On Feb 4, 8:18*pm, Paul Franklin
wrote:
On Thu, 3 Feb 2011 20:04:33 -0800 (PST), Pauli G
wrote:

We presently have substantial ice dams on a roof that was done about a
year and a half ago (complete rip-off of old shingles down to plywood,
installed 30-year GAF architectural shingles). * Our contractor, a
really reputable firm in my area, installed the ice & water shield
under the shingles along the edges of the roof. * Long story short, we
are getting water intrusion into the house now from melting ice/
snow. * *Isn't the ice & water shield supposed to be a foolproof way
of protecting against this, or is it only a half-measure? * *Also,
what are my alternatives right now? * Just let it melt off? *Or should
I get it shoveled, and if I do so, will this damage my semi-new roof?

Two ways to remove them that I know work.

1. *Get the roof heating cables. *Get a bunch of pine 1 by 4s. *Space
the 1x4s about 2-3 feet apart. *Run the heat cables in from one to the
in a series of loops about 2 feet apart; fasten with romex or coax
clips. *Put the whole mess up on your roof with one row of 1x4s up on
the roof above the ice dam, the other just over the edge so it pulls
the loops of heating cable down against the ice dam. Plug it in and
give it a few days to melt slots into the ice dam which will allow the
trapped water to flow out. *Effective, but slow. *Works best if you do
it a couple days before the roof starts to leak. *:-)

2. *Hire a professional that will use a steam generator feeding a
wand. * They will use the wand to cut the ice dam into chunks which
can be tossed off the roof. *If done properly, it won't damage your
roof or gutters.

As far as the cause of ice dams, the basic mechanism is that the low
part of your roof is coldest, especially if you have overhangs. *The
high part of the roof is warmest, because 1. any heat in the attic
will rise to the highest part, and 2, often that where the most solar
heating happens. *When the high part of the roof is above freezing,
the snow there will start to melt. *The water will run down, under the
snow, until it gets to the cold part of the roof where the temp is
below freezing. *It freezes there and starts to build the dam. *This
repeats each day/night cycle.

Poor insulation, poor ventilation, or heat leaks into the attic
increase the likelihood of this happening, but it can happen with a
well insulated attic with no air leaks and proper ventilation *when
the outside temp is only a little below freezing and there is solar
gain to the high part of the roof.

One way to minimize the process, before the dams form, is to rake the
snow off the roof, but you have to rake the top. *Many folks try to
stop it by raking just along the bottom, but that often makes it worse
because the bottom get colder faster without the insulating snow, and
you haven't removed the source of the water, which is the melting snow
higher up.

Once it starts leaking, option 2 is your best bet, if you can find
someone in your area that has the proper equipment and knows how to
use it. *Do not hire anyone that plans to chip the snow and ice off;
this will damage your roof and gutters for sure.

HTH,

Paul F.

"2. Hire a professional that will use a steam generator feeding a
wand."

I had ice dams and leakage into the house real bad one year. (I've
since solved the problems with Ice Melt cables)

My friend owned a carpet cleaning company and had a truck with the
water heater and hoses, etc.

Business was slow during the winter and he wanted to make some extra
cash, so we agreed that I would take pictures and videos in exchange
for him clearing the ice dams with hot water and high pressure nozzles
on the ends of the hoses from his truck. He was going to make a
commercial and print brochures and hire a few guys to help him.

I'll say 2 things about the experience:

1 - It worked. He cut the jams into 1' - 2' sections and then undercut
them to get them to fall off the roof. The leaks stopped.

2 - He never did it again. It took so long that there was no way he
could charge enough to make it worth his time. By the time we were
done, everything - including us - was covered in ice. Walking was
extremely hazardous, climbing ladders was next to impossible and our
hands were numb.

He went on to become a home inspector and never looked back.