Okay, so why do we need to close the vents in the crawl space? First of all, please understand that the building codes in most areas still say that leaving the vents to your crawl space open is a best practice. A lot of people say it’s okay to leave the vents open. They also say that you could close them. They’re ultimately giving the builder or the homeowner the choice of whether they want to create an encapsulated, or closed, system versus an open system. If you decide to open it, they have certain things you have to do and if you decide to close it, they have certain things you have to do, but one of the reasons why we recommend closing the crawl space is because there is no way to control external factors like humidity.
Imagine you’re living in your house. It’s 90° outside and you live in a humid south climate. You have the AC on and it has brought the temperature down to 72 degrees inside the house. It’s 90° outside the house and you decide to go open all the windows around your house. All that hot and humid air overtakes your house and your house is no longer 72 degrees! As a matter of fact, your vents (whether they are in the floor or in the ceiling) are cold from the cold air blowing through them, and now they’re building condensation. This is because you have hot, humid air blowing onto the cold metal. So the answer is: we always recommend closing the crawl space and controlling the ventilation of the crawl space. You can control the humidity with a dehumidification system. It is one of the only real ways to control humidity while ventilating a crawl space.
Builders are still building open crawl spaces in areas that the codes have not yet been changed, as they once reflected that vents in the crawl spaces were necessary to keep homes cool back in the times before families had air conditioning. Whenever you have a heating and air unit downstairs, you have hot, humid air coming into the crawlspace hitting a cold duct. This is when the condensation causes a problem in the crawl space. That’s what leads to mold and high humidity.
Now there is an option of keeping your crawl space either open or closed. Of course, it’s recommended to close the crawl space for all of the reasons mentioned above. Hopefully this article has helped you to understand the reason for closing the vents during an encapsulation job. For further information, or to schedule an encapsulation job for your crawl space to be professionally enclosed, give Barrier Waterproofing Systems a call today at (615) 257-1060 | (931) 536-1168.
