Porcelain tiles and moisture issues

Discussion in 'Ceramic and Stone Q&A' started by roxanne, Apr 25, 2015.

  1. roxanne

    roxanne Member

    I am desperate for advice! We have a 30 year old home on a concrete slab. Several months ago we did a complete remodel of our kitchen and installed new 20x20 porcelain tiles. After about a month we began to notice the grout had dark spots in areas. After extensive investigation including running a camera through our plumbing lines to rule out any leaks, we pulled up some of the tiles and discovered water under the tiles! The thin set was attached to the slab, but the tiles popped right off. The flooring company, their product representatives, and the installer said all industry recommendations/guidelines were followed with installation and the problem has to be with excessive moisture coming from the slab. They did calcium chloride tests and said our moisture level was 4 times the level recommended for flooring. They wanted to put down a moisture barrier and reinstall the tile. We previously had ceramic tile and had no problems with moist. We have wood floors in all other areas of our home and have no problems. An independent home inspector came in and told us we had moisture but not enough to hurt the wood floors. He advised AGAINST putting a moisture barrier down in the kitchen as the moisture is still present and has to escape so we would run a risk of the water moving into the walls or the other areas of our home and ruining the wood floors!! He recommended we use natural stone sealed with a water based sealer and not sealing the grout. The floor company disagrees saying we will still have problems with mildew and "salt" buildup on the grout. The floor company will not recommend any type of flooring unless we put a moisture barrier. HELP!!!!! What happens in other homes with moisture in the slab when they put down a barrier before laying tile??? Surely we are not the only house in the country with this issue. Does it travel up walls and cause mold? Should I put down porcelain without a barrier thus going against the floor company advice? They strongly advice against porcelain in this situation as it doesn't "breath". They "think" maybe a red clay ceramic tile without sealing the grout and not putting a barrier "might" be ok. I am soooooo confused and upset. Can anyone offer advice?
  2. I think some more investigation should be done. I've seen a coring drill thru slab to physically see if a moisture barrier is present underneath.

    You need an independent inspector, I would call NTCA, tell them your situation, and the recommendations you were given. they have contacts throughout the land.
  3. roxanne

    roxanne Member

    Thanks for such a quick response! They have drilled into the slab. We built the house and know there is a barrier under the slab (plastic). Thanks for referring me to another source.
  4. roxanne

    roxanne Member

    Any other recommendations?
  5. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    ...and the tiles where installed with "exactly" what type of tile adhesive? Name it. Calling it "thinset" isn't an answer, name the product used.
  6. kwfloors

    kwfloors Fuzz on the brain Charter Member Senior Member

    How is the house situated, is it on a hill or flat? How is the drainage? I have seen springs show up under slabs years after the house was built. One house they put in 3 sump pumps to take care of their problem.
  7. Source of water needs to be determined. You had tile previously and didn't notice the wet grout? Could the remodel have pierced a water supply line? Strange how it's just kitchen, and hardwood areas are fine.
  8. I visited a home being built yesterday, took some pictures. I can only post one at a time from iPhone, but here's moisture"barrier" slowing water movement.

    Attached Files:

  9. roxanne

    roxanne Member

    Bud Kline -The installer said he used Laticrete Gold as a thin set.

    KWFloors - We are on flat land. We've lived in the house for 30 years and never had any water even near the house (even after hurricanes and heavy continuous rains in the Spring) so the drainage is good. Once we discovered this problem, we even removed all of the landscaping around the house (recommended by the tile company as it might be a source of the moisture). There was no mildew or mold along the outer slab and brick of the house. They inspected around the perimeter of the house and found no standing water. They dug holes into the ground around the house and didn't see any water below the surface of the dirt. We had minimal landscaping and no large trees next to the house.

    Mike - We agree the source needs to be determined. We are now into the second month of me not having a floor or being able to use my kitchen as we keep trying to figure this out. Any suggestions of just how to determine the source? We have run cameras through the plumbing lines, we've drilled into the slab, the put pressure through the lines, they covered the floor in plastic to see if any moisture would develop (it didn't), we've removed all landscaping around the slab to check for evidence of moisture outside and found none, they dug into the ground outside around the house and saw no water.

    It is beyond "strange" to us. It's like we can have any type of floor we want all over the house, but for some reason we can't in the kitchen area. It is actually a kitchen, breakfast area, utility room, a half bath and an entrance hall from the carport that got the new floor.

