Rainscreens are defined as the exterior
Posted: Thu Jul 10, 2025 7:10 am
According to “The Rainscreen Principle” in the ninth volume of the Canadian National Research Council (NRC’s) Construction Technology Update, two exterior walls are better than one at controlling water penetration into a building. There are three required components of a rainscreen wall assembly:
the outer leaf or barrier, which is a vented or porous cladding (the rainscreen) that deters surface raindrop momentum;
a few inches of air chamber or cavity separating the cladding from the support wall, reducing splashing and capillary moisture transfer—large, protected openings (e.g. vents or weep holes) positioned at the top and bottom of the wall promote convective airflow, allowing moisture to quickly drain or evaporate from the air cavity; and
the inner leaf or barrier—comprising water-resistive barrier (WRB), insulation, and the structural wall—must act as the final moisture barrier and drainage layer protecting against any moisture bypassing both the rcs data cladding and air cavity.
The effectiveness of a rainscreen cannot be achieved without an airtight weather barrier and appropriately sized air chamber or cavity.
Rainscreen Overview
surface of a building (a cladding), which has direct contact with the weather and the elements, but is not directly attached to the building substructure. It is a barrier that sheds and attempts to control (but not prevent) the majority of the rainwater intrusion into the cavity between the rainscreen and the substructure.
The installation of weather barriers and rainscreens requires comprehensive integration with other building envelope elements such as the structure, insulation, vapor retarder, air retarder, and flashing systems.
the outer leaf or barrier, which is a vented or porous cladding (the rainscreen) that deters surface raindrop momentum;
a few inches of air chamber or cavity separating the cladding from the support wall, reducing splashing and capillary moisture transfer—large, protected openings (e.g. vents or weep holes) positioned at the top and bottom of the wall promote convective airflow, allowing moisture to quickly drain or evaporate from the air cavity; and
the inner leaf or barrier—comprising water-resistive barrier (WRB), insulation, and the structural wall—must act as the final moisture barrier and drainage layer protecting against any moisture bypassing both the rcs data cladding and air cavity.
The effectiveness of a rainscreen cannot be achieved without an airtight weather barrier and appropriately sized air chamber or cavity.
Rainscreen Overview
surface of a building (a cladding), which has direct contact with the weather and the elements, but is not directly attached to the building substructure. It is a barrier that sheds and attempts to control (but not prevent) the majority of the rainwater intrusion into the cavity between the rainscreen and the substructure.
The installation of weather barriers and rainscreens requires comprehensive integration with other building envelope elements such as the structure, insulation, vapor retarder, air retarder, and flashing systems.