Hi, I'm in SF bay area, California.

In one of the side room in my house, a section of the dry wall (inside the room) showed water marks. Since the other side of the wall is our front yard. So it is likely caused by the water sprays over the years.

The area is horizontal, about 1x3 square feets, and is about 2-3 inches above the floor. That room has 2 area like these and a third which is half the size.

My questions are:

1. What can I do outside the house to prevent the water from further damaging the wall?

2. Do I need to repair the inside wall (as described above) or I can just wait for it to dry up?

3. If I need to repair the inside wall, how should I repair it? Is it possible for do it myself? (I have some experiences build my own shed and some woodworking.)

Thanks very much.