CAUSES OF ICE DAMS

Ice Dams can form on any roof structure that is exposed to freeze and thawing temperatures. It is understandable that most cannot recognize an ice dam. After all, it looks like a harmless wall of innocent ice on roof edges. Most believe they are a result of heat escaping a heated structure only. Others believe that ice dams are a result of ambient temperature changes. Actually, both can contribute to the birth and development of a problematic ice dam.

Ice dams f­­­orm as a result of snow melt water rolling down a roof and refreezing at the roof edge.   The key question is what causes snow melt water in the first place?

Snowfall lands on a roof. If temperatures are low enough snow will just sit on a roof deck. The snow on a roof just lies uninterrupted until one of two things occurs; (1) heat escapes from a structure, or (2) the outside temperatures rise above freezing. Either will begin the process of melting snow on a roof turning it into snowmelt water.   Once snow melt water, it trickles down a roof until it reaches the roof edge. Have you ever watched carefully water droplets hanging on the roof edge? The edge is typically the region on the roof where there is no snow! Here the snow melt water is now exposed to ambient air temperatures. And that brief time the water hangs on the roof edge exposed is enough time for snow melt water to re-freeze to the roof edge before it has the chance to drop off. Once frozen to the roof edge, an ice dam is born!   Now snow melt water rolling down the roof is intercepted by a small bump of ice on the roof edge. This bump is enough interference to slow snow melt water flow giving it enough time to freeze. This cycle continues until a wall of ice is large enough that it can pool snow melt water; an ice dam.   I think we all understand that water always seeks a path of least resistance. Unfortunately, that path can be or eventually will be beneath or in between shingles, between seams, punctures or holes created by manual snow removal methods, roof clips that are used to secure heat cable, etc.

Another common location on a roof structure where ice dams form is in roof valleys. Here two walls of migrating snow pack collide and inevitable compaction is at a level where glacial type level of ice develops and obstructs snowmelt water from flowing down the center of a roof valley as it should.

CURES

This section investigates all the PRO and CONS of each known concept for controlling or eliminating ice dams. Both temporary fixes and permanent solutions. The objective is to provide you sufficient unbiased and objective information to aid you in your decision-making process and arrive at your own conclusions.

IMMEDIATE & TEMPORARY SOLUTIONS

1. Calcium Chloride Socks

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2. Manual Methods Using Shovels and/or Piks

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3. Roof Rakes

Something to keep in mind; each inch of snow has an R-value of approximately 0.5 – 1. By removing snow pack, you are essentially making the problem worse. Before the snow pack was removed with a rake, it was acting as an insulator and allowing snow melt water to roll down the roof to the roof edge. Without a blanket of snow pack, snow melt water is exposed to ambient temperatures and can refreeze higher up from roof edge. Whenever snow melt water is exposed to ambient air, it can re-freeze, hence, it is always best to leave snowpack or the blanket of insulator on the roof deck.

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4. Services Using Shovels and/or Ice Piks

Something to keep in mind; each inch of snow has an R-value of approximately 0.5 – 1. By removing snow pack, you are essentially making the problem worse. Before the snow pack was removed with a shovel, it was acting as an insulator and allowing snow melt water to roll down the roof to the roof edge. Without a blanket of snow pack, snow melt water is exposed to ambient temperatures and can refreeze higher up from roof edge. Whenever snow melt water is exposed to ambient air, it can re-freeze, hence, it is always best to leave snowpack or the blanket of insulator on the roof deck to allow snow melt water to reach the roof edge. In addition, this manual method is flawed. Imagine for a moment the task of being on a slippery roof deck and piking ice. Do you think you have control over how deep the pik travels through the ice? The answer is no, hence, the likelihood is high that you will be left with holes or puncture wounds in your roof deck which can go undetected until a leak develops. By the time you realize a leak has developed, it is typically too late and the result can be hazardous mold and structural rot. Of course, roofing companies are typically the companies performing these snow removal services throughout the winter season since it is a slow period for their core business;   installing new roofs! Now they have just created a new customer for a new roof!

PERMANENT SOLUTIONS

5. Insulating the Attic

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6. Constructing a Cold Roof

It has been said that few companies in the construction industry understand how to construct a proper functioning “cold roof”. It is a lost art. Conceptually, it sounds great and it is, however, the expense required and knowledge to construct a cold roof properly make the odds of this being a realistic remedy is low.

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*Not able to control ambient temperature changes.

7. Increase Attic Circulation by Adding Roof Vents

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*Not able to control ambient temperature changes.

8. Laying Heat Cables on a Roof Edge in a ZIG ZAG Pattern

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9. Installing Heat Panels on Roof Edges and in Roof Valleys

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10. Installing Aluminum Metal Tracks on Roof Edges and in Roof Valleys

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11. Hydronic Systems

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