Kitchen Backsplash – Mastic Vs Thinset

By Todd Fratzel on Kitchens

Choosing Mastic or Thinset for A Kitchen Backsplash

As I pointed out recently we’re writing a series of articles over the new couple of weeks on How To Tile a Kitchen Backsplash. We’ve already discussed selecting backsplash tile and how to layout tile backsplashes so this article will focus on the use of mastic vs thinset when you install the actual tiles.

What’s The Difference Between Mastic and Thinset?

Before having a conversation about selecting mastic or thinset for your kitchen backsplash you first need to understand the difference in the two products.

  • Mastic – Mastic is an acrylic product that can be thought of as an adhesive similar to a glue. Mastic is a non-cementitious material that exhibits some pros and cons compared to thinset. The advantage of mastic compared to thinset is the setting time and “stickiness” which helps make tile installation much quicker and easier. The downfall of mastic is the fact that it’s not appropriate in situations with water (bathrooms and floors). However, mastic is a great choice for kitchen walls where little to no water will be applied to the tile.
  • Thinset – Thinset is a cementitious product that requires water to create a chemical reaction much like concrete. Thinset is much stronger structurally than mastic and a waterproof product that will not lose strength when exposed to water. Thinset is the only product that I recommend be used in showers, bathrooms and even floors. Thinset is much harder to work with especially on vertical and overhead surfaces because it’s not as “sticky” as mastic.

Pros and Cons – Mastic Vs Thinset

In a perfect world all tile jobs would be done with thinset. Thinset is ultimately stronger and unaffected by water. Having said that thinset is much harder to work with especially in vertical and overhead applications. When installing tile on walls thinset will not be able to support the weight of each tile so each tile much support the tile above it and so forth. This can be very time consuming and prone to “sagging” before the thinset develops it’s full strength. Thinset must be mixed just prior to installation and it’s very important that the proper amount of water be used.

Mastic is much easier to work with when installing tiles on vertical surfaces. Mastic is very sticky and able to typically support the weight of a tile with no support from below. This benefit makes installing the tiles much quicker and less likely to sag. Mastic comes pre-mixed and ready to go. Tiling kitchen walls is one of the very few applications where mastic is appropriate in my opinion. For this project we’ll be using mastic which should really speed up the installation.

Final Thoughts on Mastic Vs Thinset

While there are some people that will disagree on this debate most reputable tile installers will agree. Mastic has very few applications that are appropriate when it comes to tile work. Kitchen backsplashes are one of those applications where it’s use is appropriate so long as there will be no significant water exposure.

If you’re having a bathroom shower or floor installed please be sure your installer uses an appropriate thinset material. Mastic should NEVER be used in bathrooms in my opinion. Using mastic in bathrooms is a poor choice and typically a choice by a contractor cutting corners.

This article is part of a series on how to install a tile backsplash. If you’d like to see the final pictures of our new backsplash along with a summary of all the backsplash articles then visit our complete guide on how to install a kitchen backsplash.

About the author

Todd Fratzel

I'm full time builder for a large construction company in New Hampshire. I run their design-build division that specializes in custom homes, commercial design-build projects and sub-divisions. I'm also a licensed civil and structural engineer with extensive experience in civil and structural design and home construction. My hope is that I can share my experience in the home construction, home improvement and home renovation profession with other builders and home owners. I'm also the Editor-in-Chief and Founder of Tool Box Buzz. Please feel free to contact me if you have any questions, suggestions or you'd like to inquire about advertising on this site.

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  1. Timothy says:

    Interesting debate. Would you ever consider a product like Bondera which is an adhesive and doesn’t require the time or have the mess that mastic does?

    • Todd says:


      It is an interesting conversation. When you talk to die hard tile setters they all say the same thing, thinset or nothing. However, I can see a few projects where other products are acceptable like doing a kitchen backsplash. The Bondera product certainly is intriguing but I’ve never had experience with it so it’s hard to say how it would perform. I’m pretty skeptical that it can develop sufficient shear strength to be used on floors but it might be worth trying on a backsplash.

  2. DanM says:

    What if your kitchen back splash tiles are somewhat fragile like onyx and you have to put some of them on a slight inside curve. If they get bumped with mastic behind them is there a greater chance they could crack compared to thin set?

    • Todd Fratzel says:

      Dan – I’d highly recommend checking with the mastic specifications. Typically, thin set is used for applications where I worry about what is suitable because it works with most every type of material. Good luck.