    When the independent home inspector tested the floor for moisture using some kind of hand held meter, he said that he was getting the same amount of moisture showing throughout the house and that it was "minimal" - not enough to cause any problem with the wood floors throughout rest of house (we do have ceramic tile in bathrooms and they are fine too). Also, our kitchen cabinets sit directly on the slab (not on top of tile) and they are not showing any signs of moisture damage.

    And...the den that butts up against the kitchen is actually sunken. It seems to us that if there is water coming up from the slab that it would be in there before the kitchen. There is no evidence of any moisture on the wood den floor.

    We've had multiple people trying to brainstorm the problem and how to determine the water source - floor installers, contractors, plumber, A/C contractor, independent home inspector, and even a friend who is an engineer. They all have no idea what is going on. Nobody has been able to tell us what else to do to see what the source of the water could be.

    We are baffled because we previously had ceramic directly on the slab (no moisture barrier beneath the tile) and had no problem. When they removed that ceramic tile the slab was dry and the tile was definitely stuck to the floor. Now - when they pulled up the porcelain tile because we saw the moisture coming through the grout, the thin set was damp in many areas, dry in some areas, and some areas had actual water in the groves of the thin set!

    I'm sorry my post is so long, but I'm trying to give as much information as I can.
  10. Incognito

    Incognito No more Mr. Nice Guy! I Support TFP Senior Member

    I'll bet your remodel workers violated the moisture barrier under the kitchen slab. Moisture won't travel THROUGH concrete horizontally to affect your adjacent wood floor but it will move under and on top and through any cracks or defects in the slab.

    What sort of penetrations were necessary during this recent remodel work?

    You've eliminated most of the usual suspects. I can only come up with sloppy CONCRETE patch work on any trenches that needed to be burst out to move gas, water and electrical lines.

    A. they failed to let those poured back CONCRETE patches fully DRY -----hard is not the same as dry (THAT'S where the moisture came from)
    B. they failed to effectively repair the moisture barrier (NOW moisture is free to enter your slab from below)
    C. both A and B
  11. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published


    Porcelain tile has the least moisture absorbency properties of any clay tile. Generally less than 1/2 of 1 percent. Slabs can always draw and contain some moisture. If and when this happens the moisture must have a means of dissipating and this is done via evaporation and the natural rising of moisture. Wet seeks dry.

    In the case of Porcelain tile the moisture would naturally migrate towards the grout lines. In the case of Porcelain tiles that are 20" square this evaporation process is even more difficult because the grout lines are far away from the centers of the tiles.

    Glazed ceramic tiles of the same large format size would present the same issues.

    It is required that large format tiles be "back-buttered" with a skim coat of thinset as well as thinset being combed onto the substrate. It doesn't sound like this "back-buttering" took place if the tiles are coming up with no thinset adhered to the backs of the tiles. The thinset used would have bonded to the tiles without question if they had been back-buttered as required.

    The moisture does sound excessive and would have difficulty evaporating because of the size and make up of the tiles used.

    The type of grout used may also be a factor in holding in some moisture. If the grout contained additives or was a modern urethane or epoxy grout it would also suppress moisture migration to the surface and not allow evaporation.

    I would be curious to know the size of the tile used in the previous tile installation. A smaller (12") tile would be more efficient in allowing moisture migration and hence proper evaporation.

    Without being there I'm guessing there is no moisture issue in the kitchen that isn't also occurring throughout the slab. The large format (20") tiles are simply reducing the ability and efficiency of the substrate to naturally evaporate moisture and allowing excessive moisture to accumulate, whereas the rest of the house is more friendly to the evaporation process.

    I'll bet if the tile size is reduced and Portland grout used the problem will go away.
  12. roxanne

    roxanne Member

    Bud - This is very helpful! The previous tiles were small ceramic - maybe 9x9??Do I understand correctly:

    I could use porcelain tiles again if:
    1. Installer will back butter the tiles (I know this was not done - the installer said he didn't)
    2. Use a smaller sized tile (maybe 12x12??) to have more grout lines and less tile surface as this will aid in evaporation
    3. Do not add additives to grout. Suggested "Portland" grout.

    Would we seal the grout at all?

    One more question:
    Since we did not have a moisture barrier between the slab and original ceramic tiles, do you think we're ok not doing so again if we go with what you mentioned above?
  13. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    If you had no moisture issues in the past, and nothing has changed as far as a new water source, and previous tiles were 9"X9", then I'm fairly confident you don't have a problem.

