I want to second the comment by Peter that it is worthwhile to get at the
underlying cause, not just the ice dam itself. Ice dams are usually caused by
air leaks, not just lack of insulation. What happens is that warm, moist air
leaks up into the attic and melts the snow on the roof, which then freezes
where that part of the roof goes beyond the house's walls. This makes an ice
dam. The next round of water melts into the dam but can't drain off, so it
works its way under the shingles and into your house. MAJOR damage occurs.
If you have a small ice dam, you can fill some old panty-hose with salt and
toss the stockings on the roof, so it makes a more downward channel for the
melting water to flow to the roof's edge. You can use those little electric
coils, except they use bunches of electricity. You can hire a contractor to
remove them.
It is NOT recommend to start climbing ladders with a hatchet. The darn things
are sharp and hurt like hell when you fall on them, even if the fall doesn't
kill you. And they are bad for the house when you chop a hole in your roof,
which is surprisingly common.
Roof rakes can help remove some of the extra snow and lessen the problem, but
they are also prime causes for holes in roof and premature roof replacement.
So also not recommended.
And you haven't solved the problem, merely treated the symptom.
What you need is a blower-door energy audit. A trained and state-licensed
specialist will come out with a huge fan and put it in your door. When it is
turned on, the special fan will blow some air out of the house, and give a
number that tells how bad your house is leaking. Then the energy auditor will
scurry around finding the small breezes from the outside, which are the leaks.
The auditor can then sit down with you and tell you which leaks should be fixed
first and which ones you might be able to easily do yourself with a bit of
caulk.
The whole thing takes about two and a half-hours, costs $60 on your Xcel bill
(yes, it is heavily subsidized) and will actually help you solve the problem.
It won't hurt your house a bit, although you should clean out your wood-burning
fireplace to make sure you don't blow ashes around the living room.
My wife, Mary Ann Crolley, does these through Xcel. Peter is quite correct
that CEE also does them; I don't know all the details of the CEE program, so I
will let you contact them directly if you wish.
I highly recommend my wife (which I would do, even if I did not know her
personally) since she is thorough and a natural teacher who loves houses. You
can call her at 612-722-1545 to get an appointment scheduled. Or if you prefer
someone else through Xcel, she would still be happy to answer your questions
and tell you how the program works.