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.
First, thanks for the great blog, and useful. information
I think you have never encountered the following problem before, and I really hope you can help !
Several complicating factors.
1) I live on a small island off the coast of Vietnam, though things are developing in the big cities, but out here all tile seems to either be wet set, or in cement over concrete. No thin set products are available.
Of course the tiles in my home are all popping up, cracked and popped tile are common occurrences here.
Now forgetting the house, I am setting tiles on the floor in the shower of our wood dive boat.
Of course along with no thinsets, there are no waterproofing membranes, so I made a pan of polyester resin and fiberglass. 6 inches up the walls and out over the curb, I now have a one piece 100% waterproof pan, with a very primitive drain, there are no adjustable drains available here either.
The bathroom is about 3 x 3.5 feet, tile will be ceramic about 6×6 pitched 3/8 per foot in dry pack, 3.5 to 1.
When the boat was built, some idiot did not think that the boat will not sit in the water at the same level as it did in the yard, so the 1.25 hardwood board subfloor is no where near level, and pitches to the back of the boat about 1/2 over the 3.5 foot width if the toilet/shower, this will create a water trap in the pan, despite the weep holes I managed to cobble into the resin and pvc drain pipe.
Will this be a problem over the long term ? Standing water in the dry pack ? I have access to the bottom of subfloor and the pan from the engine room and can drill some drains into the pan at the low side easily enough if needed.
I see you made mention of home made thinset, 1 part cement, 1 part fine sand and a bit of lime…can you please be a bit more specific as I have to make my own.
Making my own sanded grout ? Only product available here is unsanded, and as good as pouring baking flour into the joints, every time I have seen it used, it washed out in a few days.
Please, no suggestion of hiring the job out, there is nobody qualified to do anything here ! This is back woods, peasant rice farmers masquerading as mechanics.
I have 20 years experience as a carpenter, but I am out of my depth here, heck you cannot even find a margin trowel or a notched trowel on the island, and if you ask for one they look at you like you are an idiot, simply because they have never heard of it.
I can probably get some thinset from Saigon, (If I can find the supplier) but it will surely be ruined on the cargo boat, as they will put it on the deck in rainy season,…
Any help you can offer would be much appreciated !
Thanks
Steve.
Hi Floor Elf, the bathroom reno I’m helping with has a drop in acrylic tub i.e. 3 of its sides does not have a lip to be fastened on walls. There are strips which has flat sides to fasten on walls and a curved side which rests on the tub’s sides and top perimeter that needs to be siliconed for waterproofing. All 3 sides have this in lieu of the tub lips. The hardiebacker boards stops where the strips are leaving a gap of about 1″. What can you suggest on putting above the (I think acrylic strips) so that there will be something for the tiles to adhere on? Will unmodified thinset adhere to it if I score its surface with a knife?
Hi Ej,
Thinset will crack out. There actually doesn’t need to be anything there for the tile to bond to. It can just hang over that 1″ gap.
Hi Roger, thanks for the info. Have a great day!
Hi Roger,
You’ve helped me throughout shower construction and it looks great. This is the last piece.
I’ll be attaching black granite ( 1 1/4″ thick) to the outside of the shower wall (it’s a return that then meets the bathroom wall). I have an unused tube of white kerdi fix. Can I use the kerdi fix to bond the granite to the kerdi board without staining / bleeding through the granite?
The granite guy originally told me to use silicone.
Thanks in advance,
Matt
3. A imply person; one within the lowest state of life.
I am using a 12″ mosaic sheet to tile the top of a bookcase and buffet. The tile is natural stone, but I have MAPEI mastic that I used for porcelain tiles. The new tiles are natural stone, bus since these tiles are small (1″ by 1″ to 2″ by 3″), and won’t be on a floor or wall, can I use the rest of my mastic? The bookcase will have less than 4 sq feet and the buffet will only have 6 sq feet.
These are the first natural stone tiles I have laid.
Meredith
I’m (still) living in a crappy house that I’ve long planned to demo, but somehow it hasn’t happened. Though other priorities definitely are competing hard, the bathroom keeps creeping up my list, because dry-wood termites continue to chew up the floor, leaving my once-artful short-term-treatment faux-plastered floor full of ever more disgusting divots, and because shifting of the house has let the cast-iron waste-stack shift down a little…so that the toilet weeps out. Yep, it’s gross.
So I don’t want to take the time to do this expensively/conventionally/right, but I am keen to experiment a little because…well, I don’t see why this wouldn’t work better than a lot of “standard” methods.
I work a lot with epoxy resin. I’m thinking I’d saw out the whole floor to the bare walls, dump the tub, gut out the rotten joists – in short, everything will be gone from below, plumbing as well. I’d then replace joists, but would taper them to slope to the far end, and center, to create a slope support for a barrier-free shower drain. Then I’d sheath the joists with trapezoidal/triangular ply pcs to follow those pitch-lines in the new joists, screwing and gluing it liberally. Then I’d epoxy the living $hit out of the floor, at least two coats, with some heavy fiberglass laid in to the shower area and across all joints, and wrapping up a foot or so.
From experience, I have no doubt that this, in itself, would be a very durable and waterproof surface. But no, I don’t want to stop there; I’d want to follow with 1″x1″ tile sheets to follow those contours.
So finally, there’s my concern: on newish epoxy, even if sanded heavily to degloss, could I count on modified thinset to stick? Could I sprinkle some silica or some such in the top coat of epoxy to promote a bond, so that the tile doesn’t come popping off?
