Shiplap joint

Abstract

A building panel having improved shiplap joints to provide complete coverage with while providing for panel expansion and contraction. The building panel includes an overlap adapted to overlie a back portion of the backface of one or more panels laid up in the next higher course. Alternate corners of the building panels have centerlaps portions formed at a plane central to the thickness of the building panel that fit between the space defined by the front overlap and the backunderlap. The centerlaps mate to fill gaps that would otherwise open when the building panels expand and contract.

What is claimed is: 
     
         1 . An improved shiplap building panel, said building panel having two opposing faces, four edges and four corners comprising,
 (a) a first corner (A) with a backunderlap ( 230 ),   (b) a first edge (DA) with a backlap ( 240 ),   (c) a second corner (B) with a backcenterlap ( 210 ) and a frontcenterlap ( 310 ),   (d) a second edge (AB) with a backlap ( 250 ),   (e) a third corner (C) with a frontunderlap ( 330 ),   (f) a third edge (BC) with a frontlap ( 340 ),   (g) a fourth corner (D) with a backcenterlap ( 220 ) and a frontcenterlap ( 320 ),   (h) a fourth edge (CD) with a frontlap ( 350 ),   (i) a front face ( 201 ), and   (j) a back face ( 301 )   such that when the improved shiplap building panels are assembled with the same orientation the panels overlap and there no visible gaps between panels and panels are free to expand and contract.   
     
     
         2 . The improved shiplap building panel of  claim 1 , wherein all edges are beveled to facilitate drainage. 
     
     
         3 . The improved shiplap building panel of  claim 1 , designed such that all cuts may be made with a single tool. 
     
     
         4 . The improved shiplap building panel of  claim 1 , wherein all inside corners have a fillet with a radius that provides additional strength and crack resistance.