Home inspector Dwight Barnett answers your questions:
Q: My wife and I are purchasing a house, and we had the inspection recently. This turned up evidence of mold in the crawl space and the attic. I know that the crawl space lacks a vapor barrier on the ground, the furnace condenser drains to the crawl space and the clothes dryer vent potentially vents down there. There is also insulation tacked up between the floor joists, so I don't know the situation under that.
Our Realtor recommended someone to check the mold. Isn't that a conflict of interest? What sort of testing/inspection should I expect from a mold inspector?
We don't want to be alarmists, but we do have a 6-month-old son we want to keep healthy. Is there a point at which we just walk away from the deal?
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A: Your question is not all that difficult to answer. Regardless of the age of the home, if molds are visible and there is a high incidence of humidity and water problems, it is likely additional problems will be discovered in areas that were not accessible to your home inspector. A mold inspector might use a vacuum pump or other device to sample the air inside and outside the home, or a cotton swab or a tape strip to lift a sample of the mold, or he might simply remove a piece of mold-infected paper from the drywall to send to an accredited laboratory. In some cases all of these methods might be used.
On the other hand, if you see mold, then you know you have mold, either allergenic or toxic, and there may be no need for expensive sampling.
The mold-infected items need to be removed from the home and taken to a landfill. Items that cannot be removed can be sampled, then cleaned and treated by a qualified contractor and sampled again to make sure the molds have been contained.
There are four factors inside the home that lead to mold growth. Remove any one of them and the mold will either be destroyed or become dormant.
First, mold spores must be present in the right place at the right time for mold to grow. Once the spores latch onto a food source where there is also a source of moisture and a warm environment, the molds can grow into a major problem. Normally the food source is the house or items affixed to the house, so we generally rule out removing the food source. A warm environment is necessary for our comfort, so we can't take away the heat.
Now our problems have been reduced to dealing with the water source or the mold spores. On planet Earth mold spores are present almost everywhere you go and in the air we breathe. A good furnace filter and tightly sealed ducts can reduce the amount of mold spores inside the home.
We have reduced the problems to just one: Remove the amount of moisture from the air inside the home. An air conditioner or dehumidifier can reduce moisture levels, and vented bath and kitchen fans should be used when family members are bathing or cooking.
Try to maintain humidity levels between 40 percent and 70 percent with room temperatures close to 70 degrees.
Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 286, Evansville, Ind. 47702.