Kickout flashing might be one of the most important details to get right when it comes to preventing major water damage to a building. Kickout flashing is a simple little piece of metal that directs water out and away from a building when a roof surface ends at a wall. The illustration below, used with permission from the fine folks at CodeCheck, shows how this works.
Here’s an example of kickout flashing not installed, along with major water damage below the area where the kickout flashing was missing.
The rotted siding shown above is just the beginning; the real damage will be inside the wall. Here’s another photo showing some more obvious damage.