1.1 This specification covers the principal cellulosic fiber insulating board types, grades, and sizes. Requirements are specified for composition, construction, physical properties, tolerances, sampling procedures, and test methods. This specification covers the principal cellulosic fiber insulating board types, grades, and sizes. Insulating board covered by this specification consists of six types: Types I, II (Grades 1 and 2), III (Grades 1 and 2), IV (Grades 1 and 2), V, and VI