What Humidity Should a Crawl Space Be?

Crawl spaces are arguably the most important part of any home that has one. They support the entire building, and many even house crucial utilities like plumbing and an HVAC system.

As you can see, keeping the crawl space safe from damage is a good idea. Since most crawl space issues (including humidity) come from moisture, you need to control it. Here, we’ll look at what the ideal crawl space humidity level is and how you can achieve it.

Mold needs three things to grow: food, water, and oxygen. In the average crawl space, wooden support beams serve as a food source for mold and oxygen is, well, everywhere. High humidity in your crawl space will seal the deal for mold, providing it with plenty of moisture to grow and spread quickly.

Wooden beams, floor joists, and columns in the crawl space support your entire house. Excess humidity causes moisture to seep into these wooden structures.

Have you ever seen what happens to wet wood? It becomes soft and easy to break, and the same thing happens if wood is in high humidity. Over time, a fungus called wood rot develops and causes the wood to become extremely weak.

Many pests are drawn to dark humid places like a crawl space. Most often, spiders, termites, slugs, and even some rodents will be drawn to a crawl space. They can find food, water, warmth, and security below your home.

Crawl spaces usually have some kind of insulation. Fiberglass is the most popular choice, but if the crawl space is too humid, it causes big problems for the insulation.

Fiberglass is highly absorbent, so it sucks up all the humid air. This makes the insulation wet and heavy, so it eventually falls down. If this happens, your home won’t have proper protection from outdoor temperatures and may even experience higher energy bills.

During a heavy bout of rain or a hurricane, water builds up quickly on the ground. In some cases, that water can drain into a crawl space where it collects as standing water.

Essentially, this creates a big puddle of water in the crawl space, and as that puddle of water evaporates, it releases moisture into the air. Quickly, humidity levels rise and wreak havoc.

Back when crawl spaces were first being built, contractors thought that adding open vents to the walls would allow for constant airflow and dry conditions. Unfortunately, we know today that this actually makes it easier for humid air to get into your crawl space. In short, if the air outside is humid, it will seep through open vents and only increase the humidity inside the crawl space.

In a crawl space encapsulation system, the two biggest impacts on humidity are a crawl space dehumidifier and a vapor barrier. The dehumidifier will collect moist air, make it dry, and pump out the newly dry air. Meanwhile, the vapor barrier will keep humid air out of the crawl space.

Besides these two important tools, encapsulation will also have a drainage system, sump pump, foam board insulation, drainage matting, and a sealed crawl space door working to keep moisture out. Learn more about crawl space encapsulation here to see if it’s right for you.

Aim to keep crawl space humidity between 45% and 55% to avoid serious moisture issues. Working with professionals is the best way to get it done, and as Florida’s leading crawl space repair experts since 2002, we have the tools and experience to help.

With industry leading solutions and a world class team of experts, contact us today to schedule a free crawl space inspection. Let’s put crawl space moisture back in its place, together!