Marble wall mold in a bathroom (C) Daniel FriedmanHow to Find Hidden Mold & Water Damage in Tiled Bathrooms

  • MOLD BEHIND MARBLE or TILE - CONTENTS: what clues indicate hidden mold contamination behind tile or marble walls & floors in bathrooms, kitchens, or other building areas? Hidden mold may mean hidden water damage, rot, insect damage.
  • POST a QUESTION or READ FAQs about mold, rot, or water damage hidden behind or below bathroom tiles, tubs, showers.

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Hidden mold behind bathroom tile: this document gives advice on how to find, test for, remove & prevent mold in marble tiled bathrooms, including mold found on bath tiles, moldy tile grout, moldy caulk, and hidden bathroom mold.

We describe an inspection procedure that helps recognize when there may be serious water, rot, or mold damage hidden behind ceramic or marble bathroom tile.

We discuss how to decide when invasive or destructive methods are actually justified.

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Photo Guide to Finding Mold Behind Solid Marble Bathroom Walls

Following a major mold remediation project and after all mold demolition and cleaning had been completed (or so we thought), we inspected the bathroom shown in the photographs below. The bathroom floor and walls were covered with marble tiles and we all thought that it was unlikely that the surfaces behind that material had gotten wet even though we knew that water had been on the bathroom floor.

Marble wall mold in a bathroom (C) Daniel Friedman Marble wall mold in a bathroom (C) Daniel Friedman

A peep below the cast iron heating baseboard told a different story however. The tile had not been installed to floor level - the heating baseboard had been mounted on drywall. We could see a half-inch of black and green mold in a little gap below the baseboard.

The question was, is this trivial or do we need to destroy the marble to inspect and clean a large mold reservoir. The owner was a builder who was not intimidated by hammering off and replacing marble tiles. We would have carefully removed some tiles to inspect for water damage but the builder went to work with a hammer and a vengeance.

Marble wall mold in a bathroom (C) Daniel Friedman Marble wall mold in a bathroom (C) Daniel Friedman

The photographs show that considerable areas of the wall cavity had indeed become wet, wetting wall insulation as well as drywall, leading to a large area of moldy drywall and moldy wall insulation. The mold was a mix of Stachybotrys chartarum and Aspergillus sp.

How much of a health risk would this mold have been to future building occupants? Perhaps not much as there was probably little air movement through the marble-covered surfaces. But the possibility of a growing mold problem associated with a large inoculated area of building cavity mold led the builder to demolish, clean, and repair these areas before the rest of the building restoration was completed.

Watch out: in most circumstances it is not necessary to test mold to identify the genera species. That information will not change how mold should be removed or prevented in buildings. But on occasion, such as for medical reasons or for control of a larger, costly mold remediation project, there are reasons (MOLD TEST REASONS) to identify mold on surfaces or in building air or dust.


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