Conventional fire-rated one-sided construction

Abstract

A fire resistant membrane comprising a plurality of regularly spaced elongated parallel sheet metal framing elements, a first layer of fire rated wallboard attached directly to the framing elements with screws, a side of the framing elements opposite a side bearing the first wallboard layer being substantially free of any directly attached covering layer, a grid of elongated parallel sheet metal shafts overlying the first wallboard and secured to the studs with screws extending through the first wallboard layer, the shafts being oriented at right angles to the studs, and a second layer of fire rated wallboard overlying the shafts and being spaced from the first layer by the shafts, the second layer of wallboard being attached to the shafts with screws having a length insufficient to fully penetrate the first wallboard layer.

What is claimed is:  
     
         1 . A fire resistant membrane comprising a plurality of regularly spaced elongated parallel sheet metal framing elements, a first layer of fire rated wallboard attached directly to the framing elements with screws, a side of the framing elements opposite a side bearing the first wallboard layer being substantially free of any directly attached covering layer, a grid of elongated parallel sheet metal shafts overlying the first wallboard and secured to the studs with screws extending through the first wallboard layer, the shafts being oriented at right angles to the studs, and a second layer of fire rated wallboard overlying the shafts and being spaced from the first layer by the shafts, the second layer of wallboard being attached to the shafts with screws having a length insufficient to fully penetrate the first wallboard layer. 
     
     
         2 . A fire resistant membrane as set forth in  claim 1 , wherein said studs are braced with elongated metal straps extending along a side of the studs opposite a side of the studs to which the first fire rated layer of wallboard is attached or through holes in webs of the studs, the bracing straps being attached to the studs with screws driven by an installer working from a side of the studs on which the wallboard is attached. 
     
     
         3 . A fire resistant membrane as set forth in  claim 1 , wherein the shafts are elongated channels. 
     
     
         4 . A fire resistant membrane as set forth in  claim 3 , wherein the channels have an asymmetrical cross section. 
     
     
         5 . A fire resistant membrane as set forth in  claim 4 , wherein the channels each have two sides and an intermediate web, a longer one of said sides having a flange in a plane parallel to said web, the flange being attached by screws to said studs through said first fire rated layer of wallboard. 
     
     
         6 . A fire resistant membrane as set forth in  claim 5 , wherein said channels are oriented with their respective flanges depending below the associated channel side. 
     
     
         7 . A fire resistant membrane as set forth in  claim 6 , wherein said longer side is apertured in a regular pattern along its length. 
     
     
         8 . A method of making a fire rated membrane including a wall or ceiling comprising aligning a plurality of sheet metal studs in a plane laterally spaced from one another, fastening a first fire rated wallboard with screws to one side of the studs while the opposite side remains substantially free of attached covering structure, fastening a plurality of elongate flat faced shafts on the layer of fire rated wallboard in laterally spaced locations parallel to one another and perpendicular to the studs, and fastening a second layer of fire rated wallboard to the shafts with screws of lengths limited to less than the distance between a face of the first layer adjacent the studs and a face of the second layer remote from the shafts.