tile over ply in two shipping containers

chester0919

I'm wanting to install tile over a plywood floor in two 20ft shipping containers which have been wielded together and placed on permanent foundations. The inner sheet metal walls within the 2 containers have been removed creating a 16x20 floor space. The floors within the containers are solid marine ply with joists spaced approximately 12 inches apart. The ply is at least 1 inch thick. I believe the sub-floor is perfectly sound and solid. There is however a risk of grease and/or oil on or within the ply. I'd prefer to not have to remove the original floors due to budget etc. Tiles also have to be added to the center section of the room where the two containers are joined or weilded together - ie. a space approximately 5 inches of steel has to be tiled over as well.
This is my plan:
- degrease plywood floors with degreaser
- fill in any floor voids with gypsum filling compound of some description
- staple down wire mesh (chicken wire or something like it) to floor to give thinset something extra to bind to
- use thinset mixed with multibond like product
- lay tiles
Any advice or comments greatly appreciated.
Thanks.

JazMan

Chester,

I don't agree with a single step you've outlined. Doing the installation that way will increase or guarantee failure.

degrease plywood floors with degreaser

Using solvents will drive some of the grease and the solvent deeper into the substrate, creating a bond breaker.

fill in any floor voids with gypsum filling compound of some description

Gypsum is not a good patch for subfloors. When used it must the primes and then can the covered with only certain types of adhesives and flooring.

staple down wire mesh (chicken wire or something like it) to floor to give thinset something extra to bind to
use thinset mixed with multibond like product

That's what is known as a scratch-coat or Jersey-mud job. It has failed ever test is has been subjected to. It won't necessarily fail every time, but the method has a high failure rate and is not accepted by any tile association or methods body on earth.

You can not install tiles over a single subfloor even if it was new. You need either a cement backer or a membrane such as Ditra. In this case I recommend a cement backer because membranes rely solely on thin set for bond, while cement backers are installed into fresh thin set and also fastened

I would treat the threshold between the two units as a separate space. After you figure out how to make it flush, isolate it and place a matching caulk where it meets the other flooring.

In addition, how will you manage temps and humidity levels? Vapor barrier installed? Ventilation? So many other issues.

Jaz

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chester0919

Hi Jaz,
Thanks for your thoughts. You've been very helpful and I feel you have definitely put me on the right path. I'll be calling companies tomorrow to get prices on cement backer boards.
I appreciate your time.
Thanks.