Installed 12 inch granite tile on concrete floor. Where the floor needed rasied / leveling I used hardibacker underneath. The tile installed on the hardibacker has dried to the original light grey color, the tile installed directly to the concrete still has the darker wet color. Will the darker tile ever lighten up? It's been two weeks. Thanks for your reply.

 

Dear Michael :

I must assume that the concrete slab on which you installed your stone tiles is on grade.

Why did the tiles set on the hardy-board dried back to their original color, while the other didn't after two weeks?

Because the hardy-board is water-proof, while the concrete is not.

The water table under the concrete is wicking through it, and the setting material, and, eventually, the stone tiles.

Will it ever dry?

Maybe it will, but the situation will always be unstable. A few hard rains that will make the water table rise… And there it is again! L

Before setting stone tiles on concrete slab on grade a water-proofing membrane should always be applied.

Too late now, I reckon…

Sorry to be the bearer of bad news; I'll keep my fingers crossed for you… J

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Ciao and good luck,

Mauri z io Bertoli

 

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