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Attic Ventilation Openings
Water entering your attic space can soak the insulation and can lead to
collapsed ceilings. Water can get in where roof covering is lost, through attic
vents and through soffits. Gable end vents and soffit failures are the two
main areas in the ventilation system that routinely let water into your attic.
However, there have been some spectacular failures of off-ridge vents where
the vents began to act like scoops and dumped lots of water into the attic.
Ridge vents are also a common failure point although not as common in
recent years as soffits. See Soffits for ideas about
strengthening your soffits. See Gable End Vents
for ideas about keeping water from entering through your gable end vents.
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Off ridge vents have been known to turn into scoops that collect water and dump it into your attic
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Ridge vents have been another frequent failure point but not as frequent in recent years as soffits
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A ridge vent
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This metal ridge vent is very poorly attached - many of the newer products accommodate installing shingle material over the top that provides the same look as the roof shingles and covers the fastener locations - you can still lift up the edge to get a good look at the anchorage of the ridge vent.
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Ridge Vents: Ridge Vents are metal or plastic caps that are put over
gaps at the ridge of your roof that allow hot air to escape from your attic.
With this type of system, cooler air typically enters through the soffits
and hot air exits through the ridge vent. This sets up a circulation that
cools the attic, provides a route for moisture expelled from the heated roof
sheathing to exit the attic, and cools the sheathing which reduces the temperature
of the roof covering and helps to prolong the life of the roof covering.
The ridge vents are the last thing connected to the roof when a roof covering
is applied. Consequently, it is possible to get to the fasteners that attach
the ridge vent to the roof deck and sometimes to the rafters or trusses.
Ridge vents getting dislodged or lifted off roofs is relatively common in
hurricanes and this damage can lead to significant water intrusion. You
can check the type of fasteners used to attach the ridge vents by looking along
the edge of the roof deck near the cut-out at the ridge to see if there are
any fasteners that are larger or different from those used to attach the
roof covering. You should also be able to lift up the edge of the ridge vent
top so that you can see the heads of the fasteners from the top of the roof.
Check the ridge vent along its length for any loose spots by pulling up
on the edge. Be careful not to damage the shingle material that may be
attached to the top surface of the ridge vent but you can pull up firmly to
check for looseness of the vents (you should be able to pull up with a
force of about 50 pounds without any danger of pulling loose a well attached ridge
vent cover). If the ridge vent is loose or the fasteners are spaced more
than about 12 inches apart, you should reattach the ridge vent cover. We
recommend using #8 stainless steel screws to increase the anchorage of the
ridge vents. Screws at least 1-1/4" long should be sufficient, but make sure
that the screws are long enough to go through the base of the ridge vent cover
and completely through the deck below. If the ridge vent covers seem to
be well attached but are nailed to the decking, you can provide an extra measure
of anchorage protection by clinching (bending over) the nails from the inside
of your attic. However, if the nails are short and stubby or large diameter,
trying to clinch them may do more damage than good. If shingle nails were
used to hold down the vents, then you probably won't be able to clinch them
because they are too short and too fat to bend easily.
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Off-ridge vent on a shingle roof
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Attic view of inside of off-ridge vent
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Off-Ridge Vents: If you don't have gable end vents or ridge vents and
you have a vented attic, you probably have off ridge vents. The most common
form of off ridge vents are those that have a goose neck, the shape of an
inverted J. The opening is at the end of the short part of the J and the
inverted shape is intended to make it hard for water to enter the opening.
There are other products that look like tile or are the same size as one
or two tiles and can be integrated into the roof covering. In some cases,
vents are installed as pairs with one near the bottom of the roof and the
other near the ridge. We have heard a number of complaints about water blowing
in through off ridge vents including cases where they have broken loose or
flipped up and actually scooped water into the attic. The first step is
to check and make sure that the off ridge vent is securely attached to the
roof. Grab hold of the vent from the outside and try to wiggle it back and
forth. Again, the anchorage should be strong enough that you can not move
it with a force of between 50 and 100 pounds. You can also check the fasteners
from inside of the attic and if it is nailed to the roof deck, you can provide
an extra measure of anchorage protection by clinching the nails from the
inside of your attic.
Some homeowners have reported water being driven into the attic through goose
neck vents in certain locations. It appears that the roof shape and orientation
of the vent relative to the direction of the winds plays an important role
in which vents leak. As a just before the storm measure, they report success
in reducing the amount of water intrusion by stuffing the vents with foam
swimming pool floats (long foam rods) and taping plastic over the opening from
the inside of the attic.
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A typical small goose neck vent on a shingle roof - make sure it is well anchored - you could try to seal it in preparation for a hurricane
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Typical turbine vent - note the friction fit of the top part to the collar - you could add screws but the better bet would be to remove the top and cover or plug the collar stack.
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Goose Neck Vents and Turbines: Goose neck vents, turbine vents and
a variety of roof vents that work in ordinary wind probably will not keep
out water in a hurricane. Goose neck vents are really another form of
off-ridge vent but they are also frequently used for bathroom vents. Turbine
vents are not designed to keep water out in strong winds and few are designed to
stay on the roof in strong winds. The turbine vents should be removed and
the holes left by the duct sticking up from the roof should be covered and
sealed as part of your preparations for a hurricane. You need to be sure
that you securely seal the opening with a cover that will not be ripped off
during the storm. At least one roofing manufacturer (GAF's Master Flow)
makes a weather cap to replace turbines.
You can also make your own temporary cap to be used as part of your storm preparations.
Check to see if the turbine is connected with screws to the duct that comes
up from the roof. In most cases, you can just lift the turbine off the duct.
If not, remove the screws and lift the turbine off the duct. Measure the
inside diameter of the duct. You can make a cover by using a jig saw to
cut a somewhat round disk of ½" thick plywood a little larger than the size
of the duct. To do this, place the bottom of the turbine on a piece of
plywood and draw a circle around the outside of the turbine neck. Cut the
disk about ¼" larger all the way around the circle using a jig saw. Find
the center of the disk, measure, and then mark points ½ the diameter of
the duct from the middle of the disk. Attach a series of 1-1/2" thick blocks
around the perimeter of the disk so that their outside edges are just touching
the points measured ½ the diameter of the duct from the center of the disk.
(As an alternate you could cut out a disk of 1-1/2" thick boards a little
smaller than the diameter of the inside of the duct and attach it to the
plywood disk.) Slide the side of the disk with the 1-1/2" thick material into
the open hole in the duct, the larger plywood disk will keep the cover from
falling through the hole. Install screws through the walls of the turbine duct
and into the blocks or disk of 1-1/2" thick material to hold the cover in
place. Use duct tape to seal the plywood disk to the turbine duct. Do
not forget to remove the cover and re-install the turbine after the storm or
threat of the storm has passed.
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