Do we have to Replace Hollow Sounding Tiles?

QUESTION

Are some hollow tiles a problem? A year ago, we were rebuilding the bathroom and the floor in the hallway in our blockhouse apartment. When the floor in the hallway was freshly laid, then about 3 hours later I had to walk over the ceramic tiles with my wife, because we needed to go to the hospital. After all the work was finished, the tiles showed no defects or hollow spaces. About a month ago I noticed that the tiles (about 10 pieces), in the area where we walked over, had voids beneath it. The tiles are not moving, the joints are completely intact. The tiles are laid over a concrete slab. Is it necessary to replace those hollow tiles, or are these few tiles (about 10% of the surface mostly concentrated in one specific area) not a problem for the integrity of the floor? In case of repairing those tiles, do we have to remove and replace the defect tiles or is it enough by injecting epoxy under it? Thank you in advance for your answer.

ANSWER

ANSWER - Hollow sounding tile is not a defect per industry standards.  Although a hollow sounding tile can be a symptom of a defect.

If all of the floor sounds hollow or a portion of the floor sounds hollow, then it might be due to the materials and configuration of the tile assembly below.  Membranes will normally cause a hollow sound.

If only a portion of a tile is hollow sounding or only certain tiles are hollow sounding it could be that there is a void under the tile or that the tile is not bonded in those spots for some reason.

If is possible that if you walked on a tile installation before it was substantially cured, it could cause the tiles to release or to compromise the tile's adhesion.  In the later case, then perhaps a year later the tiles were subjected to some stress and those tiles were not able to resist it due to the diminished bond strength.   Lack of movement joints could be a reason the tiles were subjected to stress.

If there is no resultant damages to the tile or grout, then I would just let it go.  Make sure you have extra tile for the future just in case they do get damaged you can replace them.

Injecting epoxy is not a legitimate repair.  It is treating the symptom rather than the problem.  I have never seen it solve a problem.

19 thoughts on “Do we have to Replace Hollow Sounding Tiles?

  1. Alex Malit says:

    We installed 800mm x 800mm x 20mm thk granite stone on the flooring. It has been laying on the floor for a year. Upon recent inspection, some granite have hollow sound. There are no crack on the granite nor on the grouts. We removed some and seen that the mortar is intact and no void areas. Is the hallow sound normal? Do we need to replace the granite with hallow sound?

    • Donato Pompo says:

      The only way to determine what is causing the hollow sound is to remove a tile. There could be voids or for some reason the tile might not be bonded. In some cases the hollow sound might be due to the underlying substrate condition or that it was bonded over a membrane. In those cases all of the tiles should sound the same. When one tile or a portion of a tile sounds hollow and the others don’t, then it suggest there could be a void or bonding issue.

      If there are no resultant damages then it might not ever cause a problem. The fact that you have a dense granite that is 20 mm (3/4″) thick it will be more resistant to various types of stress or impact than a standard tile. I would wait and see.

  2. Zahrah says:

    I just had a tile installer lay all my tiles in the front entrance. I noticed today by knocking on some of them it sounds hollow. They put a floor leveller compound prior to. Is this a huge issue ? I know if I were to drop something heavy in the future on one of these hollow sounding tiles I could risk it cracking. Right?
    Can I leave it be or should I get it fixed now? It’s such a pain because I will have to purchase more tile for what seems to be a mistake by the contractor.

  3. Donato Pompo says:

    If the entire tile floor in the entrance sounds hollow, it probably is because of the underlying conditions of the floor assembly that might not be a problem. The tile floor can sound hollow if it is over a suspended floor or if the tile was installed over a membrane or a uncoupling membrane mat.

    If certain tile or certain portions of a tile sound hollow that might be an indication that there are voids under the tile in those locations or that a tile is not fully bonded. If the tile is loose the grout joints would normally be cracked.

    If the floor leveler was not properly applied it could result in it not bonding to the substrate to which it is attached, but if it was applied correctly that should not cause a hollow sound.

    The only way to verify the conditions is to remove tiles under various conditions to determine if they are bonded well and why they sound hollow.

  4. Mary Ann Mori says:

    Several ceramic tiles in my dressing area popped up slightly a week ago. (tented) I have been trying to get a tile person to come and give me estimates. One person suggested the entire floor of the walk in closet (dressing area) needs to be redone with new tiles. Another person lifted the tented tiles and said his man could remove the ones causing the pressure and the others should all fall in place. However, many of the tiles are very hollow. Doesn’t that man there will be a problem with these too shortly? I have two or three extra tiles only. and isn’t it more work to remove the tiles and clean them and replace them?

    • Donato Pompo says:

      Chances are the hollow sounding tiles adjacent to where the tented tiles were removed are probably not bonded well and should be removed. If they are not bonded well, the installer should be able to slip a margin trowel under it and pop it up. If that is the case you might be able to reuse the tile. You can just grind off any residual thin-set mortar adhesive from the back of the tile or the substrate.

      Removing the tented and hollow tiles is simply treating the symptom of the problem. If you don’t fix the problem then it is likely to reoccur. Normally when tiles tent it is due to the tiles not having a movement joint at the perimeters of restraining walls filled with a resilient ASTM C920 sealant (caulking) to mitigate the stress the tile is being subjected to. Part of the problem could be that the tiles were not bonded as well as they should have been, and they can’t resist normal stress.

  5. Ondrej Prukl says:

    Another three years passed, and now I have noticed, that the original 10 hollow tiles have expanded by another 5. The tiles around the originally hollow ones have also become hollow. There is still no visible damage to the tiles or the grout. Will the hollow spaces continue to expand? Is there anything I need to do? Or should I wait until there is some visible damage? I still have spare tiles.

