A drainscreen is a self-draining material (often a proprietary mesh or netting) between between stucco or cement cladding and the drainage plane/waterproof layer, especially common with insulation finish system (EIFS) wall assembly (which is often also the exterior air barrier in EIFS assemblies). Drainage paths allow the water to get out of the wall. Old-school stucco walls rely on the small gaps between the building paper and the lath for their drain screens. In the illustration, the black mesh layer is the drainscreen
A rainscreen is most often a non-proprietary detail that uses strapping or furring to create an air space between the sheathing and the siding in a wall assembly, allowing the moisture on the exterior side of the sheathing (the drainage plane) to both drain and evaporate out of the wall cavity. The air space is vented, so there is equal pressure on the front and back of the siding, reducing the amount of water driven into the siding.
- Both create a capillary break between the sheathing and the cladding/siding.
- Both require very careful attention to the drainage plane, especially flashing and taping at openings and connections between different assemblies and building components.