Frederick M. Hueston, PhD

It was one of those special spring mornings. I could smell honeysuckle in the air and even some orange blossoms. I love the spring in Florida. Life is good. 

I got up this morning to feed my fish. Yes, the Stone Detective has interests other than stone and tile. For example, I have several marine aquariums, raise seahorses, ride Harleys, and have a few other hobbies I won’t mention.  Anyway, I decided to take a walk and head over to my favorite greasy spoon for a cup of joe and some Spam and eggs. 

I had just grabbed my trenchcoat when my cell phone rang. I flipped it open (yes, I still have a flip phone), and answered it. The voice on the other end was foreign, possibly Indian. For a minute, I thought I was getting a call from tech support for my computer (LOL!). Anyway, the man on the other end kept saying something about his limestone floor and something to do with white stuff growing. I wasn’t clear on the details of what he was describing, but I did manage to tell him I was available for an inspection and could look. As for his address, I was hoping it wasn’t far or overseas, but lucky for me it was only a few hours away. I told him I could be there as early as tomorrow. We arranged a time and I was off for my breakfast followed by a brisk walk to work off the Spam.

I was up bright and early the next day for my trip down south to look at the white stuff, whatever that was. It again was a beautiful day, so guess what the Stone Detective rode that morning?  I put the address into my GPS and off I went. Of course, I took the scenic route. 

 I arrived at the address and pulled up to a huge mansion with a large iron security gate. There were huge stone lions on either side of the gate, and they had eyes that looked like they might be cameras. On a closer look, I discovered that they were surveillance cameras. I thought, Who is this guy?   

Just as I was about to press the intercom button, the gates opened. I rode up the long driveway to the large white mansion and pulled up to the front door. There was a slender man standing at the door wrapped in a white robe that reminded me of pictures of Gandhi. As a matter of fact, he looked exactly like Gandhi. 

He said “Hello” in a cultured British-Indian accent and started telling me about the “white stuff” he had observed and was concerned about. He led me into the house and it was like walking into a museum.  Artifacts and all kinds of ornate pieces lined the hall leading to the living room. It was like walking into the Taj Mahl. We entered the living room, and he pointed to the floor and said, “There it is.”

Sure, enough there was this white stuff on the floor. Now, my past students and anyone worth their salt as an inspector should immediately recognize this so-called white stuff as efflorescence. For those of you who don’t know, it’s the deposit of soluble salts on the surface of the stone. These salts are carried to the surface by moisture. So, the first thing I asked was had the floor ever flooded. He told me no. I took out my moisture meter and began taking readings throughout the entire floor.  It appeared that only the areas where the efflorescence was read wet, which makes sense. But where was the moisture coming from? I had my suspicions, and my first thought was that the vapor barrier had been compromised. 

I have seen this before; the vapor barrier can be punctured during installation of the slab, and if this is the case, moisture will migrate into the slab and up though the stone. So now the question is, “How can you tell?” Finding a nondestructive test to determine this has bugged me for some time. In the past, investigating this issue meant taking core samples to examine the vapor barrier, hoping to find evidence of a puncture. 

One day while feeding my seahorses and other saltwater fish, an idea hit me. Keeping marine-environment fish requires testing the water from time to time. One of the tests is for nitrates. Nitrates are harmful to marine fish and must be monitored. Nitrates are also found in soil, but not in concrete.

A little lightbulb went off over my head – yes, just like in a cartoon. If I tested the efflorescence for nitrates and I found them, there was logically a puncture in the vapor barrier, since a concrete slab should not have any nitrates.  I pulled out my test kit and tested the white stuff. Lo and behold, it tested positive for nitrates! So, I concluded that the moisture was coming from a possible punctured vapor barrier. My client’s option was to live with it, or to tear the floor up,  place a barrier on top of the slab and install new stone. Another problem solved, and as a very wise man has said: 

The difference between what we do and what we can do would suffice to solve most of the world’s problems. –Mahatma Gandhi

…and I just solved the world’s problem of vapor barrier compromise testing!

The Stone Detective is a fictional character created by Dr. Frederick M. Hueston, PhD, written to be entertaining and educational. Dr. Fred has written over 33 books on stone and tile installations, fabrication and restoration and also serves as an expert for many legal cases across the world. Send your email comments to him at .