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Grout cracking issue

8533 Views 22 Replies 11 Participants Last post by  The Coastal Craftsman
Ok guys i have a customer with a sun room and his floor has a little to much flex for my likeing and his grout has started to lift and crack. I didnt lay the tile or build the sun room but he wants me to fix it. Problem is he put the tile down. He used Ditra ontop of 3/8th's which is not enough sub floor in my mind and this is the cause of the issue. Other than taking up the hole floor and beefing up the subfloor if there another way to repair the grout. Maybe a more flexible grout??

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Soon the tiles will likely also begin to crack.

To rehash what you probably already know:
DITRA requires a minimum of a 5/8" subfloor. Minimum, minimum, minimum. The floor also must meet deflection minimums of L/360. Again a minimum.

With information about joist size and joist spacing and joist spanning you can determine the deflection criteria of the existing structure and what the "MINIMUM" thing to do would be since we are obviously talking about a minimum kind of customer.:)

There is no grout that will hold up under the circumstances you suggest you have to deal with.

Using caulk is just plain a stupid idea for a floor.

The simplest path of least resistance is going to be to go below and start installing some beams and lollies.:)

I suppose down below is a "finished area" and he won't allow any modifications.:):sad:
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I personally use Ultraflex III. Being a remodeler I'm always dealing with preexisting conditions, usually inadequate. A commercial tile guy suggested it awhile back and haven't had a problem.... yet.
I guess I don't see what that has to do with anything in this situation. Point me to what I am missing.;)

Ultraflex III is a thinset. It's too late for that now, this job is well past the thinset-choosing stage.
Use a wooden broomstick or hammer handle to tap on every tile. If you get a hollow report the tiles are also coming loose. I can tell you Ultraflex III isn't the product to put the tiles back in with either.:)
There are no flexible grouts that will survive that type of deflection. Some will argue that epoxy grout will take the punishment but it won't, it would likely break tile edges once it was adhered to the tiles edge and the flex is allowed to remain in the floor structure.

The first thing to do is to "sound" each tile and see what you are really dealing with. If you get a "hollow report" when you peck on the tile you have a loose tile. If that's the case the tile needs to be demoed and starting over after the floor structure is beefed up would be in order.:)

Also look to see if the tile is grouted tightly to the walls. If so...the floor is doomed anyway and removal is the only fix there also. All tile must have
a 1/4" gap around the perimeter of the room to allow for expansion of the installation.:)
Careful HS345. As it turns out this guy has a temper and he'll be attacking you next as he has me on another thread. I've been told he carries gun. But has no bullets in the chamber.:):):)
Thank you. I am always open to new ideas and advice.:)
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