    • Donato Pompo says:

      You probably don’t have movement joints at the perimeters of the room at restraining surfaces or every 25 feet in each direction within the field of tile.

      The fact that the hollow tiles are limited and have grown suggest they have debonded from perhaps expansion in the tiles from moisture or higher temperatures that subjected them to more stress than they could resist.

      If in fact the tiles are not bonded then they will be more prone to cracking if they are subjected to a concentrate load of some sort. Such as running a dolly with heavy equipment over the hollow tile or dropping something heave on it.

      They may never become damaged. Or if they become damage and you start removing them to replace them you might find additional tiles that will come loose. If the tiles do come loose you might be able to reinstall them. If you do make sure you install movement joints (a joint that is about 1/4″ wide filled with an ASTM C920 sealant over a backer rod or tape.

  6. Richard Williams says:

    We recently bought a house that is 20 hears old and were told in building report that the floor tiles were drummy. On closer inspection the tiles in 3 areas are drummy and in 2 of these areas the tiles actually move underfoot making a soft crunching sound, in these areas the grout is coming out. The tiles were lais without any joints the longest corridor being about 10 M. At this stage none of the tiles aer broken but I am afraid taht if I dont do anything the will crack.

    In this situation would you recommend:
    1. – Ignoring the problem and hoping it doesn’t get any worse.
    2. – Repair Injecting glue through the grout and installing expansion joints. Which is relatively inexpensive.
    3. – Or would I be better off going for the expensive option of ripping up the tiles and starting again, obviously at great expense.

    Regards

    Richard Williams

    • Donato Pompo says:

      Drummy is another word for sounding hollow. If the tiles are hollow sounding, moving and the grout is coming out then I would assume the tiles are not adequately bonded and need to be replaced.

      If it is only limited to certain areas, you might be able to repair those areas if you have replacement tiles that match.

      If the tiles are loose then injecting under the tile to fill voids is not likely to work. If you can repair it or if you end up replacing it all, then you should install expansion/movement joints. Installing movement joints after the tiles are loose won’t help.

  7. Rich says:

    Recently my house as flooded from flood waters. I have ceramic tiles installed over concrete in my bathroom which were installed approx 10 years ago. During clean up I notice a number of hollow sounding tiles mainly the tiles along the edges of the bathroom and some tiles adjacent to the edge tiles( by the shower). Could the flood water cause the tiles to de-bond and sound hollow?? asking for insurance purposes

    • Donato Pompo says:

      First of all, per industry standards a hollow sound is not a defect per se. Although it can be a symptom of a defect.

      Generally speaking tile installations over a concrete substrate that is properly installed is not damaged by a water loss event (flood). Although if the tile isn’t installed properly and tends to absorb water then it can cause resultant damages from a flood.

      If the water is a Category 2 or Category 3 meaning it is contaminated then depending on the type of contamination that could require an appropriate remediation.

      Generally speaking, insurance companies will accept claims if there is clear evidence of damages and that it is clear they are resultant damages from the water loss event and not pre-existing conditions.

    • Donato Pompo says:

      There is no industry standard that limits how many hollow sounding tiles a tile installation can have.

      Per the industry standards, a hollow sound in a tile installation is not a defect per se. It can be a symptom of a defect in the underlying conditions of the tile in question. The standards state that a tile installation with a membrane can produce hollow sounds that doesn’t mean the tile has loss bond.

      The only way to determine if a hollow sound is a symptom of a defect is to perform an intrusive test by removing the tile. If the hollow sound is due to the tile being spot bonded in an exterior application that requires 95% contact between the substrate and the back of the tile with the thin-set mortar adhesive, and it only has 50% contact, then the defect is the lack of thin-set contact and the hollow sound was a symptom of the defect.

      If upon removing the tile it is found not to be bonded, then the defect is the bond failure, and the hollow sound was a symptom of that defect.

  8. Marita Hatherly says:

    Hi, we have been living in our house for 4 years and we are recently hearing hallow tiles scattered all over the house, mostly the corridor. The tiles have been laid around 12 years ago. We are hearing new tiles almost every day and they are not close together. There isn’t any visible cracking in the tile or grouting around it. The spacing between one tile and another is 1mm ( the width of the grout). Our floors are built on concrete planks and tiles are laid on a sand like material (debris/dust from stone). Is there something we should do to avoid having all tiles sound hollow? Is this an early sign of having tiles tent in the near future? What should we do?

    • Donato Pompo says:

      First of all, hollow sounding tiles is not considered a defect per industry standards. Although hollow sounds in tiles can be a symptom of a defect.

      If I understand you correctly, you have an interior floor where concrete planks were set on ground. Then you installed tiles over it on a sand-like bed. That is not a normal type of installation and there is no industry standard for that type of installation per se.

      There are sand set thicker stone and tile installations, but they are normally installed in the exterior areas over a compacted gravel base to allow for drainage.

      The only way to determine what is causing the hollow sound is to remove a hollow sounding tile and remove a solid sounding tile to determine what is different about their condition. If in fact you have a sand based bed you should be able to easily remove the tiles and correct them.

      On the other hand, since you have no cracked grout or tiles there is not resultant damages from the hollow tiles, at least at this point, so you may never have a problem.

      Sometimes when people become aware of a hollow sound in their floors they start becoming more sensitive to listening for them. So the tiles might have always been hollow sounding, but you hadn’t noticed until now.

      • Marita Hatherly says:

        Thank you for your reply. Since yesterday, we have one particular tile that is moving a bit. It was making a hollow sound before it started moving and I am worried that this will continue spreading to other tiles. Also a new tile is making a hollow sound about two tiles above the one moving. This change is what worries me.

        • Donato Pompo says:

          You need to get a tile expert or installer and remove the tiles to determine why they are moving, so you know how to fix it.

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