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Ask Dr. Laundry

Ask Dr. Laundry

Removing Mildew from Drywall

By Dr. Laundry May 6, 2010

Q. We had a water leak inside a wall (made of drywall). We’d like to know what to do to prevent mildew build up inside the wall that had the leak. We’ve cut a hole in the wall to get air in there, can we spray Clorox inside to kill any mildew?

A. Number one priority is to get the area dried out ASAP. The following is from our EPA label on Clorox® Regular-Bleach to deal with mildew and mold. It gets a little tricky since the wallboard is not a hard, nonporous surface, and since it’s inside the wall, it’s tricky to know how to apply the solution. If you make the bleach solution and try to use a leftover spray bottle, the solution likely will react with the metal parts in the trigger and corrode them, making the bleach solution less effective and dispensing a brown colored liquid. Another approach would be to use the Clorox® Clean-Up® spray cleaner to apply a bleach solution. All the trigger parts are specially chosen to be bleach-compatible. I would re-spray the area every 2-3 days while the interior continues to dry.