Eave protection is used to protect the eave and valley areas of water-shedding roofs from ice dam damage. An ice dam usually forms when the interior heat of the building warms the snow on the roof, causing it to melt and run down to the eaves. Normally, eaves extend past the exterior face of the building and are not heated from the inside. This allows the water to freeze and form an ice dam. As the ice dam grows, it forms a barrier that prevents water from draining off the edge of the eaves. The water backs up behind the dam and gradually forces its way under the primary roof covering (asphalt shingles, metal panels, cedar shakes or shingles, etc.), where it warms and melts (the result of heat leakage through discontinuities in the air barrier system). Liquid water then leaks through the roof deck and into the structure. The results can range from minor staining to severe water damage to the structural members.
Eave protection membranes are designed to prevent the water from reaching the deck and leaking into the structure. These materials are self-adhering and manufactured with a rubberized asphaltic compound, or with butyl. Properly formulated and installed, these sheets have the potential to perform a long time. Slope and climate conditions are considerations for selection; refer to the Standard for further information and guidance.
Underlayment is used in the field areas of the roof (where eave protection is not required) to provide a secondary protection beneath the roof covering, during weather events that might force water underneath. Refer to Part 8 in the Standard for slope limitations of nail-applied underlayments (not permitted on slopes less than 1:3 (4" in 12").
* Notice to Reader: Some of the materials listed for eave or valley protection must be installed in multiple layers because, by themselves, they are too thin to satisfy the material requirements published in the Standard for Asphalt Shingle Roof Systems. Consult the product manufacturer for appropriate application requirements, and the Standard for multiple layering requirements.
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Product Name
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Product Type
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Product Thickness
mm (mil) *
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Product Weight
Kg/m2 (lb / 1002ft)
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Application Method
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Eaves *
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Valleys *
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Under-
layment
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Asphalt Shingle Roof Systems
Application
