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Everything You Need To Know About Crawl Space Ventilation and Vents

The crawl space is the name given to the area under your house. It’s earned its name as in most cases there is only enough room to crawl under the house, not walk. However, while this may seem strange, it is a very important part of your home. 

Who Has A Crawl Space?

In general, you’ll find homes that are built in moist environments have crawl spaces. They form an important part of the protection system that prevents the moisture in the soil and even in the air from getting into your home. 

As you probably know, moisture attracts pests and it isn’t good for your wood. In fact, moisture in wood can cause a reduction in strength and can even lead to wet rot. 

The crawl space is effectively an underfloor ventilation system that allows the air to move under your home, reducing the impact of moisture. 

How Does the Ventilation Work?

Warm air holds moisture better than cool air. Therefore, if the air under your house is trapped it will gradually warm up, attracting more moisture to the area. As mentioned, this is not a good idea for your wood. 

To lower the moisture level below your home you need to move the warm air out and replace it with cool air. 

The basic approach is to have vents fitted in the walls of the under house section. These are effectively holes in the walls with screens over them to prevent pests from getting in. 

Unfortunately, these are only effective if they are positioned correctly and have a good cross-current. 

A better system is to use a fan. You’ll still need two openings in the crawl space, one will have a standard screen on it and may only allow air to move in one direction.

The other opening will have a fan that is designed to either pull air out of the crawl space or pull it in. These are generally set to work at specific times, most people opt for overnight. 

The noise is minimal and unlikely to disturb you but the biggest benefit is that you are moving cool air under the house, even in the warmer months. This reduces the warm air and carries the moisture away from the crawl space.

Signs The Ventilation System Isn’t Adequate

If your ventilation system isn’t doing the job properly then you’ll find that moisture starts to creep into the house. It will be most noticeable on the floor or at the bottom of the ground floor walls. Of course, the moisture can damage the wood and it can create the perfect environment for mold to grow. As mold is bad for your health, especially if you have allergies, then this is not a good thing!

To make sure your crawl space ventilation is working properly you need to regularly check the vents are clear and clean any filters in your system. It is also important to replace any damaged screening as soon as possible. 


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