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Are Crawl Space Vent Covers a Good Idea?

Crawl space vent covers
Crawl space vent covers

Are Crawl Space Vent Covers a Good Idea?

The short answer is yes, crawl space vent covers are a great idea! But why? In this article, we will review the original purpose of crawl space vents, the benefits of covering your crawl space vents, and other ways to protect your crawl space from moisture.

Crawl space vent covers protect your crawl space from moisture, frost, mold, pests, rot, and rust. They can also save you money on your energy bill. Find out why.

Why Do Crawl Spaces Have Vents?

Crawl space vents were initially designed to promote air circulation and regulate humidity in crawl spaces. However, instead of improving the air quality, it allows heat and frost to enter the crawl space and cause much more damage than good. Problems include:

  • Moisture – An open crawl space vent allows moist, humid air to enter the crawl space and condense on cooler surfaces. Moisture leads to mold and mildew growth, rotting of your floorboards and beams, and pipes rusting.
  • Pests – Open vents make it easier for insects, rodents, snakes, and other critters to enter your home, especially when filled with warm, moist air.
  • Poor Indoor Air Quality – Up to 50% of the air in your home comes in through your crawl space. If your crawl space is full of damp and potentially musty, moldy air, it will enter your home, spreading mold and other allergens throughout. Poor air quality can negatively impact anyone, especially those with breathing problems like asthma or COPD.
  • Higher Energy Costs – If your crawl space is full of hot air during the summer and cold air during the winter, your home’s heating and cooling systems will have to work harder to regulate your home’s temperature, increasing your energy bill.
  • Damaged Pipes – Frost during the winter can enter your crawl space and freeze or crack your pipes, leading to plumbing issues.

What Are the Benefits of Using a Crawl Space Vent Cover?

Crawl space vent covers, also known as crawl space vent seals or closures, offer several benefits for homeowners seeking to improve energy efficiency, moisture control, and pest prevention. Here are some of the main benefits of crawl space vent covers:

  • Energy Efficiency – Crawl space vent covers help improve energy efficiency by preventing hot or cold air from entering the crawl space. Vent covers can reduce heat loss in winter and heat gain in summer, resulting in lower heating and cooling costs for the home.
  • Moisture Control – Sealing crawl space vents with covers helps to control moisture levels by preventing humid outdoor air from entering the crawl space. Reducing the influx of moist air will minimize condensation, mold growth, wood rot, rust, and other moisture-related issues that can compromise the home’s structural integrity.
  • Pest Prevention – By sealing off access points, vent covers create a barrier that makes it more difficult for pests to enter the crawl space and infest the home. Preventing pests can help to protect building materials, insulation, and HVAC systems from damage caused by pests.
  • Improved Indoor Air Quality – By sealing off crawl space vents, you will improve indoor air quality by preventing mold, outdoor pollutants, allergens, and contaminants from entering the home. This can create a healthier living environment for occupants, particularly those with allergies, asthma, or respiratory conditions.
  • Reduced Risk of Water Damage – Crawl space vent covers help to prevent water intrusion during heavy rainfall or flooding events. By sealing off vents, vent covers can help to reduce the risk of water entering the crawl space and causing damage to the foundation, insulation, and other structural components of the home.

While some sources may disagree, we strongly recommend that homeowners in the Midwest permanently seal and waterproof their crawl spaces. This will allow you to achieve all of the benefits mentioned above. It can even create valuable storage space below your home.

How Can You Seal a Crawl Space Vent?

Several options are available to seal crawl space vents, each with advantages and considerations. Here are some standard methods for closing crawl space vents:

  • Foam Board Insulation – Foam board insulation can be cut to size and fitted into crawl space vent openings to seal them off effectively. This method creates a solid barrier that helps prevent outside air and moisture entry. Foam board insulation is lightweight, durable, and inexpensive, making it popular for crawl space vent sealing.
  • Sealant or Caulk – Sealant or caulk can be used to seal the edges of crawl space vent openings, creating an airtight seal that prevents air and moisture infiltration. This method is quick and easy to apply but may require periodic maintenance to ensure continued effectiveness. Silicone-based sealants are often recommended for their durability and flexibility.
  • Crawl Space Vent Covers – Crawl space vent covers are designed to seal off crawl space vents, providing a durable and long-lasting barrier against outside air and moisture. These covers are typically made from durable materials such as plastic or metal and are designed to fit snugly over vent openings. Some crawl space vent covers feature insulation to enhance their effectiveness.
  • Masonry – Some homeowners hire a mason to seal the vents with cement blocks or bricks. This method is more expensive but can provide a seamless look to your home’s exterior.
  • Mechanical Ventilation Systems – Homeowners may install mechanical ventilation systems in their crawl spaces to regulate airflow and control moisture levels. These systems may include fans, dehumidifiers, or air exchange systems that can be controlled manually or automatically to maintain optimal conditions in the crawl space.

Ways to Seal a Crawl Space Vent

How Else Can You Keep Your Crawl Space Free from Moisture?

Crawl space vent covers are great tools to prevent moisture from entering your crawl space, but they cannot prevent all moisture penetration. We recommend waterproofing your crawl space by encapsulating it and installing a drainage system and a dehumidifier.

Crawl Space Encapsulation

Crawl space encapsulation involves fully covering your crawl space with an impermeable polyethylene sheet as a vapor barrier. Encapsulation prevents moisture from the soil from entering your crawl space and, eventually, your home. Many studies have proven that an encapsulated crawl space creates healthier air quality in your home and can reduce your energy bill. Encapsulation will last a lifetime when installed correctly, along with a drainage system. At Epp Concrete, we offer a 25-year warranty on our crawl space encapsulation when it is coupled with a drainage system.

Drain Tile System with a Sump Pump

If the soil around your home tends to be oversaturated, installing a drain tile system and a sump pump is wise. A drain tile system will collect excess water in the soil and direct it to a sump pit. The sump pump sits in the pit, actively diverting water from the home’s foundation and protecting your home from water damage.

How a Sump Pump Works


A dehumidifier is pivotal in regulating the moisture and airflow in your crawl space. By creating a drier, healthier environment, a dehumidifier helps maintain the home’s structural integrity and creates a more comfortable living space for occupants.

Don’t live with a damp crawl space. Close your crawl space vents and waterproof your crawl space to protect your family and home while saving money in the long run. Schedule a crawl space encapsulation and waterproofing consultation with us today, and our experts will help you find the best solution. We service clients in Nebraska, Iowa, Kansas, and Missouri.


Dave Epp

Dave is the President at Epp Foundation Repair with over 27 years of experience in the industry. Dave has worked on thousands of foundation, basement, concrete, and crawl space repair projects since 1993. Dave is involved in several civic and church organizations and enjoys coaching youth sports, mainly football, golfing, and elk hunting.



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