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Yes there is a weather
period when asphalt shingles should NOT be installed in
most northern parts of the country: January or February.
March too, most years. And
December and November.
In the South, avoiding
shingling in January and February may be all that's
necessary.
Asphalt shingles have a
sticky tar strip that adheres to the shingle above it,
and it relies on warm sunny weather to make the tar
soften and stick. Most of the shingle packages I've seen
have specific instructions warning against installing
shingles in cold weather.
However, that doesn't
stop roofing contractors from installing shingles in the
fall and winter. But doing the job properly requires
adding a couple of small dabs of roofing cement (also
called "tar") to the underside of each shingle
tab. Many of the roofing cement products I've used are
quite good at bonding in cold weather, but the tar needs
to be kept warm or else it's too thick to apply. I
prefer to use the roofing cement/tar in caulk tubes
because it's less messy and faster to apply. It's also
possible to keep a tube of caulk inside your jacket
while working in cold weather... tar doesn't flow well
when it's cold.
In mid-November 2005 I
got a call from a friend who had just paid to have his
roof re-shingled the week before. During a nasty
windstorm about two dozen shingles had peeled off. We
discovered that the "professional" roofer had
neglected to nail the shingles between the guide lines
printed on the shingles, even though he had been
specifically instructed to follow the nailing lines.
That problem, combined with the fact that the shingles
had been installed in cool early-November weather,
allowed the shingles to lift up and peel away.
Had there been a couple
of days of warm sunny weather, the shingles probably
would not have peeled away because they would've stuck
to each other.
The bottom line is: You
really need to follow the shingle manufacturers
installation instructions. Temperature range, nail
location, number of nails per shingle, how deep the
nails are driven, and so on, are some criteria listed in
the instructions. All those seemingly trivial details
have been figured out by people (engineers, I assume)
who analyze this stuff for a living.
If you hire a
contractor to re-shingle your house, I strongly
recommend that you do two things:
1. Get a copy of
the installation instructions for the shingles you are
using. You might obtain a pamphlet from the lumberyard,
or just take a wrapper from a bundle of shingles after
they are delivered.
2. Watch them like a hawk to make sure they are
following the instructions TO THE LETTER.
Personally, I would
just patch up the roof and wait until spring to
re-shingle.
IF you can find a
contractor who will guarantee that they will apply
adhesive under each and every shingle, then it could be
worth doing the job in cold weather. My experience is
that shingles installed with extra adhesive make a
superior installation that resists very high winds.
But I would monitor
them and/or inspect their work by checking a dozen spots
around the roof to see if the shingles are actually
sticking, or have some black gooey tar underneath.
You might find that
roofers are available in the winter months, but when the
weather warms up they may all be busy.
Bruce W. Maki, Editor.
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