Why are my newly refinished floors cupping?

Karin W
by Karin W
Our hardwood floors have never been cupping within the last 20 years .... until we had them refinished. Are they more sensitive to moisture now? And what should I do to prevent further damage? How do I get rid of the damages area? Will it disappear on its own? I don't think it has anything to do with me cleaning the floors since I use a special wood cleaner and it is also cupping in areas I did not clean, like under the area rug.
  4 answers
  • Terry's Flooring Terry's Flooring on Oct 02, 2013
    I don't understand what you mean by cupping....Never have heard that term..Could you be more specific on what the floor looks like ( A photo would be nice )
  • Karin W Karin W on Oct 02, 2013
    I nver heard that term either until I found it online when I looked up my floor problem. Here is an example photo. It is not a photo of my floors, my damage is not that spread yet. But I want to prevent further damage.
  • Karin W Karin W on Oct 02, 2013
    another picture
  • KMS Woodworks KMS Woodworks on Oct 02, 2013
    Most cupping is due to water issues. mainly getting between the boards and causing swelling to the bottom of the wood that is not "sealed" This causes expansion and the board edges lift. The refinishing (sanding) has opened up the seams allowing moisture to get in. Water based finishes can do this on rare occasions. The main reason is overly wet cleaning, or spills and leaks. I have done dozens of repairs in kitchens due to a drippy ice maker line or sink / dishwasher leak. A damp towel, or mircofiber pad is all the moisture that is ever needed to clean a floor. If you have any visible water on the floors surface after a minute or so you are using too much water. In many cases this cupping will calm down after is dries somewhat, but in many cases it never returns to perfect. If this cupping is re-sanded while wet , the result after drying will be "crowned" flooring. If the moisture has gotten into the subfloor the problem will take even longer to dry. Do you know what product was used to finish? and how many coats were used? I always recommend oil based and a minimum of three coats. I also do not recommend any "cleaning" for at least a week after the final coat. This allows the floor to fully cure.