Builder is installing marble tiles directly onto plywood subfloor (no backerboard). Is this done correctly?

Question

I am concerned that the way the marble tiles are being installed will cause problems later (cracks in tile, splits in grout). They are installing it directly onto the plywood subfloor using a metal cheesegrater type material instead of backerboard. Can the subfloor support the weight? Will humidity be a problem?

Answer 1

The cheesegrater what you are refering too is the base material used to add the mud that will follow. That is the proper material for the mud so it will have more strength So your marble will not crack. There are also new materials out there and new methods of installing tiles these days and it is hard to keep up with.

Answer 2

1

Answer 3

Sounds odd to me but there's so much innovation on the market it's hard to say. I have always gone by the ole advice: First and foremost make sure you do a proper installation to avoid issues with trapped moisture. That's where the backerboard comes in. It helps create a moisture barrier. I would ask "how thick is the plywood and where is the moisture being trapped?" I'm sure the answer by the installer will reveal if the installation is correct or not. The two links below seem to support my theory -- backerboard or some acceptable underlayment is mandatory. Good luck.

Answer 4

1/2" sub-flooring is not adequate. 3/4" "should be" just fine.
The 1/2" will need an underlayment sheet on it for the marble.
The 3/4" is better also with a 1/4 or 1/2 underlayment. The reason is to stagger the seams and minimize tile and grout cracking. Normal humidity is OK, but high levels from unvented crawl areas can be a problem if joints are tightly put together.

Answer 5

That's a little unusual these days, he's using metal lathe. That's a product used on corners and stress areas behind plaster and stucco walls.

Generally, if the sub floor is an aggregate 1-1/8" or more thick, you will be OK. The metal lathe combined with the thin set provides a very stable sub-surface. Unless the floor is really flexing a lot, it should be OK.

Answer 6

Thinset mortar can be applied directly to an exterior-grade plywood subfloor, but many installers opt to install cement backer board to stiffen the entire subfloor assembly and provide an extra measure of moisture resistance. - See more at: http://www.miconstruguia.com/en/installing-marble-tile/

Answer 7

No not necessary I used the concrete onto the plywood. I am not a professional but the floor has been down for four years and still in great shape- I used backerboard on the walls though because it was the bathroom

Answer 8

Oooh no! We just had to redo two of our bathrooms because the people who lived here before did that! In fact, one of them is still half done. We have a raised home with wood subflooring and it's never perfectly level and it warps with the weather changes. You MUST put backboard on. Make him fix it!

Answer 9

There are too many variables to take a chance, get a second opinion from a qualified craftsman that will check it out on location.

Answer 10

Is it on a slab or basement? You don't need "backerboard but I would want a moisture barrier!