Hints & HELP!
Ice Dams on Roofs
by Lorene Bartos, Extension Educator
This article appeared in the January
26, 2004 Lincoln Journal Star Newspaper.
though we’ve had a mild winter with little snow we know
there is more snow to come. Being aware of possible problems
when snow collects on roofs is important.
dams occur when a snow-covered roof over the attic or room
is warmer than the eaves, or overhang of a roof.
If the roof is warm, it will cause the snow to melt and
run under snow along the roof. When the melted snow hits
the cooler eaves, it freezes.
ice builds up on eaves, it eventually traps water behind
it. The water backs up under shingles and finds its way
through seams in the building paper and roof decking to
enter the attic and living area.
plaster and paint surfaces may be damaged in the process.
Fortunately, there are several ways to remedy the problem.
cooler attic area will help decrease problems with ice dams.
are two ways to keep attics cool:
Make sure the attic floor is well insulated to minimize
the amount of heat rising through the attic from within
the house. Increase insulation in the attic floor to
at least 12 inches. Also, close any thermal shortcuts
– openings that allow air to move from the heated part
of the house into the attic. Chases around chimneys,
plumbing vents, junction boxes for ceiling light fixtures,
attic hatches and ceiling fan mounts are common thermal
Create adequate attic ventilation to remove any heat
that escapes into the attic. One square foot of free
ventilation opening is recommended for every 150 square
feet of attic space. Ventilation should be divided between
eaves and the house ridge to take advantage of the fact
warm air rises. When installing eave or soffit vents,
be sure the opening isn't blocked by insulation. You
can do that by installing a cardboard or plastic channel
over the insulation lined up with each vent.
If there is an immediate problem with ice dams, remove the
snow from the part of the roof directly above the ice dam.
This limits the amount of water that can collect behind
having the snow removed from your roof. If you must do it
yourself, use safety precautions. Remove the snow using
a roof rake, hoe or push broom. Roof rakes, available at
hardware stores, have long handles that allow you to stay
on the ground when clearing a single-story roof.
using sharp instruments, such as axes, to break channels
through the ice, which is likely to cause roof and structure
in case the snowy winter weather returns be sure to check
your roof for problems that may cause damage and unwanted
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