Apartment next door got flooded and some water sipped underneath the wall. The floor buckled and had to be replaced. After removing floor trim I discovered some mold under the baseboard.

I cut out a portion of drywall (see 2nd pic below) and sure enough, there is mold on both sides of both layers of drywall. But the mold formed only on the surface, in the paper coating. The gypsum itself looks white and clean. So here's the dilemma: should I simply scrub and clean with 1:10 bleach solution, or should I cut and replace affected part of the wall? I already made the decision to replace trim boards.

Bonus question: is there something I can do to prevent this from happening again? For example, can I put some kind of water barrier inside the wall, since it is likely that I will have to open it up anyway?

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1 Answer 1


General practice is going 6 inches above molded area and cut it out. You must inspect the backside of the drywall. If you can't you need to keep cutting out until you hit 6 inches of unaffected wall. You then need to follow a mold remediation plan - not sure how anything else in the wall looks but useless replacing the drywall if you will put up new drywall on moldy framing. If there is any humidity/dampness it will continue to grow.

As far as a barrier... I guess you could put up plastic. Not sure how affective it would be because water will find a way to go somewhere. Where do you want leaks to go?

  • I have metal studs and some kind of glass wool insulation. There does not seem to be any dampness remaining inside the wall. As far as future leaks, I would prefer the water to stay where it came from, in my neighbor's apartment (not being afraid of sounding a bit selfish here). I realize this may not be possible, but what I had in mind is depositing some kind of liquid foam on the floor between the walls to form an inch-high barrier. That might be enough protection against minor leaks, or it may be completely useless. The floor would definitely need to be cleaned thoroughly prior.
    – user443854
    Jul 31, 2013 at 13:57
  • 2
    I would thoroughly clean the metal studs - bleach solution, replace insulation where you are replacing drywall, and put up new drywall.
    – DMoore
    Jul 31, 2013 at 14:10
  • Also to comment on plastic - go for it. I just don't think you will be able to keep the water out that way. You will need something from keeping the water from going under the studs. That is another question on this site though. How do I put up a water barrier for a neighboring wall?
    – DMoore
    Jul 31, 2013 at 15:13

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