How do you repair hollow sounding tiles?


How do your repair hollow floor tiles and hollow wall tiles?


ANSWER - Hollow sounding tiles is not a defect per se.  Depending on the substrate and installation materials and methods being used the tile can have a hollow sound without anything being wrong.

On the other hand, when some tiles or portions of tiles sound hollow and others don't that might be an indication that there are excessive voids under the tile or that the tile or some component in the tile assembly isn't bonded.

Spot bonding tiles is where 4 or 5 spots on the back of the tile are bonded to its substrate rather than the entire tile surface being bonded.  This is not considered a legitimate method of installing tile unless it is with an epoxy adhesive on a wall.  This means that if only 50% of the tile is bonded then the potential bond strength of the tile has been diminished by 50%.  Now 50% might still achieve a substantial attachment under ideal conditions, but it doesn't meet the standards and makes it more susceptible to potential problems.   It also means that those unsupported areas of the tile will have a greater propensity to damage than where it is supported, and that for exterior applications or in interior wet areas moisture can collect in those voids causing staining problems.

There is no way to repair the hollow tiles so they are not hollow any longer other than replace them.  Over the years many have tried to inject epoxy through the grout joints to reach under the tile, but I have never seen it work.

2 thoughts on “How do you repair hollow sounding tiles?

  1. Denise Bucklad says:

    I was reading an article you wrote about Hollow sounding tile, from July 2013, Leslie Goddin. I am hoping that you can help me, give me guidance, or point me in the right direction.

    We are the second owners of our home. Had we been the ones building it, this would not have gotten passed me. Unfortunately several of the tiles in the lanai and a few in the house sound hollow. The floor is travertine inside and out. It appears that the tile layer only put thinset in the center of the tile. Thus causing the corners of the tile to crack.

    I would like to fix it, without having the remove the entire floor. I can’t imagine the cost because it is approximately 5,000 sq ft.

    I am wondering if there is a product that can be injected into the grout line (once removed) to file the voided areas? I think there would have to be multiple areas for injection. The broken tiles would be removed, giving me a greater chance to fill the voided areas. I know that concrete is leveled by pumping a cement and limestone mixture (very thin viscosity) between the dirt and the cement to fill the void and raise the cement.

    Also is there some type of membrane or tape that can be placed over the joining of two cement slabs. They just laid the tile directly over it, and either the grout is now cracked or the tile is. Have you ever done any repair like this? Am I on the right track? What do you recommend?

    I am attaching several pictures of the issues. The last picture is of the step. The gap is in front of the step. It is like the step foundation wasn’t as wide as the tile going on top of it, and they didn’t fill in the gap, but just laid the edges of the tile on top of each other. I have more pictures, but I couldn’t attach them all.

    • Donato Pompo says:

      Spot bonding stones or tiles is against the industry standards. If the corners and edges of the stone is not fully supported by the thin-set mortar adhesive then it will have a propensity to crack or crush. That is why the industry standards for natural stone requires 95% contact with full support under corners and edges of the stone, and no voids larger than 2 sq. inches (size of a golf ball).

      Although it isn’t an industry endorsed repair method some people have used a product called Fix-a-Floor ( that is a latex-like liquid that is flow-able and can be fill voids under tiles through drilling holes into grout joints. I have seen this product work in one case and I have seen other cases where it didn’t fill all the voids. Just depends on the depth and how large the voids are and whether there is a sloped surface underneath the stone. There is no guarantee that it will work adequately. Otherwise you should remove the stones and replace them with others.

      Regarding transition joint known as a cold joint or a control joint in the concrete between two separate pours, you should never bridge those joints. Per industry standards that joint should continue up through the stone. The joint should be filled with a foam back strip and caulked with an ASTM C920 traffic grade polyurethane or silicone sealant.

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