Patent Publication Number: US-11655664-B2

Title: Door kits and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY 
     This application is a continuation of U.S. patent application Ser. No. 16/688,323, filed Nov. 19, 2019, now U.S. Pat. No. 10,988,967, which is a continuation of U.S. patent application Ser. No. 15/614,833, filed Jun. 6, 2017, now U.S. Pat. No. 10,480,240, which claims the benefit of priority of U.S. Provisional Application No. 62/347,312 filed Jun. 8, 2016, the complete disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to pre-hung doors and to related methods, including methods of packaging and installing the doors. 
     BACKGROUND 
     Preassembled doors, especially pre-hung doors, have become increasingly popular in commercial and residential settings due to their relative ease of installation. Generally, a preassembled door contains a door and a preassembled doorjamb assembly. In the case of a pre-hung door, one side edge of the door is pivotally connected, typically using two or more hinges, to a first side jamb of the doorjamb assembly, and optionally the other side edge of the door has a lockset that engages a strike plate and/or opening of a second side jamb of the doorjamb assembly. To install the preassembled door, the doorjamb assembly is placed in an opening of a wall frame, such as of a commercial or residential building, and plumbed and shimmed according to known techniques before being fastened in place to the frame. 
     A problem identified by Applicant with respect to preassembled doors is the high costs involved in transporting and delivering the doors and the associated pieces to a wholesaler, retailer, and/or installation site. For example, the relatively large thickness of the preassembled doors limits the number of doors that may be stacked upon or positioned adjacent one another within a given space, such as on the flatbed of a tractor trailer. Many wholesalers and retailers do not have sufficient storage space to maintain a large inventory of preassembled doors. Further, trim pieces and frame components typically are shipped in a cardboard carton, which may become lost, separated from the pre-hung door, and/or damaged during transit. 
     SUMMARY OF THE INVENTION 
     A first aspect of the invention provides a pre-hung door unit in kit form that includes a partially preassembled split doorjamb assembly and a door. The partially preassembled split doorjamb assembly includes first and second side bases substantially parallel to one another, a header base substantially perpendicular to and interconnecting the first and second side bases, and extensions. The door is arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity. The extensions include first and second side extensions and a header extension that are unassembled with respect to and connectable lengthwise to the first and second side bases and the header base, respectively. The extensions are stowed within the cavity of the door kit. 
     A second aspect of the invention provides a method of packaging a pre-hung door unit in kit form. The method involves providing a partially preassembled split doorjamb assembly including first and second side bases substantially parallel to one another, a header base substantially perpendicular to and interconnecting the first and second side bases, and extensions, arranging a door within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity, and stowing the extensions in the cavity. The extensions include first and second side extensions and a header extension that are unassembled with respect to and connectable lengthwise to the first and second side bases and the header base, respectively. 
     A third aspect of the invention provides a method of installing a pre-hung door unit shipped in kit form. The method involves providing a pre-hung door shipped in kit form including a partially preassembled split doorjamb assembly having first and second side bases substantially parallel to one another and a header base substantially perpendicular to and interconnecting the first and second side bases, a door arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity. The partially preassembled split doorjamb assembly further includes extensions stowed within the cavity. The stowed extensions include first and second side extensions and a header extension that are unassembled with respect to and connectable lengthwise to the first and second side bases and the header base, respectively. According to the method, the extensions are removed from the cavity, the partially preassembled split doorjamb assembly is inserted into an opening of a wall doorframe and secured to the wall doorframe, and the first and second side extensions and the header extension are connected lengthwise to the first and second side bases and the header base, respectively. 
     A fourth aspect of the invention provides a door unit in kit form, including a partially preassembled split doorjamb assembly and a door. The partially preassembled split doorjamb assembly includes first and second side bases substantially parallel to one another, a header base substantially perpendicular to and interconnecting the first and second side bases, and extensions. The door is arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity. The extensions include first and second side extensions and a header extension that are connectable lengthwise to the first and second side bases and the header base, respectively. The first and second side extensions and the header extension are removably secured adjacent to outer surfaces of the bases. 
