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Two days after laying I can pull up Tiles!

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  1. #1
    Senior Member YoungBolt's Avatar
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    Default Two days after laying I can pull up Tiles!

    Hi crew

    How long would it normally take tile glue to be rock hard and not be able to remove a tile?

    I recently Re reInstalled 300x600 porcelain tiles in my kitchen. I installed tiles about 3 years ago but it was a rush job and the result was that two tiles cracked and popped up. Back then I used a Dunlop rubbber modified adhesive but only laid with a 6mm trowel, didn’t glue down the tile substrate and buttted to sheets together. End result was that the floorboard moved under the two sheets And being that there was no expansion joint it cracked and split the tiles.
    I recently started upgrading the kitchen, changed the layout so figured it’s time to redo the flooring and hopefully do it properly now.

    Ive installed more joists Underneath and used ring shank nails to attach the boards to Them, renailed existing boards, stick down the substrate using stud adhesive and nails, And put an expansion joint.
    I also put down a Mapei primer-g primer. When laying the tiles I used a 12mm trowel Angled at approx 45-50 deg + Put a thin layer of glue on the back of the tiles.

    the glue I used was davco powder mastic.

    I glued it all Sunday night, Last night I cleaned out the grout lines. I found that much of the glue in the grout lines was still powdery and wet.

    So I thought I would give it another night to dry. This afternoon I thought I’d check how the tiles have stuck down. I wanted to check by trying to jimmy up some of the small tiles and see the resistance. To my horror two tiles have come up fairly easily, the glue underneath is still not fully dry. Coverage wise I could see my Thick trowel Lines and the back of the tiles have coverage (I.e can’t see much of the rear tile print). Ideally I would’ve liked the trowel lines to be squished down with no air gaps.

    is this just an issue of the glue not drying in time or is there something wrong with my technique?
    Should I be worried about the Rest of the tiles or does it just need more time?

    I’ve attached a picture of the tiled area, and the backs of the tiles. I forgot
    to take a pic of the glue trowel lines before I started scrapping it up.
    Attached Thumbnails Attached Thumbnails 908bfd91-cc4c-40c9-af4d-2ae86b1bc06f.jpg   113e32c7-5a0d-498b-82cf-49ee00f6165e.jpg   d56e6485-40f5-49d2-b9a4-4793a3a5bbff.jpg  

  2. #2
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    It’s been very wet and cold in Melbourne - might it be related to that?

  3. #3
    Senior Member YoungBolt's Avatar
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    I hope so?

    Yes and I'm in the foothills of the dandenongs so it gets cold!! I turned on the heating on sunday night but havent run it since. Not a huge amount of heat reaches the kitchen though because it's seperated by a wall.

    Can I get away with resticking those tiles down or do I need to make a new cut.

    Any better glues to use than powder mastic? I have a bag of smp evo I planned to use for the subway wall tiling. Is that stronger?
    I was even thinking of using araldite 2part exopy?

  4. #4
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    Was the adhesive a new bag or was it one lying around from another job ?
    How was it mixed and what consistency ?

    Yes it has been cold and wet but tile adhesive is not air setting, I would have expected that I should have good holding power by now. I prefer the SMP Evo but have not used Powder Mastic, there are a lot on here that have recommended it previously.

  5. #5
    Senior Member YoungBolt's Avatar
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    It was a new bag. Only bought it about two weeks ago.

    Davco recommended around 5-6L/20kg bag, so I went with about 1:3 to 1:4 ratio of water to powder. Mixed up around 5kg at a time, so I'd put about 1.5-1.8L of water and 5kgs of powder. I usually put the water in first and gradually add powder. I mix with a mixing paddle on my sds rotary drill. Mix until I couldn't see lumps, rest 5 min and do again. Mix to a similiar consistency to what I do for jointing/mudding walls - mostly like toothpaste although slightly runnier. I did use a square bucket so I can easily scoop glue out with a trowel and did find a bit of unmixed glue in the corners despite my best efforts.

    I must say I was surprised that these tiles can up so easily. Other ones around the area are much larger and are resisting my attempt to lift them them with my screw driver.

    Could it be these are not sticking as well because they have such small surface area?

    I'm considering trying to glue them down with something strong like araldite.

    The trim piece thing was shoved into the glue gap around 30-45min after I laid the front row of tiles. I wanted to them to settle a bit first before I shoehorned that trim in. I did find that the tiles had dropped a bit over the 30min adjustment tme so it needed to be tapped in place with a mallet. Could I have maybe forced the tiles up a bit when shoved that trim in. I need it in place to push down on the floating floorboards.

  6. #6
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    OK so power mixed, that's good and powder added to the water.

    mostly like toothpaste although slightly runnier.
    I normally go for thick toothpaste, the ratio is right so would not expect too much problem there. Did you let stand and re-mix before use ?

