Should Crawl Space Vents be Open or Closed?

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Moisture-related problems can often occur in crawl space and excessive moisture in the crawl space can lead to a host of issues, including mold growth, wood rot, and even structural damage to your home.

To resolve these problems, many homes are equipped with crawl-space vents. These vents serve as openings in the foundation walls that allow air to circulate through the crawl space. The question is: should crawl space vents be open or closed?

You should keep your crawl space vents closed and sealed off from external elements in winters. Allowing ventilation in your crawl space can result in several problems. A major concern is that open vents let moisture enter into the crawl space, which results in the growth of mold and mildew.

keep your crawl space vents closed and sealed off

In this blog, I’ll dive deeper into the reasons why keeping crawl-space vents closed is important for maintaining a healthy and structurally stable home and preventing bouncy floors dangers.

Learn how proper moisture control can not only prevent mold and mildew but also save you from potential costly repairs in the long run. Don’t miss out on the important tips and insights that will help you protect your home and your investment.

Should Crawl Space Vents Be Open Or Closed In Winter?

During the winter months when temperatures dip below freezing, it’s advisable to keep crawl space vents closed. This precaution helps prevent water pipes in the crawl space from freezing due to exposure to the dry and cold winter air.

Should Crawl Space Vents Be Open Or Closed In Winter?

Proper moisture control through sealed vents is a smart investment in your home’s structural integrity and long-term maintenance. You can also avoid moisture related issues in crawl space by installing sump pump drainage system.

Should Crawl Space Vents Be Open Or Closed In Summer?

Crawl space vents can be open during the summer months. Opening these vents allows for proper air circulation beneath the floor, which is ideal in preventing moisture buildup and reducing the risk of mold and mildew growth.

Should Crawl Space Vents Be Open Or Closed In Summer?

Keeping crawl space vents open in warm weather is an effective way to maintain a healthy and dry crawl space environment.

What Temperature To Close Crawl Space Vents?

Crawl space vents should typically be closed when the temperature drops to around 40 degrees Fahrenheit and opened when it averages around 70 degrees. To simplify this ventilation management, you can close your crawl space vents using crawl space vent covers.

French Drain along with sump pump drainage can also help maintaining a dry crawl space in your house.

How To Close Crawl Space Vents?

Having personally ventured into the world of crawl spaces, I’m excited to share my firsthand experience on how to effectively close crawl space vents. Let’s get started!

Step 1: Gather All The Necessary Tools

Before you start, make sure you have all the necessary materials ready. You’ll need:

  • Crawl space vent covers
  • A trusty screwdriver or a power drill with the right bits
  • Screws or fasteners
  • Safety goggles
  • A good flashlight or a headlamp

Step 2: Setting Up Your Workspace

I headed to the crawl space entrance, which for me was outdoors. Remember that crawl spaces can be a bit chilly and damp, so dress appropriately.

If your entrance is indoors, make sure you’ve got good lighting. Trust me; it makes things a lot easier. I’d also recommend those Dewalt DPG82 safety goggle to protect your eyes from any debris that might fall during the process.

Step 4: Placing the Best Crawl Space Vent Cover

In my extensive experience with various DIY crawl space projects, I’ve had the opportunity to test a range of crawl space vent covers.

After careful evaluation, I’ve identified three best crawl space vent covers that consistently outperform others in terms of durability, effectiveness, and ease of installation:

1. Crawl Space Recessed Foundation Vent Cover

I chose the Crawl Space Recessed Foundation Vent Cover for its durability and resistance to UV, rust, and rot. Its snug fit and solid design effectively seal off my crawl space.

Crawl Space Recessed Foundation Vent Cover

The insulation option is great for temperature control, and I can paint it to match my crawl space’s look, making it a practical and personalized choice.

2. Foundation Crawl Space Vent Cover

As an alternative choice, I found the Foundation Crawl Space Vent Cover good enough in the size of 16″x8″x1/2″.

Its durable ABS construction is paintable for customization, and the substantial open area of 38.2 sq. in, coupled with an anodized metal screen, provides effective ventilation without rust concerns.

Foundation Crawl Space Vent Cover

This versatile cover can be installed with 6 screws (not included) or silicon, offering flexibility in securing it.

3. Crawl Space Vent Cover Black

The Crawl Space Vent Cover – Outward Mounted is another ideal choice for closing crawl space vents. The sturdy ABS plastic construction of the door ensures durability and resistance to rust or rot.

Crawl Space Vent Cover Black

With easy installation, a fixed design, and the option to paint or insulate, it provides reliable and customizable protection for your crawl space.

Next, I placed the Crawl Space Recessed Foundation Vent Cover over the openings. I had to make sure they fit snugly and covered the entire vent. This was key to preventing cold air from creeping into my crawl space.

Step 5: Securing the Vent Covers

Using my trusty screwdriver, I attached the vent covers to the crawl space wall. I used the appropriate screws that came with the covers for a secure fit.

It’s better not to over-tighten them; just make them snug enough to hold the cover in place without causing any damage.

Step 6: Checking for a Proper Seal

After securing the vent covers, I inspected them closely. I wanted to make sure there were no gaps or openings around the edges. A good seal is crucial to keeping cold air out effectively.

Step 7: Entering into the Crawl Space

Now, it was time to test my handiwork. With my flashlight in hand, I entered into the crawl space to see if any light was coming through around the newly installed vent covers.

Venturing into the Crawl Space

If I spotted any gaps, I made some adjustments to the covers or screws to create a tight seal.

Step 8: Keeping Track and Regular Checks

Finally, I made a note of the date when I closed the crawl space vents. This helped me remember when to reopen them once the warmer weather rolled around.

It’s also a good idea to periodically inspect the covers to ensure they’re in good shape, free from damage or wear and tear.

What Happens If Crawl Space Is Not Vented?

Without proper ventilation, an unvented crawl space can lead to moisture buildup, mold, poor air quality, structural damage, and energy inefficiency in your home.

This not only compromises the structural integrity of your home but also poses health risks to occupants due to poor indoor air quality.

Additionally, the absence of ventilation can cause the release of harmful gases like radon into your living spaces.

Moreover, it can disrupt energy efficiency, making temperature regulation challenging, as crawl spaces become excessively hot in summer and extremely cold in winter.

To prevent these issues, it’s advisable to ensure proper ventilation in your crawl space.


By keeping crawl space vents closed during winter to prevent freezing and opening them in the summer to promote healthy air circulation, you can effectively avoid moisture-related problems and mold growth.

Additionally, sealing off these vents when necessary using reliable crawl space vent covers ensures a secure and energy-efficient solution.

Ignoring proper ventilation in your crawl space can lead to a host of issues that are best avoided, making it a vital aspect of home maintenance that should not be overlooked.

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