Abstract:
An insulated framing member for exterior wall insulation installation, and to a method for covering walls using the insulated framing member. The insulated framing member comprises a strip of insulating foam having chamfers along the edges, optionally laminated to a wooden nail base. They insulated framing member will reduce the compression of compressible insulation materials and the thermal bridging of fasteners.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an insulated framing member for exterior wall insulation installation, and to a method for covering walls using the insulated framing member. 
       BACKGROUND OF THE INVENTION 
       [0002]    Each revision of the International Residential Code (IRC) tends to increase the energy requirements specified therein. The 2012 revision of the IRC requires more insulation, a tighter building envelope, tighter ducts, better windows, and more efficient lighting than the 2009 code. Wall insulation requirements have become more stringent in climate zones 3, 4, 6, 7, and 8; for the first time, builders in climate zones 6, 7, and 8 will be required to install exterior rigid foam insulation, or to use some other comparable wall insulation strategy. Every new home built to meet the higher standards of the 2012 IRC will need to develop a strategy to prevent thermal bridging through structural members. Standard wood furring strips are currently used to provide enhanced drainage behind exterior claddings. Standard wood furring strips have low thermal resistance which is problematic in meeting the higher standards of the 2012 IRC. Additionally, furring strips reduce the R-value of conventional compressible insulation materials when they are installed over the insulation materials and reduce the entrapped air. There is a need for means to prevent thermal bridging, and increase R-value, in building envelopes. 
       SUMMARY OF THE INVENTION 
       [0003]    An insulated framing member comprising an elongate wooden strip, having a front side and a backside, a strip of insulating foam having a front side and a backside and a first edge and a second edge, the frontside of the strip of insulating foam is laminated on the backside of the elongate wooden strip, and the insulating foam has chamfers on the backside along edges. 
       DEFINITIONS 
       [0004]    The term “furring strip” is used herein to refer to an elongate strip of wood or metal fixed to a wall, floor, or ceiling to provide a surface for the fixing of building materials such as weather resistant barrier, cladding, etc. 
         [0005]    The term “building code” is used herein to refer to a series of ordinances enacted by a state or local governmental entity, establishing minimum requirements that must be met in the construction and maintenance of buildings. 
         [0006]    The term “energy code” is used herein to refer various energy standards for residential and commercial buildings which set a minimum level of energy efficiency at the time of new construction or renovation. 
         [0007]    The term “certifications” is used herein to refer to a written declaration that a particular product or service complies with stated criteria. 
         [0008]    The term “building envelope” is used herein to refer to a system or assembly of exterior wall components, including exterior wall finish materials, that provide protection of the building structural members, including framing and sheathing materials, and conditioned interior space, from the detrimental effects of the exterior environment. 
         [0009]    The term “cladding” is used herein to refer to any material that constitutes the exposed, non-load bearing, exterior covering of an exterior wall. Such material is applied over any sheathing that is present, or otherwise is directly attached to the building envelope as the outermost component of the wall system. 
         [0010]    The term “wall studs” is used herein to refer to the any of the stick-like parts that form the vertical structural framework of a wall. Wall studs may be load-bearing or nonload-bearing. 
         [0011]    The term “cavity” is used herein to refer to any air space, which is either wholly or substantially unobstructed in the building envelope. Typical cavities exist between wall studs and between the weather-resistive barrier and the back surface of the cladding. 
         [0012]    The term “cavity insulation” is used herein to refer to any thermally insulating material located in a cavity. 
         [0013]    The term “water-resistive barrier (WRB)” is used herein to refer to a material that is intended to resist liquid water that has penetrated behind the cladding from further intruding into the exterior wall assembly. The water-resistive barrier is placed on the interior side of the cladding. 
         [0014]    The term “air barrier” is used herein to refer to any material or combination of materials and assemblies that restrict or prevent the passage of air through the building thermal envelope 
         [0015]    The term “vapor retarder” is used herein to refer to any material (membrane or paint) that has a water vapor permeance (perm) rating of 57 ng/(Pasm2) (1 perm) or less. 
         [0016]    The term “Exterior Insulation and Finishing System (EIFS)” is used herein to refer to any nonload-bearing, exterior cladding that consists of a rigid insulation board attached either adhesively or mechanically, or both, to the substrate; an integrally reinforced base coat; and a textured protective finish coat. 
         [0017]    The term “exterior insulation” is used herein to refer to any rigid insulation board used as a component of Exterior Insulation and Finishing System (EIFS). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1A  depicts a side view of an insulated framing member. 
           [0019]      FIG. 1B  depicts an end view of an insulated framing member. 
           [0020]      FIG. 2A  depicts a top view of insulated framing members installed in a wall. 
           [0021]      FIG. 2B  depicts a side view of insulated framing members installed in a wall. 
           [0022]      FIG. 2C  depicts a front view of insulated framing members installed in a wall. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The 2012 IRC building code requires additional wall insulation, which will alter typical building practices. The present invention will be used with conventional compressible insulation materials such as mineral wool, fiberglass, cotton, cellulose, and vermiculite. The present invention is especially useful for use with any thermally insulating batt that contains staple fibers that pack together in an open or loose manner. Standard wood furring strips are currently used to provide enhanced drainage behind exterior claddings but their low R-Value is problematic in meeting the energy requirements of the 2012 IRC. Wood furring strips are also problematic in that they compress the insulation material. It is found that when a furring strip is installed over insulation materials they are compressed down to approximately ¼″ in thickness. Insulation materials depend on entrapped air space to provide insulation properties. Compression will reduce the entrapped air space, increase density, and result in a lower R-Value. The insulated framing member  10  of the present invention will achieve an acceptable R-Value as the conventional compressible insulation materials are compressed to an extent that does not reduce the R-value of the insulation material below that required to meet the building code requirement as summarized in Table 1. The insulated framing member of Table 1 was comprised of a ⅝ inch plywood portion laminated to a ⅝ inch foam portion. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 R-Value Comparison of Insulated Framing 
               
