Timber Floor Cupping

The simplest way to think of wood floor cupping is to imagine the edges of each plank sticking up higher than the centers.

Timber floor cupping.

Wet crawlspaces and basements will cup a floor as moisture moves upward. The general effect is easy to demonstrate by putting a small strip of paper onto a small drop of water. As the name implies the surfaces of boards that suffer from cuppinghave a concave shape. Leaks in pluming systems and fixtures sink dishwasher icemaker and toilet overflows.

As you can see moisture and wood don t go well together. Site related causes of wood floor cupping. Any wood floor can suffer from cupping. 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.

Wood cupping develops a set in boards ultimately boards that have cupped due to these moisture differences develop a set and remain cupped even when the boards have dried. See the picture at the top of this post for an example of a cupped floor. You can observe this dramatically in an interior wood floor that has been flooded then dried. Increase the relative humidity in the room with cupped floors to 20 percent to prevent cupping from the air being too dry.

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. Cupping dry or wet wood floors can be caused by humidity lack of humidity temp water. Cupping can also occur in rooms with dry humidity.

This makes the wood appear to be in a u shape. The sides of each board are higher than the middle sections. This imbalance could either be moisture from the concrete environmental conditions in the space being to dry and drying out the top of the wood and or a wood floor that wasn t properly acclimated to the environment prior to installation. Cupping means that the wood that is raised on the edges of each individual floor board.

Cupping is a common problem found in hardwood floors. There are a number of potential causes of site related wood floor cupping. When the moisture increases the wood swells and then when it decreases the wood shrinks. Wet maintenance can cause cupping.

Water vapor emissions from concrete. Wood is hygroscopic in nature and thereby tends to absorb moisture from its surroundings causing problems in hardwood floors. It is not hard to see the effect in wood flooring either. Cupping is a result of the changes in moisture in the room.

The center of the board dips below the edges. Moisture from below can. Boards will remain cupped. The paper will curl up away from the water.

The cupping is due to some type of moisture imbalance in the wood flooring itself. Wood is hygroscopic so it gains or loses moisture in your home seasonally.