Measuring moisture % in wood is different then measuring humidity in
air, dry wood is is considered less than 15%. My sill on concrete is 12%
now in a basement of 50% humidity. I can see 90 % humidity being a minor
concern but the real issue is wet wood shrinks . Properly instaled
floors have expansion gaps as the house itself will expand and contract.
Any new wood should be measured for % water, I use a Delmhorst meter.
Wood takes a long time to dry if improperly stored at warehouses.