I put down real cheap tile from a lumber store on the floor of a kitchen and bathroom in a mobile home. I first put down 1/4 inch good one side plywood and screwed it every 6 inches everywhere. But the tile cracked all the way down the middle of the kitchen and bathroom lenght ways with the mobile home.
How can I fix this and prevent this again?
I would suggest that the substrate was inadequate to carry the tile finish without shifting or deflecting. In a nutshell, tile is very stiff, so both cheap and more expensive, or thicker tiles require a very rigid base on which to lay them.
The American Tile Counsel recommends that the underlay of plywood on 16" joist spacing, be 1 1/8" thick. That translates into a standard 5/8" plywood subfloor which would then be augmented by another 1/2" sheet of plywood, screwed every 6" with staggered joints. The use of floor screws, or construction screws, which have a deeper tooth than common wood screws is also recommended. As a rule, 1/4" plywood subfloor would be used as a base for flexible flooring, such as linoleum, carpeting, or vinyl tile.
Mobile homes can often be constructed with OSB, fakeboard, or chipboard, which do not perform as well as plywood as far as stiffness and fastener retention. The floor supports can also be less stiff than a comparable space built with joists.
If you have a long crack, running down the middle of the mobile home, then I would suspect that the home itself has either shifted, or dilated, causing movement. A crack isolation membrane (such as Schluter System's Ditra) when placed on a properly prepared substrate would likely have helped avoid that sort of cracking.
Another thing to keep in mind, especially when using lower-cost tiles, is to back-butter religiously. That way, every square inch of the tile is supported by mortar, and a tile failure due to a deflection caused by incomplete support under the tile can be avoided.
It sounds like although you did try and build a proper base, your efforts met with failure. As a tile installer, I will tell you that the main problem with cheap tiles, is that they are unforgiving. If any part of your prep or install is flawed, they will fail before their time.
Unfortunately, it sounds like this job will have to be redone. Sorry to have to tell you this.
Good luck with your project.
Unfortunately there are many reasons the tiles could have cracked. I am assuming you've used a ceramic tile as they are a cheap alternative to a stone tile. Ceramic tiles need an even distribution of mortar underneath them. Voids in the mortar under the tile allow the tile to flex and crack.
Ceramic tile laid over plywood is more susceptible to cracking. As the plywood under the tiles flexes, especially along floor joists.
The best sub floor for ceramic tile is a mud bed, which is a prepared floor made of several inches of concrete reinforced with wire mesh.
The only way to be sure is to hire a professional to come and take a look.
Good Luck with your project and I hope this helps!
The subfloor should be at least 1 1/8" thick for tiles.
If this mobile home is to be moved at some future time I would be hesitant to use any tile . I would maybe concider a vinyl floor either floating or glued.
Good luck with which ever you choose
The substrate used was definitely inadequate, and I don't think G1S is a good idea either. Especially with a flexible structure such as a mobile home, it is very important to have a solid substrate. If the substrate can more, the tiles will crack. Hopefully the tile was really cheap, because I think it needs to be ripped out and the substrate improved.
I would recommend some sort of vinyl flooring for a mobile home. There are many products out there now that would work well in this application with no worries of cracking.
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