What Causes Crowning in Floors?

Moisture Imbalance

• A common cause of crowning in hardwood floors is moisture exposure. If the surface of your hardwood floor boards are left exposed to water or left in wet or humid conditions for an extended period of time, the moisture can saturate the wood and cause crowning. Water exposure due to an indoor sprinkler system, plumbing leaks, roof leaks or other causes can lead to moisture exposure and crowning.

Improper Sanding

• Crowning may also occur due to previous floor cupping problems. If the floor is cupped, or the edges of the boards have risen due to excess moisture, the floor should be given time to dry. If the floor is sanded while the boards remain cupped and moisture is still present, the sanding process can cause the raised edges of the board to flatten while lifting up the middle of the boards, resulting in crowning.

Natural Crowning

• Slight crowning can naturally occur in plain-sawn boards with wide planks, due to the rings of the tree growing at more of a curved angle. Such boards, when installed, raise higher in the middle than the edges. This crowning is normally not very noticeable unless viewed under the reflection of a low source of light.

Crowning Solutions

• Crowning can often be avoided by ensuring the hardwood floor boards are not exposed to excess moisture. If crowning does occur, the boards should be allowed to dry in order to eliminate the moisture. Fans will often expedite the drying process. After the floors have been checked for moisture and determined to be dry, sanding them should flatten down the boards and level out any crowning.