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AndrewH 03-17-2007 08:33 AM

adhesive for tile flooring?
I recently installed a ceramic floor using an adhesive rated for floor use, I waited 30 hours then grouted, it looked great until I walked on it and all the grout started cracking where I walked on it! The adhesive was rated for use on floors and I installed it per the mfg. instructions. could it be that 30 hours was not long enough? the flooring was mounted on a double layer of 5/8" plywood that was screwed thoroughly prior to tile being installed which I think would rule out flex? I regrouted the floor where it was cracked, will it set-up solid enoug to walk on without movement?

JJC 03-17-2007 09:16 AM

Was it a premixed material or a powder form you had to mix? If premixed, they might be rated for floors but have limitations as to there use. Need to know all the particulars before before we can help.

JazMan 03-17-2007 11:40 AM


There is no doubt in my mind that you used a pre-mixed mastic. You selected an absolutely inferior method to install tile. It will not get much better. :no: You should start removing the tiles now, maybe you can salvage some of the tiles? If you do try to re-use them make sure all the mastic is removed.

How did you get into this mess, did someone recommend products to you?


AndrewH 03-18-2007 04:23 PM

yep, it was a premixed mastic. I did use as specified. and only later realized I should have used thinset. The ten million dollar question is this: Will it crack again? I regrouted it again after I noticed the cracks and have stayed off the floor it will be about 10 days. I am having the surrounding rooms hardwood redone and cannot get to the bathroom now if I wanted to. The product was Omnigrip. I am a good electrician but a poor floor installer (it sure looks great but now I am afraid to walk on it!)

JazMan 03-18-2007 06:35 PM

OmniGrip is a premium mastic and is fine for kitchen backsplashes or any non wet wall area. It's a shame that manufacturers think it's ok to out and out lie about mastics and where to use them. I think they all stretch the truth. However they always write in a caution that is easy to misunderstand by its vagueness. Such as this one that you must not have noticed?

Allow a minimum of 24 hours drying time before applying
grout. Cure time can be greatly extended when setting dense
tile, tile larger than 6" x 6" (15 x 15 cm), bonding tile to dense
surfaces, in high humidity, or when temperature is below
60 F (16 C).

Even that doesn't really tell the average novice much. I guess this is a bathroom floor? Double plywood? First mistake. It's best to install tile over tile backerboard or an appropriate membrane. I don't know how your subfloor system is built. If house is fairly well built, the floor should be sturdi enough.


AndrewH 03-18-2007 08:43 PM

I guess I should preface my comments by saying that this house was a budget flip, and I would have used a backerboard except it would have raised the floor height in comparison to the hardwood outside the room. It had tile on it previously which had been partially removed the resurfaced with vinyl adhesive tiles. I thought the mastic would bond better to the plywood? I figured if it was tiled before why wouldn't it work now? I am just hoping (and praying) that it sets-up solid enough to not move anymore. When it cracked the last time I did an inspection by pealing up one of the worst offenders and the mastic was still really wet (even after 30 hours). Any thoughts on possible success or am I going to have to load up on anti-phsychotic medications before I walk on next week?:gunsmilie:

troubleseeker 03-22-2007 09:32 PM

The problem was "flex" but not in the subfloor. It is that the mastic just does not provide enough support for the weight applied to floor tiles when walked on, and the layer of mastic just compressed when the tile was stepped on. After 30 hours, the mastic under the tiles was just as wet as it was when troweled on. I do not understand why anyone recommends mastic for floors.

It will eventually cure out, but how long that will take is any body's guess.

AndrewH 03-23-2007 08:19 PM

Well the juries in, I walked on the floor today and to my suprise no cracks! I hope I am not jinxing myself with premature claims of victory but so far so good! I don't think i am ready to race across it on a pogo stick but as long as the grout doesn't crack, lesson learned I guess.

MattCoops 03-28-2007 09:10 AM

you just learned the most important lesson in tile adhesives

we won't even use it for a backsplash

I wouldn't even use it to put together a sample board
I'd use wood glue before pre-mix crud

R&D Tile 03-29-2007 05:30 PM


Originally Posted by AndrewH (Post 38137)
Well the juries in, I walked on the floor today and to my suprise no cracks! I hope I am not jinxing myself with premature claims of victory but so far so good! I don't think i am ready to race across it on a pogo stick but as long as the grout doesn't crack, lesson learned I guess.

What a shame that someone is going to buy this home with that floor, it WILL fail in time, probably sooner than later, it was all done wrong, not using a CBU over the wood floor because of a height issue is a poor excuse, someone is going to get taken here, good luck.:furious:

MattCoops 04-01-2007 08:08 AM

That's called job security RD

peter_bigblock 11-25-2007 10:38 AM

Same problem
The guys installing my tile bought some of this OmniGrip from HD the other day, trying to save a little time for us (and themselves). Needless to say, two days later they're ripping up the tiles, washing the OmniGrip off with warm water, and will have to reset them using regular thinset.

Should they have known? Not having used it before, and having the HD "tile expert" recommend it as the best they have, I suppose the answer is "probably not". Are they spending a day undoing their work and another day re-doing it, instead of grouting -- basically learning the hard way? Yes.

Bottom line: don't use OmniGrip for anything -- it is completely worthless. Also, never trust the "experts" at HD or Lowes to give you recommendations, search the internet or ask a local pro for the best info.

JazMan 11-25-2007 04:35 PM

Good advice Peter. I will add; hire a tilesetter next time...not people that have "set" tiles.


Reiguy 11-26-2007 07:58 AM

They used to have actual experts at the big stores. The guys would take a pay cut in return for more steady work. Then I know for HD when the new CEO was hired in the early 2000s he decided he needed to cut payroll. There went the experts. Now you have anyone there who would just as well be at wal mart. But hey not a big deal. Just talk to the guys on here.

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