We do a lot of work on crawl spaces. Due to the many inherent and fundamental problems with the way crawl spaces are designed, and neglected, they are often expensive repairs. This post is to help educate you on what are some of the problems we see and what caused them.
Crawl space complaints: Standing water, many species of bugs including the termite, mold contamination, musty and unwanted odors, damaged sill plate, broken joists, broken support beams, rotted rim joist, fallen insulation, poor energy efficiency, rodents, pooling water during rains, poor drainage, foundation sinking, broken foundation blocks, and structural collapse.
The common factor in all of the issues can be pointed to moisture. The crawl space, because of the design, current code requirements, our climate, and soil conditions is a breeding ground for moisture. When we think of moisture the most obvious factor that stands out is when your crawl space leaks, pools water during rains, floods, or something directly related to water intrusion. This intrusion of water increases the moisture in the air (Relative Humidity- RH) and begins to dampen the insulation and lumber used to support your home. Once this process begins mold begins to grow creating allergy and health issues, your insulation will begin to fall, musty odors, and decay. Bugs are also attracted to water and this invites them into your home. Standing water against your foundation blocks can also cause acids in the ground to begin to deteriorate your foundation walls. The solution here is simple… get the water out and protect the space from experiencing this type of water intrusion again.
The other cause for moisture in the crawl space happens in the crawl space air and we see spikes in the relative humidity that aren’t directly related to water intrusion. Your crawl space is recessed into the earth, and the earth’s temperature year-round is 52-55 degrees. Just like a cave. The current building codes require cross ventilation in the crawl space which is typically accomplished by putting in exterior vents. When builders vent a crawl space that is 52-55 degrees with 80-100-degree air in the summertime we see a massive spike in the relative humidity. For every degree of difference in an air collision the relative humidity goes up 2.2%. So, 85-degree air colliding with 55-degree air produces the relative humidity to increase 66% in that collision. Hot air rises and brings that moisture to dampen the insulation and wood support structure. Duct work begins to sweat and condensate. We have also seen many crawl spaces where the insulation itself is layered with beads of water from condensation. The process of damage referenced above begins, and all of those unwanted problems can occur even without the intrusion of water. The solution here is more complex and requires a professional who understands crawl space science to evaluate and come up with the proper plan for your home. Some of these solutions include crawl space encapsulation, sealing crawl space vents, new crawl space doors, cross ventilation systems that use conditioned air, vapor barriers, dehumidifiers, and repairing all damage created by the moisture.