Moisture from below can.
Wood floor cupping.
Cupping in hardwood floors is caused by changes in moisture levels whether decreases in the air rh above or increases in moisture from below.
A cupped floor has a concave shape across the width of the boards.
Wood is hygroscopic in nature and thereby tends to absorb moisture from its surroundings causing problems in hardwood floors.
Cupping means that the wood that is raised on the edges of each individual floor board.
This makes the wood appear to be in a u shape.
If you think you can escape cupping by installing a bamboo or laminate floor you can t for they can also cup.
Cupping is one of the unfortunately common issues that can plague hardwood floors.
Cupping can also occur in rooms with dry humidity.
As you can see moisture and wood don t go well together.
If you imagine a picture of a child drawing a boat in the water then the water will give you a good idea of what a cupped floor looks like.
Cupping is a result of the changes in moisture in the room.
The center of the board dips below the edges.
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.
What is cupping and how does it occur.
When the moisture increases the wood swells and then when it decreases the wood shrinks.
Increase the relative humidity in the room with cupped floors to 20 percent to prevent cupping from the air being too dry.
See the picture at the top of this post for an example of a cupped floor.
It can happen to most types of wood and it s often the first observable sign your floor is being affected by moisture.
The paper will curl up away from the water.
Other causes of hardwood floor cupping could include situations such as basement plumbing leaks that allow moisture to migrate up into the subfloor and into the wood flooring or the heat from a wood stove that drys out the air in the environment.
The general effect is easy to demonstrate by putting a small strip of paper onto a small drop of water.
Wood floor cupping is a common problem that occurs with both solid and engineered wood floors.