That key is an excellent idea, wish I would have known that technique when the cement was poured. I live in a high wind area 120+kmh winds, and this door is facing the prevailing wind side. I may either notch the cement out or install a rubber strip at the base.
New garage build, I installed a wayne dalton garage door and with driving wind and rain the water pours through the panel ends inside and fills garage with water. Anyone have this issue or suggestions on how to fix ?
Video attached as well: Video