Monday, March 05, 2007

(Damn) Ice Dam

Last week we received more snow. It's probably reached a depth of about 2 feet in my yard. Nothing too exciting, except all of the snow piled up on the roof and the warm March sun have started to cause ice dam problems on many of the houses.

My house is no exception. I have a worrisome ice dam on the left side of my front entry overhang. This spot has a long history of serious ice dams, and I can see clues of plaster repair on the inside wall of the house where water must have once worked it's way into the wall cavity.

The ice dams are caused when warm air from the living area of the house escapes up into the unheated attic area. When the warm air starts to warm the underside of the roof, it causes the snow to start to melt....and then get the picture. As the water melts & refreezes, it can work its way under the shingles & roof sheathing and into the insulation and ultimately into the walls & ceiling of the house. The first clue are those pretty icicles that innocently start to form at the overhang.

I've worked really hard over the past 4 years in weather proofing my house. And have pretty much eliminated the ice from forming. But, I knew this spot was going to be a problem for me this year if it snowed. I've been removing aluminum from around the house. The front overhang had this funky metal drip edge that had been clipped every few inches, so they could "fit" it around the curve. There is a huge gap that I am sure is leaking warm air. Nothing I can do until I'm able to call a roofer to redo that whole section of roof in the Spring......except periodically knock down the icicles and remove some of the snow. The weather is pretty warm so it should melt pretty fast.

You actually can tell a lot about your roof after a big snow. If I walk around the block, I can see houses where the snow is almost entirely melted off of their roof. This means that a lot of hot air is escaping through their roof and they are significantly under insulated. They essentially are heating their house & about 6" above it. Icicles & ice dams point out specific spots where more insulation or expanding foam should be used to block bypasses. Small footprints, means you might have a raccoon living in your chimney ;-)

My roof will start to develop lines in the snow soon that show where insulation was put between the studs and where drywall was attached directly to the studs (to keep headroom). I have hot air escaping through those studs. The rest of my roof holds on to the snow pretty well, so I'm generally happy.

Last night, one of the tv news stations covered a story about a guy who ended up in the ER after a 40 pound icicle fell on his head when he was knocking down ice from his roof with a broom. He had a pretty nasty gash on his forehead. Only in Minnesota :-)


Mike said...


Would running some heater tape help? Have you seen the stuff that is made to lay in the gutter and then plug in to warm up the gutter and keep water flowing down the drainspout? I would think if you plugged it in at night and unplugged in the day it might help. I can't tell from the pic if there is a gutter under there!

I obsess over a spot in my roof (above the bathroom) where it seems the snow melts faster yet is also the SW corner so it gets more sun. Knowing that I still go out every morning to look!

StuccoHouse said...

Mike - I'm sure the heater tape or that chemical tube would work. But, I've entered that "Spring is coming and I will not face any more winter problems" stage. In short, I'm in denial and will remain there until next fall.

I had to laugh at your obsession comment, because this overhang (and it's ice issues) has become one for me. My routine, step out of front door, make sure I have my keys, shut door, go down steps, stand and stare up at overhang/ice. I'm sure the neighborhood thinks I have some form of OCD (which I might..haha).

What you see there is not a gutter but a very poorly installed drip edge. At this point, after removing the aluminum, it stands about an 1" or so above the actualy membrane roof leaving a gap into the overhang. In an odd way, this has actually helped me because the icicles are hanging off of the drip edge and are being held up & away from the actually roof. Although, some bats have discovered this hole....and that's a whole other topic.

Come Spring, I need to figure out how to fix this.

Nadja and Sean said...

Yep, the snow told us a lot about our roof. We are, unfortunately, one of those homes that is heating about 6" of our outside the roof in some places. We know what we need to do before next winter... insulate, insulate, insulate....

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