I think in the early 60s when this crappy house was packaged up, trucked to the site (here in Honolulu) and built, termites must not have been so well-established. Not a stick of wood in the original house was treated, and termites LOVE oak flooring, so that alone has doomed the place, though they’re in everything else, too, including the 11/16″ redwood T&G “single-wall” construction. It’s gotta go, but I can’t get rid of it just yet.
I have been trying to find alternative options other than the ineffective diy tub & tile paint. I have an old cast iron porcelain tub that has lost its coating on the bottom and the top corners. I thought about tiling over it with something like pennies or colored glass gems, but not sure if thinset for tiles will adhere. Do you have any suggestions?
Thanks,
Brenda
Hi Brenda,
Thinset will not bond to the tub. You can have them refinished for a couple hundred dollars, just google tub refinishing in your area.
Roger,
I plan to lay tile over linoleum in an upstairs bathroom: Should I rough it up with sand paper? Will the non-modified thin-set with the latex additive make it water proof? I have a 1″ sub-floor with 7/16″ cdx over it.
Ron
Hi Ron,
No, you should not rough it up with sandpaper. No, it won’t make it waterproof. The linoleum needs to be removed.
Hi Roger
I have a schulter pan meeting a shower wall that I rolled with Mapei Aquadefense,
Can I use unmodified thinset to adhere the kerdi band, that I will use to cover the gap between the pan and wall, to the Aquadefense?
Mapei installation guidelines call for modified when installing tile and stone once the AD cures but here is no mention of using the kerdi product. Schluter calls for unmodified when laying the membrane.
I Know I will be violating one of the manufactures warranties but so be it at this time as i need to drink more Pepsi and not worry too much.
Hi Paul,
You can use either. They will both work just fine.
Which modified thinset for 1″ hex porcelain tiles?
Hello Floor Elf!
Which thinset would you use for porcelain mosaic tiles? I’m assuming it’s some kind of modified thinset because it’s porcelain. But I will listen if you say unmodified is best. I can find Laticrete products, I just don’t know which one to get. The tiles are going on my sunroom floor.
Thank you!
Hi Mariana,
I prefer the 254 as my go to thinset. But nearly any of their regular modified mortars will work just fine.
Stumbled across your website by accident. You do really well in explaining the whats and the whys. I wish you well.
I have chosen a clear, iridescent back splash title. Is there a way to mix in color on the bonding agent so that it shows through the title once set?
Hi Anita,
Yes, Laticrete grout can be mixed with their glass tile adhesive to have colored thinset.
I’m tiling the fireplace hearth and surround. A wood fireplace insert will be installed there. I’m using 12 x 12 ceramic tiles and have a thinset, but am not sure if it is heat-resistant. Can’t find a heat-resistant thinset anywhere. Is Megalite ultraperformance thinset appropriate for the job?
Hi First,
Megalite is fine. All thinset is heat resistant.
Hello Roger,
I am installing pennies as my shower floor. There are so many opinions on what I should use to set the pennies and what I should cover them with. I was going to use a porcelain thinset to set the pennies, grout them with an unsanded grout, but I don’t know what to seal it with? What is your professional opinion? Thank you so much, Kim
Hi Kim,
I would use epoxy, and sanded grout. Any good sealer should work just fine, but I would contact the manufacturer (of the sealer – not the pennies) to ensure that.
Thanks for good info, it’s helpful
Hi Roger – I used a bucket of pre-mixed thinset to connect my hardibacker, not realizing it was just mastic until I read this post. It thoroughly dried before I used Redguard over it. I’ll be getting bags of thinset for the tile application but how worried should I be about my work so far? Thanks for your work here–finding your site was like finding a gold mine.
Hi G,
You should be fine if the hardi is screwed down and not just bonded with the mastic.
Roger:
Can you tell me what is the proper setting material for mosaic tile containing glass, stone, and aluminum? I am installing the tile as a backsplash in my kitchen. I have read that certain setting materials should not be used with metals. What do you suggest?
Hi Richard,
Any good modified thinset will work just fine.
A DIY video promotes laying a thin bed of mastic powder (mixed) on a concrete floor and then laying the mortar. This is for a shower floor prior to waterproofing and tliing.Q In light of the above comments about mastic is this a recommended course of action. Frankly Im now very confused. Appreciate any comment
Hi Nifti,
To install deck mud over a concrete substrate you want to mix up the mortar, spread it with a notched trowel, then install the deck mud over it. While simply using the powder may work it will need to rob moisture from the bottom of the deck mud layer to activate it, thus weakening the deck mud mixture.
Great information! Thank you. Is there a preferred tile type for bathrooms?
Hi Ron,
Depends on the application – the generic answer is porcelain. But it can actually be anything you want.
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)
Thanks
Hi Deborah,
You can if you use epoxy setting material, thinset won’t work. And yes, you should scuff it up first.
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
Hi Shelley,
Most of your questions will be answered in the literature of whichever thinset you use. I prefer laticrete 254 or 4xlt for that type of installation. Use grout for grout – not mortar.
There are additives for nearly everything, I prefer not to use them.I would install the tiles, then seal them, then grout.
How thick should the mortar be on 13 x 13 tile for a shower wall
Hi Gary,
Minimum of 1/32″ once installed, thick as you need it to get complete coverage. It varies due to the tile and substrate.
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.
Polly
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.
Hi Roger,
We are installing Kerdi membrane and subway tiles in a shower. We have uncoupling membrane mortar (Maipai) Will it hold? Is that the right stuff to use? Thanks – Liz
Hi Liz,
Yes, it will hold. Yes, that is the right stuff.