It is important to note that weight it is not a reliable indicator of the quality and durability of asphalt shingles. Jefferson Kolle (1995) quotes a report written by W. Kent Blanchard for the National Roofing Contractors Association. According to this report...”shingle testing and observation from field performance have frequently shown that weight alone is not a sufficient indicator of shingle quality”. Better predictors of a shingle products quality are...”the quality of the individual components of the composite structure, the asphalt, the mat-core and the manufacturing controls” (p.46). Unfortunately there is no way a consumer can determine this. Talk to building suppliers and roofing contractors as a method to determine which asphalt shingle products to purchase. They may know which manufacturers reliably produce good quality shingles and which do not.