Ice damming is an insidious phenomenon, and many homeowners aren't even aware of its presence until it is too late. However, ice dams form as a result of a straightforward process that occurs with complete predictability:
1. The roof
is warmed due to interior heat passing upward from the attic. This elevates temperatures on most of the roof above freezing,except for the overhanging eaves which are exposed to cold air on both their top and bottom sides.
2. Snow melts as it strikes the warmed roof and generates a steady trickle of water that runs toward the eaves.
3. As the water approaches the colder eaves, its temperature falls and causes the water to refreeze into solid ice.
4. The ice builds a barrier that traps melting snow, and the pooling water is pushed back under the edges of shingles.
Once the water finds its way beneath shingles, it's only a matter of time before it begins to cause destruction to the roof sheathing and enters the home. The unrestricted flow of water will cause wood rot of the rafters, studs, and other components, and it will also generate conditions ideal for the growth of mold.
In addition, the moisture will also damage drywall and even flooring as it works its way downward. In short, significant areas of your home, from top to bottom, can be affected negatively by ice damming.
Since the causal factor in ice damming is the loss of heat through the roof, the key to prevention is cooling the attic space. This will keep temperatures consistently below freezing from rooftop down to the leaves. Keeping the attic cold can be accomplished by implementing one or both of the following:
- Additional insulation over interior areas. If your attic floor isn't insulated or has insufficient insulation, then adding insulation will keep attic temperatures cooler and also help lower your heating bill. Loose Insulation can be blown in by a contractor, or it can be installed in rolls, depending on your preference.
- Increased circulation in the attic. Good attic ventilation allows cold air to flow up through the soffits under the leaves, along the under side of the roof sheathing and out of the vents at top. If your roof is missing vents, or has inadequate ventilation features, then this is a must to install or fix.
If you are the middle of winter, and ice is forming dams on your roof as you read this, you will need to address the issue immediately to prevent or lessen damage. Here are few things you can do temporarily until you have the opportunity to permanently address ice damming:
- Scrape snow from your roof. It is a lot of work, but if you are able to remove the snow as it accumulates on your roof, then it will prevent damming. However, be sure to remove excess snow from ground level using long rakes. Also, never climb on a slippery, snow-laden roof,or you may suffer a nasty fall.
- Place heat tape. Heat tape consists of cables that heat up with an electrical current, thus heating up to a level sufficient to melt ice. If you are able to safely access the eaves of your roof by ladder, then you can place heat tape across the bottom few rows of shingles in a zigzag pattern. This will keep the roof surface melted enough to prevent ice from forming.
If you need help keeping your roof free of ice and preventing damage from ice damming, then contact a qualified roofing installation and repairspecialist to help. They can provide you with guidance and perform the necessary repairs.