The answer to 'underlayment or underlayment' is that they are the same thing. Underlayment, also known as roofing felt or tar paper, is a critical component of a roof system that provides an additional layer of protection between the roof deck and the outer roofing material. Underlayment helps prevent water damage, provides a smooth surface for the roofing, and improves fire resistance.
Underlayment comes in various types, including asphalt-based, synthetic, and rubberized options. The choice of underlayment depends on the type of roofing material, the climate, and the specific needs of the home. Proper installation of underlayment is crucial to ensure the long-term performance and integrity of the roof.