Replies

1. 
   billyg | Jul 25, 2004 03:29am | #1

   My guess is that the substrate under the tile is the problem, as indicated by the broken grout and popped tiles.  It could be the thinset, but I doubt it.

   Is the joist sizing and spacing O.K. for tiles (more important for larger format tiles such as 12x12 and up)?

   If there is OSB or luan underlayment, you should rip it up.  They are not suitable substrates for tile, particularly because they will get wet and expand in a bathroom floor.

   Hopefully they didn't thinset directly to the plywood, although some people have success doing this with the right thinset.  It's not the "best" way though, as cement board should be thinsetted and screwed to a solid plywood subfloor. (Actually the best would be a mud floor, but you're not going there.)

   I also suggest using a membrane such as Ditra over the heating mats or cables.

   Billy

1. 
   oolong86 | Jul 25, 2004 04:09pm | #2

   Ripping up the floor is more extreme than the client can handle.  We need to preserve the existing heating wires and the other 90% of perfect tiles.  Is it possible to remove the loose tiles without damaging the wires?  Would it be possible to leave them in place and inject some type of suitable adhesive?

   Edited 7/25/2004 9:17 am ET by aisha

1. 
   billyg | Jul 25, 2004 04:45pm | #3

   There's another possibility that I should have mentioned first -- perhaps there was not sufficent thinset contact between the tile and the floor.  The installer needs to use enough thinset over the heating mat and press in the tile so that it gets about 90% or more coverage on the tile.  Or they can back butter the tile to insure good coverage.

   Can you get up one of the tiles and check to see if there is sufficient thinset coverage under the tile?  Can you tell if the thinset was spread thickly enough over the mat?  

   If you cannot pry up one of the tiles without breaking it, then you are going to have to chisel it out.  :-(  Is there any spare tile, or can you match it?  The heating mat manufacturer will have instructions for removing the tile without damaging the mat.  Obviously, you need to be very careful and work slowly. 

   Use a good quality modified thinset to reset the tiles.  Hopefully the original installer did not use mastic on a bathroom floor (if they did, it could have caused the problem you describe).

   If the problem was caused by inadequate support or an improper substrate under the tiles, your fix probably will not be permanent.

   Maybe Boris Yeltsin or some of the others here have additional suggestions.

   Or check here:http://johnbridge.com/vbulletin/forumdisplay.php?&forumid=1

   Billy

   Edited 7/25/2004 10:05 am ET by Billy

1. 
   Dinosaur | Jul 25, 2004 05:06pm | #4

   I've successfully (15-year-old installations still problem free) used mastic on both bathroom and laundry room floors. Also on both concrete slabs and plywood on joists as substrates. I believe that as long as the grout is well done and sealed, and there is no more than occasional 'casual water' on the floor, there shouldn't be any major problems. (Major flooding or permanent water hazards are another story....)

   That said, my experience with thinset on plywood substrate supports what you said about this not being the best combination. A 6x6 terra cotta kitchen floor I did that way many years ago is now full of hairline cracks and will have to be torn up and re-done. I suspect insufficient substrate stiffness, but perhaps the use of thinset also contributed to the problem.

   I too would like to hear Boris's opinion on this one....Dinosaur

   'Y-a-tu de la justice dans ce maudit monde?

1. 
   JeffBuck | Jul 26, 2004 01:59am | #6

   stop using mastic on floors ...

   JeffBuck Construction, llc   Pittsburgh,PA

        Artistry in Carpentry                

2. 
   Dinosaur | Jul 26, 2004 05:55am | #7

   Elucidate....Dinosaur

   'Y-a-tu de la justice dans ce maudit monde?

3. 
   billyg | Jul 26, 2004 12:14pm | #8

   Dinosaur, that was a killer glass block and wood bath you did in that basement. 

   But why use mastic on floors, particularly concrete floors?  You know they are prone to failure if there is too much moisture.  All it takes is some landscaping change or clogged gutters and there may water in the basement... and the mastic will not fare too well.  It's easy and cheap to mix thinset.  Why cut corners and use mastic on floors?  It's kind of like skipping PT wood for the sills.  Thinset will handle the water if it comes and mastic may fail.

