The "wet buildings" I see have waterpenetration
problems for a number of
reasons. Some buildings have poorly
installed or punctured vapor barriers,
others have inadequate ventilation.
Sometimes, the building has a wet
basement or crawlspace, or the owner
may be at fault (four cords of wet
firewood in the basement, for
instance, or a clothes dryer vented
indoors). But the most common
problem I see is inadequate caulking
and flashing.
Faulty Flashing
Let's review a few cases. Recently, I
was called to look at a water problem
at a hospital in the Midwest. The
exterior wall was brick. Behind the
brick there was a small air gap. Then
came a layer of gypsum, 6 inches of
insulation, and, finally, foil-backed
drywall.