5 Ice Dam Myths

The Truth About Ice Dams

Everyone seems to have their own ideas and theories about ice dams. With so much misinformation floating around, it’s important to clear the air and settle a few debates. Here are five ice dam myths that every homeowner should know:

1. Ventilated Roofs Prevent Ice Dams and Icicles

Homeowners falsely believe that a ventilated roof can prevent ice dams. While ventilation is certainly beneficial for a home, there are several things that need to be taken into consideration in order to successfully prevent ice dams, such as the roof layout, air leaks, slop, the size of the airway passages and true insulation values.

Even when these factors are carefully calculated and added into the equation, ice dams may still form. It doesn’t matter how well the ventilation system is designed – just a few inches of snow can impede ventilation.

2. The Roof Must Be Heated Several Feet above the Eave Edge

Here’s what happens when ice dams are left unabated:

Meltwater exits the snow at the drip edge.
The water starts building up to the wall line, and creates a standing water condition.
The interior leaks.

The common belief is that the roof must be heated several feet above the eave edge to prevent ice dams, but this is simply not true. The goal instead should be to stop the ice dam from forming at the eave, and that will prevent the dam from proliferating up the entire roof.

3. Metal Edging Prevents Ice Dams

Many homeowners have metal edging installed along roof eaves as a way to prevent ice dams, but more often than not, this edging causes other property damage and leaks.

Here’s the issue:

Ice dams break and fall off the roof.
A new ice dam forms at or above the wall line.

Leaks can become an issue when this occurs, and it also damages the transition between composite shingles and the metal edging.

Ultimately, metal edging can do more harm than good and will not necessarily prevent damaging ice dams from forming.

4. Shoveling Snow from the Roof’s Eave Edges Eliminates Ice Dams

Unfortunately, all shoveling will do is put your roof – and you – in danger. Not only is there the danger of falling, but there’s also a danger of damaging your roof and/or eaves in the process.

Shoveling is just a temporary fix. Unless it’s an emergency situation where structural damage is a very real possibility, it is not practical to shovel your roof. Use it as a last-ditch effort. Otherwise, you might find yourself doing it all over again the next weekend.

6. Zig Zag Heat Tape Prevents Ice Dams

At best, zig zag heat tapes create a tiny pathway for the water to pass through. Heat tape is easily overwhelmed by large amounts of snow, and is really only useful in areas that receive minimal snowfall each year.

Zig zag heat tapes are often installed improperly, leaving parts of the roof exposed and vulnerable to ice damage. They also tend to collect pine needles and other debris that can create a fire hazard.