I ran into an example of a small water trap in my newest house, the Spanish style of my previous posts uptopic.
The first picture below shows a small water trap, where the roof pitch would direct rainwater against the wall of the house. In Sims 2, examples such as this are no big deal, since they often cannot be fixed. In real life, an area such as this might have the corner of the roof pitch slightly away from the house, or just have added flashing against the wall to prevent leaks, or both. Nevertheless, in real life this is a good example of a "problem area" that would need to be kept an eye on.
The second picture shows that I was able to add a small section of Lean-To roofing in that area, and the third and fourth pictures show the end result once the Lean-To roof angle was reduced to 15 degrees to match the rest of the roof. There are no roof sections visible inside the house.
Come to think of it, making the angle of the little Lean-To piece a bit steeper, say about 18 degrees, might look even better