... ,36''X144' 15# ASTM D226,36''X144' 30# ASTM D4869,36''X72' 30# ASTM D226,36''X72' roofing underlay ASTM D-226 15# roofing ... used as an underlay beneath asphalt shingles, wood shakes, tiles and other sloped coverings.Physical Specificatons:Average roll weight,Lbs/roll ... /m21270g/m2400g/m2660g/m2Saturation,%by wt., min120%150%100%120% astm 226 and astm 4869 #15 #30 ASTM roofing felt