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Serving NE Ohio Since 1956 |
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Ice Damming and Backup Ice
Dam: a mass of ice formed at the transition
from a warm to a cold roof surface, frequently
formed by refreezing meltwater at the overhang of a
roof, causing ice and water to back up under
roofing materials. Ice Dams are functions of
environmental conditions, attic and roof design,
insulation, and ventilation. Specialized
ice and water barrier membranes are available which
can be applied under shingles when installing a new
roof. Ice
and Water Shield is a tough, pliable sheet membrane
designed to help prevent moisture penetration and
interior damage when ice dam buildup causes water
to back up during the winter season, and helps
protect against wind driven rain. Ice and water
shield, along with a properly insulated and
ventilated attic, will help minimize or prevent
leaks caused by ice backup. This
waterproof underlayment can be installed in new
construction or during installation of new roof,
under shingles, tile, slate, metal and shakes, is
compatible with accepted roofing materials, and
provides an effective concealed waterproofing
system without detracting from the roof or building
design. Some cities now require the use of ice
shield around the perimeter of your home when you
install a new roof. A few of these include Bay
Village, Berea, Brecksville, Broadview Hgts., Brook
Park, Brunswick, Garfield Hgts., Independence,
Lakewood, Maple Hgts., Medina, North Royalton,
Olmstead Twp., Parma Hgts., Rocky River,
Strongsville, and Westlake. Other area cities are
recommending Ice and Water Shield but not yet
requiring it. Ice
Dams are Damaging, Dangerous and Preventable. A
cubic foot of snow can weigh as much as 30 lbs.
Multiply that times the area of your roof and you
get a good idea of the kind of strain that can
result when snow piles up overhead through the
winter. The longer it remains, the higher the
moisture content and weight become. The buildup of
moisture leads to the formation of ice dams. Ice
dams can cause water to migrate into interior walls
and ceilings. The damage to plaster, paint,
wallpaper results in substantial repair costs. The
risks don't end there. Water seeks channels. Often
this leads to water following the path of
electrical wiring to ceiling fixtures and wall
sockets. Roofs
that "leak" in the winter (when there has been snow
and ice), but have not previously leaked at the
same spot during rain storms...are most likely not
leaks at all. This condition is called "ice
damming". It is a temporary condition and it occurs
when snow and ice buildup on the roof. When the
temperature warms up, the ice begins to liquefy.
When trapped by layers of ice and snow, the water
is forced up and under the shingles, over and
around flashings and valleys, and behind the siding
of sidewalls; leaving it to drain through the
ceiling of your home. This is a common condition
related to winter weather conditions, attic and
roof design, insulation, and ventilation. It is
often impossible to find or correct roof leaks
thought to be related to ice damming during the
winter. Once the snow and ice are gone from your
roof, and the leak does not continue into the
Spring during normal rain storms, you know you have
an ice backup problem and need to take corrective
action. Because so many different factors
play a part in the formation of ice dams, most
roofing companies can not guarantee to prevent them
or warranty against damage they may cause. See
below. Ice
Dam Prevention Ice
Dams are functions of environmental conditions,
attic and roof design, insulation, and
ventilation. Debris filled gutters can also
contribute to the problem by allowing snow and ice
to collect and buildup on your roof because it can
not drain properly. Roofs with no or limited attic
space can also cause problems. Improving your
attic's insulation and ventilation is one of the
most effective strategies for combating ice dams.
The higher the R rating of the insulation the
better. The object is to make the roof as uniformly
close to the ambient outdoor temperature as
possible. Homes in cold climate zones that receive
significant snowfall should be protected with
ceiling insulation that has an R rating of at least
38 and is about 12" deep. Seal openings around
plumbing and wiring that will allow warm air to
escape from below with aerosol foam (exercise
caution, as this type of material expands after
escaping the can). Make
sure that there is no insulation outside the
outside wall of your house or above the top plate
of your exterior wall. All insulation should lie on
top of the ceiling and none of it should touch the
roof. This allows the ventilating air to circulate
under the entire roof so that it will stay at the
same temperature all over. Good roof venting plays
an important role in preventing the melting that
feeds the formation of ice dams. If
it does not already exist, create a way for air to
enter the attic through the soffit. Ideally, there
should be an intake vent between each rafter tail.
Better yet, you can replace the soffit board with
material that has openings all along it, this
provides a continuous intake vent. Depending on
which you prefer, you can install vent screens that
pop into holes you cut into your soffit with a hole
saw, as well as the continuous vent
material. Ensure
that the outlet vents - along the ridge or high in
the gable ends, are open and free of any
obstruction that might slow down the air that is
trying to get out. The
best thing about good vent systems is that they
adapt natural forces to our needs. Done right, they
operate on their own with no electrical or
mechanical power required. Breaking
Ice Dams Even
if you are able to eliminate or minimize the
formation of ice dams, leaving large quantities of
snow on your roof can result in structural damage
and pose a risk to plants, pets and people if it
slides off in mass. Once you've got water seeping
into your house, you need to deal with the ice dam.
Here's the challenge: you have to balance removing
the ice dam and preventing further damage with the
possibility of causing damage to the roof as you
remove the ice. No solution is ideal. Do as little
as you must. Here
are some ways to deal with the ice dam if there is
water seepage. Be cautious: working on the roof or
below it can be dangerous in the best of weather,
and ice, cold, and snow can make it more dangerous.
Roofing materials are more brittle in cold weather,
and more susceptible to damage. Best
solution: Find a contractor. This is usually the
best solution, as the professional will know what
substances are safe and effective to use, and will
know how to use ladders safely under these
conditions. Do
not use hammers, picks, axes, or ordinary de-icing
salt. Set
and secure any ladders properly. Clear
dangerous overhangs and icicles -- being cautious
that you position yourself so these and other ice
that may become loosened don't fall on
you. Remove
snow from the roof behind the ice dam, to prevent
further ice dam buildup and seepage. Use a roof
rake or push broom. Use caution to avoid slipping
and falling, and be careful not to damage roofing
materials. A well designed roof or snow rake is the
safest, most effective way to remove snow from roof
areas. When
selecting a roof rake, keep in mind that even
though it is as light as a feather as it falls,
accumulated snow becomes heavy. Many roof rakes are
lightweight and flimsy. Look for one that is sturdy
and durable. Sharp edges can also cause damage to
shingles and siding, so selecting one with rounded
edges and wheels to keep the blade slightly above
the roof surfaces is also a good idea. Be sure that
the roof rake has an adequate reach - at least 16
feet - and that the pole comes in sections that
separate easily for convenient storage. Make
channels in the ice so the melting snow can run off
the roof. If
there's a dormer window above the roof, try running
hot water from there. Hose
the roof with tap water from below on a warm day,
in selected spots to make the needed
channels. None
of these solutions is a permanent solution; if you
have a problem with ice dams, you'll need to take
action to prevent the problem from
repeating. Also
please see this excellent article, including
photos: |
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