Cupping and Crowning: What They Are and What You Can Do About Them

Cupping and Crowning: What They Are and What You Can Do About Them

By In flooring care On April 26, 2018


It’s the stuff of nightmares for a homeowner. You install a beautiful new hardwood floor in your home, perhaps even a custom design. You’re incredibly proud of the floor; you take great pains to keep it looking at its best, and it’s a conversation piece for guests. But within a few months, you notice the planks in your floor look uneven, or “wavy.” It may or may not be obvious to the casual onlooker, but you can tell: Your beautiful floor appears warped!

Don’t panic. First things first—this is most likely NOT a result of poor quality wood, nor of bad installation. Believe it or not, this is a common occurrence for wood flooring—a result of the wood interacting with moisture and humidity. You’re seeing either cupping or crowning of the wood. In most cases, it’s treatable, and in mild cases, it even resolves on its own. That said, let’s discuss what crowning and cupping are, and more importantly, what you can do about them.

What Is Cupping?

Cupping is a situation where the edges of your wood planks curve up higher than their center, in a concave matter. Cupping occurs when the moisture content underneath your floors (your subfloor) is considerably higher than the moisture above. Wood is porous, and when it absorbs moisture, it expands. When moisture is higher underneath your floors, the wood planks compress against each other and have nowhere to go but upward—hence, the cupping of the edges.

Some common reasons for cupping:

  • Sudden changes in humidity in the air, often due to weather (springtime in Oklahoma is notorious for this).
  • Sudden changes in temperature, causing the subfloor to be warmer/colder than the outside air.
  • Accumulating moisture in the subfloor. This can be caused by anything from plumbing leaks to moisture seeping under the home during a particularly rainy spell.

What is Crowning?

Crowning is effectively the opposite of cupping: The centers of your wood planks bulge higher than their edges. This typically happens when the moisture content of the surface of the floor is much higher than the moisture underneath the floors—either due to extended periods of high humidity or perhaps by a liquid spill left for a long period of time. Crowning can also happen as an unintended result of sanding down cupped planks before allowing them to dry fully.

Dealing with Cupping and Crowning Floors

Mild cupping and crowning are actually natural functions of your hardwood floors as they respond to moisture, and once the relative humidity equalizes in the wood, your floors should return to normal over time, even with Oklahoma’s extreme weather changes. However, in instances where cupping/crowning happen due to leaks or excessive water, the damage may be more sustained. Crowning floors can often be evened out by sanding them, and dehumidifiers may be able to restore cupping planks. In extreme cases (usually due to prolonged negligence or natural disasters like flooding), the flooring may need to be replaced.

Preventing or Reducing Cupping and Crowning

To keep cupping or crowning at a minimum, your best defense is humidity and temperature control. Take steps to keep the relative humidity in your home between 35-45 percent by alternating between humidifiers and dehumidifiers as needed. Keep your home at a consistent temperature in the summer months using your air conditioner.

If cupping or crowning floors become particularly noticeable, or if you have concerns that the issue is beyond the normal function of your hardwood floors, call the experts sooner rather than later to minimize damage. For more information or an inspection of your floors, call Renaissance Hardwood Flooring at 918-298-4477.


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Renaissance Hardwood Flooring

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