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The Problem
I received a request to inspect a hardwood flooring installation in the Southwest to determine the causes of noises that were described by the homeowner as "snap, crackle, pop" sounds. The owner reported that the noises did not start until a few weeks after the installation was completed and that the sounds were getting worse with time. The project was a remodel, and the homeowner was present during the installation. The central heat and air system was operational throughout the acclimation period as well as during and after the installation. The project was finished at the end of April, and the complaint was filed four months later.
The Procedure
The home's foundation was a concrete slab built on grade level. Hardwood was installed covering 2,400 square feet of floor space. The floor was a factoryfinished, long-plank engineered product with an HDF core. It locked together at all sides and was designed to be installed as a floating floor only. The specifications for this product require a vapor retardant underlay pad specifically designed for floating wood floor installations. The specifications also require that all concrete subfloors be fully cured and declared dry, and that this be confirmed using a simple mat test, a concrete moisture meter or a calcium chloride test, as well as a pH alkalinity test if one of the other tests indicated high moisture. All test results should have been documented, but test documentation for this job was not available.
The Cause
Entering the home, I walked through the foyer into a hallway and then into the great room. I could feel minor deflection with almost every step. The hardwood planks did not show any sign of cupping or crowning. I could faintly hear scraping friction sounds in certain areas that seemed to have more deflection from my steps. I immediately thought that this was a problem caused by inadequate perimeter expansion space, resulting in extreme pressure in the locked joints. The "snap, crackle, pop" noises were wood-to-wood friction sounds. I checked for expansion zones and found the hardwood was pressed tight to every vertical obstruction I could examine.
My thermo-hygrometer measured indoor relative humidity at 48 percent and temperature at 77 degrees Fahrenheit. Both readings were close to the high end of the industry guidelines. I used a pin/probe wood moisture meter to measure the hardwood moisture content, which varied from 12 to 19 percent, which is very high compared with the normal factory level, which is 7 to 9 percent.
In three separate areas, light gray discolorations were visible in the hardwood planks, indicating early signs of decay. Those three sections measured 19 percent moisture content.
While checking for plumbing leaks and exterior drainage problems, the homeowner spoke up and explained that the original home builder put "saw cuts" completely through the slab in the areas where I found high moisture. The floor had been covered with wall-to-wall carpet until this hardwood installation. The carpet allowed vapor emissions to escape into the air unnoticed, but the vapor retardant pad under the hardwood suppressed the moisture in the slab until excessive hydro-static pressure migrated through the pad seams and into the hardwood. The pad seams were taped with paper masking tape instead of the recommended plastic tape, and the pad seams proved to be the path of least resistance for the vapor emissions to flow through. The hardwood was saturated and over-expanded, causing excessive compression through the entire hardwood floating installation.
How to Fix the Floor
This particular hardwood floor was designed to be removed and re-installed relatively easily. The hardwood and underlay pad had to be removed. The pad was disposed of, and the hardwood was airdried back to a normal 8 percent moisture content. Corrective measures were completed to divert water away from the home's exterior foundation, and the mysterious saw cuts were filled with a flexible sealant to prevent water from moving from the outside perimeters to the interior of the slab foundation. The entire concrete slab was treated with an appropriate sealant to ensure vapor suppression.
In the Future
Always take the extra time and make the effort on the front end of the job to ensure that the job site is prepared for the work you are performing. Invest in the tools you need, such as hygrometers and moisture meters, to be able to adequately check the job site and the floor covering product. Your business will profit immensely while you enjoy positive callbacks and eliminate failures. Good news travels fast, but when it comes to floor covering failures, bad news tends to travel faster and linger longer.