Solid Hardwood, Engineered and Laminate Flooring - Strip Hardwood Floor Couping

Contractor installed prefinished strip hardwood flooring,and now it is cupping (edges are higher than centre). Boards appear to be swelling and are so tight that they are forced up at the edges. The flooring sat in our house (August) when the moisture level was relatively high (approx 60% humidity). They were installed using a vapor barrier and air gun over 3/4 " ASP (chip board). The job on completion looked excellent. Two years later (now), there is pronounced couping. Since this is the winter (I live in Canada), the furnace has the house humidity down to 40%; I cannot figure out why this problem exists. The boards should be shrinking; not expanding. The only element that may explain it is the vapor barrier somehow holding moisture at the bottom of the hardwood stripping.

Has anyone got experience with this problem? Or even a theory that makes sense?

There is 1200 sq ft, so the problem is a serious one for me.

thanks................for any help

Your theory makes sense. You have moisture from somewhere, perhaps from the ground or perhaps from a plumbing leak.

After checking to make sure that there is not a plumbing leak I would be contacting the contractor who did this job.
The product should have at least a 10 year warrenty. If its due to improper installation then I would be holding the installer accountable.