A: Hire a licensed mold assessor to test your walls and the air to make sure the underlying issue — excessive moisture — has been addressed. A persistent smell hints that mold or mildew (the term for specific kinds of mold) may still be growing because moisture levels are high.
If you were to hire a company that does assessments as well as remediation and were told more remediation work needs to be done, you may wonder whether the advice was just a way to drum up more business. So hire a company that does mold assessments but not remediation work, suggested Joe Mulieri, owner of MoldGone in Silver Spring (240-970-6533; moldgone.net), which does both types of work throughout the Washington area. He said an assessment might cost a few hundred dollars. The D.C. government website lists licensed mold professionals in two categories: assessors and remediators. To view the list, type “mold professionals” into the search box at DC.gov .
Assuming you aren’t seeing any mold now, the smell could be coming from inside the wall cavities, perhaps within insulation stuffed into the walls, with the smells then wafting into the room through gaps around trim and between the walls and flooring. These air gaps could also be allowing warm, moisture-laden air to settle on a cold surface, where it condenses and raises the moisture level enough to support mildew growth. If the room didn’t have a moldy smell before the gutter problem, it’s possible that 3½ months of leaks soaked the insulation enough to compress it, allowing condensation to occur where it wasn’t an issue before. Or mildew could be in the ceiling or the floor, perhaps in carpet padding.
If the walls in your condo were covered in drywall, the best solution probably would be to remove the damaged materials, see what’s going on inside the wall and start fresh. Replacing drywall makes sense because mildew can feed on the paper that covers both sides of drywall’s gypsum core and because drywall is relatively inexpensive to replace.
Plaster, however, is less prone to harboring mildew because it doesn’t provide food for mildew, and it is more expensive to replace. “Plaster is more dense and less absorbent than drywall,” Mulieri said. Although it’s sometimes necessary to remove plaster to address hidden issues, it’s often sufficient — once a leak is plugged — to go with the procedure your plasterer used: scraping off the outer layer, then applying an encapsulant. Mulieri said he uses AfterShock, a sealant produced by Fiberlock Technologies that was designed to disinfect surfaces and prevent mold from re-growing.
Many contractors, like yours, encapsulate by using a less-expensive oil-based sealer, such as Zinsser Odorless Oil-Based Stain Blocker or Kilz Orignal. But if you read the technical documents for these products, they don’t mention using them to encapsulate mildew. The Zinsser product sheet says only that it blocks stains from water, fire and smoke damage, while the Kilz sheet says it blocks stains from a longer list of sources and “seals pet, food and smoke odors.” There is no mention of mildew with either product.
There is a lot of confusion about how mildew grows and the risks it poses. People often focus on “killing” mildew by spraying it with bleach or similar products. But that kills only mildew hit by the spray.
And if you inhale dead spores, the health risks are the same as if they were alive. That’s why the Environmental Protection Agency’s advice for do-it-yourself mildew cleanup focuses on wiping away mildew, using just water and detergent, on hard surfaces. The EPA says consumers can generally clean up moldy areas of less than 10 square feet by following its safety advice, which you can read by typing “mold cleanup in your home” into the search box at EPA.gov. For larger areas, it recommends getting a pro — one that is licensed.
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