Underlayments refer to a layer of material that is installed between the roof deck and the final roofing material, such as shingles or tiles. The underlayment serves as an additional layer of protection for the roof, providing a barrier against water and other types of damage that can occur over time. Underlayments are typically made from a variety of materials, such as asphalt-saturated felt, synthetic materials, or rubberized asphalt. They can be installed in different configurations, depending on the type of roofing material and the climate in which the building is located. The primary function of underlayments is to prevent water from infiltrating the roof system and causing damage to the building structure. They also provide an additional layer of insulation and can help to improve the energy efficiency of the building. Underlayments are an essential component of many roofing systems, and their proper installation and maintenance can help to ensure the continued performance and longevity of the roof.