What kind of Tile Should I install over my concrete slab that has high moisture readings?


I had to remove all the flooring in my house due to moisture and mold under my engineer hardwood floor and carpet that had a moisture resistant pad.

I have been told by 3 different leak detectors that I have high moisture levels coming from the foundation.

I had ordered porcelain tile to put down but the 2 of the leak detectors said to send it back and get ceramic tile and lay it with no moisture barrier and not to seal the grout so the moisture can escape..

Very confused. What tile is recommended for moisture coming up though the foundation?

I would appreciate any info. I'm currently in a hotel trying what flooring to install .


ANSWER - I assume you had a water leak of some sort that resulted in your concrete slab having a high level of moisture.  If that is the case, then you should let the slab dry out to the extent that it isn't wet or has an excessively high level of moisture.  If you have a moisture migration problem where moisture from the outside is migrating inside, then you need to first install a moisture migration system, which is normally an epoxy coating system.  The worst thing you can have is hydrostatic water pressure.  This is where water from a high water table, or water from some higher outside area drains down where it creates an upward pressure on and through the concrete that can affect the tile bonded to it.   In this case you have install french drains around the perimeter of the house or employ other methods to mitigate it.

Porcelain tile is a type of ceramic tile.  Porcelain tile is very dense and is considered impervious with an absorption of less than 0.5%.  So it is very resistant to moisture because it will not absorb much moisture.

A porous ceramic tile that we often see in Florida absorbs moisture which will cause the tile to expand and can lead to damages if there isn't adequate movement joints to mitigate the movements.

If the moisture coming through the slab is high which would be over 90% relative humidity, then the companies who sell installation products like Laticrete, Mapei, Custom Building Products, and others do sell moisture mitigation systems that can first be applied to the concrete slab and then the tile can be bonded to it.

If you have a moisture migration problem by installing over the concrete slab the moisture will evaporate through the grout joints, but it could cause white efflorescence staining in the grout as the moisture picks up minerals and as the moisture evaporates it precipitates the minerals that can cause staining and spalling.

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