Should I be concerned about 2 Hollow Sounding Tiles?


We had our small kitchen concrete floor area fitted with large porcelain tiles in late November 2016, replacing the original glass tiles which had broken over the years
The company is reputable and registered and had fitted our bathroom in 2008 with no issues so we were confident of an equally professional job on the kitchen floor.

2 of the tiles now have a hollow sound if you tap on them compared to the rest. The grout is intact and there is no movement. The only issue so far is the sound. We are unsure how long this has been the case as we wear soft shoes indoors and it only became apparent when my son walked into the kitchen in his work shoes.
I rang the tiler and expressed my unease and asked him to come and check it out. I felt that he was unconcerned that there is a problem. He asked if I wanted the tiles lifted and re-fitted and said it would be a "messy job"
I said I was concerned about it but trust him and would be guided by his professional opinion. He said it was "just an air pocket" but agreed to call to the house next week to see it. He asked if the grout was still intact and if there was any movement. When I said there wasn't, he said it was simply an air pocket and was probably there from the start and he had seen that happen before many times.

I have searched for information on Google and I am of the belief that the affected tiles would be compromised should something fall on them. I am also convinced by various reports I have read, that these tiles were applied with the method of spot adhesive at the four corners and the centre and not on the entire tile area and that there are voids where the tiles are not making full contact with the mortar underneath.
I would welcome your observations in the matter or your assurance that the tiler is right and that there is no cause for concern. We would feel more equipped to put my case to him when he arrives, if I have some expert opinions.
I understand that any reply is merely an opinion and that I will need to deal with the matter when he comes out.
I know that we are covered legally by the Sales of Goods and Services Act but I am hoping for a favourable outcome without having to resort to litigation
Many thanks for your assistance


ANSWER - According to industry standards having hollow sounding tile is not a defect in itself.  Although a hollow sounding tile can be a symptom of a defect.

A tile having a hollow sound could be an indication that there is a void under those hollow sounding spots and/or the tile isn't bonded at those hollow sounding spots.  A hollow sound can be caused by the configuration of the tile assembly, it could be the result of having some sort of membrane under the tile.  It could be an indication that the underlying substrate has a condition that is causing the hollow sound.  The only way to determine what is causing the hollow sound is to carefully remove the tile and evaluate the underlying conditions.

If the hollow sound is the result of having a void under the tile that is larger than 2 square inches (about the size of a golf ball), then the tile could be susceptible to being damaged if a hard sharp object fell on that spot.  Residential floor tiles can have up to 20% voids as long as the voids are dispersed and not larger than 2 square inches, and that the corners and edges of the tile are adequately supported.

If only two tiles out of many sound hollow, then I would not expect that all tiles were installed in a spot bonded method.  If the grout joints are not cracked around the tile, then the tile is not likely loose.  It is not that difficult for a professional tile installer to replace two tiles.  Having a wet and dry vacuum and taking some simple precautions for dust control, it can be done within a couple of hours.  So if the 2 hollow sounding  tiles bother you, then you should consider having the installer replace them.

29 thoughts on “Should I be concerned about 2 Hollow Sounding Tiles?

  1. Anne Beirne says:

    Dear Donato

    Thank you so very much for your email . We are indebted to you for your comprehensive reply.
    Everything you wrote and advised makes sense .

    As you pointed out, any considerable void under the affected tiles could potentially cause problems should any weight be placed on them . We are planning to change our carpet next year and we are concerned that the weight of the furniture placed on the affected tiles during the fitting could cause them to crack or break . There is definitely more than a golf ball size void on the affected tiles .

    I am pleased to read that there is no assumption that all of the other tiles were adhered with the spot method so we are hoping that this matter can be rectified with our tiler as you described

    We will ask that the two tiles be lifted and re-fitted. We are so pleased to have the advantage of your timely advice on time for his inspection.

    Thank you Donato. We will let you know the outcome
    This is a truly wonderful service to ordinary people like us who accessed your website while searching hopefully for some advice .
    With warm regards
    Anne Beirne

  2. Donato Pompo says:

    The standards don’t recognize hollow sounding tile as a defect. Tiles can sound hollow because of what it is bonded over and to what it is bonded.

