certainly some asbestos in the tile is why i prefer not want to remove it. It seems well bonded to the concrete and when I did remove the tile in the bathroom even the the glue residue was impossible to remove. My question is what is the best thin set or cement mortar product to use over the asphalt tile? I’ve read either a fast setting latex Portland cement mortar – ANSI118.4 or ANSI118.11 (taken from DITRA literature) or an unmodified thin set. Appreciate your advice. Thanks!
I would go with a highly modified (ANSI118.11) mortar over that. As long as the current tiles are well bonded you should be fine with that.
Hi Roger-
Love the site- both advice and jackassery are priceless! I’m redoing a master bath that includes a whirlpool tub with a plastic surround- looks very dated. We’ve redone the floor in ceramic tile and would like to continue this up onto the tub surround. My plan is to sand the plastic surround to get better adherence, then use thinset to place ceramic tile directly onto the plastic. I’d like to avoid backerboard if I can, since that will make the installation thick enough it will make the tub look funny. Does this sound like a reasonable approach? I had planned to use mastick, but your advice above turned me toward thinset in a wet environment. Thanks!
PB
Hey Paul,
That is not going to work. The acrylic is not stable enough for a tile installation over it. Your tile will begin to pop off fairly quickly. You need to remove the acrylic and use a proper substrate like cement backerboard on your shower walls.
Hey roger,
I need to know specifically what type of thinset to use for porcelain tile in a shower. I have already used hardbacker 500 and painted on my water membrane. I built a recessed shelf thanks to your instructions and am having a hard time finding a product specifically to go over the membrane to adhere my tiles to. Thanks so much for your help.
Hi Mark,
Thinset manufacturers rarely recommend their products over specific products, they only specify the ansi requirements. Any good modified thinset will work fine. I prefer laticrete 253 but versabond or mapei ultraflex will work fine if you have more access to them.
Hi there,
When installing tile in a shower with 2 different tiles, let’s say a 12″X12″ main pattern with a 3″ strip of 1/2″ glass mosaic border at eye level, are there any tricks to accommodate the different thicknesses of the tiles (I’ve found the glass is typically thinner than the 12X12′s ) and not end up with thinset oozing out from in-between the glass?
Hi Dominique,
Like this: Installing different thicknesses of tile.
What is the difference between modified and unmodified thinset? And the different applications for each?
Thanks
Tim
Hi Tim,
What’s the difference between white paint and beige paint? And the different applications of each?
That’s essentially what you’re asking. I’m not trying to be an ass, it really is that general of a question which would require literally books for a proper answer.
The modified thinset has powdered (or liquid, if mixed in such a manner) latex polymers added into it which do several things, some things better than others with different types depending on the amount and/or type of polymer added. The biggest would be the allowable movement in a specific cured product – the more polymers the more movement before the tile lamination becomes debonded.
For the most part, unless specifically requested by the manufacturer to use a specific type, modified thinset will be what you need. They both install exactly the same. Modified is stickier.
Hi Roger,
I am Building a Kerdi shower, over cement backerboard. I know I am supposed to used unmodified thinset according to Schluter when putting up the Kerdi. I also read somewhere that Motar Mix might be preferred, cause it supposedly uses a finer sand. Is there any drawback to using Mortar Mix vs. Thinset, or are they essentially the same ? My other question has to do with prepping the substrate, which in this case is an osb floor with 1/4 inch cement backerboard as tile underlayment. Should I use a primer on the osb before setting the backerboard and then prime the floor (cement board) prior to tiling. The same goes for the cement board in the shower should I prime it before putting the Kerdi up ? And if so what type of primer should I be using ?
Thanks for your help
Hey Jesse,
No reason to prime anything you have there. You do need to place thinset beneath your backerboard over the osb, but it’s just there to fill voids – it doesn’t bond anything.
The term ‘mortar mix’ covers an absolutely huge array of different products. You’ll need to be a bit more specific about which product you mean before I can even begin to answer that question for you.
Hi! I am installing 12×12 ceramic tiles over a 1″substrate. The tile Ihave says to use “latex modified thinset. Others are telling me to use non-modified. Can you please help. I am not planning on using a distraught type product so what are my options. Thanks in advance for your help. PS. This is I floor heating under the subfloor between the joists (if that makes a difference). Michelle
Type o!!! I am not planning on using a Ditra type product. And type o #2. There is “in-floor “heating under the subfloor between the joist? Hope that reads better. Thanks again!!!!
Hi Michelle,
Dunno who’s telling you to use unmodified but if you are not using Ditra then use modified – especially with in-floor joist heating.
What I am concerned with, though, is what you are going to use for your substrate. Backerboard? Backer needs fasteners which don’t get along will with heating elements.
Roger,
What is the proper underlayment for ceramic/porcelain tiles on the shower walls? Greenboard? Wonderboard? Hardiboard?
