3 Crawl Space Ventilation Tips and Basics

A natural, non-mechanical way to maintain ventilation in unoccupied areas of one’s home and keep too much water in the air is to install crawl space vents. By diluting VOC concentrations in crawl space air, ventilation reduces vapor intrusion (VI). In addition, a crawl space may be ventilated by extracting the crawlspace’s air and substituting it with fresh air. If any external vents are already present around the crawlspace, CSV typically entails opening them to offer a source of supply air.

Why Do Homes Need Cross-Space Ventilation

Source: freepik.com

For many reasons, crawl space vents are a crucial component of one’s house. They are essential to many other systems and vital to someone’s home’s ventilation. The vents promote air circulation, which aids in removing surplus moisture and halting the spread of mold. The flooring, plaster, and padding in the higher parts of one’s home may become compromised if mold is discovered in the crawl space’s walls, joists, or ductwork. Suppose someone is considering having CSV installed in their homes. In that case, they can always consult VanityVents. They provide the perfect solution regarding Crawl Space Vents to their client’s issues and do according to their wishes and prioritize their satisfaction. Some of the most significant factors are listed below:

1. Humidity

Humid air might reach one’s home’s lower level through the vents in the crawl area. Humidity leads to water, which leads to mold if there is water. Additionally, moisture can destroy the wood in their floorboards and support columns by causing mildew and rot.

2. Pests

Pests could enter the crawl area through the vents during the winter. In addition, they can lure rodents like rats, mice, snakes, and opossums into one’s home.

3. Purity Of Air

One will start smelling moldy if their crawl space lets in humid, wet air; this is just an opportunity for respiratory disorders.

Tips Regarding Cross Space Ventilation In Homes

Source: freepik.com

Some individuals are still doubtful about the impacts of crawl space venting on their homes. Many individuals still have questions about ventilation in crawl spaces.

1. Airing The Cross Space

Adding ventilation to a crawl space takes time, depending on the structure or foundation. There are many possibilities. The majority of crawl spaces are vented to the outside. However, encapsulation has grown in favor over the past ten years due to its energy efficiency. Encapsulation involves enclosing support structures, such as floors and walls, with plastic sheeting to keep the area dry.

2. Ventilation

By the IRC, a crawl area should have one square foot of covered outlet for every 150 square feet of space. In addition, residents can protect the concrete floor with a vapor-barrier material that has been authorized to decrease dampness further. The IRC also mandates one vented aperture in each corner of the structure to provide a cross-flow of air.

3. Vents Should Be A Bit High On The Wall

At the very least, two vents, no more than three feet from the corners, are required for a rectangular crawl space. To effectively collect winds, the vents should be as elevated on the wall as feasible, and vegetation should be designed to avoid blocking the vents. A minimum of 1/1500 of the floor space should be the combined free area of all vents. The vent area should be extended to 1/150 of the floor area if there isn’t a ground cover.

Why Do We Need Crawl Space Covers?

Source: freepik.com

For sealing vents that create more issues than they solve, crawl space vent covers are an excellent choice. Although they served a purpose, crawl space vents are now generally advised to be sealed.

However, it also includes situations, such as seasons, where it could be beneficial to keep them open temporarily.

The vents are shut during the winter when the air is drier to lessen the possibility of the piping in the crawlspace freezing. So, one solution may be to keep them closed during the winter and open during the summer. However, remember that most experts advise shutting them completely to maintain the dampness in the crawl area below 60%.

Crawl space vents are ineffective. Designed initially to utilize external air for drying crawl spaces, they have the opposite effect when the weather is humid, wet, or freezing. Therefore, vent covers for crawl spaces should be purchased to prevent moisture and humidity.

It is strongly advised that one blocks up the crawl space vents since they are a crucial component of the crawl space restoration method. This blocks out the outside air and all the dampness, vermin, winter cold, and summer heat it brings.

How Much Crawl Space Does A House Need

The region between the bottom of the floor beams and the ground under the structure (excluding the basement), as defined by Section R408.1, must have ventilation apertures through the foundation walls or outside walls. One hundred fifty square feet of underfloor space depicts that there must be at least one square foot of net ventilation opening space.

What Causes Problems In Crawl Spaces?

Source: freepik.com

The noxious crawl space air, which contains moisture, germs, mold and mildew spores, and musty, moldy aromas, is dragged up through the living area and vented through the attic due to a phenomenon known as the stack effect. This is the unpleasant air that residents of a home with an unfinished crawl space inhale.

Things Ventilated Crawl Spaces Should Have

1. Sealed Exterior Walls

Doors and hatches, connections between beams and subfloor, joists and sills, and areas surrounding ducts, pipes, and other penetrations should all be air-sealed.

2. Protected Walls

Both interior and exterior surfaces can be insulated; however, don’t use internal insulation solutions that contain vapor barrier material since they may retain dampness from the foundation.


The crawl space ventilation system regulates the air pressure to prevent conditioned outside air from entering the crawl space. The crawl space unit maintains regulated ventilation to remove damp, filthy air and musty odors. It is replaced with conditioned, drier air, producing a better environment in the crawl space. In addition, foundation vents allow for random air movement of unconditioned air.