   Billy

4. 
   Dinosaur | Jul 27, 2004 08:26am | #16

   Fair enough. I haven't had any callbacks so far for water damage...but that doesn't mean it couldn't happen on a job I do tomorrow if a washing-machine hose lets go while the HO's off on vacation....

   I'll think of it as cheap insurance in the future....

   Dinosaur

   'Y-a-tu de la justice dans ce maudit monde?

2. 
   Frankie | Jul 25, 2004 05:21pm | #5

   You can't inject anything. If the tile is loose and wobbles then:

   a) Score-out the grout and remove the tile.

   b) Dollars to donuts, there was not a complete bond between floor and tile. Thinset voids. Was the tile back-buttered?

   c) Carefully remove whatever thinset remains on the floor.

   d) If you removed the tile w/out breaking it and are abe to get most of the thinset off the back, use it over again.

   e) This time set the tile with a modified thinset. Trowel the thinset on the floor and butter the tile back. Lay two lengths of fishing line in the tile space and rest the tile. Check fo wobble and tile height. If everything is okay, pull out the fishing line. If some adjustment is required, use the fishing line to remove the tile.

   f) Post #4 had many good points.

   F

3. 
   pebble | Jul 26, 2004 04:42pm | #9

   The isnstallation instruction for electric radiant floor say one should wait for the mortar to cure first before operating the system. One should only turn it on right after installation for less than ten minutes to make sure its working properly. Being less than six months old it might be just theres not enough thinset under those three tiles but also it could be possible the system was operated before the thinset had a chance to properly cure (maybe even dry out), causing the the movements in the tiles.

   Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK

   "If yer gonna drive fast on the highway why not go as fast as you can? Like... a hundred miles per hour or more lol."

1. 
   JeffBuck | Jul 27, 2004 07:26am | #15

   knock on all of them to see exactly how many are loose ...

   just like ya knock hard on a door ...

   you'll hear the difference ...

   if just a couple ... hope for the best.

   Like Boris said ... this isn't a good install from the start ...

   but people have gotten lucky .. maybe ya lead a clean life up till now ...

   me ... I'd smack the center of the loosest tiles and see what happended.

   Then ... I'd smack it again. If it's loose enough to rattle .. chances are it'll come right up.

   I have a little finish carp pry bar I use ... it's a japanese model ...

   and .. I have a nice heavy duty thick putty knife that is used primarily for delicate destruction.

   Get the tiles up ... level the thinset underneath as much as possible without cutting the electric lines ... usually scraping with either or both tools works ...

   know what else works good ... the claw on an estwing hammer ...

   but ya better use control.

   Now ... shop vac ... and since the first install is crap ...

   I'd just mix up some nice fat thinset ... lightly butter the floor ...

   then with a small notch trowel ... I'd take a look at my 3/16th V notch ...

   back butter the new tile and set her in.

   now ... smack it down tight with your mallet .. or my hand ...

   and away ya go.

   Make sure to clean out the grout lines nice and neat all around any open areas ...

   sucks when you get the tile to lay down nice again ...

   but there's an old chuck of grout holding ya cockeyed ...

   And like someone else said ... if this is for money ...

   no guarantee ...

   shoulda been some backer ... and one layer of 3/4 ain't enough.

   JeffBuck Construction, llc   Pittsburgh,PA

        Artistry in Carpentry                

1. 
   ANDYSZ2 | Jul 27, 2004 08:38am | #17

   One trick is to get good big cedar shakes and use them as wedges to gently pry  tile free.

   Removed a full length mirror that was glued on with mastic or vulcum last week and I used about 8 regular shims without breaking .

   ANDYSZ2I MAY DISAGREE WITH WHAT YOUR SAYING BUT I WILL DEFEND TO THE DEATH YOUR RIGHT TO SAY IT.

   Remodeler/Punchout

1. 
   Scooter1 | Jul 27, 2004 06:05pm | #18

   The problem is that by simply replacing the offending tiles, you are installiing them over plywood and thinset and the installation is doomed to failure. Yes you can fix a tile or two now, but more will crack and come loose in 6 months, and the ones you are replacing now will also fail.

   This is like trying to fix an oil leak by adding more oil.

