Crawl Space Venting

It is very common for a crawl space to be built with venting, but why is this the case? It seems to be an automatic assumption that the air inside a crawl space gets stuffy and then needs fresh air to be vented through it. However, this can be the cause of multiple problems.

First off, an obvious issue with venting a crawl space is that it allows water to get inside. This water from rain and runoff can rot floor joists and erode the dirt around a foundation. It also gets moisture in the crawl space air that conditions the crawl space for mold growth. These two factors alone are enough to make your crawl space at risk for serious issues later down the road.

Even when it is not humid or wet outside the relative humidity of a crawl space can be affected by its venting. Relative humidity is how much water is held within the air. Whenever crawl space air is cooler than the outside air and the outside air gets vented through it the relative humidity increases for every degree it gets warmer. This is because cooler air cannot hold as much water as hot air. In this instance, even if the outside air is not incredibly humid, it will still mix with the cooler crawl space air and cause the crawl space air to be very moist and creates a dew point within your crawl space. When this happens, water will most definitely be inside your crawl space, getting the exposed wood wet and affecting the air quality.

The best solution for this is to seal off the crawl space’s venting. It may seem counter intuitive but sealing the crawl space from outside factors helps to control the air inside the crawl space. There are many other issues and negative affects a crawl space can cause a home to have, but when it comes to moisture and inconsistent temperatures inside a crawl space sealing the venting is a great place to start.