QUESTION

Flood Damage - I have been asked to look at couple of interior ceramic tile floors in Central Florida that have had flooding occurrences, then noticed loose, lifted and/or cracked tile (not just cracked grout joints). In the flooding cases, the thin-set is bonded partially to the tile and partially to the substrate as well as small areas of debonding at the tile. These cases are residential so typically the room dimensions are less than 20 feet thus not requiring expansion joints. Are different types of tiles and mortars used in outdoor applications versus indoor? I am being pressed to explain why the tiles outside do not fail.

I have done some reading on alkalinity degrading adhesives. Is thin-set an adhesive or a mortar? And does alkalinity affect (degrade) thin-set?

ANSWER

ANSWER - You are asking a very big question that would take a lot of investigation. I'll give you a few comments to help put it into perspective, but ultimately you will have to hire someone to do a thorough investigation to narrow down the cause of the problem or problems.

First of all there are always compounding problems in failures, it is never just one thing.

Movements in tile can be caused by structural movement, thermo movements, and moisture movements (tile expands as it absorbs water to some degree), that is why expansion joints are always required to some degree. In your case, where it does not run in any direction more than 20' there should have been open or caulked joints along the perimeter; unless it is adjacent to a window or sky light providing substantial lighting, then it should have joints every 12' to 16'.

The term "thin-set" is used two ways; one as a method of a thin installation bonding directly to the substrate, and the other referring to a thin-set/dry set mortar, which is a cement based product that comes in many different versions. Most thin-set mortars are not affected by moisture. The fact that you had mortar on the tile and slab (I'm assuming a concrete substrate; if not then it is a different story) suggests it got adhesion to both and should be considered a good sign.

Can't make a generalization about the outdoor tiles. There are some limitations in which thin-set mortars can be used outside, but most work. Unless it is a freeze-thaw climate there aren't many limitations on what you can use unless you consider slip resistance.

Concrete is naturally high in alkalinity, but there are some extreme cases where extremely high alkalinity can be degrading of other materials other than cement.

I would focus on whether there were contaminates on the slab or tile, if there were excessive movements in substrate and not enough expansion relief, or if there was not enough thin-set coverage.

You would need to do destructive testing (DT) to further investigate and look for clues. If you need a forensic expert, such as myself, let me know.

Hope that helps.
ANSWER - You are asking a very big question that would take a lot of investigation. I'll give you a few comments to help put it into perspective, but ultimately you will have to hire someone to do a thorough investigation to narrow down the cause of the problem or problems.

First of all there are always compounding problems in failures, it is never just one thing.

Movements in tile can be caused by structural movement, thermo movements, and moisture movements (tile expands as it absorbs water to some degree), that is why expansion joints are always required to some degree. In your case, where it does not run in any direction more than 20' there should have been open or caulked joints along the perimeter; unless it is adjacent to a window or sky light providing substantial lighting, then it should have joints every 12' to 16'.

The term "thin-set" is used two ways; one as a method of a thin installation bonding directly to the substrate, and the other referring to a thin-set/dry set mortar, which is a cement based product that comes in many different versions. Most thin-set mortars are not affected by moisture. The fact that you had mortar on the tile and slab (I'm assuming a concrete substrate; if not then it is a different story) suggests it got adhesion to both and should be considered a good sign.

Can't make a generalization about the outdoor tiles. There are some limitations in which thin-set mortars can be used outside, but most work. Unless it is a freeze-thaw climate there aren't many limitations on what you can use unless you consider slip resistance.

Concrete is naturally high in alkalinity, but there are some extreme cases where extremely high alkalinity can be degrading of other materials other than cement.

I would focus on whether there were contaminates on the slab or tile, if there were excessive movements in substrate and not enough expansion relief, or if there was not enough thin-set coverage.

You would need to do destructive testing (DT) to further investigate and look for clues. If you need a forensic expert, such as myself, let me know.

Hope that helps.