  3. Susan says:

    I’ve only worked with thin set and larger tile in a bathroom. But my Mother has asked me to install mosaic tiles on her kitchen backsplash. Originally I was going to go with thinset, but the smaller tiles and saging has me worried. Would thinset or mastic be more appropriate for installation over painted dry wall (gypsum)?

    • Todd Fratzel says:

      Susan – For a kitchen backsplash you can definitely use mastic and it will make the job much easier. It works fine over drywall. Good luck.

  4. Charles says:

    I do shower ceilings alot, and mastic is the only option. Using thinset overhead is an effort of constant manipulation until it’s set enough.

    • Todd Fratzel says:

      Not the best practice though. There are modified thin sets on the market today that do hold. My tile installer just did a large steam shower for one of my clients and the thinset worked great. I’d recommend speaking with your local supplier and stepping up to thinset, mastic doesn’t belong in a shower.

  5. CC says:

    Charles, modified thinset for shower ceilings, sticks great and very strong. And Susan be sure to clean, scuff sand and prime previously painted drywall before installing kitchen backsplash, whether using mastic or thinset. Personally, I never use mastic, just because.

  6. Phil says:

    First time diy for doing kitchen backsplash. I have ceramic tile 7.75 x 7.75 by .25 thick, totally confused on what to use mastic or thinset. From reading your replies & others what I haven’t read is if I use mastic can I clean the tile with a damp sponge ?

    • Todd Fratzel says:

      Phil – You can definitely clean with a damp sponge. I think it’s fine to use mastic in this application unless it’s a commercial kitchen. Good luck.

  7. Moly says:

    We just had glass tile put in my kitchen and the installer used mastic. He was suppose to use thinset.The glass company said No mastic. Reason is because it may not dry. Then the guy used sanded grout on my glass. The job is going to be redone.

  8. Jeremy says:

    What do you think about mastic for a vanity cabinet backsplash in the bathroom. Is humidity from the shower an issue?

  9. Can I use mastic to install tile over tile on a fireplace surround? Will it stick to the existing tile? Will mastic soften when exposed to heat? Its a gas insert, not woodburning, and I’ve really never noticed the existing tile being warm, but just to be sure….

    • Todd Fratzel says:

      Interesting question. I doubt the heat will bother it at all. I’m not sure if it will stick or not, probably depends on how smooth the existing tile is.

  10. I removed an ugly back splash and sanded and scraped the morter…what adhesive should I use for the new penny/oval tile??


  12. Hans Deppenschmidt says:

    If i am installing marble tiles for a backsplash in kitchen would you recommend mastic or thinset. Unfortunately it iss going over painted drywall, would have prefered backer board, but to late to change that

  13. Jamie says:

    I’m new to the tiling world, but after some research I think it might be appropriate to use mastic on a small area of tile around my fireplace. Thoughts on this? In theory a fireplace shouldn’t get wet, but I don’t want the quality to suffer over the years. I’m worried if I don’t use thinset that the tiles may not hold as time passes.

  14. Kim says:

    Can you use a white powder mastic for kitchen backsplash? The tile company is saying that it could yellow over time and that we should use the set. We are installing a white-ish marble subway tile? Our contractor says he has used white powdered mastic with no issues. Don’t know what to do?

  15. Can I use mastic on walls in commercial bathroom with no shower installing 13 × 13 inch tile

    • Todd Fratzel says:

      That’s really a question for the owner :) You get what you pay for…sure it will work…will it last? not sure.

  16. Jason Hathcock says:

    We’re remodeling entire bathroom. I’m using standard thinset and backerboard for shower creation, however we’ve selected a thin mosaic tile, it’s a “shell” or mother-of-pearl type tile, to cover one entire wall, about 8×11 foot. Currently the wall is painted drywall. Trying to decide if I just keep that drywall when re-configuring, and use a “mastic” to set the tile sheets, or demo the drywall and use a backerboard an then either mastic or thinset on that. The wall won’t see any water, just a little raised humidity from shower, but our bathroom as it is now never gets very steamy anyway. Thanks for any advice!

  17. David Routenberg says:

    Is white mastic more likely to discolor white marble tile than white modified thinset. This will be for a kitchen backsplash.

  18. Stuart Flechner says:

    I have an irregular white tile kitchen backsplash and will drill out a single row of about 8 tiles (each 5×5″) and replace them with straight flat tiles to make a row for a floating wood shelf. I will need to drill a few holes in the tile for the shelf posts. Thinset or Mastic? Many thanks.

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