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The Problem
A flooring distributor requested I look at a consumer's 5/16 -by-2¼-inch solid oak prefinished hardwood floor that had buckled about a week after installation. The mill rep had denied the claim.
The Procedure
The consumer's grandchildren had stayed overnight. Before leaving for an amusement park early one morning, one of the grandchildren went back into the home to use the restroom and apparently left the faucet running. When they returned late that evening, they were greeted at the door by running water. The water flooded the carpeted bedrooms and buckled the hardwood floor in the 18-by36-foot great room.
A restoration company extracted the water from the carpets and installed dehumidifiers and air movers. The hardwood flooring was removed where it had buckled. This restoration company was a preferred vendor by the insurance company and handled all phases of the remediation, which included hiring the flooring installer. The manufacturer had discontinued the previous flooring, so new flooring was purchased. The installer stated the flooring was stored in the great room, where the dehumidifiers were running, for about three days prior to installation. The flooring was glued in place over the slab, which was above-grade concrete over a four-block-high foundation wall that was dirt-filled. Within a week after the replacement flooring was installed, it buckled about 6 inches off the floor. The time frame between the flooded floors and installation was less than two weeks.
The Cause
This flooring was doomed from the start. Running commercial dehumidifiers in the home did wonders for drying the carpet, but it created an atmosphere the flooring might never encounter. The dehumidifiers reduced the moisture content (MC) of the flooring, which also likely reduced the dimension of the flooring.
The installer stated there was no moisture testing preformed prior to installation since the remediation company told the installer everything was dry. Most likely, the slab was dry to the touch, but moisture was still in the concrete and moving upward, since water had been running over it for hours.
When the drying equipment was removed, the room returned to its normal environment. The flooring picked up moisture both from the air and from water vapor moving up from the slab. MC results of 15 to 18 percent were obtained across the flooring with a pin meter. The EMC of this flooring based on relative humidity (RH) and temperature at the time of inspection should have been around 9 percent. A 7 percent increase in MC for plainsawn oak flooring would mean about a 5½-inch expansion over the 18-foot expanse of flooring. Under these conditions, there was no place for the floor to expand but upward.
How to Fix the Floor
The floor had to be removed. New flooring had to be installed, starting with proper moisture testing of the subfloor and the wood flooring, and acclimation.
In the Future
"Dry" is a subjective term that needs to be verified by testing. NWFA publications and classes both stress the importance of proper acclimation and moisture testing techniques. One of the items that I learned from both of these is that "rewetted" concrete takes as long as or even longer to dry than "placed" concrete. Never assume a slab is dry enough for wood flooring installation, no matter how long it has been in place.