Multiple sheet building wrap for use in external wall assemblies having wet-applied facades

Abstract

A multiple sheet building wrap for wrapping the structural components of a building in order to protect the underlying structural components and optional building sheathing from moisture is provided. The building wrap is particularly useful under facades such as wet applied stucco or engineered stone, demonstrating good drainage of liquid water and moisture vapor permeability. The building wrap is a composite of a water resistive barrier, a three-dimensional mesh layer and a porous intervening layer which acts to filter the stucco as it is applied. An exterior wall construction incorporating such building wrap is also provided.

1 . A multiple sheet building wrap for wrapping the structural components and optional sheathing of a building in order to protect the structural components and optional sheathing from moisture, the sheet comprising:
 a) a moisture vapor permeable water-resistive barrier selected from the group consisting of asphalt-saturated papers, felts, woven fabrics, flash-spun plexifilamentary sheets, spunbond nonwoven sheets, spunbond-meltblown nonwoven sheets, spunbond-meltblown-spunbond nonwoven sheets, microperforated coated sheets comprising woven tapes, laminates thereof, and laminates comprising a nonwoven or woven fabric and a porous moisture vapor permeable film;   b) an intervening layer comprising a porous, liquid permeable layer having a maximum pore size of between about 20 micrometers and about 750 micrometers selected from the group consisting of asphalt-saturated papers, felts, woven fabrics, flash-spun plexifilamentary sheets, spunbond nonwoven sheets, spunbond-meltblown nonwoven sheets, spunbond-meltblown-spunbond nonwoven sheets, microperforated coated sheets comprising woven tapes, laminates thereof, and laminates comprising a nonwoven or woven fabric and a porous moisture vapor permeable film; and   c) a three-dimensional mesh layer disposed between the water resistive barrier and the liquid permeable layer having a thickness between about 0.32 cm and about 0.63 cm;   
       wherein a drainage space is provided between the water resistive barrier and the intervening layer through which liquid water can pass. 
     
     
         2 . The multiple sheet building wrap of  claim 1 , wherein the intervening layer has a maximum pore size of between about 30 micrometers and about 370 micrometers. 
     
     
         3 . The multiple sheet building wrap of  claim 1 , wherein the intervening layer has a hydrostatic head of less than 51 cm of water and is nonabsorbent to facilitate drying of the building wrap. 
     
     
         4 . The multiple sheet building wrap of  claim 1 , wherein either or both of the water resistive barrier and the intervening layer comprise a metallized surface. 
     
     
         5 . The multiple sheet building wrap of  claim 1 , wherein the water resistive barrier, the mesh layer and the intervening layer are attached by means of discontinuous adhesive or discontinuous ultrasonic bonding. 
     
     
         6 . The multiple sheet building wrap of  claim 1 , wherein the water resistive barrier and the intervening layer are attached by means of discontinuous adhesive or discontinuous ultrasonic bonding and the mesh layer is unattached sandwiched between the water resistive barrier and the intervening layer. 
     
     
         7 . A process of wrapping the structural components and optional sheathing of a building in order to protect the building structure from moisture, comprising wrapping the structural components and optional sheathing of the building with the multiple sheet building wrap of  claim 1 . 
     
     
         8 . The multiple sheet building wrap of  claim 1 , further comprising a lath layer adjacent the intervening layer, wherein the water resistive barrier, the intervening layer and the lath layer are attached. 
     
     
         9 . A process of wrapping the structural components and optional sheathing of a building in order to protect the structural components and optional sheathing from moisture, comprising wrapping the sheathing or structural components of the building with the multiple sheet building wrap of  claim 8 . 
     
     
         10 . A process of wrapping the structural components and optional sheathing of a building in order to protect the structural components and optional sheathing from moisture, comprising, in sequence:
 wrapping the structural components and optional sheathing of the building with a moisture vapor permeable, water resistive barrier; and   wrapping the building with the composite sheet of  claim 8 .   
     
     
         11 . An external wall assembly of a building, comprising:
 a) structural components providing structural support for the building;   b) optional sheathing material surrounding the structural components;   c) a multiple sheet building wrap according to  claim 1  surrounding the structural components and optional sheathing material wherein the water-resistive barrier is the inner layer and the intervening layer is the outer layer;   d) a lath layer capable of supporting a wet-applied facade material surrounding the multiple sheet building wrap contacting the intervening layer; and   e) wet-applied facade material contacting the lath layer and forming the outermost layer of the external wall assembly.