Hardwood Hints: Measuring Moisture on a Cupped Floor

There are times a client may want you to sand a previously cupped floor. As an example, if a floor that was flooded a while back, where you feel enough time has passed,  many contractors would assume the floor is ok to sand. The danger of doing that before the floor is really ready is you can have a moisture imbalance.

Take a moisture meter and set it for the species, the temperature, and the conditions. For example, with an insulated pin meter, the top is around 6.5-7.0 percent. As the pins go deeper, the moisture goes past 10 percent, so we are going to be dealing with at least 3 or 4 percent difference in moisture content for that wood from top to bottom.

If you were to sand it flat, it will be a pristine looking floor. But after a while as that wood comes back and the imbalance settles, the top is going to end up crowning because the wood is going to lose the excess moisture and go back to its equilibrium state. The edges are up, so by sanding it too quick we are going to cut those edges and the sides of each board are going to be narrower than the actual middle. As the wood comes back to moisture content equilibrium those are going to show as a crown floor. That’s why even though visually it might look like the floor is ready and we don’t feel any moisture, it’s really important to rely on facts and take moisture readings.