Outdoor House Maintenance

Dam! Ice dam, that is...

There’s only one thing to say if you look up at your roof this winter and ice is blocking the orderly flow of water to the gutters and downspouts.

Dam. Ice dam.

This is a situation you don’t want to ignore. Water takes the easiest way down from any elevation. On your roof, that means if it can’t get to the ground via the gutters and downspouts, water will pool and eventually leak into your house.

Roof damage is the more minimal problem. The real issue is wondering if the water leaked into your house from the roof, and if so, where. Water can seep between and crack walls, soak into the insulation in your attic and ruin ceilings, or even travel from the point of entry to the opposite side of the house, depending on gravity and how level your home is.

“We’ve had people come in and tell us water is dripping, or pouring, through ceiling light fixtures,” Mike Frentz says.

There are two basic ways to stop ice dams from forming.

* A roof snow rake is the simplest, most straight-forward way to get the snow off your roof before it freezes. Mike says this solution works well if you own a bungalow, because from the ground, you’ll need to hold the rake at close to the same angle as the roof in order to pull off large amounts of snow.

For two-story homes such as colonials, handle extensions for the rake are available in 5-foot segments. Though your reach onto the roof might not be as great, you can still clear the edges near the gutters -- one of the two places ice dams form.

“The key here is getting out there during or right after the snow is falling, before things start to freeze,” Mike says.

The Roof Snow Rake, comes with a 16-foot handle and a 7-by-24-inch-blade, both made of aluminum. It’s easy to assemble, light, and the blade sits at an angle to the handle to improve your reach.

This is one of the new generation of snow rakes – it has rollers on the edges of the blade. Those little wheels, rather than the blade itself, are what come into contact with your roof. That means the blade rolls over, rather tears off, shingles.

* If snow rakes aren’t your style, then Wrap-On Roof and Gutter Cables are the way to go.

These, basically, are heavily insulated electrical cables you string horizontally along your roof, in a zig-zag pattern, just above the gutters.

Ice dams form because your entire roof is not heated. Heated air moves to the highest point it can, which is at the peak of your house.

That means snow and ice starts to melt there. But as gravity takes over and melted snow starts to run off your roof, it cools because it’s moving away from the heat source. Since your gutters edge your roof, they are furthest from the heat source, and the water freezes rather than continuing through the gutters and downspouts.

Mike says the other most common place for an ice dam to form is in a valley on the roof. This is where two sections of your roof meet – for instance, the place where the roofing on a dormer meets the rest of the house.

“Getting this cabling up now, before bad weather sets in, is the most important thing. You can’t install this cable properly when snow and ice are already on the roof,” Mike says.

Installing the cable will take a little pre-planning, because no matter how long the cable is, using an extension cord is not recommended. The way to do it is plan backward – think the installation through from the outlet, rather than just starting on one area of the roof and worrying about plugging it in later.

Mike says the installation isn’t just a safety issue. It’s also a matter of economics – you’ll want the plug within easy reach. These cables really work, and do so by drawing a large amount of electricity. For example, a 40-foot cable draws 200 watts of power.

So once installed, you only want to plug the cable in when you need it, when the snow is falling on your roof or when the conditions are right for the snow to melt on the higher sections of your roof. That occurs during the day when the temps are in the teens to the mid 20's. It’s not something to plug in and leave on all the time.

“Some people have been upset because they’ve installed the cable, plugged it in, and gone to Florida for three or four months,” Mike says. “When that happens, they’ve come home to a $700 or $800 electric bill. But if you just plug it in when you need it, it’s not at all expensive to operate.”

Take a look at the diagram, which comes from the instructions for the type of roof and gutter cable available at Frentz. It shows the insulated end of the cable at the end of the downspout and then goes up and down across the roof. The cable attaches to the shingles with aluminum clips.

To handle a roof valley, just run the cable up one side of the valley, down the other, and then keep moving across the roof.

Mike says the average home is about 25 feet across. There are quick formulas on the cable boxes to help you calculate the length of a cable you’ll need. He says their store stocks the cable all year, and not only is it best to install it before a storm, but after the first storm, and all the television new stories that go with it, these cables become a real sought after item.