Walls and Ceilings - Mold on drywall....need help

I live in NJ. A couple of weeks back we had heavy rain after which my wife noticed a smell coming from my son's room

On checking his closet we found one wall (this wall is part of the outside wall) stained and damp with black patches on it, which we assume is mold. Water seems to have run down all the way to the carpet which was damp as well. As his closet is always jammed with stuff we did not notice this before.

As it's a town house we called the management company and they sent a contractor. He had a look at the roof and said the problem was with a couple of nails on the roof which were loose. He sealed them and left.

I have my doubts that a couple of nails could let in so much moisture.

Questions -

1. Could a few loose nails cause this problem ?
2. How long does the wall have to be damp for the mold to grow ?
3. What do I need to do now to fix the problem ?

TIA

Any opinions on this ?

Welcome to the forums

Sorry it took so long to get a reply - I guess your post just got overlooked.
Yes a small leak can let in a lot of water under the right circumstances. Mold/mildew can grow fast under the right conditions - it takes heat and moisture.

Mildew and some molds can be killed and removed by cleaning with bleach water. As long as the drywall is sound all you need to do [after cleaning] is to prime the affected area with a stain hiding primer [like kilz] and then repaint.

Marksr, thanks for your response.