    Back-buttering the 20" tiles would not have changed your moisture issues that you now have but you can see that you also didn't have a proper bonding of the tiles to the substrate. Back-buttering large format tiles is common knowledge throughout the industry, well almost, apparently there is at least one installer that hasn't heard of it, and that is your guy.

    Be sure to use regular (powdered) thinset, don't get into any of the pre-mixed thinset products. The Laticrete Gold would be an excellent choice next time around also.

    Most Portland grout products today are "polymer modified" and that's okay. Just don't beef-up the grout with any other additives. You can then seal the grout with any grout sealer and you won't cause any moisture trapping issues. Today's grout sealers are "vapor transmissive" for just this reason. Grout sealers don't really seal the grout like one would think they should. Grout sealers just give you a little more time to clean up a spill that could otherwise stain the grout.

    A moisture barrier isn't necessary in my opinion. All that would do is move your moisture-trapping issue downward one layer and you would be back in the same boat you are in now. Eventually the barrier product could become detached from hydraulic forces and then blister and tent, thereby de-bonding the tiles. Leave the slab alone and let it breathe.

    One can argue all day long about how dry a concrete slab is, I can tell you they are never really dry. Their very nature draws moisture through natural capillary action. Moisture doesn't require any outside forces to draw/wick moisture into a concrete slab.

    Your initial inquiry was quite complete with findings and you seem to have exhausted all other avenues explanation. So, this is my best-guess. And yes...there is no reason you couldn't again use Porcelain tile as long as the tiles are smaller than a soccer field.;)
  14. roxanne

    roxanne Member

    Thank you soooooo much for your thorough and prompt reply! I am feeling very optimistic that we finally have a recommendation of what to do and can move forward with finishing up this job.
  15. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    Well this is only my thinking and opinion based on almost forty years in the tile installation business and watching these products evolve over the years. My opinion...your dollars. I can't satisfy myself with any other explanation since you have so thoroughly already investigated a lot of possibilities. Saved us asking all those same questions. I love it when a person comes here prepared and has done all of their homework.

    I gotta tell ya...when the large format tiles came along several years ago they met the market with great acceptance. Now they are proving to be a huge pain in the ass in a lot of ways. Large format tiles create more issues then they solve in my experience.
  16. MCameau

    MCameau Member

    Hello, I am having the EXACT same problem as described above. Were you able to resolve your flooring issue? We installed porcelain tile made in Italy, and shortly after we experienced the same, a lot water under the tiles, wet walls, tiles just popping right off. Did you end up resetting your floors with another ceramic tile or another porcelain? We had our water table tested, french drains installed, everything under the sun, and it's a condensation issue with this tile. We have ceramic in other areas of the house and there is no weeping grout, no indication of water.
  17. Jim McClain

    Jim McClain TFP Owner/Founder Administrator

    This topic is more than 2½ years old. Most of our consumer/DIY members come here to address a problem and usually don't return. You would do better to start a whole new topic and ask for help from our pros.
  18. Justin Lee

    Justin Lee Not A Fan Of Forum Process

    Hi Roxanne,

    I am in the exact same situation you are. Literally, mind blowing. Have you found any solutions? I have lost sleep over the last 2 yrs because I invested so much money installing my large porcelain wood like tiles. I have consulted with 3 geotech engineer firms, 3 full leak detection tests, building scientist consultation, flooring experts and cant fins a solution. I even teied a radon mitigation system (subslab depressurization). Even thay didnt work. Im desparate
  19. Jim McClain

    Jim McClain TFP Owner/Founder Administrator

    @Justin Lee You quoted my post where I told the previous person who replied to a 2½ year old topic, which is now a 4 year old topic, that consumer/DIY members don't usually come back to reply to posts like yours. You should have also seen that the last person to ask a similar question as yours also didn't get a reply (except for mine). Please take the time to read what is presented for you. Me and the rest of the regular members here do our best to help you, but you gotta meet us half way. Don't reply to old topics. Don't ask the same questions in multiple topics. Stay focused, ask us for help in your own topic and we'll do our best to provide you with assistance.

    Or am I just talking to a hole in the ether? :hmmm:
  20. Justin Lee

    Justin Lee Not A Fan Of Forum Process

    My apologies,

    I have never done a forum online before. I got excited when I saw others with the same mysterious problems as me. I will refrain.
    • Like Like x 1

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