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Installing ceramic tile for shower walls.

I thought I knew for sure what I needed until I learned of Mastic.

So, what's best to use, Mastic or Mortar?

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Posted 2011-06-11T02:07:52+0000  by graphicleeink graphicleeink

Hey graphicleeink,


Thanks for your tile question, & welcome to the community!


I work in the flooring department at my store here in Atlanta, and I get asked that question a lot in my tile aisle. It's a good question, as now you have another option, mastic, to choose from for your shower walls.


So with that said...what is the best, mastic or mortar? Let me break them both down so you can decide which one is better for you.  Mastics and mortars have pros and cons to them, so with my information, you can decide which one is best for your shower wall. All of the products I will mention are found in our tile aisle at your local Home Depot.



Below are the 3 most popular pre-mixed mastics we sell, below that image, I'll go into a bit more detail as to why and where to use them..



Anything that comes in a can that says it is pre-mixed, adhesive, water-based acrylic, or even thin-set mortar is essentially a mastic. Mastics are great for small jobs, like your shower wall where you want an easy product to work with (since it's pre-mixed) and is ready to use. They are water-based adhesives that spread easily and come in high strength bond formulas. For this reason, I like mastics in these situations. The reason we sell more than one kind is for various reasons, one being that mainly you are looking for a faster drying time and you are setting heavier tiles, such as stone. Which leads me to the cons of mastics......If you are deciding to tile other areas in the bathroom such as your shower floor or floors in general, pre-mixed mastic adhesives aren't the best choice, due to the long wait time for floors to dry. The acrylic in the adhesive needs proper time to dry, usually requiring several days if not more for a floor, due to foot traffic constantly being on it, even if it says it's a pre-mixed thin-set mortar. With the shower walls, you won't have to worry about that.




We sell a ton of mortar in bags at my store, almost literally! While there are many types we sell, the one below is the only one I recommend for shower walls...




Thin-set mortars are typically sold in large bags or smaller containers depending on how much you will need. Mortars that are fortified or have additives have some acrylic in them, but they are usually referred to as Polymer based adhesives. A cousin of thin-set mortars is portland cement, which is what mortar almost is, but with ingredients that make it great for adhering tile. Polymer-based mortars when mixed with water sets off a chemical reaction that immediately starts to cure and set up once it is mixed. It can't be frozen or boiled to slow down the reaction....once it's mixed, it's starting its curing no matter what, which is what makes it a great and strong adhesive.


What I like about thin-set mortars is the fact that they go a long way in terms of square footage coverage vs. pre-mixed mastics, and the drying time is pretty fast, some even can dry in as quick as 4 hours! However, just like mastics, a DIY'er may find particular disadvantages to them. One is that you do have to mix the mortar up yourself with a paddle and stirrer. Also, thin-set mortars are typically done for floors, not walls, but our Marble and Granite Fortified Premium Mortar will work on shower walls as well. It's the very best mortar, really tile adhesive, we sell at The Home Depot in our tile aisle.


So in conclusion, depending on what and where you are tiling, I would recommend a pre-mixed mastic if you are only doing the shower wall.  Standard subway, square, or just regular 3/8" field tiles will have a instant bond on the walls using them.


If you are doing larger, thicker, or stone tiles on the wall use our Marble and Granite Fortified Premium Mortar. Also use mortar if you are doing additional tiles around the house as well...buying a bag of this stuff will prevent you having to buy one thing of mastic and one thing of mortar.


Now that you've got your adhesive picked out, remember your tools and preparation of the walls. Install the tiles over something moisture-resistant like tile backerboard using a V-notched trowel to spread the adhesive of your choice on top of it for the tiles....



Hope this helps you out,



Posted 2011-06-11T14:00:07+0000  by Joseph_HD_ATL
Thanks for ther info. I was going to ask the same question. I'm tiling a 5ft x 5ft shower with 12 in sq tiles. I think I'll use the water based acylic
Posted 2013-01-05T13:05:15+0000  by Digger54
very helpful info - thanks; i'm renovating a 6 X 8ft bathroom and using ceramic tile on the walls and river stone in the shower pan
Posted 2013-05-30T13:54:03+0000  by DP

Hello DP and Digger54,


Thanks to you both for your input and joining us here on the community.


