Roof Ice Dam Solutions

Roof Edge Ice Melting 

When roof top snow and ice over the heated area of a structure melts, liquid snow melt water drains to the
colder roof overhang drip edge. Since the overhang is not heated, this snow melt water re-freezes, creating
an ice dam. Providing a heated drain path is the objective. Three systems have been developed to provide
this heated drain path.



1) Zig-Zag Heating Cable

   

Zig-Zag heating cable is a common low cost solution

They provide a heated drain path, around the cable, through the ice dam for the ice melt water. Normally this water drains into a gutter & downspout that also has heating cable, providing a drainage path away from the structure’s foundation. This type of system only provides narrow heated drain paths through the ice dam. Between the Zig and the Zag large icicles can form causing structural damage. When these large icicles break off and fall, there is a danger to people and property below.

Using self-regulating heating cable, this type of system usually costs about $40 per foot of roof edge (installed), plus the cost of the heated gutter & downspout and electrical power feed.

Although constant current heating cable is available in most hardware stores, most professional installations use self-regulating heating cable that greatly reduces the energy consumption per foot when the cable is no longer in direct contact with ice and snow. After the drain path around the self-regulating heating cable has been cleared, the energy usage of the cable goes down. In this regard, the Zig-Zag System offers energy efficiency and has been used for many years.





2) Extruded Metal Panel System

 

Heating cables are placed inside a heavy Extruded Metal Panel

These panels are placed along the roof edge (left picture) or in the valleys (right picture) on new construction commercial buildings. Two or three runs of self-regulating heating cable are placed in the oval slots. These panels are effective in providing a continuous heated metal surface that completely clears the roof edge of snow and ice. The Extruded Metal Panel provides a wide heated surface area compared to the narrow channel of the Zig-Zag System. A roof edge ice dam never forms and the snow and ice from the upper roof continues to melt and the melt water drains over the heated drip edge into the heated gutter and downspout and away from the structure’s foundation.

Retro-fitting an existing roof usually requires removal of some of the roofing material. This type of system normally uses expensive control circuits and can cost over $100 per foot of roof edge (installed) plus the cost of the heated gutter & downspout and electrical power feed.

The Extruded Metal Panel acts as a high mass heat sink and draws heat away from the self-regulating heating cable. The cable responds by drawing more electrical energy (Watts) per foot until the internal temperature of the cable stabilizes. When the ice and snow melt water has drained away, the heavy mass of the extrusion continues to act like a heat sink and the self-regulating heating cable continues to draw large amounts of electrical energy.





3) Heated Sheet Metal Panel System

Before

After

The Sheet Metal Panel System is a new concept
This system was invented and tested in Aspen by Malcolm Nark

The light weight and low cost panels securely hold a single run of self-regulating heating cable designed and Safety Agency Listed for roof ice melting. Using much less heating cable than a Zig-Zag or Extruded Metal Panel system, the AspenSnowMelt System uses less energy.
Less Cable = Less Energy.
Placed along the roof edge or in the roof valleys, the panels have a similar result as the Extruded Metal Panel System. Unlike the narrow Zig-Zag System, the footprint of the Sheet Metal Panel System creates a wide heated drain path for the snow melt water.

In most cases retro-fitting to an existing roof is easy. The heated drip edge panel slides under the third shingle or under the metal roofing material. The U shaped valley panel is attached in the roof valleys. The light weight sheet metal uses less material and is easier to manufacture and install compared to the heavy Extruded Metal Panel product.

The Sheet Metal Panel System usually costs about $50 to $60 per foot of roof edge (installed) plus the cost of the heated gutter & downspout and electrical power feed.

The single run of heating cable at the roof edge conducts heat up and across the panel surface, providing a continuous heated melt path along the edge of the roof. The effective thermal mass of the panel is large when in direct contact with snow, ice or melt water. This causes the self-regulating heating cable to use larger amounts of electrical energy to stabilize its internal temperature.

After the snow, ice and melt water has drained away from the panel, the light weight panel’s effective mass decreases which reduces the electrical energy used by the self-regulating heating cable. Additional information on the Variable Thermal Mass concept can be found on the next page.

Like the Zig-Zag System, the Sheet Metal Panel System uses less wattage per foot of cable under a no snow load condition. However, the Sheet Metal Panel System uses much less cable than the up-down Zig-Zag System. The net result is a larger heating surface when required and lower energy usage under a no snow load condition. This is best solution for both conditions.




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