Abstract: A siding panel for installation on walls, soffits or other exposed surfaces of a structure, having a nailing hem folded back upon itself to form a double thick lateral edge of the siding panel. A plurality of elongated apertures are defined in the nailing hem, which apertures are surrounded by longitudinally extended protrusions or bumps. The protrusions or bumps are spaced apart less than the width of the head of a carpenter's hammer, such that a nail or other fastener cannot be fully set flush against the surface of the nailing hem. The double thick nailing hem provides increased strength and the provision of the bumps permits relatively longitudinal movement of the siding relative to the head of the fastener. A novel interlocking reverse S configuration is provided adjacent the nailing hem so as to interlock with a corresponding portion on the opposing longitudinal edge of the siding.