Interlocking building siding

Claim 1

In a building siding panel extruded from a synthetic resin material and being adapted for mounting in generally horizontal overlaping relation with similar panels on a building wall to simulate weatherboard siding, the siding panel including a nailing strip having a plurality of elongated slot-like openings extending along its edge, a locking flange integrally formed on and projecting outwardly from and downwardly along the outer surface of the panel adjacent the nailing strip and an upwardly directing locking lip integrally formed on and extending along its bottom edge, the locking flange cooperating with the outer surface of the panel to define a downwardly open locking channel having a relatively narrow opening adjacent its open bottom and being substantially wider adjacent its upper portion, and the upwardly directed locking strip being dimensioned to fit within the narrow open bottom of the locking channel, the improvement comprising, an elongated bead integrally formed on and extending longitudinally of said upwardly directed locking lip adjacent its uppermost edge, and a plurality of dimples formed in said bead at spaced intervals along its length, said dimples having a dimension measured in a direction generally perpendicular to the plane of the lip which is substantially greater than the width of the narrow opening of said locking channel but less than the corresponding dimension of the locking channel adjacent its upper end.