Posts Tagged ‘preventing ice dams’

Ice Dams and Chainsaws or You May be Right, They May be Crazy….

January 29, 2013

Don’t try this at home!  Chain saws and snow blowers don’t belong on roofs, and I would suggest you don’t either, especially in the winter. These guys are clearly…ahem, professionals.

One obvious down side would be landing in your living room snow blower and all.  Preventative maintenance is the way to go.  What does that mean? Start with some tips in our fact sheet on ice dams. You could also check out past articles such as this one in the Wall Street Journal .  It’s that season again so be safe and be smart,  take steps this year, with a home energy assessment and make sure you air seal and insulate right to avoid the problem in the future.

Thanks,

Jason

Roof killers—icicles and ice damming

November 18, 2009

I touched on insulation and air-sealing in a few recent posts. And as happens in the winter, we’ve noticed a big increase in the last few weeks on people asking about icicles and ice damming. It’s probably time for a quick refresh and retread of an earlier post.

What is Ice Damming?
Big icicles and ice dams are typically caused by poor or missing insulation and air leakage from your house into your attic.  In the winter, this warms the roof and causes the snow to melt. The melting snow then moves down the roof slope until it reaches the cold overhang, where it refreezes.

The process forms icicles and can actually create a dam that eventually forces the water to back up under the shingles and sometimes into the ceiling or wall inside the home. In addition to roof and water damage, ice dams can cause structural decay and mold and mildew to form in attics and on wall surfaces. 

Big icicles are a good sign of too much heat loss through your attic.

Big icicles themselves, like those shown here, are obvious signs that you’re at risk.

But snow melt patterns can also indicate a problem of too much heat loss. In this photo below, you can see snow melting off the roof at different rates, driven by heat loss from the house. 

roof snow melt patterns

Uneven snow melt also is a sign that something is awry

And in the townhouse complex below you can see the building that GreenHomes treated with even snow still on the roof—a sign the building isn’t losing energy rapidly. Conversely, you see the untreated building with the snow melted–a sign that it’s losing a lot of energy. No big icicles this time—but had it been a bit colder, the melting snow would have refrozen at the eaves and created big problems.
treated townhouse retains heat
The townhome treated by GreenHomes loses heat more slowly through the attic and thus snow melts slowly and doesn’t accumulate as ice out at the eaves.
 

  

a leaky and poorly insulation town home attic melts snow quicly

This town home has not been treated and the wasted heat melts snow quickly. In the right temperatures, the melted snow would refreeze and create ice problems--bad news. And in any event, this folks in this building are spending a lot more on energy than they should.

The Fix
Fortunately, you can dramatically reduce damage from ice damming by sealing the holes connecting your heated living space and the attic, as well as properly insulating your attic. There are different techniques to stop air leaking through recessed lights, leaky heating ducts, attic access doors, and plumbing and electrical penetrations. Sealing these leaks keeps warm air in your house were it belongs. Together, with adequate levels of insulation, this greatly reduces the chance of ice damming and large icicles.  You do NOT just want to add more insulation before sealing the air leaks—this can actually create additional problems that can also damage your roof. 

It’s important to not that you can’t eliminate icicles completely.  Small icicles are normal.  And some roof architecture–especially big valleys draining to a small corner–are especially challenging.  But if you have long icicles or thick heavy ice you should act quickly to prevent damage.  (And this means preventing the ice from forming in the first place, not risk life, limb, and your roof trying to chip off ice that’s there.)
 
 Do it right.  Find the important leakage points and seal them up.  Then add a lot of insulation.  And afterwards, as with any time you change the way your house works, have your combustion appliances tested to make sure they’re operating safely and efficiently.

An added benefit to this, of course, is you’ll save energy, save money, and be more comfortable in your home, too!

Save the ice for your holiday cocktails!

[Update, see more roof melt and icicle photos.]

Thanks,
Mike

P.S.  The added insulation can qualify for the $1,500 federal credit.  Save money while you save you roof!

DAMNED TOUGH DAMS TO FIX.

February 24, 2009

Jay Romano wrote a great column in his New York Times home improvement series, “The Fix” last week addressing ice dam solutions. I think it only goes half way, though, since the article offers roof shoveling and heat tape as partial solutions. The truth is, only with a well-sealed and well-insulated attic can you reliably and permanently control the expensive damage wrought by ice dams and avoid unnecessarily high utility bills.

Here’s the thing about raking snow—it’s only potentially effective if you decide that you have an ice-damming problem the day of a big snowstorm.  You can do it yourself by buying a snow rake, or hire someone to do it for you each time you get a snowfall. But do you really want to add shoveling the roof to your existing shoveling chores, or add to your current snow removal bills? And just shoveling the snow off the first two or three feet of the roof isn’t going to do it: the show further up the roof can melt down and create dams.

Ditto with heat tape, which not only costs $300-600 according to Mr. Romano, but must then be installed and can be very expensive to run.  (Set an electric heater outside and then tell me about your electric bill!)  Electric heat tape requires fasteners, which penetrate the shingles to hold it in place, and can damage shingles.  And unfortunately, many people let heat tape run even when not needed – when there is no snow on the roof (or, yikes, all summer long!), for example – causing even higher bills.

The rigid foam method Tom Silva recommends, in which the attic is insulated all the way up to the peak, between the rafters, can work—but air sealing along with it is critical, and probably beyond what most homeowners can tackle solo. For twice the price of the materials, which are expensive in and of themselves, a homeowner could have closed cell polyurethane insulation installed (that is, with all labor included) to an equivalent depth, which will do the trick. But many homeowners don’t use the attic as living space. If you rarely venture up there, you can insulate just as well, if not better, for a fraction of the cost.  A well-sealed and well-insulated flat attic, with good attic ventilation—of the kind we do every day—will outperform Mr. Silva’s approach. (Again—it depends on whether and how you’re using the attic—mine is conditioned living space so the flat attic treatment was out.)

Now, go outside, and take that heat tape off!  (And then call someone to insulate and air-seal your attic!)
 
Stay warm,
Mike


%d bloggers like this: