Frederick M. Hueston, PhD

Brrrrrrrrrrr – it must be 60 degrees this morning! I know to you snow birds that’s flip-flop and shorts weather, but here in Florida, that’s down right cold!

I grabbed my winter coat and gloves and headed out the door for my morning walk. Wouldn’t you know it – just as I stepped outside into the cool Florida air my cell rang. 

“Stone detective here – can I help you?” The voice that replied sounded really serious. He had a very deep voice and introduced himself as an attorney representing a homeowner who claimed their stone tile floor was not installed properly. 

He asked me the typical questions about my experience and after an investigation of my qualifications he asked if I was available to take a look at the jobsite.  Well, I felt like I was just interrogated by Sgt. Joe Friday of Dragnet.  I told him I would look at my calendar when I got back to my office and thawed out.

Later that day I returned a call to Joe Friday and told him I could take a look at the floor sometime next week. I also asked him if there were any letters, emails etc. that I could review concerning the installation. He told me he would email them to me right away. 

I hung up the phone,  opened my laptop and Lo! and behold, an email from him arrived within minutes. 

In fact, there were several emails, and one report from another expert. I opened the report to see what this colleague had to say.  As I read the report, everything the other expert had written made sense. He noticed no cracks and said he sounded the floor and found no hollow tiles, and concluded that it was a sound installation. Well, this should be straight forward, I thought. I was keeping an open mind, but then again, this was all his conjecture and opinion. I would have to judge for myself, depending on what I found during my inspection.

The day of the inspection finally arrived. I woke up early since it was a four-hour drive and I wanted to grab a hot breakfast and a cup of jo before the long drive. I showered, got dressed, and hopped into the ole Woody, heading to my favorite greasy spoon. And then the phone rang. Yup– you guessed – it was Sgt. Friday. He wanted to know if I could move the inspection up by an hour. Darn it, I thought. There goes my decent breakfast. Sigh.

I told him, “Yes, I can be there,” as I pulled into a fast food place for a mediocre cup of coffee and a 99 cent heart attack breakfast sandwich. As a consolation prize, I put in a cassette of Frank Sinatra and headed down the highway. At least the coffee was hot.

A few hours later I arrived at the home in question. To my surprise, I discovered it was a condo on the top floor of a high-rise. Great I thought, I’ll have to valet park my ole Woody and probably have to also teach the valet how to drive a stick shift

I pulled up and some young kid politely opens my door and welcomes me, and then – I kid you not – he notices that the Woody has a manual transmission. He got this look of panic on his face and then told me to just park it at the end of the drive. I had to laugh – kids today really don’t know the fun of driving a stick. Chuckling to myself, I parked the Woody, grabbed my inspection tools and headed for the condo.

I walked out of the elevator and into one of the most beautiful condos I have ever seen. The place was like a palace. There was even marble on the ceilings. I was greeted by three people, the homeowners, and Joe Friday. They took me all over the condo and were pointing out tiny flaws that I found were normal for natural stone, but then they got my attention: they said as they walked across the floor, several tiles seemed to be moving – shifting underfoot. I asked if I could do a sounding test. So I took out my sounding device (a golf ball!) and proceeded to bounce it on the floor.  I couldn’t find one hollow tile. This usually indicates that the tile is bonded well. But I wasn’t totally convinced. This old stone man has years of experience, and I can tell you that what seems the most obvious answer is not always the truth.  

I reached into my bag and pulled out a suction cup. I looked over at the owners and Joe and told them that I was going to attempt to pull some tiles up. They said go ahead.  

I placed the suction cup on one of the tiles, gave it a gentle pull, and guess what? It came up as easily as if it was placed on a bed of sand. My suspicions were correct– the tiles were not bonded.

So: the question you should now be asking is how come they don’t sound hollow? The answer is simple and I refer you back to my analogy of the bed of sand. You can have 100% coverage under the tile but 0% bond. 

You also need a trained ear to perform a sounding test. Underlayment, soundproof barriers, etc. can result in false/positive results. I looked at Joe Friday and the homeowners and told them the installation was certainly not up to industry standards and should be replaced. They could roll with a lawsuit on the evidence, if that is what they wanted. Just the facts...

The Stone Detective is a fictional character created by Fred Hueston, written to be entertaining and educational. He 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. You can send any email comments to him at