     According to a fifth aspect of the invention, a method is provided of packaging a door unit in kit form. The method involves providing a partially preassembled split doorjamb assembly comprising first and second side bases substantially parallel to one another, a header base substantially perpendicular to and interconnecting the first and second side bases, and extensions. A door is arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity. The extensions include first and second extensions and a header extension that are connectable lengthwise to the first and second side bases and the header base, respectively, removably secured adjacent to outer surfaces of the bases. 
     A sixth aspect of the invention provides a method of installing a door unit shipped in kit form. The door unit shipped in kit form includes a partially preassembled split doorjamb assembly including first and second side bases substantially parallel to one another, a header base substantially perpendicular to and interconnecting the first and second side bases, and extensions, and a door arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity. The extensions include first and second side extensions and a header extension that are connectable lengthwise to the first and second side bases and the header base, respectively, and are removably secured adjacent to outer surfaces of the bases. The partially preassembled split doorjamb assembly is inserted into and secured to an opening of a wall doorframe. The first side extension, the second extension, and the header extension are secured lengthwise to the first side base, the second side base, and the header base, respectively, in order to provide a completed doorframe that spans the width or thickness of the wall opening. 
     A seventh aspect of the invention provides a door unit in kit form including a partially preassembled split doorjamb assembly that includes first and second side bases substantially parallel to one another and a header base substantially perpendicular to and interconnecting the first and second side bases, and a door arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity. The partially preassembled split doorjamb assembly further includes extensions comprising first and second side extensions and a header extension that are movably connected to and secured adjacent to outer surfaces of the first and second side bases and the header base, respectively. 
     An eighth aspect of the invention provides a method of packaging a door unit in kit form. The method involved providing a partially preassembled split doorjamb assembly including first and second side bases substantially parallel to one another and a header base substantially perpendicular to and interconnecting the first and second side bases, the partially preassembled split doorjamb assembly further including first and second side extensions and a header extension that are movably connected to the first and second side bases and the header base, respectively. A door is arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity. The first and second side extensions and the header extension are arranged adjacent to outer surfaces of the first and second side bases and the header base, respectively. 
     A ninth aspect of the invention provides a method of installing a door shipped in kit form. The door unit shipped in kit form includes a partially preassembled split doorjamb assembly including first and second side bases substantially parallel to one another and a header base substantially perpendicular to and interconnecting the first and second side bases, a door arranged within a space defined by the first and second side bases and the header base of the partially preassembled split doorjamb assembly so that the door, the first and second side bases, and the header base collectively establish a cavity, and first and second side extensions and a header extension that are movably connected to and secured adjacent to outer surfaces of the first and second side bases and the header base, respectively. The extensions are unsecured from the outer surfaces of the bases, the partially preassembled split doorjamb assembly is inserted into an opening of a wall doorframe, and the partially preassembled doorjamb assembly is secured to the wall doorframe. 
     Aspects and exemplary aspects, embodiments and methods described herein are particularly advantageous for and applicable to door packaging, transportation, and installation, especially pre-hung doors. 
