Skip to Content

How to Seal Crawl Space Vents (And 3 Reasons Why You Should)

How to Seal Crawl Space Vents (And 3 Reasons Why You Should)

Share this post:

This post may contain affiliate links. If you click one of these links and make a purchase, I may earn a commission at no additional cost to you. In addition, as an Amazon Associate I earn from qualifying purchases.

Crawl spaces serve as a barrier between the house and its residents and the moist, soggy earth beneath. However, they can be difficult to maintain.

The dirt and moisture in the air can cause mold and mildew to grow on your stored cables and wiring, as well as attract insects and rodents. One of the best ways to prevent these things from entering your crawl space is by sealing vents that lead outside.

In addition, sealing up your vents will prevent moisture from entering them so they don’t rot or rust over time. In this article, we’ll go over how to seal crawl space vents, why you should close them, and more!

Why You Should Seal Crawl Space Vents

There are a few reasons why you should consider sealing your crawl space vents.

1 – Water and Pests Can Get In

The first reason is that water can get into the crawl space and cause it to flood, which will then cause mold growth and other issues such as wood rot, structural damage, etc.

It’s also possible for animals to get in through these openings and make a home out of your crawl space.

2 – It Makes Your Home More Energy Efficient

If you seal off these vents completely (or partially), then this will help keep out heat or cold air from escaping into the house during winter months. This means less money spent on heating bills!

3 – It Prevents Mold

Crawl spaces are notorious for being damp, musty places that promote mold growth and increase humidity in the home.

They also tend to be poorly ventilated, which can lead to condensation forming on cold surfaces inside the house during winter months.

What You’ll Need For the Job

The materials you will need to seal crawl space vents with foam boards are:

  • Foam boards, preferably the kind that can be cut using a utility knife.
  • Scissors or a utility knife to cut your foam board into the desired shape.
  • Tape measure and pencil or pen to mark measurements on your foam board. (optional)
  • Sealant (you can use caulk for this job), any kind of sealant will do as long as it is safe for use in crawl spaces and attics

How to Seal Crawl Space Vents Using Foam Boards

If you’re looking for a material that will last longer than other options, there’s no better choice than foam boards.

Foam is your best bet for this job because it’s flexible, durable, resistant to moisture and pests (including termites), and easy to install. Additionally, it’s inexpensive and long-lasting.

That said, here’s how to seal your crawl space vents so that you don’t have any issues with them going forward.

Step 1: Remove Excess Water

Before getting started, you must address and deal with any excess water in your crawl area. Any standing water may be removed with the use of a drainage system and a sump pump.

With the help of this system, any water in your crawl area will be gathered and pumped outside of your house.

Don’t forget to inspect your ductwork as well, in case there are any leaks. If you find any, make sure to seal the seams thoroughly.

Step 2: Measure the Size of the Vent

Once you have the foam board, the next step is to measure your vent to make sure it fits into the space. The foam board needs to be cut down so that it will fit inside the vent completely.

Measure the length and width of your vent opening. Then, use these measurements as outlines for cutting out an appropriate-sized piece of foam.

Be sure not to leave any excess beyond these outlines or else it won’t fit!

Step 3: Cut Your Foam Board

Cut the foam board to size. If you want to follow a perfect fit, use a piece of cardboard as a template for cutting out your first piece, then trace it onto another sheet of foam board.

Cut that piece out and check if it fits into the vent properly. If it doesn’t, cut out another one until you have one that does.

Step 4: Place Your Foam Board Over the Vent

Place the foam board over the vent, making sure it fits perfectly. The foam board should cover your vent entirely so that no insects, animals, or unwanted moisture can get in.

Once the foam board is in place, fill in the spaces with a caulk gun and seal it firmly.

Step 5: Install a Dehumidifier

Last but not least, it’s best to install a dehumidifier in your crawl space. With the help of this dehumidifier, you can be certain that the humidity down there will always be kept at a manageable level.

This then prevents mold, rot, and rust from forming (which can lead to a hefty bill to take care of).

Final Thoughts

Insulating your crawl space is an important part of home maintenance. The crawl space under your house can have a big impact on the comfort of your home, so it’s important to keep it sealed and insulated.

The amount of time it takes to complete this job can vary greatly depending on how many vents are in your crawl space. It could take anywhere from a few hours to several days if there are large amounts of vents to seal up.

By following these simple steps, you can seal your crawl space vents and keep out moisture, pests, and other problems!

Share this post: