The answer to 'what is underlayment' is underlayment is a protective layer installed between the roof deck and the roof covering (such as shingles or tiles). It serves as a secondary barrier against water intrusion, providing an extra layer of protection for the home. Underlayment is typically made of asphalt-saturated felt paper, synthetic materials, or rubberized asphalt and is an essential component of a properly installed roof system.
Underlayment helps prevent leaks by creating a waterproof barrier, even if the primary roof covering becomes damaged or fails. It also helps to regulate the temperature under the roof, reducing the risk of ice dams and other weather-related issues. Proper installation of underlayment is crucial to the long-term performance and durability of a roof.