Water Damage and Mold Mold test services and mold remediation Q&A


I live in a home built in 1961 in Virginia. I recently discovered water damage to our interior wall framing and plasterboard, from what I suspect to be an old plumbing leak. I found it because, in an adjacent linen closet to our downstairs shower, the skim coat on the plaster walls was breaking off and we noticed that the lower portion of the wall had been plastered and the baseboards had been replaced by the previous owner. Also when I checked the plumbing access panel upstairs to this area in our bedroom, I saw some wood and plaster wallboard that has areas that appear to be discolored gray to black from water and, on top of it, a white residue that feels soft like talcum powder (rather than like sand).

We suspect that the water damage occurred at least 10 years ago because the previous owners had remodeled both bathrooms and the new areas look fine. We are having a structural engineer come look at the area, because there are some cracks on the upstairs walls near this area. So what I am wondering is, aside from structural reinforcement/repairs that may be needed, to address IAQ and allergy issues, how do I decide what wood and plaster board needs to be removed versus left alone versus maybe encapsulated by paint or some other treatment? Is there a moisture level that I should be looking for with a moisture meter? Is it effervescence or mold? I can't seem to find a moisture inspector in my area - what type of professional do I look for to help with this and what qualifications should they have?
This project could involve significant plaster board removal and interior wall reconstruction, and I want to know whether this is truly needed or whether I can encapsulate the affected areas since the water leak no longer exists.
-Alison, Virginia
Such plumbing leaks (which are often slow) are quite common. In fact, if most homeowners were to look hard enough, they would likely find some similar damage/mold infestation particularly in homes 10 years old or older.
Based on what you describe, it is suggestive that the plumbing leak which apparently was remediated, continued after the remediation. The white residue is likely to be gypsum. It may have effloresced from the wallboard (by the action of water) or may have been generated in the remediation.
The gray discoloration is likely due to mold such as Cladosporium, the blacker mold may be Stachybotrys.
The area in question needs to be carefully opened up for inspection before one can make any remediation recommendations. The plumbing leak needs to be found (if it is still continuing) and corrected. Wood materials in many cases can be brushed, vacuumed and sealed. Gypsumboard should be removed and replaced. Such remediation should be conducted by an experienced remediation contractor to ensure that mold is not dispersed into the living areas of your house.
I recommend that you look in your yellow pages under Ecological and Environmental Services. There are likely to be many IAQ/mold services consultants listed. Unfortunately, most individuals who provide such services are relatively new to it (less than 5 years of experience). Qualifications? There are none. Just about any one can claim to be an expert and at this time most "experts" are still in their early to mid learning curves. In theory, a certified industrial hygienist should be better than most. However, many in this profession are also early into learning the mold/moisture trade.

June 9, 2003
Indoor Environmental Quality (2000), Thad Godish PhD

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