    If the hollow sound is proved to be voids under the tile, then for interior wet areas and exterior areas there should not be any more voids than 5% of the surface area. No void should be larger than 2 sq. inches, and all edges and corners of the tile should be fully supported.

    For residential interior dry areas you can have up to 20% voids under each tile, but all corners and edges are to be fully supported.

  3. Mick says:

    I have 1 hollow tile 600x 300 in my corner shower floor only been layed 4 weeks ago should it be repaired by the tiler at no charge ?

    • Donato Pompo says:

      Per the industry standards hollow sounding tiles per se are not considered a defect. A hollow sound can be a symptom of a defect, but there can be hollow sounds that are not defects.

      The hollow sound might be a reflection of the condition of the substrate beneath the tile. It could be from a void under the tile that is within allowable tolerances.

      If the tile in your shower is entirely hollow then I would expect it to be loose. If the tile is loose, then I would expect the grout joints to be cracked and the tile will move to some degree. On the other hand, the might be partially hollow because of an excessively large void. The standards say that for a shower application there should be at least 95% adhesive contact between the tile and its substrate. The 5% voids should be dispersed.

      A partially hollow sounding tile can be well bonded. If it has an excessively large portion of the tile with a void, then if something heavy impacts the portion of the tile where there is a void, then it can have a propensity to crack at that spot.

      If you replace the one tile then you have to have a matching replacement that blends in with the other tiles. The grout color will not match at first, even if you have the same grout left over, as it will dry differently and be new that results in a different color. Over tile as it gets soiled it will likely blend in.

    • Donato Pompo says:

      If you mean that there is one tile that is hollow sounding, then yes I would expect the installer should replace it at no charge.

  4. Anthony Houghton says:

    We have been in our new home for a year now. We have so many hollow sounding tile full 24 x 24 . The builder came out once and replaced 23 and found that they were put down with mastic. Now there telling us the industires standard allows for 65% of the tile to be hollow , so they wont fix our floor. I thought the standard was 20%.

    • Donato Pompo says:

      The industry standard for tiles installed in dry interior applications is that it has to have at least 80% continuous contact between the back of the tile and its substrate. The 20% of voids allowed have to be dispersed and no void should be larger than 2 square inches. All corners and edges of the tile have to be fully supported.

      The ANSI A108.5 standard does not mention hollow sounds because hollow sounds can be due to voids or due to other underlying conditions. The only way to determine if the tiles were installed with excessive voids is to remove some and document the underlying conditions.

  5. Mariam Noujaim says:

    Resurfacing my swimming pool with ceramic title to cover the ‘infinity edge’. The edge is 2 equal lines covered with ceramic tiles. The first 3 tiles on both rows (total 6 tiles) are very very hollow; the rest is fine. I brought it up to his attention; but he said it was nothing…?!!!
    Your thoughts?

    Thanking you in anticipation

    • Donato Pompo says:

      A hollow condition doesn’t automatically make it a defect, but often it is a symptom of a defect. That fact that some tiles sound solid and some sound hollow could be suspect, unless the underlying substrate is causing the hollow sound. If there is a pipe or a filter opening under those tiles it could cause a hollow sound. If all tiles are installed over the same substrate that has the same underlying configuration and materials, then I would want to remove a hollow sounding tile to determine if there are excessive voids or if it appears to be well attached. It normally isn’t that much work to remove and replace a tile for a qualified tile installer.

  6. Marisa says:

    Sounds like elephants and hammering above new apartment. They say a 2 year old running. 4 days a week and can’t stop them
    Any ideas
    I have many hollow tiles. And assume they do also mine some . Moves and. Makes a sound

    • Donato Pompo says:

      There are sound control systems that are installed with the tile, but obviously it is too late in your case. Also it is possible to fill the floor cavity between your ceiling and the apartment floor above with an acoustical foam to help deaden the sound.

      Tile can sound hollow depending on how they are installed. Sometimes it is a symptom of a defect in how they were installed. If the tile moves then that is a problem as they should not move.

