Thoughts on what may have caused this? Not sure how long it’s been a issue. Noticed the moisture under the ledge today that led to the discovery of what’s in the picture…. advice on what to do next? In South Carolina

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  • Looks like water damage and mold Commented Jul 27, 2023 at 0:50

1 Answer 1


It's water damage, but the source isn't clear. Could be:

  • A leak at the window frame
  • A leak at the head of the window or higher up the wall
  • A leak at the window sash
  • Condensation on the inside

You'll want to track that down with some observation. The fix is basic drywall work:

  • Scrape away the loose material. Try not to damage the metal corner bead, if present.

  • Use a setting type joint compound for best future moisture resistance (as opposed to premix) to fill and skim.

  • Sand, prime, paint.

I don't worry much about mold. Unless you're overly sensitive or there's a huge amount of it, that's just life. Mold is already everywhere.

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