CONTROLLING
MOISTURE
in Mixed
Climates
Details for
keeping rain
and water
vapor out of
wall cavities
Controlling moisture problems is difficult in climates where seasonal
changes necessitate both heating and cooling of interior spaces. In addition
to common concerns about rain penetration through exterior cladding,
builders in a mixed climate must take special precautions to prevent moisture from
becoming trapped in wall and roof cavities — a problem that is complicated by high
humidity levels both inside and outside the structure.
Infiltration & Exfiltration
During heating periods, when interior air pressure is high, humid air inside the
building is driven outward, either by air leaks into wall and roof cavities (exfiltration)
or by diffusion (passage of water