The disclosure provides example drainage channels, drainage systems, building walls and methods. An example drainage channel includes a drainage panel for conveying water within a building wall. The drainage panel is impermeable and has a first end and a second end. A support panel is coupled to the first end or the second end of the drainage panel such that the support panel is configured to be arranged vertically relative to the building wall. The drainage panel is configured to be arranged either perpendicular to an exterior sheathing of the building wall or angled downward from the first end of the drainage panel toward both the second end of the drainage panel and the exterior sheathing of the building wall.