  7. Andrew says:

    Where can I find the information that states how much area can be hollow, that there cant be more than 2 square inches of void, and that all edges and corners need to be firmly bonded?
    I have been fighting with a tile setting company who Supposedly follows all code and standards for over a month since I stopped them from working. I stopped them when i noticed a bunch of problems with what i have read and learned.
    I had 12 x 24 porcelain tiles installed and I have hundreds of tiles with edges and corners voided along the entire long edge. Many of them are up to 2 inches under the tiles and run 50 to 80% the length of the tile. You can tap on the tiles and the one edge is obviously hollow over the rest of the tile.
    I stopped them before they grouted and can actually shine a flashlight and see all the voids under the same edge on those 100+ tiles. I bent a paperclip and am able to stick it under most of those tiles about an inch and run it the length of the tile.
    They keep giving me the runaround and telling me I am just being picky. They said the grout would fill those voids.
    I contacted the AZ roc and will have them out to inspect the project, but I cant find this specific info about hollowness on their site and would like to be able to show it to them.
    Thank you in advance for any and all info you can give me.

    • Donato Pompo says:

      For 12×24 inch porcelain tiles in an interior dry area application, the industry standard ANSI A108.5 states that the tiles should have a minimum of 80% coverage that shall be sufficiently distributed to give full support to the tile with particular attention to the support under all corners of the tile.

      The TCNA 2021 Handbook says Average contact area for dry areas is 80% . Mortar coverage is to be evenly distributed to support edges and corners.

      We do have an inspector in Arizona as well and inspections there. Go to for more info.

  8. Darren B says:

    Hi Donato,

    Do you know of any tests or recommendations for sand seed the last coat of an acrylic waterproof membrane before applying a sand/cement screed? The waterproofer did not sand seed the membrane as there was no requirement in the manufacturer’s literature; however, the owner, on completion of the tiling, said the tiles sound drummy in all 5 wet areas and is blain the waterproofer for not sand seeding. I understand that drumminess is not a defect unless there is movement.

    I would appreciate it if you could point me in the direction of any literature that agrees or disagrees with sand seeding.



    • Donato Pompo says:

      Regular liquid applied waterproof/crack isolation membranes that meet ANSI A118.10 and A118.12 are a latex based membrane that can be an acrylic based product as an acrylic is a latex. These products do not require sand seeding. You can bond the tile directly to the membrane.

      Only epoxy or urethane based vapor barriers or waterproof membranes require a sand seeding in order to have a tile bond directly to it with a polymer modified thin-set mortar that meets ANSI A118.4 or ANSI A118.15.

      The TCNA handbook states that sometimes when tiles are installed over a membrane it can give a hollow sound. If the hollow sound is uniform throughout then it may be the membrane causing it. Although sometimes hollow sounds can indicate excessive voids under the tile or that the tile is not bonded. If the tile is not bonded then normally the grout will crack.

  9. Zacc says:

    I had about 20 ceramic tiles (10 in each row) (dimension: 300×300) that pop up last night. Do you think Fix-A-Floor would help to stop my other ceramic floor tile (living room) from popping up?
    Pop up due to hollow tiles and changes in weather.

    • Donato Pompo says:

      If your tiles popped up, what we call tented, then the problem is that the tile floor has expanded, but it is constrained, so the only way to release that tension is to lift up. This could be due to the weather where you have more rain and humidity, where the tiles absorb moisture and expand.

      By those tiles coming loose may have relieved the stress in the other tiles. So the problem might not be that you have voids under the tile and that you need to try to inject Fix-A-Floor under the tiles through the grout joint.

      You may just need to add some movement joints at the perimeters where the tile butts up to a wall or within the field of tile every 20-25 feet for interior applications if there is no direct lighting, and if there is direct lighting then every 8 to 12 feet in each direction.

      A movement joint is either a open gap between the wall and tile that can be covered with a base or filled in with an ASTM C920 sealant caulking. Movement joints in the field of tile is the ASTM C920 traffic grade sealant caulking to fill in between tiles in lieu of a cementitious grout.

      The only way to determine what your condition is, is to remove some of the tiles in various conditions to see what underlying evidence there is to explain the resultant damages.

