I was driving down a back road and came upon a sign located on the side of the road that said... SUMMER CANCELLED. I had to laugh since my summer has been spent performing inspections all over the country. From Salt Lake City to Florida to upstate NY, I have seen and heard it all until today, when my cell phone rang and delivered up a completely new scenario to solve.

"Hello, Mr. Stone Detective... I don't know who else to turn to for this problem." The lady on the other end sounded a bit distraught, so to speak. I could hear her sniffling and hiccoughing. She composed herself and went on to tell me that every time she enters her master bathroom she get a sneezing attack and starts coughing and it's difficult to breathe. She said that the master bath has marble from floor to ceiling and was wondering if her marble could be making her sick.

I considered telling her just to not use that bathroom. Well, I'm not a doctor or, as my mom used to tell people, "My son is a doctor but not the kind that helps people." Ok, so I'm not a medical doctor, but now I'd heard everything. How could marble make someone sick? A marble allergy certainly would make the headlines, but was pretty far-fetched. The trouble had to be something else. I had to check this one out, first-hand.

I pulled up to a modest house in a nice neighborhood. I walked up the gravel walkway and knocked on the door. Mrs. Jones answered wearing a robe and bearing a handful of tissues. Her eyes were red and swollen and she was sneezing.

"Highb," she said, and almost sneezed right in my face. "Come this way," she honked, leading me upstairs, into her master suite and then to the master bath.

The minute I walked in I suspected what the problem was. You could smell it in the air, that all-too familiar musty smell. I looked at the floor and it seemed to be OK, and then I opened the shower door and noticed that the white Carrara marble had this shadow behind one section of the back wall.

My first reaction was: this had to be mold, but what was puzzling is that it is very unusual for mold to grow on marble. First, mold needs a food source and the addition of water to grow. Secondly, why was it occurring only on the back wall and only on the first half.

I suggested that I take some air quality samples to have them analyzed for the type of mold and then to do a destructive test to find out why it was growing only there.

She looked at me, sniffled and said, "Whatever it takes. I can't keep using this bathroom, like this." Lucky for her I'd just completed my certification to become an indoor air quality technician and have had extensive training on mold remediation.

So, I set up some air samplers and got out my space suit, grabbed some tools and started tearing that part of the shower out. I took a chisel and hit the first piece of stone and the wall almost collapsed.

The backup material was soaking wet and full of black mold- a serious health hazard. I took several samples for analysis and then I noticed that this soft, wet crumbling mess was normal, everyday dry wall.

Well, if you're an installer, you know the first rule when you install stone or tile in a wet area... DO NOT USE dry wall. The dry wall was getting wet and breaking down, providing not only a moist environment but a food source for the mold to grow.

I removed the rest of the wall and discovered that cement backer board was used everywhere else except for this section. Unfortunately, mold cannot be killed and the shower would need to be replaced. I handed Mrs. Jones the tissue box and gave her the prognosis... the shower was a goner, and a candidate for replacement due to improper and below-code materials installed.

The Stone Detective is a fictional character created by Fred Hueston, written to be entertaining and educational. Frederick M. Hueston is the founder of Stone Forensics (stoneforensics.com), a nationally known stone consulting company, and also the technical director for Stoneandtilepros.com. He has written over 33 books on stone and tile installations, fabrication and restoration. He also serves as a expert for many legal cases across the world. Email comments to him at fhueston@stoneforensics.com

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