Many building codes now mandate intake and exhaust ventilation for attics. It’s easy to see why. A properly ventilated attic can save energy, eliminate excess moisture, prevent mold, and prevent ice damming in winter. And, by minimizing heat buildup in the attic, proper ventilation can even prolong the life of the roof system.
Many building codes now mandate intake and
exhaust ventilation for attics. It’s easy to see why. A properly ventilated
attic can save energy, eliminate excess moisture, prevent mold, and prevent ice
damming in winter. And, by minimizing heat buildup in the attic, proper
ventilation can even prolong the life of the roof system.
Industry experts agree that a balanced ventilation system -
with intake ventilation meeting or exceeding exhaust ventilation - is ideal.
However, in my neighborhood, a suburb of Detroit,
intake ventilation is pretty rare. Most of the houses were built in the 1950s,
and very few of them have overhangs at the eaves that allow for perforated
soffits. With the exception of the newer houses or houses that have undergone
major remodeling projects, there are very few houses with intake ventilation at
the eaves. I should know, because I walk my dog every day, and, because I work
for a roofing magazine, I’m often looking at the roofs in my neighborhood.
I see a lot of can vents at the ridge and quite a few in the
lower third of the roof deck - some in areas where they are not recommended. I
also see a lot of ridge vents with no intake ventilation at the eaves. I
recently spoke Steve Henderson of DCI Products, who cautioned that ridge vents
aren’t effective without intake ventilation. “We explain it this way: It’s like
sucking on one end of a straw with your finger over the other end,” he said.
“You need proper intake ventilation, and that’s why my father invented the
father, Jack, was a general contractor who did a lot of roofing work. “He saw
the void in the industry,” said Henderson.
“In many cases, houses had no intake ventilation at all, with the exception of
some gable vents, which only covered the top third of the attic. He knew a
product designed for the lower roof edges would be effective, and since the
SmartVent tapers, it blends into the roof.”
The tapered, corrugated plastic vent installs under the
shingles and can be used for both intake and exhaust ventilation in reroofing
work as well as new construction. According to Henderson, the most popular usage of the
SmartVent is at the lower eaves edge for intake ventilation in cases where
there are no overhangs. (For more information about SmartVent, visit
How do you cope with houses with no overhangs in a reroofing