Tapered wood filler strips placed along the butts of old wood shingles to create a level surface when reroofing over existing wood shingle roofs. Also called horsefeathers.

Fibrous material saturated with asphalt and used as an underlayment or sheathing paper.

An asphalt roofing base material manufactured from glass fibers.

See asphalt roofing cement.

Factory Mutual Research Corp.

Shingles that do not contain factory-applied strips or spots of self-sealing adhesive.