   I repeat, this is a tear out, or perpetual replacement.Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

1. 
   oolong86 | Jul 28, 2004 02:00am | #19

   Thanks to all for your input.  Still have a couple of questions.  Please explain why a 3/4" plywood base, covered by a 1/2" of cementitious product, on top of which tiles laid with thinset should fail?  Has anyone actually tried to inject or apply anything such as hi-temp silicone or various epoxy compounds in the voids of loose tiles?  This is too large, complicated, and expensive a job to tear out.  Fewer than 5% of the tiles show any signs of movement & no hairline cracks are visible.

2. 
   Scooter1 | Jul 28, 2004 02:13am | #20

   The half of cementious product you talk about is thinset, not a mortar bed. Thinset is not very strong (because it has no sand) and is about as structural as Elmers Glue.

   Portland Cement, by itself is stupidly weak (less than 500 psi). Add some sand, it suddenly becomes stronger (1800 psi); Add aggregate and you can build buildings out of it; Add steel, and you can make skyscrapers.

   The same is true with thinset. It is all glue, and no structure.

   I would have contacted the manufacturer of the heating element and got a specification from them as to installation, which presumably would be embedded in a gypcrete or mortar bed substrate. The latter is an excellent setting bed; the former is a good substrate, but needs a membrane over it to hold tile. The other alternative for this might be a "cementous layer" as you call it, covered with a membrane like Ditra or NobelTS. Dunno, I would have checked with the manufacturer.

   Plywood expands and contracts at much a different rate than masonry products. Thats why no one ever ever tiles directly on top of plywood. If you must, one uses a Membrane like Ditra or NobelTS, but the better choice is always a mud bed. So what happened is that with the expansion and constraction, the thinset lost its bond and the tiles cracked. You won't have to worry, there will be more failures.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

   Edited 7/27/2004 7:16 pm ET by BORISYELTSIN

3. 
   oolong86 | Jul 28, 2004 05:36pm | #21

   The approx. 1/2" cementitious layer's exact compostion is unknown to me, as I'm still waiting for the "expert" installer to re-view his work.  I have contacted WarmTiles for advice but have yet to hear from them.  Their installation guide is at this link: http://www.warmtiles.com/_PDF_Files/WTMC_ii_020716.pdf

   Oddly enough, even tho they say this about suitable substrates, their photo illustrations all show a plywood base:

   •The heating cable and the factory splice joining it to the cold lead must be embedded in a masonry base (cementitious based mortar).

   To minimize potential tile cracking, it is important that the sub-floor on which the tile is to be laid is sufficiently rigid.

   •It may be necessary to apply an underlayment such as backerboard and/or mesh and mortar to achieve a solid application surface to ensure the floor is stable, smooth and clean. Tile experts typically require a 1¼" thick sub-floor base for ceramic tile.

4. 
   Scooter1 | Jul 28, 2004 05:55pm | #22

   I couldn't load those instructions other than the first few pages.

   Based on what I saw in the booklet and you have told me, I suspect the installer used a "scratch coat" or "thin bed" method of installation, which might even recommended by Warm Tiles, so it seems.

   The technique is to use plywood, then diamond lathe, then a layer of thinset, then embed the electric matting, then more thinset. This would add up to about a half an inch.

   At the Tile Council they have a machine which I think is called a Robinson Flooring Machine, which is a huge roller thingy that rolls over floors and tests, underlayment, setting beds, and completed installations. I was told that the TCA has repeatedly tested "scratch coat" methods and they always fail. The thinset provides no strength.

   I would install this matting in a full mortar bed or gypcrete with a membrane on top.

   If the installer actually followed the instructions and the installation failed, then I might look to Warm Tiles on their Warranty. If they are stupid enough to warrant a scratch coat, then you ought to take advantage of their warranty.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

5. 
   splintergroupie | Jul 30, 2004 12:08pm | #23

   I'm not meaning to contradict your experience by any means, but i had this happen to me last January on my own kitchen floor:

   I set tiles on underlayment-grade plywood with a thinset material called Versabond, but two days later lifted each tile up by hand. (first attachment). After they were all scraped clean, they were re-laid with Mapei Ultra/Flex 1, then i waited a day and attempted to pull one up with no luck, so i grouted (second pic).

