typical installation, tile one day grout the following morning. instructions on the bag say grout after 16 hours. I did remove and replace the underlayment with 5/8 underlayment grade plywood because the old tile would not come off and there were signs of dryrot where a washer sat. it was just easier
customer supplied the thinset, ultraflex with polymer. the bag says good to install on plywood.
I noticed the grout cracking and further examination revealed the tile coming loose. the thinset cannot be removed from the tile
I can remove the loose tiles no problem. there is full coverage of thinset. the underlayment is dark stained from the thinset but not one spec of it is adhered
what went wrong?
Replies
You didn't use a suitable cement backerboard such as hardi.
thats just bs
I've done many and fought with many others doing removal over plywood. never had problems before
I would agree with pelipeth, and add that if you saw the grout cracking that might be a sign of too much flex in the floor."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
5/8 underlayment over 3/4 subfloor, glued and screwed
I think the grout cracking is a symtom of poor adhesion
>>I think the grout cracking is a symtom of poor adhesion<<
I think you are right, but do not have a good explanation for why this is only seen in a few tiles -- it's not the whole floor, right?
Could there have been some sort of contamination present on your 5/8" plywood in the areas where the tiles are popping? Oil of some sort maybe? Silicone? WD-40? Heavy sap? Sometimes plywood has a "history" when you buy it..........
Are the failing tiles together in an area you can identify / remember as being at the end of the thinset mix? -- I have gotten lousy adhesion when the thinset was nearing the end of it's pot life.
FWIW, I usually build up to 1-1/8" floor thickness (3/4"+3/8") then thinset and screw 1/4" HardiBacker on top. Thinset, tile, grout. HardiBacker usually does not have a "history"....... and if it does, it shows on the face of the sheet.
Jim
Never underestimate the value of a sharp pencil or good light.
/Are the failing tiles together in an area you can identify / remember as being at the end of the thinset mix? -- I have gotten lousy adhesion when the thinset was nearing the end of it's pot life./this has happened to me, twice. honest, only twice. but not at the end of the bucket, 'cuz i usually mix too much lol, but at the end of a row that i have spread out too far along. both times the last tile i laid on that particular spread.i like the idea of misting the ply.but as someone mentioned, the OP's cracking grout seems to indicate something else going on.
Is that thick enough?
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
grout cracking can also be a sign that the tset sucked moisture outta the grout.
me ... I'm not a fan of working over ply.
also wanna add ... joist sizing and spacing are as important as build up ply thickness.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
You didn't use a suitable cement backerboard such as hardi.
Malarky. CBU is required in wet areas but that has nothing to do with the OP's problem. Modified thinset will adhere to plywood quite well under normal conditions.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Is it possible that the polymer settled in the thinset bag.............mix the whole bag or dry mix the whole if only preping a partial bag?Sounds to me like there could be a number of reasons for his problem.
Edited 5/18/2009 10:50 pm ET by JerryHill
Is it possible that the polymer settled in the thinset bag.............mix the whole bag or dry mix the whole if only preping a partial bag?
Sure, that's possible...and your suggested remedies are logical. But if the thinset was the problem--or specific partial-bag batches of the thinset--why are his loose tiles scattered randomly throughout the job? If he mixed one bad batch, the loose tiles would be those set with that batch in one discrete area. They wouldn't be scattered all over the place.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
The plywood sucked the moisture out of the thinset. I always mist the plywood prior to troweling on the thinset. IMO.
Questions:
How much of the job failed? The whole thing? One isolated area? Individual tiles or small groups of tiles randomly scattered throughout the floor?
Which type of Ultraflex did the HO supply? Ultraflex 1, 2, 3, LFT, or RS?
How big are the tiles?
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
8 inch porcelain tiles.
I think maybe 6 or 7 are loose. I can tell by the way the grout is cracking around them. its not an isolated area, randomly scattered
its ultraflex professional, not sure about 1,2,3 or otherwise
Ultraflex 3 is the pro version; it has the highest dry polymer content. But since this is a random problem, it's not the thinset nor your mixing of it.
Most likely reason would seem to be spot contamination of the plywood surface before you laid the tile. Was anybody walking across that subfloor with oil or some other kind of greasy stuff on his boots?
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
With the pocelain tiles I think you (or someone) may have brken the bond at the plywood walking or putting weight on them too early. Porcelain does not suck up the moisture in the thinset as doeas ceramic.
Was the ply clean? No drywall construction dust film?
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." — Sherlock Holmes, 1896
When tiling over ply, I recommend dryset and modifying it yourself with liquid admix.
Your ply could have been dusty? Contaminated? Dry? Burnished slick?
The thinset might have been old and it might have already partially hydrated while sitting on the shelf. Or in the garage. Or in a basement. Partial hydration can reduce or totally kill your final bond strength, and over ply you need all of it.
I'm sure you mixed it properly, then let it slake for full hydration?
Partially hydrated dryset gets chunky or clumpy in the bag. You can break them up in your hand, but you still have clumps. Modifieds are harder to diagnose, they can stay nice and powdery, but the powder has a slightly heavier texture. Hard to describe, but to me it's a "you brush it off your hands and it still feels like it's there" type of feeling.
the ply was new and clean. matter of fact I did all my drywall repairs before installing. I mixed partial bags as I went, back buttering the tiles with a 3/8 notched trowel because the pattern was diagonal.
I'm thinking the thinset was old. usually I supply my own but since it was there already I went ahead with it
today I am going to see how strong the bond is with the rest of the floor. if the tiles will come up easily then I am going to rip the whole floor out and redo. its only 90 sq ft, could be worse
Argh. What a pain. Good luck with the repairs.Several years ago my father-in-law did a small tile repair in his bathroom, when he was done the tile didn't stick. My brother-in-law called to ask for advice. Got the full story from him, which included my father-in-law using a partial bag of thinset that had been in the basement for well over 10 years. Over that time the basement had been flooded about 3 or 4 times. He had used a hammer to break it up solid thinset into powder. Hmm.
you possibly have something there
this morning I called the owner of my lumber yard and asked him if there were any problems with contaminated plywood. the georgia-pacific rep just happened to be in his office. they both never had a problem
then I called the customer service # on the bag of thinset. the rep there said I did everything right and most likely got a bad batch. he said the shelf life is 12 months no exceptions. there is supposed to be a batch # and manufacture date on the bag which of course is nonexistant. take it up with the retailer he said
next I mixed up a small batch of the suspect thinset and installed a tile to a piece of left over underlayment, a piece of underlayment from another job and a piece of 3/4 cdx. then I did the same with a different brand thinset that was in my trailor left over from 2 bathroom floors I did last month.
everything is labeled, tomorrow when the thinsets set up I should have some real data
I tend to be with the theory that the dry ply sucked moisture out of the mix for poor bond. When tiling on ply, I like to seal it first, usually with a bonding agent.
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A bonding agent such as...?
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generally, any white glue will work fine.Any place I have been able to buy tile, grout and thinset has bonding sealers also. I ask and they selll. That way it is definitely compatible with the thinset itself being same brand.Another way to go is bonding agent for concrete and thin it down a bit with water. It is a really thick white glue.
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It is a really thick white glue.
I used a bonding agent sold specifically for concrete topping a sidewalk, it was pink like pepto bismol, but it smelled and worked exactly like white glue."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I used a plaster bond/seal once that was pink like that.
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Since no on else has mentioned it, I am wondering about keying the thinset into the floor. Normally I will back-trowel the area I am about to work in so that I know that the thinset is bonded. Maybe not the first day, but after a while the thinset should have bonded better to the plywood than to the porcelain tile