Dehumidifying Your Crawl Space Without Encapsulation

By: Evan Scoboria, Last updated: June 28, 2023

Crawl spaces are notorious for being damp, musty, and conducive to mold growth. Encapsulation is often recommended as the most effective way to deal with these issues. However, encapsulation can be a costly and time-consuming process. If you're not ready to fully encapsulate, using a dehumidifier in your crawl space can help reduce moisture levels and improve air quality. This comprehensive guide will discuss effectively using a dehumidifier in your crawl space without encapsulation.

Crawl Space Without Vapor Barrier

Assessing Your Crawl Space:

Assessing your crawl space for moisture problems is an essential preliminary step before using a dehumidifier. Focus on identifying mold or mildew, signs of excess dampness often identifiable by their distinctive dark spots or patches, and their telltale musty odor. These harmful fungi thrive on organic substrates, such as wood, insulation, or drywall paper backing.

To evaluate humidity quantitatively, you can use a hygrometer. These devices record the moisture content in the air; a reading surpassing 50% indicates heightened moisture that could potentially encourage mold growth or incite other moisture-related complications. Furthermore, investigate possible sources of water intrusion, like faulty plumbing, HVAC systems, or issues stemming from the foundation or external drainage system. The presence of standing water is an urgent call for immediate action.

Lastly, examine the integrity of your existing vapor barrier if one is present. These protective shields, crafted from plastic or foil, prevent ground moisture from infiltrating the crawl space. Over time, the barrier can suffer from wear and tear, developing punctures or detaching from the walls or floor. If this happens, immediate remediation via repair or replacement is necessary.

Remember that severe moisture problems, such as chronic leaks, persistent standing water, or widespread mold infestation, often necessitate professional intervention. Utilizing a dehumidifier while simultaneously addressing these issues enables a comprehensive crawl space moisture management approach.

Choosing the Right Dehumidifier:

Choosing the right dehumidifier for your crawl space is crucial for effectively managing humidity levels. Here's a more detailed look at the factors you should consider:

  1. Size: The size of the dehumidifier should be able to handle the square footage of your crawl space. Dehumidifiers come in various sizes, generally expressed in the amount of moisture they can remove from the air in 24 hours, measured in pints. To determine the right size, you'll need to know the space's square footage and the space's conditions (moderately damp, very damp, wet, or extremely wet).

  2. Pint Capacity: refers to the amount of moisture the dehumidifier can remove from the air within 24 hours. Higher pint capacities are generally better for crawl spaces since they tend to be more damp than other areas of the home.

  3. Energy Efficiency: Energy efficiency is another crucial factor. Look for models that are ENERGY STAR certified. These models are more efficient and can save energy costs in the long run.

  4. Drainage Options: Dehumidifiers collect the excess moisture from the air into a collection tank that needs to be emptied regularly. A dehumidifier with continuous drainage options is ideal for a crawl space, so you don't have to go into the crawl space to empty the tank. These models will have a port to attach a hose that allows the water to drain out by gravity or a built-in pump.

  5. Durability: Crawl spaces are often harsh environments, so choosing a dehumidifier designed to work in such conditions is essential. Models specifically designed for crawl spaces or basements are often more durable and able to handle the humidity levels in these areas.

  6. Auto Restart and Humidistat: Auto restart automatically allows the dehumidifier to restart after a power outage. A humidistat allows you to set the desired humidity level, and the dehumidifier will cycle on and off to maintain that level, saving energy and preserving the lifespan of the dehumidifier.

Remember to consider the unique conditions of your crawl space, including its size, current humidity level, and any particular issues, such as flooding or leaks, when choosing a dehumidifier.

Proper Dehumidifier Placement:

Proper dehumidifier placement in your crawl space is critical to its effectiveness. Here are some guidelines:

  1. Central Location: Ideally, the dehumidifier should be placed in a central location within the crawl space to maximize its effectiveness and allow it to evenly remove moisture from all crawl space areas.

