Ice and Water Barrier and Underlayment both are used to prevent water leaking through a roof but they are not the same material.
Ice and water barrier is different from underlayment, although they are both components used in roofing systems.
Underlayment is a layer of material that is installed on top of the roof deck and beneath the roofing material (it is installed before the shingles or roofing material). Its primary function is to provide an additional layer of protection against water infiltration, as well as to provide a smooth surface for the roofing material to be installed on. Common types of underlayment include felt paper, synthetic underlayment, and rubberized asphalt.
Ice and water barrier, on the other hand, is a self-adhesive, waterproofing membrane that is typically used in areas of the roof that are prone to water infiltration, such as eaves and valleys, as well as around roof penetrations such as chimneys and skylights. Its primary purpose is to prevent water from entering the roof system in the event of ice damming or wind-driven rain. Ice and water barrier is typically installed on top of the underlayment and is a more robust and specialized type of waterproofing membrane than standard underlayment.
While both underlayment and ice and water barrier provide additional layers of protection against water infiltration, they serve different purposes and are used in different areas of the roof. It’s important to follow the manufacturer’s recommendations for both underlayment and ice and water barrier to ensure that your roof system provides adequate protection against the elements.
