Water movement must be controlled by design.á There are many possible approaches to
achieving continuity of the
moisture ingress plane and these depend greatly on other design
considerations.á The design must utilize assemblies that have acceptable
inherent water management characteristics
for the particular application.
To ensure the integrity of the building envelope
weather-resistive barriers need to be integrated with other components, including structure, insulation,
vapor retarder, air retarder and flashing systems.á In
addition to water moving due to gravity, wind-driven rainwater can go up at
upper levels.á Water can move horizontally into the building at windows
heads and soffits and migrate between adjacent surfaces due to capillary action.á Humid air causes water vapor to enter
through cracks.