Severe cupping

Q: I bought a home in New Mexico (extremely dry climate) three years ago which had been completely renovated. The entire home had been installed with soft wood flooring. The subflooring I believe is wood with a crawl space under the house. I noticed this winter that the floor was severely cupping in certain areas (the onset of which appeared to be quite sudden).

Since moving into the house I have noticed that the house creaks very loudly which appears to occur more frequently during seasons with greater temperature differentials (cold nights, warm days). I’ve wondered whether the creaking is a sign of the house settling and therefore a possible cause of the cupping in the floors.

I did pull up the moldingĀ along the walls closest to the most severe cupping and the there was absolutely no gap between the wood floor and plaster wall – in fact the floor looked like it was burrowing into the plaster along one wall and along the opposite wall was being forced downward so the plank had assumed about a 30 degree angle. I’ve just assumed the cause could not be due to moisture since we have been experiencing the driest winter in recorded history. And there has been no water damage to the floors or in the crawl space.

The only change I have made over the last year is have a wood burning stove installed. Are there other possible causes of cupping floors aside from moisture? Do you have any suggestions? My inclination is to create space between the wood floor and the plaster walls but am reluctant to do that before determining the cause of the cupping. Any advice would be greatly appreciated.

A: The only reason a floor will cup is from excessive moisture and lack of expansion along the side walls does not help at all. Your floor is picking up moisture from some place. I would definitely cut the floor back along the walls 1/2″ at least. A moisture meter and hygrometer could help you to know exactly what the environment is at the floors surface. The moisture source is likely from the crawl space. If the crawl space has a dirt surface, I would place heavy plastic sheeting over it and make sure it is cross ventilated.