pre-seal the back of marble tile?

[conrad_sf]

I am a novice at this, so excuse this question if its too naive.

I am about to tile my bathroom with 12 x 12 marble tile (on top of backerboard). I am also laying heated floor pads under this tile.

Should I be sealing the back of the marble tile before I lay it down? If I dont, will the moisture from the thin-set affect the look of the tile?

I am planning on laying this tile without any grout space between the tiles. Any cons to this idea?

Also, any other precautions that I should take during this project? I have laid ceramic tile before, but not marble.

Please advise.

-Conrad

[Sponsored Links]

[Stonehenge]

Hi Conrad,

I preface this statement as a marble restoration contractor that passes on repairing poorly installed natural stone.

A sealant on the back of your marble is ill advised, go with a white thinset or epoxy based material. Grout performs multiple functions including the reduction of a joints' grit and moisture accumulation.

Input for grout spacing by installation contractors may differ, 1/16th or 1/8th inch, no more and no less.... Unsanded Grout.

What is the color/name of your marble ?

Michael

[conrad_sf]

Unfortunately I dont know the name of the marble Im using. It says "Made in Turkiye" on the boxes they came in, and I would describe them as "white with tan/gold accents and some grey lines as well". Not sure if that will help.

Thanks for your response.

[Shaughnn]

Hi Conrad,
I think you'll need to do a bit more research before you can begin your installation project. Everything you need to know is already here in our archives but if you aren't able to find some of your answers, we're happy to fill in the blanks.
Firstly, you'll need to understand how your underlayment needs to be installed, including all of the preparation to ensure a lasting installation. Next, you'll need to consider how your radiant electric heating elements are going to be installed in relation to your underlayment AND your marble. Using a white mortar rather than a grey mortar is deffinately going to help you to avoid shadowing showing through the marble, but you'll also need to trowel a thin even coat of thinset over the backs of each tile to prevent the comb channels from the trowel from showing through as well. Groutless joints works only when your tile is exactly square and exactly of uniform size. Any variance and your entire layout will quickly be thrown out of whack. Grout joints allow you to make those minor adjustments AND prevent the empty joints from collecting gunk. As well, when two surfaces of equal hardness are butted up against each other and some sort of movement occurs, that movement will most often create tension which will then cause your marble to chip and/or crack. Grout serves as a very minor buffer against that sort of damage.
It's absolutely possible for you to accomplish this project but you'll need to arm yourself with a bit more knowledge first. :)
Shaughnn

[doitright]

Hi Conrad, Welcome! :)

As a minimum you'll need double layer plywood. You'll also need to meet the minimum deflection standard for natural stone of L/720.

Before a grout joint size can be established, we will need to know whether this stone is polished, honed, or tumbled.

Can you post a photo? :shades: