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Mitigation
Ice dams on sloped roofs can be mitigated in several ways:
Assuring sufficient insulation in the roof to prevent freezing at the roof surface under a deep snow pack.
Providing ventilation under the roofing material that carries escaping building heat elsewhere and assures a cold roof surface. Attic/roof temperatures can be controlled by installing sufficient insulation and providing natural or mechanical ventilation to produce a "cold roof" to keep the roof temperature below 30 °F (−1 °C).
Providing  heat tape or cables that create channels for meltwater to escape through any ice dam at the eaves. Heat tapes incur energy expense, may cause long-term damage to asphalt shingles, and may present a risk of fire. Some insurance companies do not allow the use of heat tapes due to the fire danger. Ice dams can also form just above the heat tape.
Constructing a roof with a slippery surface that is steep enough for snow to slide off, before it can melt. An ice belt—a band of metal roofing—installed at the eaves helps prevent the formation of ices dams by placing a low-friction surface where ice dams are likely to form.  If an ice dam does form, the ice belt may reduce the penetration of standing water. Metal roofs with adequate roof pitch and minimal valleys are effective at shedding snow.
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