     Other aspects of the invention, including kits, assemblies, subassemblies, door units, processes, and the like which constitute part of the invention, will become more apparent upon reading the following detailed description of the exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
       The accompanying drawings are incorporated in and constitute a part of the specification. The drawings, together with the general description given above and the detailed description of the exemplary embodiments and methods given below, serve to explain the principles of the invention. In such drawings: 
         FIG.  1    is a bottom perspective view of a door kit according to an embodiment of the invention; 
         FIG.  2    is a cross-sectional perspective end view of a split side jamb and door trim of the door unit of  FIG.  1    installed in a wall doorframe according to another embodiment of the invention; 
         FIG.  3    is bottom perspective view of the door kit of  FIG.  1    with an enclosure in the form of a plastic wrap; 
         FIG.  4    is a bottom perspective view of a door kit according to another embodiment of the invention; 
         FIG.  5    is a top perspective view of the door kit of  FIG.  4   ; 
         FIG.  6    is a bottom perspective view of the door kit of  FIG.  4    with an enclosure in the form of a plastic wrap; 
         FIG.  7    is a front perspective view of a door kit in an extended or deployed state according to still another embodiment of the invention; 
         FIG.  8    is a front perspective view of the door kit of  FIG.  7    in a folded state; 
         FIG.  9    is a partial cross-sectional view of the door kit in the extended or deployed state; and 
         FIG.  10    is a bottom perspective view of the door kit of  FIG.  8    in the folded state with an enclosure in the form of a plastic wrap. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS AND EXEMPLARY METHODS 
     Reference will now be made in detail to exemplary embodiments and methods of the invention as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the drawings. It should be noted, however, that the invention in its broader aspects is not necessarily limited to the specific details, representative materials and methods, and illustrative examples shown and described in connection with the exemplary embodiments and methods. Like reference characters refer to like parts throughout the drawings. 
     An exemplary pre-hung door unit in kit form is generally designated by reference numeral  10  in  FIG.  1   , and is also referred to herein as a door kit  10 . In its illustrated form, the exemplary door kit  10  is a pre-hung door unit in kit form that can be assembled into a door unit for or during installation into a framed opening, such as a framed opening of a wall of a residential or commercial building. 
     The door kit  10  includes a “split” jamb assembly generally designated by reference numeral  12  in a partially preassembled state. The split jamb assembly  12  includes a first split side jamb  14 , a second split side jamb  16 , and a split header  18 . The first split side jamb  14  includes a first side base  14   a  and a first side extension  14   b  that are separable and connectable to one another lengthwise. The second split side jamb  16  includes a second side base  16   a  and a second side extension  16   b  that are separable and connectable to one another lengthwise. The split header  18  includes a header base  18   a  and a header extension  18   b  that are separable and connectable to one another lengthwise. 
     The split jamb assembly  12  is partially preassembled for packaging and transportation, for example, to a retail or wholesale store or an installation site. As shown in  FIG.  1   , when the split jamb assembly  12  is in the partially preassembled state, such as for packaging and/or shipping, the first and second side bases  14   a  and  16   a  are spaced apart from one another and are substantially parallel to one another. The header base  18   a  extends between and interconnects respective top end portions of the first and second side bases  14   a  and  16   a  to one another. The header base  18   a  is substantially perpendicular to the first and second side bases  14   a  and  16   a . By “substantially,” it is understood that the bases  14   a ,  16   a , and  18   a  may be subject to plumbing and shimming during installment to fit the building doorframe. Manufacturing, packaging, and installation tolerances that may cause the first and second side bases  14   a  and  16   a  to be not exactly parallel to one another and cause the header base  18   a  to be not exactly perpendicular to the first and second side bases  14   a  and  16   a  are not unexpected. 
     Any suitable fastener, adhesive, sealant, or other adjoining mechanism(s) and/or chemical(s) may be used to connect the header base  18   a  to the first and second side bases  14   a  and  16   a . For example, L-shaped brackets and screws or nails (not shown) may be used to establish the connections of the partially preassembled split jamb assembly  12 . 
     Although not shown, the partially preassembled split jamb assembly  12  may also include a sill, which optionally may be a split sill including a sill base and a sill extension. The sill, if provided, typically is substantially perpendicular to the first and second side bases  14   a  and  16   a  and interconnects respective bottom end portions of the first side base  14   a  and the second side base  16   a  to one another. 
     As also shown in  FIG.  1   , the door kit  10  further includes a door  20  having a rectangular shape. The door  20  is preferably an entryway door or interior door movable between an open position for providing a passageway between rooms and a closed position for separating rooms from one another. As packaged and transported, the door  20  is received within a space provided by the bases  14   a ,  16   a , and  18   a  of the partially preassembled split jamb assembly  12 . The door  20  preferably is pre-hung, such as by using one, two, three, or more hinges to connect a first side edge of the door  20  to the first side base  14   a . Optionally, an opposite second side edge of the door  20  may include a lockset that engages a strike plate and/or opening of the second side base  16   a.    
