Non-Uniform Coatings for Building Boards

Abstract

Disclosed is a building board construction with increased surface strength. More specifically, increased nail pull strength is achieved via the application of an external surface coating. The surface coating is ideally applied to a paper faced gypsum building board. In one possible embodiment, the coating is formed from a water soluble polymer.

What is claimed is: 
     
         1 . A composite building board with enhanced nail pull strength, the composite building board comprising:
 an exterior face;   a set plaster core positioned beneath the exterior face, the set plaster core formed from a cementitious slurry of predominantly calcium sulfate hemi-hydrate,   a polymer based coating applied to the exterior face of the building board in a non-uniform manner.   
     
     
         2 . The composite building board as described in  claim 1  wherein the composite building board includes a center line and opposing lateral edges and wherein the polymer based coating is thicker along the center line. 
     
     
         3 . The composite building board as described in  claim 1  wherein the composite building board includes a center line and opposing lateral edges and wherein the polymer based coating is thinner along the opposing lateral edges. 
     
     
         4 . The composite building board as described in  claim 1  wherein the polymer coating includes thicker and thinner areas and wherein the thicker areas comprises less than 10 grams per square foot of polymer coating. 
     
     
         5 . The composite building board as described in  claim 1  wherein the set plaster core is formed with a plurality of internal voids. 
     
     
         6 . The composite building board as described in  claim 1  wherein the exterior face is formed from paper. 
     
     
         7 . A composite building board with enhanced nail pull strength, the composite building board comprising:
 first and second liners, the first liner having an exterior face forming a decorative outer face of the building board;   a set plaster core positioned between and bonded with the first and second liners, the set plaster core formed from a cementitious slurry of predominantly calcium sulfate hemi-hydrate, the set plaster core being formed with a plurality of internal voids, the internal voids functioning to decrease the overall weight of the building board;   a polymer based coating applied to the decorative outer face of the building board, the polymer based coating being applied in an uneven manner across the outer face.   
     
     
         8 . The composite building board as described in  claim 7  wherein the coating comprises less than 10 grams per square foot of polymer. 
     
     
         9 . The composite building board as described in  claim 7  wherein the coating polymer comprises a synthetic polymer. 
     
     
         10 . The composite building board as described in  claim 7  wherein the composite building board includes a center line and opposing lateral edges and wherein the polymer based coating is thicker along the center line. 
     
     
         11 . The composite building board as described in  claim 7  wherein the composite building board includes a center line and opposing lateral edges and wherein the polymer based coating is thinner along the opposing lateral edges. 
     
     
         12 . The composite building board as described in  claim 7  wherein the first and second liners are formed from paper.