What can you expect to find in a typical crawlspace? It has been determined, after reviewing thousands of air samples collected from properties with occupants that suffer from poor indoor air quality, that the source of contamination in 9 out of 10 homes comes from a poorly ventilated crawlspace. Common environmental contaminants found in crawlspaces include mold contamination, radon gas, pathogenic bacteria, fiberglass, pesticides, foul odors, asbestos fibers, raw sewage, and/or rodent excretions. Although some of these contaminants are classified as allergens, some are classified as carcinogens, which is why evaluating these air contaminants is important and significant.
If it’s in your crawlspace, it’s in your home! Studies have shown that approximately 40%-50% of the air inside the home generates from the crawlspace. Contaminated crawlspace air will enter the home through pressurization differentials or a condition known as the “Stacking Effect.” Inside a house, warm air rises (especially in multi-story properties) which then reduces the pressure in the base of the house (i.e. crawlspace or basement). This reduction in pressure then forces cooler air from the crawlspace to infiltrate the home through plumbing and electrical penetrations, through cracks or seams in flooring, and up into wall cavities.
During property inspections, crawlspaces are often the most overlooked and under-inspected areas of a property, yet they continue to be the source of more damage than any other area of the house. Crawlspaces are a major source of indoor air quality (IAQ) problems and should be one of the first places you and/or your IAQ Specialist inspect when trying to determine any suspect indoor air quality issues.