As you can see moisture and wood don t go well together.
Wet hardwood floor cupping.
The paper will curl up away from the water.
Cupping is a result of the changes in moisture in the room.
The simplest way to think of wood floor cupping is to imagine the edges of each plank sticking up higher than the centers.
When moisture interacts with a hardwood floor the side of the boards closest to the moisture expands.
It ends up looking a little like an accordion.
Cupping in solid wood floors cupping occurs in solid wood flooring as a result of an elevated mc in the bottom of the flooring compared with the mc of the face.
Underlayment and or subfloor that is too wet at the time of installation will cause wood floor cupping.
Wood is hygroscopic in nature and thereby tends to absorb moisture from its surroundings causing problems in hardwood floors.
This expansion can be in the form of cupping the center of the board is lower than the edges or crowning the center of the board is higher than the edges.
When the moisture increases the wood swells and then when it decreases the wood shrinks.