The outer cladding sheds most rain, and the air gap behind it breaks capillary contact, lets water drain down to flashings and allows drying. Pressure-equalized versions compartmentalize and vent the cavity so wind pressure does not push water across it. In open-joint systems the cladding joints stay unsealed and the air and water barrier on the backup wall does the sealing.
It's a rainscreen, don't caulk the panel joints, the cavity's meant to drain and vent.
Also heard as
- rain screen
- drained and back-ventilated cladding
Related terms
WRB
Water-resistive barrier, the layer behind cladding that sheds water that gets past the outer skin.
Two-stage joint
A joint with an outer rain seal and an inner air seal separated by a drained cavity.
Weep
An opening at the base of a wall or window system that lets collected water drain out.
Flashing
Thin sheet metal or membrane installed at joints and interruptions in a wall or roof to direct water back outside.