vented crawl space

Unfortunately in the southern U.S. most homes have vented crawl spaces.

We have enough research now to know that this isn’t the most effective way to keep them dry. But because foundation vents made their way into the code years ago, it’s difficult to change.

The trouble with crawlspace construction is that it’s more likely to have mold and wood rot problems than other types of construction. Both of these issues are types of fungal growth.

Thanks to a combination of humid climate and a vented crawl space, you will find yourself with a moisture problem under your home.


Why Moisture Is Bad

Excessive moisture in your home is bad for a few reasons:


1. Mold, Mildew

The main problem is mold, fungi, and mildew. A recurring mold-related problem is expensive.

Crawl space moisture can start blackening floor cavity insulation and structural elements.  Because there is no light and only minimal ventilation, the problem never improves on its own.


2. Rot

Structural elements of your house (joists, sills, posts, beams) are made of wood.  Being an organic material, wood will begin to rot when it comes into contact with water.  


3. Creatures

Animals of all types are drawn to water and can infest your home.  This includes rats, carpenter ants, and termites. If you need a refresher on the problems they bring check out some of our older posts.


4. Resale

Even if your home isn’t suffering from one of the problems mentioned above, it will turn homebuyers away.

When you try to sell your house, the property inspector will explore the crawl space and note the presence of water on the report.

It doesn’t matter if you’ve lived with this issue for decades, the buyer will want the problem fixed or demand a credit.


How Moisture Gets in Your Crawl Space

  • Plumbing leaks:

A lot of plumbing pipes, both supply lines and drain lines, run through crawl spaces. They do leak occasionally. Because crawl spaces are visited infrequently these leaks can go unnoticed for a long time.


  • Foundation walls:

Moisture can also come from the ground outside the house by migrating through the foundation walls.

Vented crawl spaces rarely get any kind of damp-proofing or perimeter drains on the exterior. As a result, wet soil outside the crawl space can come right through.


  • Soil:

Although it may appear to be dry, uncovered soil is actually evaporating moisture into the air of the crawl space.

The good news is that most new homes do get vapor barriers put down on the ground, eliminating a lot of the moisture that comes from the soil.


  • Foundation vents:

Yes, the very thing that was constructed in order to keep moisture out of the crawl space is the main culprit. In the summer the humidity seeps in and releases moisture into your vented crawl space.


If you’re worried that your crawl space may be the victim of excessive moisture, don’t hesitate to call in a professional opinion. EIG offers an easy online scheduling tool, and we’ll be out to see you in 48 hours or less!


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Article Name
How Moisture Invades Your Vented Crawl Space
If you have a vented crawl space then you should keep an eye out for the different ways moisture can get in and wreak havoc on your home.