The Bulging Floor Blues
John Nixon is an ICRI Certified Testing Technician and owner of Concrete Restoration Services, LLC. With over 15 years of experience in substrate preparation, moisture mitigation and installation, Nixon provides independent, third-party ASTM-compliant testing and consultation services throughout PA, OH, Western NY, MD, WV, VA, DE and KY. The company’s website is

As the owner of an independent testing agency, I’m often called upon to test and investigate moisture-related flooring failures. Typically, I find that the failure could have been avoided if someone had paid closer attention to the conditions that can contribute to these types of failures. Sometimes I also find product installation issues, but I leave those evaluations to the manufacturer representatives unless otherwise requested to do so.

Either way, I often find myself stuck in the middle between the flooring contractor, GC, owner and architect, or any combination thereof. This can be a challenge because inevitably someone asks, “Whose fault was this?” I wish I had a standard answer, but there isn’t one. Every situation is different. My purpose is to simply provide the test results factually, diplomatically, and not throw anyone under the bus. Let the responsible parties determine who will be left with the financial burden of moisture mitigation and flooring replacement. 

Such was the case last year when I was contracted by a business owner to investigate a moisture-related flooring failure at a small retail establishment. The site was a standalone building that sat like a tiny island in an ocean of asphalt, adjacent to a large shopping plaza. The business owner did not own the building, but she had occupied the space for a number of years. She invested several thousand dollars in the installation of luxury sheet vinyl, which was professionally installed over a raised wood platform within the space. However, the failing area was the 240 sq. ft. entrance area, which was slab on-grade. 

When I walked in the door, all I could focus on was the considerable heaving bulge in the floor, covered by rubber mats strategically placed over the severe tripping hazard. It was one of the worst failures I have ever seen. The sight resembled two large puppies trying to hide under a blanket after doing something they shouldn’t have been doing: Sorry, but I know you’re in there, and I know I’m going to find something ugly underneath.

I began my usual series of open-ended questions that require more than just a yes or no answer. That’s truly the only way to get the information I need. I learned the installation company was reputable, well-known in the area, and that they did an RH test based on previous moisture issues with the old carpet. So already things didn’t add up. That was, until the owner showed me the test, which was in a closet about 10 ft. away from the installation failure where no new flooring had even been installed! 

What I found was a 3/4” hole where no sensor or insert remained. When I asked how they tested, she said they drilled the hole, “put something in the hole” and after about 20 minutes, informed her there was no moisture problem. Really??? Probing further, I learned she did not know what products were used throughout the installation process, except for the flooring she picked. Additionally, I found out that her window for installation was very limited: A mere three days for tear out, prep, installation and set time.

Next, I lifted the floor only to find dis-bonded, damp flooring, dis-bonded underlayment, cutback adhesive residue, carpet adhesive and a damp substrate. I even found a dead bug. It was obvious no grinder, shot blaster, or scraper had been used at any point where I lifted the floor. And with all the mess, determining if a primer had even been used for the leveler was virtually impossible. All they did was perhaps sweep the floor (and not very well, if the bug were any indication), install a couple of bags of an unknown self-leveler and slap the expensive sheet flooring down over it. According to the owner, within a couple of weeks the flooring had already begun to lift. 

After measuring the thickness of the exposed slab outside, I drilled 3 holes, 1.6” deep and covered them temporarily while I looked around the building’s exterior as the holes cooled down, before inserting some Wagner sensors. From my previous questions, I learned the roof was in good shape and no water had ever found its way inside the walls, and the gutters were functioning properly as evident by the previous night’s rain.

I looked closely at the sidewalk along the front door close to where the floor was failing and found the possible penetration points for moisture. Not only was there deteriorating caulk along the base of the ground-level windows; it appeared that the narrow strip of concrete ramp at the front door had settled below the level of the adjoining slab.

Worse still, the expansion joint between the slabs had no backer rod or sealant. This provided a perfect entry point for water to work its way down and migrate under the slab, saturate the sub-base under the affected area and remain indefinitely. And with no vapor barrier, the moisture sought warm, dry air in the occupied space above, and you know the rest.

I went back inside to set the sensors and take initial readings. In the few minutes it took to place three sensors, the reading in sensor #1 jumped from 65% to 80%. My last readings for the first visit were 81%, 82%, and 80% respectively. I sealed the Wagner orange protective caps, secured the area and left until my return 72 hours later. When I returned to take new readings, each one maxed out at 99%! 

So, who should be responsible? Who should pay for everything? Of course there are three issues:

•Allowing such conditions to exist (building owner responsibility)

•Conducted an erroneous RH test (installer responsibility)

•Poor installation practices (installer responsibility) 

These issues can exist with any flooring failure – moisture-related or otherwise – and are usually the result of fast-track schedules, lack of planning and budgeting, or, in many cases, lack of knowledge. Today, moisture failures are common occurrences in businesses, hospitals, schools and retail establishments. That said, there was no excuse for the conditions I found. 

When I finished, I provided the owner with my report and recommendations to correct all the problems. Unfortunately, I had to decline her request to install a moisture mitigation system due to my belief that it’s a conflict of interest for independent testers to install systems.

So what was the outcome? As of yet, nothing has been resolved at this job site, and the customer is already paying a price beyond the initial cost of the flooring and installation. I do know that the flooring company is ready to correct their mistakes and redo the job at their expense, with their reputation intact. So perhaps it’s time for the owner to fix the building.

Until then, it’s a waiting game and no one is winning.