  10. Deborah J Rowe says:

    Have about 8 tiles sound hollow. Only have 4 replacement. Should we try something like fix a floor? Concerned as we have limited tiles throughtout. Plank type tiles (which resemble wood).

    Also, what type of contractors/handyman would I hire to do this?
    The grout is intact for 6 tiles. Noticing not intact for 2 hollow tiles

    • Donato Pompo says:

      Just because the tiles sound hollow doesn’t mean they are not adequately installed. It can me a symptom of problem or that they didn’t install the tiles per industry standards to get at least 80% dispersed contact and full support along the tile edges and corners.

      The fact that the grout is cracked at the two hollow tiles, might be an indication that they are loose and you should replace them. That will give you an idea of how the tile was installed and help you determine whether to remove the other tiles.

      Always best to hire a full time tile installer since they have the experience and are less likely to damage the adjacent tiles to the tiles that are removed. Although often licensed tile installers don’t like fixing someone else’s work as it could become a problem for them.

  11. Janice says:

    I have had a slab leak meaning a pipe leaked somewhere under my tiled slab floor. Prior to finding out about the leak and having located by a professional leak detector, I had noticed a couple of “hollow” sounding tiles in my entry area of my home. After locating the leak to be under the entry area, the water came out from under a baseboard about 16 inches away from the pinpointed leak under the tile and cement. I noticed that there were many more hollow sounding tiles along the walls that tested wet by the water abatement company, and no hollow sounding tiles a distance of 15′ or so away from the location of the leak. The leaking pipe was canceled so is no longer leaking. Could this water leak have caused the bond between the tile and the slab to have loosened and resulted in the many more hollow sounding tiles? My insurance company is trying to say that a “hollow” sound on tile can be due to installation or wear and tear as a reason not to replace tiles that are within 6 feet of the leak but sounding hollow. It seems to me that they are failing to recognize that this water leak may have caused the problem.

    • Donato Pompo says:

      The water itself should not harm the tile if the tile had been properly installed originally. The insurance covers resultant damages from the water loss. They don’t cover pre-existing conditions. Hollow sounding tile per the industry standards isn’t a defect per se because there are many conditions where tiles sound hollow and are not compromised. Although sometimes a hollow sound can be a symptom of a defect. When some tiles are hollow sounding and some are not, then that might be an indication that the tiles sounding hollow either have excessive voids causing the hollow sound or that the tile has debonded. If the tile has debonded then normally the grout joints will be cracked and the tile will move to some degree when pushed upon it.

      It is possible that if the tile wasn’t originally installed correctly, that the tile is very porous, and there are no movement joints at the perimeters or within the field of tile per industry standards that a the flooding could have caused a tile to expand and debond. But a hollow sound by itself isn’t considered damage unless you can show that the tile isn’t bonded. The only way to determine cause of the hollow sound is to remove those tiles to see what are the underlying conditions.

  12. Kent says:

    I have few hollow sounding wall tiles in my bathrooms (this is new house under defect check). The hollow sounding happen at one side of 24″ x 24″ wall tile (another three-side and center sound solid). The developer defect team said this is okay can withstand 50 years (won’t drop) and no need to replace. If replace may have color variation.

    I went to tiles shop, the person told me since I will not apply any pressure on the wall tiles, it should be fine. It is different with floor tiles as we normally step on (pressure) it, any hollow sounding floor tile should be replaced.

    What is your thought on it? Should I consider my one-side hollow sounding wall tiles are fine not to be replaced? And I shouldn’t worry hollow sounding wall tiles, right? Thank you

    • Donato Pompo says:

      Technically hollow sounding tiles is not considered a defect. Although often it can be a symptom of a defect. When one portion of the tile sounds hollow and the other portions sound solid, it is likely because there are voids under the tile in that spot. The industry standards state that tiles in wet areas like a shower or exterior areas, the tile should have at least 95% thinset (adhesive) continuous contact between the back of the tile and its substrate with the 5% being dispersed throughout the tile and that all edges and corners are fully supported.