I'm glad the information assisted you in your project decisions. I've had this question asked so many times in the tile aisle, so its good to have it public here for everyone to see.


Remember that if you have any specific tiling or any home improvement project you have, you can share or ask questions here on our forums.


Thanks again for letting us know about your renovations, and I hope they turned out great!



Posted 2013-06-08T21:28:42+0000  by Joseph_HD_ATL
I will have to disagree and say mastic adhesive should not be used in shower areas.
It should not be used on large format tile as mastic needs air to cure and once wet turns to playdoe. The better question should be should I use modified or unmodified thinset.
Posted 2013-06-09T15:16:10+0000  by jetswet

Hey jetswet,


I agree with you that mastic shouldn't be used for very large tiles, and you are correct about the slow drying time.


However, lots of DIY'ers who are tiling for the first tile on shower walls find that using a pre-mixed mastic is easier than mixing up thinsets.


It boils down to personal preference and their own knowledge and comfort level. Lots of bagged thin-sets won't adhere to vertical surfaces except for the Granite and Marble mortar.


I'm not a fan of using mastics over floors and when moisture is a constant issue. However, if the area has been dried for a while, you can apply mastic on walls.


Mastics also work great for small backsplashes and countertops. It's just the slow drying time that is needed for it. Even if the tiles seem firm, grouting can't be done unless you are certain it is completely dry. Unfortunately, this is a lot longer than mortars.


As of using modified or unmodified mortars, almost all we carry in-stock is modified, save for one type. The additives found in modified thin-sets can give the mortar a bit more flexibility for older subfloors, like plywood. They also give more stability and a better bond than any other tile adhesive we sell in our store.


The only time I would use an unmodified mortar would be placing a vinyl-based upcoupling membrane, like Schluter's Ditra or Kerdi-Shower systems (shown below).

Kerdi-Shower 48 in. x 48 in. PVC Shower Kit with Brushed Nickel Drain


This is needed because the acrylics in the modified thin-sets wouldn't cure properly due to lack of air, leading to failure.


Thanks again jetswet for your input, and I hope to see you again here on our forums.



Posted 2013-06-12T17:46:09+0000  by Joseph_HD_ATL

HI!  our installer is using mastic type 1 on the walls and he is leaving a sliver of a space between the 12x 24 tiles...also where the glass tiles meet the stone tiles, there is no gap for the grout at all.  The durock was covered with a painted on water proofing membrane.  should i be concerned that he is using the wrong adhesive under the large tiles, that there is no room for any grout and that the adhesive will be wet forever?

Posted 2013-11-20T16:52:49+0000  by tilesneedhelp

Good afternoon tilesneedhelp!


Thank you for your question and welcome to the community!


If the installer put mastic on vertical surfaces, your tiles will eventually dry....not be 'wet forever' as you stated.


I've seen some mastics dry as long as almost a month, but this was tile on a concrete slab. Since yours is a vertical surface that has a suitable moisture-resistant finish and no grout, your drying time should be much faster.


While I'm not there and not sure how your tiles are, you can press and move the tiles to see if any are loose. If one is, then I'd suggest to wait several days until the mastic fully cures underneath.


Even hairline (1/16th") cracks really need some kind of grout/sealer in them so that the tiles won't become loose. If this is in a shower, high traffic, or wet location area, this is very crucial. If it isn't, then you can get away with not having to grout....if the joints are as thin as you say they are.


I personally would grout the lines, regardless of how small the gap is, to ensure the tiles will look better and work more effectively. Just as important, you'll also need to seal your tiles to make sure that no moisture gets through and get behind the tiles.


Since your tiles are on the wall, you won't encounter as much of an issue versus them being walked on.


Please let me know if you have any additional questions,


Posted 2013-11-20T18:10:03+0000  by Joseph_HD_ATL
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