  2. Adequate Airflow: Ensure that there is sufficient airflow around the unit. This allows the dehumidifier to pull air from all sides and operate more efficiently. Avoid placing the dehumidifier in a corner or close to walls or other obstructions.

  3. Level Surface: Place the dehumidifier on a level surface to ensure it operates correctly. An uneven surface could cause the dehumidifier to tip or not drain properly if it features continuous draining.

  4. Away from Water Source: If there are known areas in the crawl space where water tends to pool or leak, try to place the dehumidifier away to prevent potential damage to the unit.

  5. Accessible for Maintenance: Remember that you'll need to perform regular maintenance on the dehumidifier, such as cleaning or replacing filters and checking the operation of the continuous drain (if applicable). 

Remember, the effectiveness of a dehumidifier is not only about its specifications but also about how and where it is installed. A well-placed dehumidifier can more efficiently reduce humidity levels and improve the air quality in your crawl space.

Sealing and Ventilation:

Sealing breaches and strategizing ventilation are essential in mitigating crawl space humidity, even absent complete encapsulation.

Start by inspecting cracks in the foundation or walls. Such breaches are portals for moisture ingress and must be sealed with suitable sealants or foams. Additionally, installing a vapor barrier on the crawl space floor yields significant benefits even without encapsulation. Comprised typically of polyethylene plastic, this barrier impedes moisture ascent from the ground into the crawl space.

Crawl space vents have traditionally been touted to promote air circulation. Yet, in humid climates, these can inadvertently become conduits for damp air, potentially escalating humidity levels. Verify that the vents are operating as intended and free from debris blockage. In some scenarios, closing off these vents, supplemented by a dehumidifier, proves beneficial.

Some homeowners install exhaust fans to circulate air and expel moisture-laden air. If this route is chosen, thoughtful placement of the fans is crucial to maximizing airflow.

Remember, sealing and ventilation practices aim to limit moisture ingress from the external environment and the ground, consequently easing the dehumidifier's task of maintaining a healthy humidity level and enhancing its overall efficiency.

Regular Maintenance:

Regular maintenance ensures your dehumidifier operates at peak efficiency and longevity. Here are some key points to consider:

  1. Cleaning the Filter: Dehumidifiers come with a filter that collects dust and allergens from the air. Over time, these filters can become clogged, reducing the unit's efficiency. Check the manufacturer's instructions for how often to clean the filter. Typically, filters should be cleaned every few weeks, but this can depend on the dust levels in your crawl space. A clean filter allows your dehumidifier to function more efficiently and improve the air quality in the crawl space.

  2. Emptying the Water Collection Bucket: If your dehumidifier doesn't have a built-in pump or a continuous gravity drain, you must manually empty the water collection bucket regularly. If the bucket becomes full, the dehumidifier will automatically shut off to prevent overflowing. Depending on the humidity levels, you might have to empty the bucket once a day or every few days.

  3. Continuous Drainage Check: If your dehumidifier is set up for continuous drainage, ensure it functions properly. Ensure the hose isn't kinked or clogged and the water is effectively drained away from your home's foundation.

  4. General Unit Inspection: Inspect the unit regularly for any signs of wear or damage, including unusual noises, vibrations, or leaks. Address any issues promptly to prevent more significant problems in the future.

  5. Professional Servicing: Consider having the dehumidifier professionally serviced every few years to ensure it's running efficiently. A professional can thoroughly clean the unit, check the refrigerant levels, and perform necessary repairs.

By maintaining your dehumidifier correctly, you'll keep it running effectively for many years, improving the air quality in your crawl space and preventing potential mold and mildew issues.


While encapsulation is often considered the gold standard for addressing crawl space moisture issues, using a dehumidifier without encapsulation can still effectively reduce humidity and improve the overall air quality in your crawl space. By choosing the right dehumidifier, correctly placing it, addressing air leaks, and performing regular maintenance, you can make a noticeable difference in your crawl space environment without the expense and effort of complete encapsulation.