    I would have put the trim in before or while laying, often I put a nail or two in to locate it. It may be that it was enough to disturb it particularly it the floating floor continued upwards pressure against the tile.

  7. #7
    Senior Member YoungBolt's Avatar
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    I wouldn't bother with premixed glues. They're hideously expensive and I dont trust they've been made to be strong but rather cost effective for the manufacturer.

    I didn't want to go too thick as I was concerned it might be too powdery or hard to spready. Next time I'll make it thicker.

    I did let it stand for a few minutes and quickly remixed it. I've never understood why it's meant to be left to stand though. The mix looks no different a few minutes later.

    I'm wondering if that bastard trim might have been the culprit.
    If I wasn't dealing with the floaters, I'd have opted for a L shaped trim at 12mm high or tacked down 14/15 mm trim on the FC sheet and fit the tiles around it, however in this case I was needing the trim to push down on the floating floors. I did fit the trim while the tlles were setting but the glue may have already got a bit hard. Although that little corner piece of tile that came up I did fit last as it was being a PITA. I didn't use any trowel lines for that, just squished it in a big splodge of glue.
    The floating boards were about 8mm, the underlay is 4mm, so I had 12mms of height to work against. FC sheet was 6mm, accounted for about 4mm glue under the tiles and the tiles were 10mm tiles meaning the trim is pushed in at an slight angle but slipsunder ok. There is a very slight amount of play in the floating floors underneath but I'm not worried as it needs flexibility for hot days.

    I put bricks on the trim and floor to push it all down while drying though.

    Should I use just the same glue or change to the SMP evo or even something like an epoxy?
    Bad idea to reuse those tiles? Ive still got 2 spare, but wanted to keep them for spares. These tiles are still ranged at old Frank walker's house but they've now been on offer for almost 5 years so I suspect it wont be long before they EOL it.

  8. #8
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    I assume your first reference is to my comment of “power mixed” ? That was in reference to being mixed by a drill rather than hand, not reference to pre-mixed.
    Allowing it to sit and then re-mixing helps to get a complete and even consistency to the adhesive.

    If the rest of the tiles appear to be set I would suggest the trim install may be the culprit, I would just be using the same adhesive but suggest nailing the trim into position before re-laying the tiles, just scrape the old adhesive off and use the same ones.

  9. #9
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    Powder Mastic is a good glue, I have used it on many jobs.

    You need to leave them alone and let them dry out, it's cold and winter the moisture in the glue needs tine to evaporate, if you don't have enough warmth in the house it will evaporate very slowly.
    I wouldn't worry until after 7 days, being a cement based product it needs 7 days to set properly in normal conditions, so of course it's going to let go if you go jimmying them up !!!,

    Being colder this could take longer, Davco say 24 hours for grouting and return to service for a dry area and 7 days for wet
    I put some weathershield on the other day, it was sunny but not particularly warm, paint went on at 10.00am was till wet at 4.00pm, had to get the heatgun on it to dry it out.

    My advice is replace the ones you ripped up and just leave it alone and don;t be impatient with it, it will dry out, if you can warm the house it will dry out quicker, if you can't then you just have to wait.

    How cold has it got down there, it's not recommended to be applied if temps go below 5C, I can say 99% the problem is related to being cold.

    You should be able to reuse the tiles, because the glue is still green, get a scrubbing brush onto them with some detergent and hot water, it should clean most of it off,
    Mieux vaut prévenir que guérir

  10. #10
    Senior Member YoungBolt's Avatar
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    Thanks heaps droog and metrix for your help!

    This place is a goldmine!!

    Quote Originally Posted by METRIX View Post
    Powder Mastic is a good glue, I have used it on many jobs.

    You need to leave them alone and let them dry out, it's cold and winter the moisture in the glue needs tine to evaporate, if you don't have enough warmth in the house it will evaporate very slowly.
    I wouldn't worry until after 7 days, being a cement based product it needs 7 days to set properly in normal conditions, so of course it's going to let go if you go jimmying them up !!!,

    Being colder this could take longer, Davco say 24 hours for grouting and return to service for a dry area and 7 days for wet
    I put some weathershield on the other day, it was sunny but not particularly warm, paint went on at 10.00am was till wet at 4.00pm, had to get the heatgun on it to dry it out.

    My advice is replace the ones you ripped up and just leave it alone and don;t be impatient with it, it will dry out, if you can warm the house it will dry out quicker, if you can't then you just have to wait.

    How cold has it got down there, it's not recommended to be applied if temps go below 5C, I can say 99% the problem is related to being cold.

