Sealing Crawl Space Vents and Installing Foundation Vent Fans

Sealing Crawl Space Vents and Installing Foundation Vent Fans

Posted by Arthur Jackson on Jul 1st 2024

The Key to Efficient Summer Humidity Control

When it comes to maintaining a comfortable and healthy home environment, controlling humidity levels is crucial, especially during the summer months. One often overlooked area that significantly impacts indoor humidity is the crawl space. Sealing all the vents in your crawl space and installing a foundation vent fan can be incredibly effective in assisting a dehumidifier to regulate humidity. Let’s delve into how these steps can make a substantial difference.

The Benefits of Sealing Crawl Space Vents

Sealing crawl space vents is the first step in creating a controlled environment. Here’s why it’s effective:

  1. Preventing Moisture Ingress: By sealing the vents, you stop warm, humid air from entering the crawl space. This significantly reduces the amount of moisture that can condense and accumulate in this area.
  2. Reducing Temperature Fluctuations: Sealed vents help maintain a more consistent temperature in the crawl space, reducing the likelihood of condensation and moisture buildup.
  3. Improving Energy Efficiency: A sealed crawl space acts as a buffer against outdoor temperature extremes, helping to keep your home cooler in the summer and warmer in the winter, which can lower your energy bills.

The Role of Foundation Vent Fans

While sealing vents is crucial, installing a foundation vent fan adds an extra layer of protection and efficiency:

  1. Enhancing Air Circulation: Foundation vent fans improve air circulation in the crawl space, ensuring any residual moisture is quickly evaporated and removed out of the crawl space. This continuous airflow prevents keeps humidity levels consistent allowing your Aprilaire dehumidifier to turn itself off sooner and saving you money on electricity
  2. Preventing Mold and Mildew: By maintaining lower humidity levels, foundation vent fans help prevent mold and mildew growth, which can damage your home’s structure and pose health risks to your family.

Implementing the Solution

To achieve the best results, follow these steps:

  1. Seal All Crawl Space Vents: Use vent covers and/or spray foam to close off all vents leading to the crawl space. Ensure they are airtight to prevent any moisture-laden air from entering.
  2. Install a Foundation Vent Fan: Place the fan strategically to promote optimal airflow throughout the crawl space. Consider using a fan with a built-in humidistat that activates the fan when humidity levels rise above a certain threshold.
  3. Add a Dehumidifier: Choose a dehumidifier designed for crawl spaces and place it in an accessible location. Set it to maintain humidity levels below 60% to inhibit mold growth and keep the air dry.
  4. Monitor and Maintain: Regularly check the crawl space for signs of moisture and ensure the fan and dehumidifier are functioning correctly. Routine maintenance will help keep the system effective.


By sealing crawl space vents and installing a foundation vent fan, you create a controlled environment that works in tandem with a dehumidifier to keep humidity levels in check during the summer. This combination not only protects your home from moisture-related issues but also enhances overall comfort and energy efficiency. Taking these steps ensures a healthier, more comfortable living environment for you and your family, even in the most humid months.