   I've been walking on the floor ever since with no loose tiles happening. I've become a Mapei convert*, or maybe the first failed layer made the second one work...somehow...but the only easily identifiable variable is the brand of thinset.

   *I experimented with one bag of the more-expensive white UltraFlex and it seemed to stick to stuff even more aggressively than the gray.

6. 
   aimless | Jul 30, 2004 02:01pm | #24

   SG,

     Pretty floor - I really like the colors. 

   When my husband and I decided to tile a floor and knew nothing about it we went to a local tile supply store and asked some questions. Even though the ceramic tile we bought from them was cheap, they steered us towards Mapei products - a cheaper thinset for setting the concrete backer board and Ultraflex for the tile. The install looks great and has for years. As a result of their kind treatment of us, the tile store now has lifetime customers - we've gone back again and again since. No, we aren't a good customer like a real tile guy because we only have the one house, but that makes their attitude towards us all the more admirable.

7. 
   splintergroupie | Jul 30, 2004 09:07pm | #26

   Thanks, aimless. As for as the small amount of tile products you bought, i would bet you've referred people to that good store, too, so the time they spent with you was well worth it.

8. 
   Scooter1 | Jul 30, 2004 06:41pm | #25

   Ultraflex is an awesome thinset; it has so much latex in it, its sorta like combining caulk and thinset. It is also about $30 a bag, double the price of ordinary thinset, but a bargain, if you need it.

   Read the label on Ultraflex carefully--it is not, repeat not, designed for wet locations. So I would not recommend it for any kitchen or bath. It will re-emulsify.

   I hope you keep your floor dry. Setting tiles directly on wood is not recommended by any tilesetter, although it is done all the time. Maybe you will get lucky.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

9. 
   splintergroupie | Jul 30, 2004 09:28pm | #27

   There is one major masonry retailer besides the box stores here, where i originally tried to buy something i'd used before, for a slate floor in a bath, called Spec Mix. The owner tried to tell me the Quickcrete-brand product he was now retailing in its place was the exact same stuff, only that the Spec Mix people had just run out of their own bags for that run. Speaking of run...i did!

   Anyhow, i ended up at Lowe's for the Mapei, from good mentions it got here in BT. I just looked up a receipt from January: a 50# bag was $12.29, a bit cheaper than what you're saying, but maybe retailer-sized bags are smaller than the ones a pro buys wholesale? I also scored four torn bags for $5 ea, which is how i managed to experiment with the white Ultra/Flex.

   I just read the bag in regard to what you said about plywood and water concerns. It says not to use in *prolonged* damp locations, so i suppose much depends on how messy one is. It allows a plywood substrate, but only if underlayment rated. (There go my plans for all that CDX i've stored outside for 3 years...<g>)

10. 
    Scooter1 | Jul 30, 2004 11:14pm | #28

    Yeah, its good stuff alright. And yes the technical bullitin allows tiling over EGP in DRY locations. Kitchens and Baths are not, by definition dry. The information in their technical bulletin is at odds with the material on their bag, which you correctly point out says "prolonged" water exposure. I think I would go with the technical bulletin, not the stuff on the bag.

    Personally, I wouldn't put any tile over plywood, but if Mapei warrants the installation and it fails, then you go guy! I just don't want to be in a warranty claim position. The customer is angry and I've lost a referral, and I am out money for many weeks, probably months.

    Regards,

    Boris

    "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

11. 
    splintergroupie | Jul 31, 2004 12:23am | #29

    Yeah, i'd have been livid if a professional tiler had done my floor like i did the first time! For a DIY, it's only time, money, and ibuprofen. It's good to know the technical bulletin info on that stuff and i'll definitely heed your warning about a cement substrate in the future. Thx.

    Colleen

12. 
    Dinosaur | Aug 04, 2004 06:36am | #30

    Boris--Good informative posts in this thread. I'm learning stuff I oughta have known before....

    So...question time. You got me curious with your explanation about thinset lacking any structural strength worth mentioning:

    What about these new 'self-levelling' products--I have refrained from using one yet, because I don't know enough about how they perform. What's the skinny on them and do you have experience working with them?

    Dinosaur

    'Y-a-tu de la justice dans ce maudit monde?

