Condensation on the undersides of roof decks in attics can be a
common problem for different residential roof systems. Condensation
in attics can occur more frequently in the colder climates of the
upper Midwest and Northeast and typically on roofs that have
inadequate ventilation and insulation, as well as attic bypasses.
When dryer vents, bathroom fans or furnace exhaust ducts vent
directly into an attic space, the problem is intensified.
Although building codes recommend and require adequate attic
ventilation above roof insulation to remove heated air and water
vapor that has entered an attic from the surrounding air or a
structure's occupied portion, the codes are not strictly adhered to
during the design or construction phases. In addition, attic
bypasses and openings in dryer vents and furnace ducts must be
sealed to minimize moisture infiltration into an attic. This would
prevent troublesome condensation within the attic space and on the
roof deck's underside. Unfortunately, joints in vents and furnace
ducts sometimes are not installed in...
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