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Random Moisture Migration, Where is it coming from?

By: Billy Simmons

Just as the world we know continues to change, so does the construction industry. I have been around the construction industry for most of my life and have seen many changes. For instance, I have seen contractors using wood 4×4’s as screeds with a cement type product put between the 4×4’s to hold them in place, or using burlap between the soil and concrete.

As inspectors, we are asked to go out and look at problems every day. Over the last couple of years, I have noticed an increase in moisture related problems in concrete substrates that seem to be occurring more often every year. The moisture issues within the concrete substrate are not from new construction or even construction within the past twenty (20) years; it seems more relevant in older slabs laid around the 1980s and before. Old subdivisions with track-style homes and regions that have high water tables appear to have the greatest percent of moisture problems.

As professionals, we get the call to go out and evaluate a hardwood floor where the homeowner is having a problem with random areas of dark discoloration and/or opaque bubbles appearing in their engineered or solid hardwood flooring. For example, once entering the home, we may notice two (2) or (3) places in the living room, one (1) in the master bedroom or dining room, and two (2) more places in the guest bedroom. The remainder of the hardwood flooring has no issues noted anywhere. The first thing that comes to mind is MOISTURE, but we find that the areas affected are not around any water sources.  We proceed to test those discolored areas and find the areas of the discoloration and/or opaque bubbles have high moisture readings, while the other areas unaffected to be within normal regional limits. What is the causation of the discoloration or opaque bubbles?

During our investigation, we find out that the house was built in the late 1970s, and 1000 ft.² of ½” prefinished solid oak hardwood flooring was installed. The installer is present and shows documentation of their calcium chloride test results of three (3) test locations all below four (4) pounds MVER. The adhesive used is recommended for up to eight (8) pounds MVER, and the moisture content readings of the hardwood flooring were at EMC of the home at the time of installation.  The installer removes planks from both the discolored and unaffected areas and you find the coverage rate of the adhesive to be per the manufacturer’s guidelines. All the evidence so far shows the installer has followed all the necessary guidelines to have a successful installation. So, is the installer at fault for the failure?

The homeowner has decided to hire a leak detection service before your arrival, and the results show that there were no leaks detected. Now let’s take the facts one step at a time.  1) We know the moisture content of the hardwood flooring was at EMC, no problem there. 2) We know the calcium chloride results were below the adhesives limitations, and the coverage rate was achieved, no problem there. 3) The leak detection service found no leaks, and there were no signs of leaks before installation, no problem there. So the facts in evidence show the installer is not at fault, and this is a site-related problem, but yet some inspectors will blame the installer.

So, where is the moisture coming from? The only source left is the concrete substrate, but how? The calcium chloride test showed to be acceptable; the installer performed the test in three (3) random locations, per the standard ASTM 1869. For the sake of the article, let’s say one test equals 1 ft.² so only 3 ft.² out of 1000 ft.² was tested that is less 0.3% of the total job, or in other words 99.7 % was not tested. The odds of testing in the problem areas are pretty slim. Through my experience and taking numerous core samples to view the condition below the slab, has showed that this problem is occurring with the polyethylene sheeting. The polyethylene is found to have holes, become brittle, or degraded, and if has not broken down in some way, there moisture on the top of the sheeting. The polyethylene from this era would turn brittle and break apart if it sat in the sun too long. We need to remember this was the best technology of the time for preventing moisture from migrating upward into the floor covering. Even today most, if not all, insurance companies have exclusions in their policy under “property exclusions” that will not cover moisture related damage of this type. For example a general statement may state, “Water below the surface of the ground, including that which exerts pressure on, or seeps or leaks through a building, wall, bulkhead, sidewalk, driveway, foundation, swimming pool, hot tub or spa, including their filtration and circulation systems, or other structures are not covered”.

So how can an installer or retailer protect themselves from such a scenario?  The first course of action is to complete a thorough site evaluation of the home or facility. Is the landscaping designed to flow water away from or towards the home, is the landscaping below the slab, does the home have a musty or wet smell? Ask questions, such as when was the home was built, what kind of floor covering was originally installed (if not visually evident), have they had any other water-related damage? Take several moisture readings and record them even if they do not show elevated. Inform the customer that due to the age of the home, there is a possibility that installing a wood floor now could reveal an underlining problem. Let them know you would recommend a moisture remediation system, such as a one-step adhesive, two-part adhesive system or even an epoxy system all of which can handle elevated moisture vapor emissions and you are taking every effort to have a successful installation.

On the legal side of things is your contract of services. Every installer or retailer should have a contract of services before starting any job. The contract should include provisions for this type of failure. Here is just an example, “It is hereby mutually agreed that the Contractor shall not be held responsible or liable for any monetary loss, damages, or inconveniences from underlying moisture emissions not detected at the time of installation, that all efforts have been made to detect such a problem, and are therefore not warranted”.

Unfortunately, in today’s society, there are people who are always looking for a way to litigate a problem, and this has gotten worst over the years. In order to help protect yourself remember as with any successful installation, it all starts with prep work. Conduct thorough job site evaluations, complete quantified moisture test, follow the manufacturer guidelines, have proper contracts and always remember to document everything.