Thank you, Jim
Hey Jim,
There are several – greenboard IS NOT one – Green E-Board is, as is wonderboard and hardibacker, durock or any other cement backerboard. There are also topically waterproofed boards such as denshield or Wedi. the standard is cement backerboard with either a traditional waterproof barrier behind it or a topical membrane over the top of it.
Roger,
What is the waterproof barrier made of? And it goes on the studs under the backerboard, correct?
In a traditionally built shower it is either 4-6 mil plastic or roofing felt. Yes, it is installed directly to the studs and the backer is place right over it.
Roger,
What type of fastener should be used with the cement boards or Densheild?
You need the appropriate screw for the backer – the layered concrete board or the durock-type product. Screws with waterproof coating are used for the denshield.
Roger,
Thank you for all of your comments. They have been very helpful. Jim
Hi Roger,
I have a polyurethane shower base that is securely sealed in a mortar bed, but is 1/8″ off on the level from the drain. Can I level off with epoxy, let it harden then lay down tile on top of that with epoxy?
Hey Scott,
Not really a good idea – the pan is not made for that and the bond long-term is untested. It may work, it may not, I honestly have no idea. Never had any reason to do that. I do not, and really can not, guarantee a failure – I can only give advice about methods that are guaranteed to succeed. That said, people do stuff all the time that is not an ‘approved’ method and it works just fine. However, they also do many, many more which don’t work out so well.
I’m a lot of help, huh?
Roger,
I had a tile floor installed on a cement subfloor. The installer used a thin set mortar and I had the floor leveled off years before for a floating hardwood floor. The contractor and flooring guy said that if there was any other areas that needed leveling that the floor was fine and he could use the mortar.
Little Elf continued….
So after all was done with some areas of tile being not level and between 1/8 and 1/4 of an inch difference between adjacent tiles, these tiles that are higher seem to have no mortar underneath? For example if u bounce a golf ball on a tile that seems to have not been set in the mortar it has a hollow or echo sound. So would those tiles be more prone to cracking and damage over the long term and was this a bad installation?
Hey Little Elf (if that is your real name
),
That is a very, very significant height difference. The ones that sound hollow probably simply have less thinset beneath them. They aren’t necessarily more prone to cracking (unless he had incomplete thinset coverage) but that is something you really can’t predict without taking one or two up and seeing how the coverage is beneath it. Yes, it was a bad installation, the maximum allowable lippage depends on the individual tile but is rarely over 1/16″ height difference, even that is a lot, and NEVER more than 1/8″. Attempting to level part of the floor that much lower normally requires a medium-bed mortar which doesn’t shrink as much.
HI. I am installing a tile redi shower pan. Need to replace a loose ceramic tile. I do not have more epoxy. What can I use in replacement of buying a bunch epoxy? Can you use thinset on polyurethane shower pans? Thanks.
Hey Jeff,
Nope, thinset won’t bond to the polyurethane. You can get any regular epoxy at a big box store. If you’re only fixing one tile any epoxy product will bond just fine.
I have a pebbled concrete floor that i would like to put porcelin tile on. Can i use thin set over this floor to install the tile.
I would appreciate your advice.
Thanks
Hi Robert,
Unfortunately no. If it’s the pebbled tile floor I’m thinking of it’s just little 1/8″ or smaller pebbles locked into a surface in a bed of epoxy. This type of flooring will peel or chip up in layers. It is not stable enough nor adhered enough (in most cases) to have a tile installation over the top of it.
The floor i have is pebbles on top of a concrete slab in my screened area.
Robert
That should be able to be removed in layers. A lot of times you can simply scrape it up off the concrete. Tile installed on top of that is relying on the bond of the pebbles to the concrete in order to last – that is rarely a competent bond for long-term durability of a tile installation.
Can Hardi Board be applied over the pebbled surface using thin set as a base for tile
Robert
Hey Robert,
Nope, won’t last long-term. That type of floor covering (pebbles in epoxy) IS NOT suitable in any form to have tile installed above it. If you want tile over that concrete slab, and want it to last, it MUST be removed.
Thanks Roger for the info. I appreciate your taking time to answer my questions.
Robert
Un-modified VS Modified
My project is a tiled shower. I have selected Hardie Backer 500 and Schluter Kerdi for substrate and water proofing. Hardie Backer instructions calls for modified thin set and Schluter Kerdi calls for un-modified thin set. Is there any risk of using un-modified thin set to bond the Kerdi to the Hardie? I would like to say you have a great site, I have read a lot of your posts and articles. Thanks to your site I have found information most valued in planning my project and yes the no holds humour has made reading enjoyable.
Thanks again,
David
Hi David,
Absolutely no risk at all using the unmodified over hardi provided you use a quality unmodified like Laticrete 317 and not that $5 / bag customblend from home depot – I wouldn’t weigh down the back of a pickup in the snow with that crap.
Rodger
I do not have access to Laticrete products in my region. I picked up PremiumPlus standard thin set, @ 20 buck a bag I’m hoping this is simlier to Laticrete 317.
Thanks,
David
Yup, that’ll work just fine.
Rodger
Thanks a bunch for the help
David
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