water leak from top floor to main floor

[homie27]

Hi all, we had a toilet leaking the other day on the top floor and the water went down down the walls and into the powder room on the main floor. the paint started bubbling in a few spots, part of the ceiling is stained, etc. the leak is now fixed. can mold start growing behind those walls as a result of just one leak?

[BartBandy]

In a word? Yes. I've seen it.

[homie27]

I had a plumber come over yesterday for something else and showed him the walls. He had this detector with two spikes. He pushed the spikes into the wall a little and some areas detected moisture and some didn't. so he said to wait a couple more months and call him back and he'll check again.