               
                 Member and Traditional Wood Furring Strip 
               
             
          
           
               
                   
                 R-Value of 
                 R-Value of 
                   
               
               
                   
                 Foam 
                 wood 
                 Total R-value 
               
               
                   
                   
               
             
          
           
               
                 1¼″ Insulated 
                 3.75 
                 0.6 
                 4.35 
               
               
                 Framing Member 
               
               
                 1¼″ Wood 
                 N/A 
                 1.2 
                 1.2 
               
               
                 Furring Strip 
               
               
                   
               
             
          
         
       
     
         [0024]    In addition, the insulated framing member  10  will reduce the thermal bridging of fasteners used to fasten the insulated framing member to a wall in comparison to furring strips. 
         [0025]    In response to the increased requirements of the 2012 IRC there is a trend to add additional insulation to the exterior of buildings, such as windows and door surrounds. In another embodiment if the invention, the insulated framing member can help provide additional insulation around windows, doors and any penetration. 
         [0026]    The insulated framing member of the present invention  10  will consist of a rigid foam strip  12  having a chamfer  12   a  on each edge. The elongate rigid foam strip  12  of the insulated framing member has a front side, a backside, and a first edge and a second edge as depicted in  FIG. 1A . The first edge and the second edge along the backside of foam strip  12  are chamfered  12   a.  Chamfer  12   a  functions to reduce the compression of conventional insulation materials along with which the insulated framing member is installed. Foam  12  provides necessary thermal resistance to the wall where conventional compressible insulation materials  20  are compressed. Foam materials that may be used include polyisocyanurates polyurethanes, extruded polystyrene, expanded polystyrene, tannic foams, phenolic foams, biophenolics foams, and combinations thereof. 
         [0027]    Optionally, the insulated framing member of the present invention  10  will consist of a layer of foam  12  laminated to an elongate wooden strip  14 , having a chamfer  12   a  on each edge of the foam portion as depicted in  FIG. 1B . The elongate wooden strip  14  portion of the insulated framing member may be used as a nail base for the exterior cladding. This is a benefit since the cladding fastener would not penetrate the water-resistive barrier (WRB) and thus reduce the possibility of air and water infiltration. Wooden materials that may be used include oriented strand board (OSB), various densities of fiberboard such as MDF, pine, spruce, fir, plywood, and combinations thereof. Plywood is the preferred wooden portion. The wooden portion may, optionally, be pressure treated for improved resistance to insects, microorganisms and fungal decay. Elongate wooden strip  14  has a front side, a backside, and a first edge and a second edge. 
         [0028]    The backside of wooden strip  14  is laminated to the frontside of foam strip  12  as depicted in  FIG. 1A . The lamination may use any conventional lamination process. The adhesive may be any applicable adhesive that is compatible with foams and wood. 
         [0029]    Although there is no limitation to the dimensions of the insulated framing member, it is illustrative to discuss them in a size comparable to a standard furring strip. Illustratively, the insulated framing member  10  will be approximately 2½″×1″×48″. The thickness of the insulated framing member  10  plays a critical role. In terms of thickness, a properly designed insulated framing member  10  will provide an air space between the WRB and the exterior cladding. The air space is illustrated in  FIG. 2A  and  FIG. 2B  as the difference in the front surfaces of compressible insulation material  20  and insulated framing member  10 . This space acts as a rain screen and provides drainage and drying of any moisture that may get behind the cladding. 
       EXAMPLES 
     Comparative Example 1 
       [0030]    Typical wooden furring strips were fastened onto a wall overtop of a compressible insulation that was coverd by a water-resistive barrier. Since the insulation and water-resistive barrier were compressed, the thermal resistance (R-value) was reduced. 
       Example 1 
       [0031]    Rigid insulation was laminated to the back of wood furring strips. Chamfers were cut on each side of the rigid insulation to form insulated framing members. Insulated framing members were fastened onto a wall overtop of a compressible insulation that was coverd by a water-resistive barrier as depicted in  FIGS. 2A ,  2 B, and  2 C. The chamfers reduced the gradual compression of the insulation and water-resistive barrier product. This provided the necessary thermal resistance to the wall where the insulation was compressed in Comparative Example 1.The wooden portion of the insulated framing member was used as a fastener base for the exterior cladding. This provided a benefit since the cladding fastener did not penetrate the water-reistive barrier (WRB) and thus reduced the possibility of air and water infiltration.