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Crawl Space Humidity Level

Believe it or not, the biggest threat to your dirt crawl space is high relative humidity levels. Relative humidity is the amount of water in the air relative to the maximum amount of water the air can hold at that temperature. Meaning crawl space humidity can spell trouble for your home if you leave your crawl space humidity level unchecked.

crawl space humidity level - a high relative humidity creates mold, moisture, and wood rot

A hygrometer measures relative humidity. Your crawl space humidity should be under 55%.

Maintaining a safe crawl space humidity level means maintaining a humidity level below 55%. Keeping your home’s crawl space humidity level under 55% prevents mold and mildew from growing and hinders dust mite invasion.

Maintaining a safe crawl space humidity level means maintaining a humidity level below 55%.

A crawl space humidity level lower than 55% also minimizes the possibility of structural damage caused by wood rot. Therefore, your crawl space humidity level should never be ignored.

Crawl Space Humidity Level and Mold

Crawl Space Humidity Level

Mold eats organic matter, meaning it likes anything that was once living, i.e. trees and anything processed from them such as crawl space insulation, drywall, plywood, etc…

A high crawl space humidity level causes the porous material in your crawl space – wood and insulation, to soak up moisture like a sponge. This becomes the perfect environment for mold to grow and thrive. 

During rainy and humid weather, crawl spaces often become damp with moisture levels exceeding 70% relative humidity for long periods of time. Meaning, the weeks following heavy rain are usually when symptoms are the worst. When this happens, the excess moisture encourages mold to grow on your wooden floor joists and on any other organic material located in your crawl space.

Mold eats organic matter, meaning it likes anything that was once living, i.e. trees and anything processed from them. This is why mold is frequently found growing on fiberboard, chipboard, plywood, drywall, and lumber inside of crawl spaces.

During rainy and humid weather, crawl spaces often become damp with moisture levels exceeding 70% relative humidity for long periods of time. Meaning, the weeks following heavy rain are usually when symptoms are the worst.

How to Control Your Crawl Space Humidity Level

crawl space humidity levelControlling moisture is the key to eliminating problems with mold, dust mites, and wood rot in your crawl space. A vented crawl space that has a dirt floor is certain to be a damp environment where mold, mildew and even wood rot can easily grow and multiple. Even a crawl space with a concrete slab floor can have excessive moisture.

Drying out your damp crawl space is a smart move, not only for your family’s health but also for your home’s value. The only way to ensure your crawl space stays dry is to encapsulate it. Crawl space encapsulation is your best solution for removing excess moisture and ensuring your crawl space humidity level stays below 55%.

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