Backer for tabbed composite shingles

Abstract

In a rectangular composite shingle unit including (a) a top sheet having a lower butt portion which is longitudinally divided into spaced tabs and an upper undivided headlap portion having a horizontal line of markings immediately above the butt portion indicating nailable sites for attachment of the shingle unit to a roof deck and (b) a continuous, elongated backer strip underlying the tabs and nail markings of the headlap which is aligned in offset or flush position along the longitudinal margin of the butt portion and which extends from the bottom edges of the tabs to the top area of the nail line markings; the improvement which comprises a backer strip having a plurality of extended projections on the top longitudinal margin of said backer which projections are spaced apart and vertically extend upwardly beyond the nail line markings and underlay the headlap portion of the top sheet.

Dependencies are inferred from the claim text.