13. 
    Scooter1 | Aug 04, 2004 06:55pm | #31

    Oh yes. I use Custom's LevelQuick, but I'm sure that others are equally good. The problem with them are that they set up incredibly quick--you have about 4 minutes to mix and spread them and you can't have cold joints. So if you have 5 bags of the stuff to apply, you essentially have to have 5 helpers, each with a bag and 5 gal bucket and a drill with a mixer paddle. Small deep pours can be a Chinese fire drill. All surfaces have to be sealed and and sides have to be blocked to dam the area in. Thick pours over about a half inch have to have diamond lathe.

    I do have an amusing story of a time we were doing an old bathroom and we didn't seal the subfloor very well with felt. We poured about 50% more than I had estimated and I was scratching my head as to why. Suddenly I hear a scream downstairs and run into the living room, only to find SLC pouring out of a light socket, sparks shooting out of the box, and a hysterical homeowner. It took us a week to chisel out the SLC from the joist cavity, repair the drywall, and re-wire the fixture.

    Regards,

    Boris

    "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

14. 
    Dinosaur | Aug 04, 2004 10:08pm | #32

    Ooooh-kay....

    I think I'm gonna limit my use of that stuff to basements....

    Actually, it sounds like the hydraulic cement I use to stop leaks in foundation walls--it will actually set up under water, and if you're not fast on your feet, it'll set up on your trowel....

    Supplementary question: are there any issues involved with having the floor leveller poured on a layer of felt or plastic, which would seem to me to prevent it forming any kind of permanent bond with the solid substrate?Dinosaur

    'Y-a-tu de la justice dans ce maudit monde?

15. 
    Scooter1 | Aug 05, 2004 01:43am | #33

    Most SLC I use is perfectly safe. I was just a moron.

    I use felt, appropriately overlapped by 2 inches, stapled to the floor; then 3.5 pound diamond lathe, also appropriately stapled to the floor; then the SLC.

    If you skip the felt and wire (like in the case of a slab or mud bed), use the primer sold with the SLC. In that instance you really don't want a de-coupler, and actually want it to bond with the substrate. This is true for all masonry to masonry applications.

    On masonry to wood, you are correct, you really need a de-coupler, which is the felt, and it seals the floor so there are no leaks. It sets up in 5 minutes, and is rock hard in about 3 hours, so really unless there is a huge hole, it will pretty much self seal. Great stuff. In applications over a half or three quarters, you need the diamond lathe.

    Regards,

    Boris

    "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

16. 
    davidmeiland | Aug 05, 2004 04:36am | #34

    Question for you on SLC....

    Watched tilesetters on a job apply the Quikcrete version thusly: screw down 1/4" hardi to the subfloor, install heating mat wires to the hardi (taped 'em down), poured SLC over the wires, and then thinset tile to the SLC. The SLC was mixed in a galv trash can, wheeled to the bathroom on a hand truck, and poured. Two guys had no problem and no particular hurry getting it done. They went about 3/8" thick as far as I could tell. Part of the goal was to level the floor (in new construction) and part was to cover those damn wires.

    Sound copasetic?

17. 
    Scooter1 | Aug 05, 2004 04:50am | #35

    Yep.

    I haven't used the the Quickcrete version, but my experience as to the masonry types of SLC's are not good. Because of the lime and sand in them, they tend to slump more, e.g., hills and valley's and have to be screeded somewhat, which sorta defeats the purpose of a Self Leveling Compound, and adds inherent errors to the installation.

    So the non-masonry types, e.g., white powders, that cure through reaction to water quickly are thinner, slump less, and cure about 10 times faster.

    Self Leveling Compound: Two lies in one.

    1. First, it doesn't level by itself. Any project over about 100 square feet and ya'all will need some helpers. Like I said, the stuff I have used all sets up very, very quickly.

    2. Second, it is rarely level. At least the liquids like LevelQuick are better than the sand and masonry types, but in any event, there will be slight hills and valleys in any product. If you are installing small mosiacs, you will need a dead flat setting bed, and some patching compound and a straight edge might be necessary to get it dead flat after the SLC cures. Larger format tiles you won't have that problem.

