How do you get the moist air in the winter and the hot air in the summer
out of your attic? Answer: lots of
You want to allow the moist air to escape, especially in winter time
when the interior of the attic is warmer than the outside
temperature. The moisture (humidity) will condense at a cool enough
temperature. In warmer seasons you benefit from allowing hot air to
The homes constructed today are tighter and therefore trap more
moisture and heat in the attic if not vented adequately. Building
standards have sewn up the homes that we live in tighter than a
drum. Surprisingly, standards of ventilation adopted in the 1930s
are still in use today! Most homes are woefully under ventilated.
Ventilation and roofing
should be a major concern to anyone who is contemplating having
their home re-roofed. It is common for the average household to
produce from four to five pounds of water vapor per day. In poorly
ventilated homes, this moisture has nowhere to go. So it forms
condensation on the underside of the plywood sheeting of the roof,
causing the plywood to expand, buckle and delaminate. This degrading
plywood has an ill effect on the roofing, including reduced nail
holding power, wind damage due to an uneven deck and stress cracks
due to unstable decking materials.
In the summertime attic temperatures can reach 180 degrees
and more. A proper attic vent system consists of an intake and an
exhaust. A properly vented attic works like this; as warm air rises,
it creates a slight suction at the intake vents. This relatively
cooler air removes excess heat from the underside of the sheeting as
it exits the exhaust. This cycle of heat exchange regulates the
temperatures of the new shingle, saving your investment in roofing
from becoming a cinder.
Choices are many in ventilation. The turbine ventilators are
a good product, however they can require a lot of maintenance as
they get older. Dormer vents are another option. They are simple and
can be installed out of sight at the rear of the
building. Continuance ridge vents is another option. Another
option for removing hot air is a solar powered electric fan.
Your consideration of proper ventilation in your roof may be the
difference between a successful, long lived roof or a complete
failure in a very short period of time.
When it comes to roof vents we say "The more the better".
If the ventilation is not doing the trick, you could try a portable or
crawlspace dehumidifier to reduce moisture.