Mold Growth and Remediation in a Crawl Space Mold removal in homes with indoor moisture problems

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Q. We recently purchased a home in central Illinois. Our crawl space gets a great deal of moisture, and has resulted in mold growing on the floor joists. Also, our son has an allergy problem that wasn't a factor until moving into this home. My question is in three parts. What can I do to get rid of the mold? Could this be a factor in my son's allergies? Is this a situation that the previous home owner should be responsible for? - Jon, Illinois
A. Wet/moist crawl spaces are common here in the Midwest because of the high clay content of soils in many building sites. Such soils are poorly drained and as such water often sits in crawlspaces for weeks or more during rainy periods of the year. This is even the case when pea gravel and polyethylene plastic are put down (though they likely do help). The problem is further exacerbated if the crawlspace has few or no vents, the vents are blocked by shrubbery, or vents are closed. When the house was built, the drainage should have been put in place around the perimeter of the house as well as under it to carry the water away.
Because of the moisture, high relative humidity occurs in the crawlspace that provides an optimum environment for mold growth. The problem may be made worse by subsequent condensation on floor joists and other wood materials.
My experience with wet crawlspaces is that they are major sources of mold growth and subsequent human exposures in living spaces. As such, it is highly probable that the allergy problem that your son has is associated with your house.
Before you attempt to remediate the problem, you should have the crawlspace inspected by a professional to ascertain the true nature of the problem. I can only provide generic advice. This includes: vacuuming all infested timbers with heavy-duty vacuum cleaner (minimum 5 horsepower), brushing with a stiff brush, re-vacuuming and application of mold-inhibiting paint to both seal the mold in and prevent it from growing. This should be done taking appropriate safety measures (approved respirator, disposable/washable clothing, gloves, etc. ).
Mold infestation will return if the drainage problem is not resolved. This will require engaging a professional to install an appropriate drainage system.
The previous owner is only legally liable for this problem if he/she knew about it and failed to disclose it to you. The problem is a construction defect. As such, primary liability would likely fall on the house's contractor.