Balcony Drainage Details: Ensuring Effective Water Removal
http://ratten-wiki.de/index.php?title=Rainfall_Effects_on_Building_Assemblies:_Mitigation_Through_Membrane_Selection
Balconies sit at the edge of a building envelope, a small outdoor stage where weather performance meets daily use. When drainage is overlooked, water can linger on the deck, migrate into parapets, or infiltrate railing pockets and stair lands