In most cases, this is a minor problem and is easily fixed. The squeaking may be caused by loose boards rubbing against their nails, or perhaps by movement of the tongue and groove. Other causes may be a poor subfloor, inadequate adhesive coverage and/or an unstable environment. Both the National Oak Flooring Manufacturers Association (NOFMA) and the National Wood Flooring Association (NWFA) recommend using graphite, wax or baby powder as a fix for minor problems. NOFMA warns that if the floor is a seal-and-wax, graphite or penetrating oil may discolor the surface.
If the squeak is determined to originate from a subfloor problem where joist movement is loosening the nails, you will have to correct the situation by wedging the subfloor up from the joist. Face nailing and glazing points are two other means of correcting squeaking boards.
It is impossible to remind the end-user too often about the “Greenhouse Effect.” More and more people are taking longer and longer vacations, shutting up their homes and drastically affecting the indoor air environment. The heat of the day followed by the coolness of night will cause dramatic changes in the humidity inside a closed home, which can result in cupping of the wood floor. In colder weather, heating systems without humidifiers will remove moisture from the air. This can result in shrinkage and cracks in the flooring.
In today’s high-pressure, “get-it-done” construction environment, surface floor preparation gets a “wave” of the hand, if that. Most of the bond problems I have seen are the result of poor prep, or no prep at all. For example, a job glued down over old asphalt cutback resulted in a black, gooey mess and subsequent failure. Another common occurrence is gluing directly over concrete curing compound; it is destined to release eventually.
A few drops of water will test the porosity of the concrete slab. Aside from using a trowel that is worn out or the incorrect size, there is the flatness of the concrete to consider. There may be a beautiful spread pattern, but if the substrate is uneven, the adhesive transfer may not be realized, resulting in a hollow-sounding wood floor. An issue that I seem to be continuously “honking” about is moisture from below. I am happy to see that many installers now carry a moisture meter to check for and avoid problems related to moisture. A professional installer takes no pleasure in seeing a buckled floor, as it probably means there is excessive moisture.
The problem may be amplified by not having “relief gaps” around the perimeter. These gaps are necessary to accommodate the floor’s expansion. Other factors contributing to buckling include deficient nailing, mastic (which is affected by moisture and akalinity), poor adhesive transfer, and trowels that are worn out or the incorrect size. Repairs will need to be performed by experienced flooring contractors. Each case needs to be approached singularly, and repairs made using the proper technique or techniques, including addressing shrinkage cracks the wood dries out.
One last note: A four percent increase of moisture in the wood will cause approximately ½” expansion in a 20-foot room (the wood will expand to a greater degree in width and thickness). Knowing that, it is not that far-fetched that one major wood manufacturer claims that 90 percent of its callbacks and complaints are moisture related.