Excessive moisture intrusion, combined with inadequate drainage leads to trapped moisture. This moisture can rot sheathing and framing and lead to mold. The source of water intrusion is most often caused by incorrect installation of windows, specifically the lack of sill pan flashing, and a lack of proper flashings and kickouts above windows and doors and at roof line. Other causes are unsealed penetrations and a lack of caulk between stucco and other materials.
Kick out flashing directs water away from the wall into the gutter system.