Attention Tile guys! Need your assistance

[Justind97]

I’ve been doing tiling for a number of years, but this is definitely a first for me.

Layed some tile on Sunday. Everything looked perfect when I left. I spent a fair bit of time to make sure the tiles were perfectly level. I came back today to find 2 of the tiles had lifted about 3/16. WTF?! I said to myself.

This isn’t acceptable so I ripped out one of the tiles. And that’s where the questions started.

Substrate is. 5/8 ply, 5/8 ply and 1/4 ply. Each layer is screwed together about 4x4 using 1 3/4 flooring screws.

The 1/4 plywood buckled on me. I’ve never seen this before. This happened right near a seam. Seam is 1/4 on one end and just kisses on the other. I can see there is a gap between the pieces, so I doubt this is the issue. Especially considering the other one happened 2’ in, in the middle of the plywood.

The mortar was not very wet, it was probably on the dryer side of what I would normally use.

Attached are the photos that I took.

Any insight??

 

[PoorOwner]

I am not sure how you think putting thinset on 1/4" ply is going to work setting your tiles directly on it, but you need backerboard of some sorts. I have gotten some 1/4" wet outside and they just delaminate like your picture shows.

 

[Kaizen]

This is why I use cement type boards. Wood absorbs moisture even if it’s not a lot the ply can behave as seen. Cut it out. Replace and move on.


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[trashmanssd]

This is why I use cement type boards. Wood absorbs moisture even if it’s not a lot the ply can behave as seen. Cut it out. Replace and move on.


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I dont tile but have heard that while it is more expensive the way to go for longevity is using cement type boards also.

 

[ddurrett896]

Hopefully the tile was cheap. What hasn't broke will eventually break.

Rip up, lay backerboard or Ditra and re tile.

 

[Dakota00]

It all has to come up, there's no saving this... In a short period of time the grout and tiles will break loose. Remove the 1/4" layer of plywood and install Ditra.

 

[PugetDude]

Cement board.... No way can you tile over 1/4" plywood. That stuff is like cardboard when it gets wet- it wicked all the moisture out of your thinset, expanded, delaminated and then pushed the tiles up. The tiles that haven't failed yet will fail soon, as the plywood dries out.
Sorry, dude- rip it all out and start over.
Good luck with your project.

 

[jhelrey]

You need a backer board... not plywood.

 

[signcrafter]

Like already mentioned you can't go over ply like that and get a good result. Might get lucky on a few but it is not the right way to tile. Also looks like the thinset came off the ply way to easy. Did you use modified thinset? Or did the ply separating from itself end up breaking the thinset off clean like that? I've ripped out bad jobs of tile before were they went over wood and the thinset still stuck to the wood pretty good in most spots and I had to use a chipping bit on SDS to get it off before I went over it with thinset and then cement board.

 

[Justind97]

I hear you guys. Flooring had been ripped up. Sourced the backerboard. Going down tomorrow.
Tile wasn’t necessarily cheap, $1.75/ft but I only laid 20 feet. Saving grace of running out of space I suppose!
That mortar wasn’t easy to take up. What you see is after I’ve sat there and ground off all the mortar with a flap disc. Took me a good amount of time.

2 issues that could very well be the culprit. I probably could have gotten away with the 1/4 if I had laminated between it and the piece below with PL. it seemed to have billed and valleyed between the screws running with the grain.
Based on what I found, it seems the plywood just sponged up the water and then buckled. Lesson learned.
Modified thin set is what I was using.

 

[ddurrett896]

That mortar wasn’t easy to take up. What you see is after I’ve sat there and ground off all the mortar with a flap disc. Took me a good amount of time.

2 issues that could very well be the culprit. I probably could have gotten away with the 1/4 if I had laminated between it and the piece below with PL. it seemed to have billed and valleyed between the screws running with the grain.
Based on what I found, it seems the plywood just sponged up the water and then buckled. Lesson learned.
Modified thin set is what I was using.

I wouldn't grind. Just rip up the 1/4 and be done with it. Be sure to thinset UNDER the backerboard before screwing it down.

 

[Justind97]

I wouldn't grind. Just rip up the 1/4 and be done with it. Be sure to thinset UNDER the backerboard before screwing it down.

As I said, everything was ripped up and starting with backboard this afternoon. Thinset is there waiting. Time is the only thing missing right now.

Thanks for all the help guys!

 

[Todd.Brock]

That *****. I haven’t ever seen this before! Hopefully backer board will treat you right!

 

[D.J.]

I just started a project an didn't thinset under the backer board did I screw up big time or will I squeak by? I used bb on top of 1/4" Luan that was set on top of 17/32 osb with liquid nails when I rebuilt the floor of my utility room?

 

[ddurrett896]

I just started a project an didn't thinset under the backer board did I screw up big time or will I squeak by? I used bb on top of 1/4" Luan that was set on top of 17/32 osb with liquid nails when I rebuilt the floor of my utility room?

Might, might not! I would let it ride until something, if anything happens.

 

[Kaizen]

As I said, everything was ripped up and starting with backboard this afternoon. Thinset is there waiting. Time is the only thing missing right now.



Thanks for all the help guys!

You should find it’s a lot easier to get them level as well. Good luck post up results. Focus on the grout lines. In that room the long run will be very noticeable if off


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[PugetDude]

I just started a project an didn't thinset under the backer board did I screw up big time or will I squeak by? I used bb on top of 1/4" Luan that was set on top of 17/32 osb with liquid nails when I rebuilt the floor of my utility room?

99% you're OK, since you are tiling over well-secured backerboard.
1% Murphy's Law...

 

[jkuro]

Plywood is acceptable as long as it's exterior grade, per most adhesive manufactures. My guess, it's not.

1/4" Ply is also fine as long as your total floor thickness is at least 1 1/4" thick, going over floor joists at 16" on ctr. This will have minimal deflection when walked on and also be warranted by the tile manufacture.

Mt suggestion, replace top layer with exterior grade 1/4" Ply or 1/4" cement board.

 

[Mathis Hard]

I just started a project an didn't thinset under the backer board did I screw up big time or will I squeak by? I used bb on top of 1/4" Luan that was set on top of 17/32 osb with liquid nails when I rebuilt the floor of my utility room?

There's a number of differing opinions on this. Personally I don't like to use thin-set or sub-floor adhesive under backer board unless there is an issue with sub-floor stability (IE going over shiplap). Bonding backer board to the subfloor pretty much means that you have to cut the floor out if/when it needs replacement. When not adhering backer to the substrate using a proper fastening schedule is important.

I think you should be OK with what you did on your project. Was the Luan subfloor rated? usually it's not. Any noticeable deflection in the floor when walking?

 

[Sonic-Boom]

Ditra.

 

[redneckcharlie]

There is no need to put thinset under backer board. Unless you are using a modified thinset it will not bond affectively. I use fiberock by the pallet, my preference. I dont use screws either any more, but thats a time and cost choice for me. I use construction staples, 1/2”x 1 1/2, pneumatic. On average we do 6-8k sq ft a month.