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Ask an Expert

Monday, August 1st, 2016 by Chantele Machado


System Design SpecialistThis week, we asked one of our system design specialist some of the most common questions we hear from our clients. Here is what Ed Upenieks had to say:

Why is my crawl space wet?

The most common reason a crawl space gets standing water is because of hydrostatic pressure. This term refers to the pressure that is placed on foundation walls when the backfill soil around a home becomes heavy with ground water. The pressure can become so great that water particles are forced to migrate through the foundation walls or seep up from the ground causing a wet crawl space or basement.

Why does it matter if my crawl space is wet? I don’t go down there or use the space for anything…

It matters because of the natural stack effect all homes experience. Air naturally rises and when a crawl space is full of moisture it draws that moist air up into the living space which create a variety of concerns. Problems such as mold, mildew, dust mites and asthma-like symptoms can all be attributed to high levels of moisture in the home. So whether the crawl space is used, the air in it is certainly being breathed.

Why are vents not enough to rid my crawl space of moisture?

Vents are installed in homes for the idea of “cross ventilation.” They figured the air would come in one side and simply go out the other. But, we now know that isn’t the case. Air gets pulled into the crawl space from all vents where it rises up through the house where it likely escapes through an attic vent. It’s a process that truly does not work.

Why is it so important to seal the entire crawl space?

There are many important reasons to seal the crawl space in a home. The main objective is to help prevent moisture-related problems to the structure of the home like mold, rot and pests. Once this is accomplished, it greatly improves the air-quality inside the home and lowers utility costs by allowing duct work to operate more efficiently. Some building scientists have said that venting crawl spaces was one of the biggest building fiascos that ever happened. Yet, most building codes still require a ventilated system. The practice is incomprehensible considering the U.S. Department of Energy now acknowledges that the best option for moisture control is to seal the crawl space and treat it just like any other floor of the home.