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Easy Steps to Dry Out a Crawl Space (And Keep It Dry)

Easy Steps to Dry Out a Crawl Space (And Keep It Dry)

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A wet crawl space can lead to serious problems if you leave it unchecked. For that reason, it’s pretty important to keep it dry, especially during the rainy season.

Fortunately, there are effective ways to dry your house’s crawl space and keep it that way. You can install vapor retarders, dehumidifiers, fans, a French drain, or even encapsulate the space.

In this post, we’ll go over everything you need to know about how to dry out a crawl space. We’ll also discuss some alternatives, guides, and tips to maintain this vital part of your home.

Are Crawl Spaces Supposed To Be Dry?

A damp or flooded crawl space can be disastrous. It can endanger your family’s health and compromise the structural integrity of your house.

Health Hazards of Damp Crawl Spaces

What makes a damp crawl space hazardous to you and your family’s health isn’t the dampness per se. The problem is mold, which can land and grow in moist environments.

According to the Environmental Protection Agency (EPA), the mold spores that grow in your wet crawl space can produce allergens, irritants, and toxic substances.

Inhaling these allergens and irritants can cause allergic reactions in sensitive members of your family. For a person with asthma, it can trigger attacks, which can easily prove fatal.

Irritations on the skin, eyes, nose, throat, and lungs are also common, even in people with no any allergic history.

Although it’s impossible to get rid of mold spores completely, you can minimize the health risk they can cause. To accomplish this, keep your entire home clean and dry.

Structural Issues of Damp Crawl Spaces

Aside from the health problems, leaving your crawl space wet jeopardizes the integrity of your house’s foundation. If you’re planning to sell, this can reduce the value of your house as well.

The stagnant water down your crawl space won’t evaporate on its own. This wet condition will gradually damage the wooden beams and joints keeping your home upright.

Over time, it can deteriorate the drywall and the concrete floor—even corroding steel components. A proper drying and ventilation system is necessary to avoid these headaches.

How to Dry Out A Wet Crawl Space

If you have a wet crawl space problem, dry it before installing any drying or ventilating system. Follow these steps to dry out a wet crawl space:

Step 1: Remove Wet Debris

The first step when drying your crawl space is to remove any wet materials. Debris like wood or rags can keep water for quite a long time and should be taken out as well.

In case you’re using your crawl space as storage, chances are that’ll double the moisture level too. So, it’s best to clear out everything and find another suitable space for storage.

Step 2: Remove Stagnant Water

After removing wet debris, the next step is to take care of stagnant water. For this, you can use thick rags to absorb the liquid or use a wet vacuum.

If you have a flooded crawl space, you can use a submersible pump to take the water out of your house. It’s a portable device specifically made for transferring large volumes of water.

Step 3: Reduce Moisture

The moisture in a crawl space can come from two primary sources: leaks and groundwater. If you live in a low-lying area, rainwater can easily seep through.

To reduce the moisture coming from your house, check for any leaks in your walls or plumbing system. Be sure to seal and repair any damage to ensure that no water can flow inside.

How to Keep Your Crawl Space Dry: 5 Ways

After drying and cleaning, you can now install a system to ventilate and keep your crawl space‌ dry. There are several solutions and tools you can use for this purpose.

1 – Crawl Space Fans

Installing vent fans is one of the easiest ways to manage crawl space moisture. They function by pulling in dry air from outside and replacing the stale and damp air inside.

If your crawl space has dirt flooring, the fans can help expunge the soil gas that the ground can release. It’s a good preventive measure against harmful soil gasses.

Finally, this method would help lessen the growth of molds and mildew. In turn, this reduces spores, helping clean the air that circulates inside your home.

The only downside to crawl space fans is they need dry, crisp air from outside. For that reason, you need to keep an eye on the weather to maintain the desired environment.

The price of a crawl space fan goes around $100 to $200 on Amazon. The number of fans to install will depend on the size of your crawl space.

2 – Dehumidifier

Setting up a dehumidifier is one of the best options, if you want a surefire way to maintain your crawl space. It’s a device that controls the humidity level by extracting water from the air.

There are many benefits to this method too.

First, it keeps the level of humidity within the most optimal range of 30% to 40%. This helps improve the quality of the air you breathe inside your home.

Second, a dehumidifier can help you with pest control. A damp, chilly crawl space can attract pests, so by keeping it dry and clean, there’s no place for insects or rodents to infest.

Third, using this method can also prevent unpleasant odors. Reducing the growth of mold and mildew prevents any unpleasant smell from building up as well.

The cost is the only downside to installing a dehumidifier. The price of a unit hovers around $1000 to $2800, depending on the size and brand.

3 – Vapor Retarder

A vapor retarder is another effective technique to control moisture inside your crawl space. It serves the same purpose as a dehumidifier and a fan, only it uses a different approach.

