National Green Building Standard
This exert was extracted from the National Green Building Standard ICC 700-2012. For a complete version of the standard, please click here.

602.1.9 Flashing
(5) A Rainscreen wall design as follows is used for exterior wall assemblies
                (a) a system designed with minimum 1/4 –inch air space exterior to the water-resistive barrier, vented to the exterior at top and bottom of the wall, and integrated with flashing details. OR
                (b) a cladding material or a water-resistive barrier with enhanced drainage, meeting 75 percent drainage efficiency determined in accordance with ASTM E2273.