Is It Normal to Have Moisture in My Crawl Space

Many homeowners are wondering, “Is it normal to have moisture in my crawl space?” Homeowners might expect there to be a certain amount of moisture from humidity, flooding, and plumbing leaks in the crawl space, but is it normal for the crawl space to be damp and flooding?  Many people don’t realize that 50% of the crawl space air makes its way into their living space. Having high humidity in your crawl space also makes the humidity in your living space high.

Crawl Space Humidity Affects Your Home

Controlling humidity can improve indoor air quality. Keeping the humidity under control in your crawl space helps to lower the risk of bacteria, mold, virus, dust mites, and other indoor air quality pollutants in your home. The stack effect (or chimney effect) will move the air from the bottom of your home to the top. If your basement or crawl space is damp, chances are the rest of your home is suffering as well. Dehumidification is one of the best ways to ensure your home is dry all year.

Controlling Crawl Space Humidity

Installing a crawl space dehumidifier is the first thing we recommend when correcting a wet crawl space. When doing crawl space repair, installing dehumidifiers and sump pumps, sealing the vents, and air sealing the sub-floor is vital.

Many crawl space contractors frown upon the installation of dehumidifiers. They have been taught vent fans and plastic are all that is needed to control crawl space humidity. We agree they are vital in controlling crawl space moisture, but a dehumidifier is the key to making sure humidity is controlled all year. Homeowners tend not to like dehumidifiers because they feel like it will cause their energy bills to increase. Many studies have shown that lower humidity actually should decrease the energy consumption of your home. When heating and cooling your home, installing a dehumidifier is not only a great way to control moisture but also improve energy efficiency. It is easier for the HVAC system to cool and warm air that has low humidity.

Wet Crawl Spaces and Flooding

A flooded crawl space can cause humidity to get out of control. Standing water is not the only source for high humidity in the crawl space. Standing water in the crawl space is certainly one of the top sources of high humidity. By controlling the flooding of the crawl space you can improve the overall humidity of your home. Waterproofing the crawl space is no substitute for a dehumidifier. Using sump pumps and french drain trench systems along with properly installed vapor barrier and a dehumidifier will improve the humidity of your crawl space and the overall air quality of your home.

Crawl Space Moisture Repair

Do you need help fixing your crawl space or basement? If so, we can help. Please contact us to schedule your assessment. Also, let us know in the comments below if you’d like to suggest a future blog post.

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5 thoughts on “Is It Normal to Have Moisture in My Crawl Space”

  1. There’s a balance somewhere between paying too much in energy bills and allowing unchecked crawl space moisture to affect indoor air quality and efficient operation of HVAC. We feel like using the proper dehumidifier is a key step in minding the pocketbook and the health of the house and household. It’s also important to use the right dehumidifier, one rated for use in the crawl space, not the portable unit on wheels that we often see in crawl spaces here in NW Atlanta.

  2. Hi there, I have a bare earth, open crawl space under my raised home. We have batt insulation, but it collected moisture and has begun rotting out subfloor. There is mold. I see that you often recommend against spray foam, but the batt insulation created this problem for us and all the local companies are telling me spray foam is the solution. Would love you thoughts on how to insulate and protect our subfloor going forward.

    Separately, I have one company who insists we have to pay him to use a forced air heater under the house to get the joists under 10% moisture, while the other guy says leaving it open to the air without the fiber insulation will be enough to get it down to 18% and install the spray foam. I don’t know who to trust, but the first guy costs twice as much..

    1. It sounds like you have a moisture problem that needs to be addressed before insulating. Spray foam is great at insulating and air sealing but doesn’t fix moisture problems or address mold/rotten wood. I suggest trying to find someone in your are that understands humidity/building moisture before spending money on spray foam. Adding spray foam could make it worse if they are covering wet wood and mold. Hope that helps. Where are you located?

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