Dehumidifier in Crawlspace Without Encapsulation

Using a dehumidifier in crawl space without encapsulation might not be the best solution for eliminating dampness. But it’s important to follow necessary dehumidifying measures to keep the humidity low. A damp crawl space is the ideal breeding ground for mold and various other harmful microorganisms. It even attracts pests and rodents that damage the crawl space wood. The benefits of a crawl space dehumidifier include overcoming all these issues by keeping the area dry.


What Causes a Damp Crawl Space?

Dampness in crawl spaces is usually caused by excess moisture in the ground. Here are some reasons for higher levels of groundwater around the foundation.

  • Clogged gutters cause water to overflow into the ground near the foundation. It also happens when the downspouts are too short to direct the water away from the house. You can install extensions to discharge the water elsewhere to a distant location.
  • Improper grading of the land around the house, causes water to pool close to the foundation. If this is the case in your house, get a landscaper or foundation repair professional to regrade the yard into a suitable slope.
  • Sometimes, this can be due to natural causes such as the water table being high in the area. This could be the reason if you find standing water in the crawl space after rain.
  • If you find water in your crawl space when it’s not the rainy season, then it will most possibly be due to a plumbing leak. Sewer or water lines can leak underground, causing this issue.
  • The moisture condensed due to poor ventilation is another possibility. The moisture in the soil increases the humidity inside the crawl space.

What is Crawl Space Encapsulation?

Encapsulation of a crawl space refers to the installation of a heavy-duty moisture barrier to the crawl space floor. It is usually a polyurethane plastic covering. This also includes sealed foundation vents, insulated walls, and a dehumidifier. Sealing the space completely makes the encapsulation most effective. Crawl space encapsulation prevents any moisture from the soil from penetrating the foundation walls. However, encapsulation alone cannot prevent moisture formation in the crawl space. It also needs a dehumidifier to reduce the humidity levels.

Why Do Crawl Spaces Need a Dehumidifier?

It is important to have a dehumidifier in crawl space regardless of having encapsulation or not. The following are the signs that you need a dehumidifier.

  • Some of the air in the crawl space enters the house. So, if your indoor air smells musty and stale, it can be due to the moist condition of the crawl space.
  • If you suddenly get allergies and breathing problems, it may be due to unhealthy air conditions.
  • Condensation of moisture on the glass doors and windows indicates that there’s high humidity inside the house.
  • The rotting of wood on the beams, floor, and ceiling also points to higher levels of moisture. 
  • This is also the case if you see mold growing on the wood in your crawl space. Wood damages by pests and termites often occur as they prefer humid habitats.

Is It Useless to Have a Dehumidifier in Crawl Space Without Encapsulation?

It is better to have encapsulation in crawl space along with a dehumidifier. This is because water can freely enter the crawl space without encapsulation. Standing water can accumulate, especially if there is a pipe leak. Having a sump pump in the crawl space can minimize this risk to a certain level. 

Dehumidifiers are particularly designed only to handle moisture and humidity levels. They cannot get rid of large amounts of standing water. So, having a dehumidifier in crawl space without encapsulation could be pointless at times. Crawl space dehumidifiers can prevent the growth of mold by keeping the surfaces dry. But if the mold has already grown on the wood, it cannot prevent the spread. A dehumidifier may even spread the spores across the space into the house.

What is the Cost of a Crawl Space Encapsulation With a Dehumidifier?

The cost of encapsulation with a crawl space dehumidifier ranges from $5,000 to $20,000. This may vary, as the cost of a square foot depends on the side of the crawl space and geographical locations. This may even increase if you want to add a drainage system to the installation. The best way to find the real cost is to contact a foundation repair contractor for inspection and estimation. 

Frequently Asked Questions

What Are the Cons of Encapsulating a Crawl Space?

Encapsulations are not a cheap solution to keep water away from the crawl space. They may also need new crawl space insulation and HVAC upgrades for the system to be more effective. Encapsulation needs more preventive maintenance, including a routine inspection.

How Long Does an Encapsulated Crawl Space Last?

Crawl space encapsulation lasts around 10 – 15 years on average. Some moisture and vapor barriers are known to last for over 20 years. Crawl space encapsulation improves the energy efficiency of the house by up to 20%. So, installing an encapsulation is worth the investment, especially with the high utility costs that increase every day. Consumption of less energy also reduces the carbon footprint of the house.

Is a Vapor Barrier the Same as Encapsulation?

Encapsulation is not the same as vapor barriers. Encapsulation seals out the water completely and prevents moisture from moving up from the ground. It covers the entire area including the walls and floor. The vapor barrier only reduces the rate at which water vapor passes through the surface. Therefore, encapsulation reduces moisture problems better than vapor barriers.


You can use a dehumidifier in crawl space without encapsulation if there are no major water penetrations through the floor. If you live in an area with a high water table or frequent rain and floods, having a mere dehumidifier will not solve the issue. Use a suitable water discharge method to keep water from pooling around near the foundation. Proper ventilation also helps to reduce the humidity inside. Check your crawl space routinely to identify any pest or mold infestations.