Ice damming, Part 2 - snow removal and heat tape
In Part 1 of our look at ice damming and what to do about it, you saw how an ice dam forms. As I mentioned, an ice dam needs three things in order to develop; cold temperatures, a thick snow layer, and heat loss from the house. If you can control any of those three things, and you can prevent the ice dam.
I also mentioned that you can't control the outside temperature, so the second two elements are the only things you can have an impact on. We already talked about the importance of insulation and ventilation, so can you do anything to be proactive about preventing that snow layer from building up in the first place?
Clean gutters
You can start in the fall with cleaning out the gutters. Keeping gutters and downspouts free of leaves and pine needles should already be an essential part of your fall chores, and it's also an important part of preventing ice buildups.
If you have guards designed to catch the leaves and needles and keep them from getting into the gutters, those can also be a problem when it comes to ice buildup. Those barriers can create a number of small crevices that trap ice and snow, making it difficult to keep them clear and for the water to run through them freely during the winter. If you live in a cold climate, any type of leaf barrier on your gutters is probably not a great idea.
Snow removal
First of all, assuming a normal seasonal snowfall and assuming your home is designed to handle the weight of it
you don't need to remove the snow from the entire roof. What you're looking to do is remove snow from the eaves – that part of the house where the melting water that runs down under the snow later could potentially freeze. In most houses, that means clearing the lower 3 to 4 feet.
One good way to do this is with a snow rake. A snow rake is an angled metal blade with a couple of rollers on the bottom, attached to a handle. Additional handle sections can be added as needed, depending on how much length is required. The rakes are typically made out of light-weight aluminum, to make them easier to lift and maneuver.
To use, simply attach the number of handle sections needed to easily reach up onto the roof, then use the rake to pull the accumulated snow off. It's best to do this when the snow has not built up too much, and as soon as possible after it's fallen, before it's had a chance to harden. They're very easy to use, but there are lots of on-line videos that demonstrate the use of snow rake if you'd like a little additional coaching.
If all that seems like a bit too much effort, consider hiring a professional to remove snow for you. Compared to the potential damage that an ice dam can do, the small cost of occasional snow removal is well worth the investment. Be sure whoever you hire is properly licensed and insured as required in your area.
Heat tape, and why it’s not a great idea
Another option is heat tape, or heat cable, which is used to keep the eaves free of snow and ice. It's simply an electrically-heated cable that's attached to the lower portion of the roof, typically in a zigzag pattern, and is controlled by a thermostat to come on at a certain temperature.
There are several reasons why I'm not a fan of heat tape. For one thing, there's the initial cost of all that cable, and the cost to operate it. Heat cable uses about 5 watts of electricity per foot, so a 100 foot cable is the same as having five 100-watt light bulbs burning. A typical house can require several hundred feet of heat cable on the roof, so that's a lot of additional utility bills. If the thermostats don't operate correctly, or if you forget to unplug them, they can end up operating all year round, and that's a real waste of money!
In areas that have a lot of snow, there's evidence that the snow buildup is simply too great around the cables to make them very effective. Re-freezing can occur a short distance away from the cables, and the ice dams occur anyway.
Then there's the potential for fire danger. I personally have seen several roof fires over the years that have been started by heat cables on the roof that have malfunctioned, that have been damaged somehow, or that have simply worn out, particularly on shake roofs.
If you do want to use heat tape, I would limit it to your gutters and downspouts. Be sure it's GFCI protected and UL-approved, and that you disconnect it whenever it's not needed.