There are many types of vapor retarders you can use. They’re generally divided into two, though: membranes and coatings.

Membranes are flexible and thinner varieties, like polyethylene sheets and foil-backed wallboards. These moisture retarders are most suitable for cramped spots like crawl spaces.

Coatings, on the other hand, are tough materials that insulate vapor. Some examples of this type are rigid foam, aluminum, and reinforced plastic.

The cost of installing vapor retarders can go around $1200 to $4000, depending on the size of your crawl space and the material you want to use.

4 – Encapsulation

Encapsulation is a moist-management technique that involves lining the floor of your crawl space with heavy-duty polyethylene. If what you have is a dirt floor, this method is for you.

Like all the techniques above, encapsulation cleans the air inside your home. It can significantly reduce the build-up of molds and mildew as well.

Most importantly, it protects your house’s foundation from pests, rots, and fungal decay. It also lowers the operating cost of your heating and cooling systems.

The only issue with this method is it needs to be airtight. So, if your crawl space is unenclosed, you might need to seal it down first.

The cost of encapsulating will depend on three factors: the crawl space size, the material, and the contractor. On average, you can spend $1500 up to $15000 for an encapsulation.

5 – French Drain

A French drain is another way to deal with a wet crawl space. It’s especially effective when your house is on a slope and you have a pooling issue.

The purpose of a French drain is to divert water away from your property. You can typically find it installed in basements and around a house’s exterior.

There are three materials used for this drainage system: perforated pipe, pea gravel, and heavy-duty landscape fabric. You can either build it yourself or hire professional workers.

Overall, a French drain can cost you around $500 to $18000. This cost can go lower or higher depending on the price of the materials and the labor charge in your area.

Other Methods to Keep Crawl Spaces Dry

Dealing with a damp crawl space can cost you a lot of money. So, if you’re looking for some cheap alternatives, we’ve got you covered.


If you live in a relatively flat area, you may not need to spend thousands of dollars to keep your basement or crawl space dry. This method requires sweat and hard labor, though.

Using sandbags is pretty straightforward. Still, they’re effective at preventing or reducing water from flooding the underside of your house.

The trick to this technique lies in the arrangement of the sandbags. You should stack them solidly around the gaps of your crawl space.

Keep in mind, however, that the sandbags can deteriorate after a few months of exposure. So, you might need to replace them a few times every year.

Sump Pumps

Turns out, you can permanently install a sump pump in your crawl space or basement to keep water from accumulating. Plus, it only costs a few hundred dollars and a little labor.

In installing a sump pump, you need to locate the lowest point of your crawl space. There, you need to set up your sump basin where it catches and gathers water.

One of the advantages of a sump pump is that you don’t need to activate it manually. Once the water level reaches a certain point, it automatically pumps the water out of your basement.

Sump pump installation is relatively cheap too. The price of the machine itself is only around $200 to $300, with an extra $100 to $200 if you opt to hire a professional.

Wet and Dry Vacuum Cleaner

A dry and wet can help with minor pooling and leaking issues. It can also clean debris and particles out of your crawl space.

Remember, though, that a wet vac only serves as a cleaning tool. So, you still need to locate the source of the water and seal it to get rid of the problem for good.

The price of a wet and dry vac ranges from $50 to $400. In cleaning a messy crawl space, it’s better to pick a professional-grade vacuum for better performance.

Can A Crawl Space Be Too Dry?

Okay, so we’ve talked about why it’s important to keep the crawl space dry, but how dry should it be? Are there any negative effects of an overly dry crawl space?

Level of Dryness

You can measure the dryness of a place through the level of its humidity. In crawl spaces and other cramped spots in your home, the ideal humidity should be between 30% and 40%.

You can use a hygrometer to measure the level of humidity under your house. It’s a device that monitors the temperature and the amount of moisture in the air.

Issues of Low Humidity

Several problems arise if the humidity goes lower than recommended. One of them is that it encourages viruses and bacteria to flourish.

According to research, flu viruses are more likely to spread in conditions with low humidity. With that in mind, you should maintain the right level of humidity in every corner of your home.

In addition, an overly dried crawl space can pose issues similar to a damp one. An example of such an issue is the possibility of dry rot in wooden pillars and joints.

Dry rotting is a type of fungal decay that can spread even in dry environments. It’s a serious problem that, like wet rot, can impair the structural integrity of your home’s foundation.

Final Thoughts

Proper maintenance of a crawl space is an essential part of every homeowner’s book. You need to keep it dry to avoid problems that compromise your property’s stability.

Serious health risks can also arise from a damp basement. The poor ventilation can cause allergens and irritants, as well as viruses and bacteria, to spread and thrive easily.

This is why learning how to dry out a crawl space is crucial. Your best options for the job are fans, dehumidifiers, vapor retarders, French drains, and encapsulation.

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