Cupping due to rubber mat by dishwasher and sink?

Q: Can cupping of laminate floors be caused by using a rubber-like kitchen mat by the sink and dishwasher area?

A: This is an interesting question to ponder. It isn’t having a mat there that is a big problem. However, this is near a water source and in the case of the dishwasher, hot steamy water. If that vents steam and it can get under the mat it would be trapped, and that would be a problem.

Foam mat causing cupping by a dishwasher?

Related Q: We have a long memory-foam mat, covered by a hallway runner, in front of our sink, dishwasher, and stove. When we took them up to clean recently, I noticed that the oak floor underneath was mildly cupped. We can’t find any source of water, and the subfloor is completely dry. Could the cupping have been caused by moisture trapped in the memory foam mat?

A: Cupping usually happens from a moisture imbalance coming from the underside of the wood. When there is excessive moisture applied to the surface it can twist the other way, with a raised center called crowning. I’m assuming you have pre-finished hardwood. Dishwashers usually vent steam and I’m wondering if that is getting under the mat, running between the boards and causing the trouble. It seems clear enough that the mat and damaged area are connected.

Follow-up: Yes, it is pre-finished hardwood. It sounds reasonable that the dishwasher is involved because it seems to be at the center of the problem. In any event, we will never use that kind of mat again.