      It isn’t as critical for a tile on a wall not to have supported edges since it isn’t subject to foot or other traffic. Unsupported portions of a tile are more susceptible to damage if that portion of the tile is subjected to a heavy load. In theory whatever percentage of the tile that is not bonded that means that reduces the overall potential bond strength of the tile by that same percentage. In wet areas you want to avoid voids behind the tile so water doesn’t collect in them and lead to excessive efflorescence staining.

      From a practical point of view, if the tile is adhered with a good quality thinset mortar and if it was only 50% bonded the overall bond strength of the tile would still be very high. For example, if you have a 24×24 inch tile and the bond strength was 100 psi, which is reasonable if it was bonded correctly, it would require a load of 57,600 lbs of force to dislodge it. So if the tile was only 50% bonded then in theory it would require 28,800 lbs of force to dislodge it.

  13. Lee Staley says:

    I installed 12×24 wall tile in my shower remodel. I realize now that I should have used a 1/2 x 1/2 trowel, but used a 1/4″x1/4″ trowel. I back buttered and troweled each tile as well as the wall. I pullled up tiles every so often and always had good coverage of the back. The tiles were very hard to pry up and took a lot of force. Should I be worried that this mistake will cause issues down the line?
    I understand why improper trowel size may cause issues on a floor where there is a lot of force and weight, but if the wall tiles hold strong will it really matter?
    Appreciate any insight you may provide

    • Donato Pompo says:

      Actually you used the right size trowel and based on your description it sounds like you got good thinset contact/coverage. It was good for you to pull tiles as you install them to make sure you are achieving adequate thinset coverage, which our industry standard ANSI A108.5 states that you should do. As they say in the construction world it is up to the installer to use the means and methods to achieve the intended results regardless of how they do it. It sounds like you did do that.

      With a larger tile you have to be concerned about trapping air under the tile. That is why it is recommended to trowel parallel to the short side of the tile and after beating the tile into the thinset to then shift the tile perpendicular to the trowel ridges so the trowel ridges collapse into the trowel valleys.

      It is not recommended to use a 1/2″ x 1/2″ square notch trowel because there is too wide of a gap in the valley and requires too much of shift to get it to collapse into the valley as we often see uncollapsed thinset ridges in failed installations.

      Today they now have slanted trowels were the thinset ridges is applied at an angle so it facilitates it collapsing into the thinset valley.

      The standards state that all corners and edges of the tile need to be fully supported by the thinset mortar. Installers often fail to back fill the edge of the tiles as they install them to make sure the tile edges are fully supported.

  14. Michelle says:

    My new house is currently undergoing defect inspection. Upon finding out some tiles with hollow sound, we requested the developer to have them changed for us.

    The developer is saying that it is normal to have some spots underneath the tile to be hollow due to these hollow spots are to cater for absorbing the impact coming from the movement of the entire building from daily activities of all residents (which he’s saying is not earthquake, but just some general movements which we might not be able to feel). They claimed that without these hollow spots, our tiles are more likely to crack & pop up as there’s no room for movement/expansion. Would like to hear from you how true is all these sayings?

    I’m currently struggling whether to accept what they’re explaining to me or to go ahead with insisting the hollow-sounded tiles to be changed.

    Hope to hear from you soon, thank you.

    • Donato Pompo says:

      Whoever made those statements is either dishonest or ignorant. It is a completely illogical rational.

      The ANSI A108.5 standards state that for a residential interior floor tile in a dry application there has to be at least 80% thinset/adhesive continuous contact between the back of the tile and the substrate. All corners and edges are to be fully supported. There should be no void larger than 2 square inches (size of a golf ball).

      Manufacturers of the thinset mortar generally recommend full adhesive contact.

      Excessive voids or voids along the edges or corners of tile will have a propensity to crack or crush if they are unsupported.

      Technically a hollow sounding tile is not a defect, but often it can be a symptom of a defect. There are many reasons why a tile might should hollow. Generally speaking if one portion of a tile or random areas of an installation are hollow it is more likely due to voids under the tile. If the tile isn’t bonded well then we would expect to see the adjacent grout joints being cracked. The only way to determine what a hollow sound means is to remove some tiles that are hollow and remove some tiles that do not sound hollow and compare the difference of the the underlying conditions.

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