     As best shown in  FIG.  1   , the thickness of the door  20  is less than the width of the first and second side bases  14   a  and  16   a  and the header base  18   a . Consequently, a cavity  22  bounded around its perimeter by the bases  14   a ,  16   a , and  18   a , bounded at one side by the door  20 , and bounded at the opposite side by packaging such as a plastic wrap enclosure  26  ( FIG.  3   ) is established. As discussed in further detail below, the cavity  22  provides space for storage of the first and second side extensions  14   b  and  16   b , the header extension  18   b , and other trim parts  24 , such as brick molding, during packaging, transportation, and storage of the door kit  10 . 
     The first and second side bases  14   a  and  16   a  and the header base  18   a  include respective grooves  14   c ,  16   c , and  18   c  that align with one another about the perimeter of the partially assembled split jamb assembly  12 . The first and second side extensions  14   b  and  16   b  and the header extension  18   b  include respective tongues  14   d ,  16   d , and  18   d  that are receivable in the grooves  14   c ,  16   c , and  18   c , respectively. As shown in  FIG.  1   , in the kit form the extensions  14   b ,  16   b , and  18   b  are in an unassembled state relative to the bases  14   a ,  16   a , and  18   a , so that the tongues  14   d ,  16   d , and  18   d  are not inserted into the grooves  14   c ,  16   c , and  18   c , respectively. As best shown in  FIG.  2   , the tongue  14   d  is inserted into the grooves  14   c  after the door unit in kit form  10  has been delivered to its destination (e.g., building site) and unpackaged for installation. Likewise, the tongues  16   d  and  18   d  are inserted into the grooves  16   c  and  18   c , respectively, in the same manner as shown in  FIG.  2    after the door unit in kit form  10  has been delivered to its destination and unpackaged for installation. Optionally, the tongues  14   d ,  16   d , and  18   d  have widths slightly less than the width of the openings of the grooves  14   c ,  16   c , and  18   c , respectively, to establish frictionally mated tongue-in-groove connections. Brackets, fasteners, adhesives, sealants, and/or other adjoining mechanism(s) and/or chemical(s) may be employed to connect and/or secure the extensions  14   b ,  16   b , and  18   b  to the bases  14   a ,  16   a , and  18   a , respectively. Although not shown, it should be understood that reversing the tongues and grooves is possible, so that the bases  14   a ,  16   a , and  18   a  are provided with the tongues, and the extensions  14   b ,  16   b , and  18   b  are provided with the grooves. 
     As best shown in  FIG.  1   , the first and second side bases  14   a  and  16   a  and the header base  18   a  each include a protruding part that forms one side of the grooves  14   c ,  16   c , and  18   c . The protruding part acts as a jamb doorstop. In  FIG.  1   , for example, the door  20  abuts against the jamb doorstop protruding part of the bases  14   a ,  16   a , and  18   a  to prevent pass through of the door  20  and possible resulting damage to the hinges. 
     As indicated above, the split jamb assembly  12  of the door kit  10  is partially preassembled for packaging and transportation to a delivery site (e.g., a retailer, wholesaler, or installation site). The first and second side extensions  14   b  and  16   b  and the header extension  18   b  of the door kit  10  are not preassembled with the first and second side bases  14   a  and  16   a  and the header base  18   a , respectively. The extensions  14   b ,  16   b , and  18   b  and other trim parts (e.g., brick molding)  24 , as well as brackets, fasteners, and/or adhesive, are stowed in the cavity  22  during packaging and retained in the cavity  22  during shipping and preferably until unpacking for installation at the installation site. As best shown in  FIG.  1   , because the first and second side extensions  14   b  and  16   b  are about the same length as the first and second side bases  14   a  and  16   a , the first and second side extensions  14   b  and  16   b  are stowed within the cavity  22  diagonally, i.e., at an oblique angle relative to the first and second side bases  14   a  and  16   a . The header extension  18   b  and additional trim parts  24  are likewise stowed within the cavity  22  for packaging and transportation. Packaging the first split side jamb  14 , the second split side jamb  16 , and the split header  18  in their unassembled states reduces the overall thickness of the split jamb assembly  12  and the door kit  10  as a whole for transportation and storage. 
