Fixing it could cost lots of money, but warding it off could save you not only those big bucks - but plenty of aggravation.
On "The Early Show," John DeSilvia, host of the DIY Network's "10 Grand in Your Hand", demonstrated ways homeowners can keep Old Man Winter at bay - at least as far as harming your house is concerned:
Snow damage to roofs
Let's start with how much snow weighs. A one inch layer of water or ice weighs approximately five pounds per square foot. Translated for snow, one foot of snow is going to equal five pounds per square foot. Wet and packed snow weighs more, so considering all these factors, your roof should only be able to hold up one-to-two feet of snow. Keep in mind that this weight puts stress on the roof over time, so you want to minimize the amount of time that all of this snow and ice spend up there.
What should a person do if they have too much snow on their roof?
The simple answer is to remove it as soon as possible. The safest way to remove snow from a roof is by using a roof rake. Remove the snow by carefully pulling it down the slope of the roof line. Never pull snow across the roof, or it may break off the shingles and cause other damage. You want to find rakes with telescopic poles so you don't have to get up on the roof to solve the problem.
These rakes have rollers, so the actual blade of the rake never messes with your shingles, because the key is to avoid damaging your roof.
PRODUCT: From Home Depot: Ames 17 ft. snow rake $40
Ice dams usually occur after a heavy snowfall and several days of freezing temperatures. Warm air inside your home leaks into the attic and will warm the underside of the roof, causing snow and ice on the roof to melt. The melted water will drain along the roof, under the snow, until it reaches the cold overhang. The overhang tends to be at the same temperature as the outdoors, and the melted water will refreeze and form an ice dam and icicles.
What can you do if you have an ice dam?
If you've already got an ice dam, we suggest carefully chipping away a channel through the middle of the ice dam so the water will be able to flow through; just make sure you stop when you get close to the roofing. It's not necessary to remove all the ice in the ice dam if you have removed the snow from the roof, because then the rest of it will melt when temperatures rise.
Even better than chipping is to use a product like Roof Melt that will melt the ice and snow in the dammed areas. These calcium chloride tablets melt the ice and make channels through the ice dam that enable the water behind the dam to drain off the roof.
How can you make sure this doesn't happen in the future?
Install De-Icing Cables. Controlled by a thermostat, de-icing cables make use of heating wires to stop any ice from forming between your shingles.
De-icing cables often come in a kit that includes the thermostat, control box, and hardware required to complete the installation of the entire system. Installing de-icing cables is an easy job, but should only be attempted when the roof is completely dry and free of snow. The cable should be installed over the unheated portion of your roof in a zigzag pattern. This is normally the lower three feet of your roof right above the overhang.
In addition, you will want to add the cables near your rain gutters and drain spouts. To determine how much cable you will need, the formula is basically one foot of cable for every foot of roof edge. Check your local home improvement store for a kit that is appropriately sized for your particular home size and needs.
PRODUCTS: Roof Melt tablets from RoofMelt.com ($25)
ADKS Kit from HeatersPlus.com that includes the Electric Roof De-icing Cable (Residential Grade, 120 Volt, 5 Watts/foot) and six foot power cord with plug and enough roof clips and cable spacers to complete the installation.