1.1 This specification covers (1) inorganic fiber-reinforced organic felt underlayment and (2) inorganic fiber-based felt for use as underlayment with steep-slope roofing products. The intent of this specification is to provide criteria This specification covers inorganic fiber-reinforced organic felt, and inorganic fiber-based asphaltic and nonasphaltic felt underlayments for use as underlayment with steep-slope roofing products. The intent of this specification is to provide criteri