An interlocking panel system for top-down installation on an underlying structure including a plurality of panels, with an uphill course and a downhill course where each panel is generally rectangular, having an uphill edge and opposing downhill edge. An interlocking member is disposed along the uphill edge, and a receiving member adapted to receive the interlocking member and a joining flange are disposed along the downhill edge. A panel of the uphill course is affixed to an underlying structure via fasteners through the joining flange. The interlocking member of a panel of the downhill course is insertable into the receiving member of the uphill course, and the position of the panel of the downhill course is adjustable within the span of the receiving member.

A panel for attachment to a mounting surface includes a plurality of raised faces formed and extending between an upper edge and a lower edge of the panel, and a plurality of recessed keyways defined between each of the raised faces. The panel may have a recessed base at the lower edge of the keyways defining a fold lip adjacent the mounting surface, and a full base formed at the lower edge of the raised faces and extending beyond the recessed base.

A shingle, a method of making it, and a roof embodying the shingle is provided, in which an exterior surface of the shingle is provided with an attached reinforcement layer through which fasteners may be applied when the shingle is applied to a roof.

A panel for attachment to a mounting surface includes a plurality of raised faces formed and extending between an upper edge and a lower edge of the panel, and a plurality of recessed keyways defined between each of the raised faces. The panel may have a recessed base at the lower edge of the keyways defining a fold lip adjacent the mounting surface, and a full base formed at the lower edge of the raised faces and extending beyond the recessed base. The fold lip provides a reaction point for an under lap extending from the lower edge toward the upper edge. The panel may include a lock flange formed at the upper edge. The lock flange defines a lock slot between layers of the panel, and closes the lock slot to substantially zero depth at a first touch point and a second touch point.

A shingle coating asphalt composition is provided that is produced from a paving grade asphalt. The asphalt composition comprises a paving-grade asphalt that has been modified with one or more polymer additives; and a secondary additive comprising one or more of a viscosity reducing agent, a wax, a salt of a fatty acid ester, and an amide of a fatty acid. The shingle coating asphalt coating composition is used to make a shingle. The shingle includes a substrate, the asphalt, and roofing granules.

A shingle coating asphalt composition is provided that is produced from a paving grade asphalt. The asphalt composition comprises a paving-grade asphalt that has been modified with one or more polymer additives; and a secondary additive comprising one or more of a viscosity reducing agent, a wax, a salt of a fatty acid ester, and an amide of a fatty acid. The shingle coating asphalt coating composition is used to make a shingle. The shingle includes a substrate, the asphalt, and roofing granules.