    You should be able to reuse the tiles, because the glue is still green, get a scrubbing brush onto them with some detergent and hot water, it should clean most of it off,
    Thank you for that. That's a relief! After my first failed attempt at tiling a few years ago I thought I may have stuffed something up here again. I was just trying to put a bit of pressure on them to make sure they've stuck on right. I don't want them to pop up.

    I assumed that if it's trafficable and grout-able then it's basically cured to 80-90% and should not still be wet in places. Didn't realise the cold can make it take so long to make it set.
    I was going to move the fridge back onto the tiles this week, but i'll likely wait until next week if it takes so long to dry.

    It's been a very cold winter here in gloomy desolate melbourne so it makes sense if that's the problem. You can feel the cold radiating from the floor in the kitchen. I'm missing a cornice and there's the holes around the taps so I'm sure the area is getting a bt of draft too. I ran the heater a bit last night too but it's a split system so positioned quite high up and the kitchen is separated by a wall so little heat actually gets into the kitchen area.

    The soapy water trick was really good in removing the glue off the back of the tiles. Managed to get jut about all of it off! However I did get in hot water with the misso when she caught me using her dish scrubber!! Needless to say i'm buying her a new one

    Where that davco glue has dried, it is rock hard so I'm sold on the glue. I've used a dunlop rubber modifed dunlop adhesive last time, and when i pulled up the tiles, the glue was powdery and had little rigidity. Pretty disappointed with that glue. Rubbish!

    Re-laid my two delinquent tiles last night. Didn't trowel any lines, just caked the area in glue and pushed the tiles into a nice pool of glue. Should hopefully ensure it the tiles dont come loose in that area.
    I have seen one tiler basically just make a bed of glue and squish tiles into it, was interested, but he was installing 300x300 tiles.

    Thanks again for the help. What a relief. Now to keep working on this kitchen. Timing is just ace considering it's stage4 lockdown in melbourne ....

  11. #11
    Je pense, donc METRIX's Avatar
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    Quote Originally Posted by YoungBolt View Post
    I assumed that if it's trafficable and grout-able then it's basically cured to 80-90% and should not still be wet in places. Didn't realise the cold can make it take so long to make it set.
    I was going to move the fridge back onto the tiles this week, but i'll likely wait until next week if it takes so long to dry.

    It's been a very cold winter here in gloomy desolate melbourne so it makes sense if that's the problem. You can feel the cold radiating from the floor in the kitchen. I'm missing a cornice and there's the holes around the taps so I'm sure the area is getting a bt of draft too. I ran the heater a bit last night too but it's a split system so positioned quite high up and the kitchen is separated by a wall so little heat actually gets into the kitchen area.

    The soapy water trick was really good in removing the glue off the back of the tiles. Managed to get jut about all of it off! However I did get in hot water with the misso when she caught me using her dish scrubber!! Needless to say i'm buying her a new one

    Where that davco glue has dried, it is rock hard so I'm sold on the glue. I've used a dunlop rubber modifed dunlop adhesive last time, and when i pulled up the tiles, the glue was powdery and had little rigidity. Pretty disappointed with that glue. Rubbish!

    Re-laid my two delinquent tiles last night. Didn't trowel any lines, just caked the area in glue and pushed the tiles into a nice pool of glue. Should hopefully ensure it the tiles dont come loose in that area.
    I have seen one tiler basically just make a bed of glue and squish tiles into it, was interested, but he was installing 300x300 tiles.

    Thanks again for the help. What a relief. Now to keep working on this kitchen. Timing is just ace considering it's stage4 lockdown in melbourne ....

    80-90% after 24 hours in this weather, no chance, more like 10% strength, just enough to be gentle walking on them and allows you to grout the tiles, even in summer conditions probably at best 24 hours 30%.
    I would normally leave the tiles for a few days before grouting as you want the moisture under the tile to escape, if you grout the tiles then that small gap that was assisting the moisture get out has been blocked it will slow the process down

    The ones you relaid with a blob will take a LOT longer to dry out as the moisture will take some time to get out from the middle of the blob.

    Be very careful running the fridge over them, you can easily dis lodge them if they are not cured enough, you might not dislodge them to pop up, but can fracture the bond of glue and tile, which can lead to a drummy tile or cracked grout in 6 months.
    My advice is if the house is cold, and Melbourne is cold, hang on Melbourne /cold DOH of course it's cold , then be patient and let the glue do it's thing.

    I'm sure there is plenty of other jobs you can do while you leave the tiles to set properly.
    BTW I have used the Rubber modified glues in the past and had no issues, it wasn't Dunlop branded but they are all basically the same, I have had good results with Powdermastic and SMP EVO, EVO is a really versatile glue.
    Mieux vaut prévenir que guérir

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