Crawl Space Ventilation in New York

How Crawl Space Vents Affect Crawl Space Humidity... And Why

Crawl space vents can usually keep out mice and rodents, but what about termites, carpenter ants, and other insects?

Crawl Space ventilation is the answer that contractors have historically given to the issue of crawl space humidity in homes.

Generally, this involves installing vented openings in a cross-sectional area equal to 1/150 of the floor area served.

These crawl space vents are usually fitted with a covering -- usually a wooden/metal grating, or a mesh covering.

The covering is installed to prevent infestations from rodents and animals, but they cannot prevent insects such as termites and carpenter ants.

Crawl space ventilation moves outside air through the house. This affects utility bills and, when that air holds mold spores, your health.

The Theory Behind Vented Crawl Spaces

Crawl space ventilation was meant to keep a constant supply of fresh air circulating throughout the crawl space environment. It was thought that this would help to purge the space of the heavy, damp air in the house that settles in the lower levels by sucking the dry air that exists upstairs down into the basement.

Additionally, some contractors claim that damp, humid air is heavier than dry air, causing all the moisture in the home to sink down into the crawl space.

So by their thinking, air moves downwards in a home, not upwards.

This belief had become so widespread that crawl space vents were actually written into the International Building Code!

In recent years, however, these codes are quickly changing to reflect improvements in the industry and scientific study, and people are realizing that these practices are based on false science.

Basement Systems of New York, has been drying out basements and crawl spaces since 1994, and they've seen time and again that this just isn't the way it works.

What Crawl Space Humidity Research Says

Consider these crawl space humidity facts:

• Isaac Newton discovered in 1717 that wet air is actually lighter than dry air! It makes a lot of sense - if damp air was heavier, what would clouds be made of? And why would crawl space vents, which are at ground level, ever bring dry air into your home?
• If it's rainy, humid, foggy, or snowing outside, you're bringing wet air into your home.
• Advanced Energy reports that crawl space ventilation brings wet air into your home [PDF] when it's wet outside. Water that is pooling around your vents, will also flow into the space.
• Crawl space moisture helps mold, rot, and mildew grow. This means serious damage for your crawl space!

Here's a little more science: Hot air rises, leaving your house through the roof and upper levels. This creates a vacuum below that is filled by air from your crawl space, basement, and from outside. Air in your crawl space eventually enters the rest of your home!

When crawl space insulation is saturated with water, it drips off onto the floor.

Crawl Space Encapsulation

Crawl space ventilation does not work. If your crawl space is rotting and moldy, then you already know this.

To protect your crawl space, follow these steps:

1. Eliminate any flooding with a crawl space sump pump system
2. Seal your crawl space vents and doors with airtight covers.
3. Line your crawl space walls and floors (even if they are concrete) with a thick, durable plastic liner
4. Install a self-draining, strong dehumidifier in the crawl space.

This keeps everything you don't want in your crawl space outside- including moisture, cold air, termites, and ants.

Your crawl space will be dry and usable as storage space, and as an added benefit, a crawl space liner will even serve as a passive radon mitigation system!

Basement Systems of New York would like to help you create a dry, healthier crawl space. If you'd like a free, on-site consultation, call or e-mail us today!

We service the Ulster, Orange, Sullivan, Dutchess, Rockland, Putnam counties, including Hyde Park, Kingston, Middletown, New City, Poughkeepsie, and Spring Valley.

More information about Crawl Space Vapor Barriers