Can Ceramic Tile be Installed over CMU (concrete masonry unit) block?

QUESTION

Can Ceramic Tile be Installed over CMU (concrete masonry unit) block? - Can I install Ceramic tile over a CMU wall?

ANSWER

ANSWER - Yes you can install ceramic tile over CMU (concrete masonry unit) blocks.

You need to properly prepare it to make sure it is free of any structural cracks, clean, and plumb. You can bond the tile directly to it or you can fasten metal lath and apply a scratch and brown coat of mortar.

For a direct bond to the CMU, it is recommended to skim coat it with the thin-set mortar to smooth it out prior to applying a liquid applied waterproof/crack isolation membrane. Then use a high performance modified thin-set mortar exceeding ANSI A118.4 and make sure you achieve 95% contact bonding the tile to the membrane. Then grout it. To see a list of manufacturers who produce tile installation products go to our website at www.CTaSC.com and go to the Resource and Links page and there will be a list with links to their websites. Good luck.

5 thoughts on “Can Ceramic Tile be Installed over CMU (concrete masonry unit) block?

  1. Kyle C Wipf says:

    Do I need the membrane on an interior wall (for an office), as well, or just exterior, where there may be moisture? That stuff is expensive!

    • Donato Pompo says:

      No you don’t need a membrane on the interior wall for moisture control. If you do have cracks in the CMU then you might need to apply a crack isolation membrane. Otherwise you can just grind the surface flat, clean the wall, and adjust the wall with a patching mortar if it isn’t plumb or has low spots. Then adhere the tile direction to the properly prepared CMU wall.

  2. Michelle M Rumsa, RA says:

    How are the ends of the cmu wall covered with tile? I have 6″ cmu walls to 7′-0″ tall dividing three showers so the end of the wall also needs tile. Would you recommend using Schluter edges at the outside corners ? What is your recommendation? Thank you

    • Donato Pompo says:

      Using a metal profile at the outside corners of the CMU wall is one way of doing it. Although a more professional way is to do a quirk miter at those transitions. That is where you cut a 45 degree angle not starting at the top edge of the tile, but drop down an 1/8″ and cut the miter there. This way you don’t have a sharp edge at the corner.

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