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Why Are My Hardwood Floors Cupping?

crawl space moisture causing warped cupped floors
Figure 1

One of the most common identifiers that there is an issue in the crawl space is when the hardwood floors on the first floor of the home start cupping, buckling, or warping. This usually happens because of three different issues. If this is the case in your home, we recommend scheduling a crawl space inspection. Figure 1 is an image of a VERY developed buckling issue. Usually, it is more subtle than what has happened at this home.

The reason the floors are cupping is that the cellulose in the wood is absorbing moisture and expanding. 99% of the time that moisture is coming from beneath the sub-floor. Now that we know the moisture is originating in the crawl space, we can begin to assess what measures are required to ensure the floors stop cupping, and being certain it does not happen again.

The first step is to identify the way moisture/water/humidity is entering the crawl space. This is usually happening in one of 3 ways.

1 The water in the ground is evaporating up into the crawl space air, causing the humidity/moisture levels to rise to a point where the hardwoods are absorbing this moisture straight out of the air. The remedy in this situation is to install a vapor barrier to protect the crawl space from the groundwater evaporation. (See missing vapor barrier in Figure 2.)

crawl space air causing moisture levels to rise
Figure 2

2 Warm, humid air is infiltrating the crawl space through the foundation vents, causing the humidity levels to go up. The warm air will also interact with the cool HVAC ductwork, and this causes condensation. Combined, these are enough to cause hardwood floor warping in the home. See both missing vapor barrier and condensation on ductwork in Figure 2. The best way to handle this is to seal the foundation vents and install a commercial-grade dehumidifier.

3 Standing water is the third reason the crawl space has enough humidity causing warped floors. When you have open water standing in your crawl space (see Figure 3), it starts to evaporate into the air, rapidly raising moisture levels. This can be addressed with an interior drain line and a sump pump.

crawl space standing water
Figure 3

If you’re concerned with your hardwood floors, call the experts at Crawl Space Brothers and take advantage of your free inspection today! And always remember, buckling floors, high humidity, and standing water issues never get better on their own. They either stay the same or get worse. We always recommend being proactive instead of reactive when it comes to protecting the biggest investment in life, your home.

— The Crawl Space Brothers

Call to schedule a free inspection today!

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