    Regards,

    Boris

    "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

18. 
    davidmeiland | Aug 05, 2004 07:56am | #36

    These guys got a very flat floor. They made a sort of crude rake without tines and sluiced the stuff around a little to get it into corners, and then had coffee. A couple hours later it was still green enough to cut with a bread knife but you could walk on it.

    My concern was mostly about thinsetting right to it. I had expected them to level the floor first, put hardi over that, and then tile. Since they wanted to bury the wires they did the hardi first.

19. 
    billyg | Aug 06, 2004 08:15pm | #37

    Here's what the SLC looks when it's wet.  Boris is right about the Chinese fire drill -- you don't have much time to work.  Make sure that you use expansion strips (such as sill seal) around the perimeter.  (Boris, I meant to post this to the thread , not to you, but I'll post it anyway.)

    Billy

20. 
    FamilyResidential | Apr 04, 2016 02:14am | #38

    Fix-a-Floor

    Home Depot sells an injectable product that could work if you can get it in, weigh it down and keep clients off it.

    It's probably not a permanant solution, but it might buy them a few years until they can afford to redo. Just make 

    sure to get the 12 pack of 10.1 oz tubes. The nozzle is narrower and you will need A LOT more than you think, 

    a full tube or more for every sq. ft. of loose tile. I would only ever recommned this as a temporary fix on electric

    radiant floors. As to how to remove carefully from earlier post, diamond triangle and grit tool on grout, hammer 

    to break tile AND thinset. Don't try to cut, grind, etc. Those wires will be everywhere and are impossible to splice

    without a HUGE hassle. You might try an oscillating scraper once you can see more or less where the wires are,

    but once you wack it a few times with a hammer, thinset should come off enough to reset tile. Backbutter it good.

4. 
   Scooter1 | Jul 26, 2004 10:05pm | #10

   Please give us details regarding the construction. Start with joists, then subfloor, then the heating element, then the setting bed. I need brand names and specs for everything that went in there.

   This is probably a tear out, but one never knows.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

1. 
   oolong86 | Jul 27, 2004 12:01am | #11

   Joists are 3" x 12" x 16' on 24" centers along the width.   A 6x10 beam runs the length under the joists in the middle.  The subfloor is 2" x 8" pine laid diagonally.  Shims cut from lengths of 2x4x8 and varying in height from 1 1/2" to 1/4" are screwed into the subfloor at 12" centers.  3/4" t&g plywood is screwed to these lengths of 2x4.  The wires (no mats in this system) for the Warm Tile Easy Heat is fixed to the plywood and embedded in a thin layer of modified thinset. Once this layer dried, the lines of the wires appeared as small ridges in the thinset.  The tiles were applied with thinset. 

1. 
   Scooter1 | Jul 27, 2004 02:26am | #12

   Tile applied directly to wood (with thinset of course)?

   If so, I'm surprised it lasted this long. Tile needs to be applied to a mortar bed, cementous backer board unit (CBU) or in some cases over a membrane.

   This is a tear out.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

1. 
   davidmeiland | Jul 27, 2004 03:10am | #13

   But... the man said he can't tear it out. It may be possible to get the tiles out and reset them, but it will be (a) difficult (b) dangerous to the heating wires, and (c) temporary at best. Take a knife and VERY carefully start to score out the grout around one of the loose tiles. You need to be absolutely sure you are not cutting deep enough to hit the wires. If you can work out enough grout and increase the amount that the tile wiggles, it will be possible to remove it. Believe it or not a glazier's suction cup can be a nice tool for pulling on tiles if they're polished and flat enough. Once you get one out, reset it with enough thinset and then regrout it.

   Be prepared for catastrophic failure. Or maybe just walk and go to a different job without so much damn risk.

   I was working recently in a new house with 4 of those heating mats. Two were damaged before the tile went in and had to be replaced. The tilesetter was quite nervous about them and I'm sure he didn't smear the thinset against the floor nearly hard enough. Those tiles will probably pop too.

5. 
   USAnigel | Jul 27, 2004 05:39am | #14

   If they move or "rock" then the bond is broken and you should be able to lift then up. Maybe with a glass "sucker" scrap off what you can and then re-thinset. The old stuff might have skinned over before the tile was installed and thats why the coming loose. Tell the owner this is a repair with fingers crossed, so no warranty as how long it will last.