     An enclosure  26  is placed around the partially preassembly split jamb assembly  12  and the stowed extensions  14   b ,  16   b , and  18   b  and other trim parts  24 . In an exemplary embodiment shown in  FIG.  3   , the enclosure  26  is a plastic wrap or seal, desirably is a transparent material such as a plastic sheath wrapped around the door kit  10  for packaging purposes and having sufficient strength to withstand shipping and handling during transportation without tearing the plastic wrapping/sheath. Part of the enclosure  26  faces the side of the door  20  against which the extensions  14   b ,  16   b , and  18   b  are stowed to establish a side of the cavity  22  and retain the extensions  14   b ,  16   b , and  18   b  in the cavity  22  for safe transport. The plastic wrapping/sheath enclosure  26  may be stapled, tied, strapped, banded, tightly wrapped, or otherwise secured about the door kit  10 , and thus may be easily removed at the place of installation. Alternatively, the enclosure  26  may be a shipping container, such as a cardboard box. 
     The first and second split side jambs  14  and  16 , the split header  18 , and the additional trim parts  24  made be made of the same materials as one another or may be made of different materials. Similarly, the bases  14   a ,  16   a ,  18   a  may be made of the same material or different materials than the extensions  14   b ,  16   b , and  18   b . Suitable materials include wood, metal such as steel, plastics, and wood composites. Fire resistant materials are especially useful. Various types of materials may be used for making the door  20 , such as wood doors, composite doors, fiber-reinforced doors, steel doors, etc. The door  20  may be solid core or hollow core. 
     Stowing the extensions  14   b ,  16   b , and  18   b  and other parts (e.g., the trim parts  24 , fasteners, adhesive, lockset, strike plate, etc.) that do not form part of the partially preassembled split jamb assembly  12  within the cavity  22  provides several advantages. The overall thickness of the door kit  10  is significantly reduced, thereby simplifying shipping and substantially reducing storage space requirements for transport and inventory. The stowing of the extensions  14   b ,  16   b , and  18   b  and other parts within the cavity  22  also reduces instances of accidental loss of the unassembled parts. Further, the door  20  can be pre-hung to the partially preassembled split jamb assembly  12  of the door kit  10  by one, two, three, or more hinges connecting the door  20  to one of the side bases  14   a  or  16   a , so that installation is simplified. 
     A method of packaging the door kit  10  will now be described in greater detail. The partially preassembled split jamb assembly  12  including the first and second side bases  14   a  and  16   a  substantially parallel to one another and the header base  18   a  substantially perpendicular to and interconnecting the first and second side bases  14   a  and  16   a  is provided. Fasteners, adhesives, sealants, and/or other adjoining mechanism(s) and/or chemical(s) may be used to connect the bases  14   a ,  16   a , and  18   a  to one another and form the partially preassembled split jamb assembly  12 . Optionally, a sill or sill base may be included in the partially preassembled split jamb assembly. The door  20  is arranged within a space defined by the first and second side bases  14   a  and  16   a  and the header base  18   a  of the partially preassembled split jamb assembly  12  so that the door  20 , the first and second side bases  14   a  and  16   a , and the header base  18   a  collectively establish the cavity  22 . The extensions  14   b ,  16   b , and  18   b  are stowed in the cavity  22  so that the first and second side extensions  14   b  and  16   b  and the header extension  18   b  are unassembled with respect to one another, yet removable from the cavity  22  so as to be connected lengthwise to the first and second side bases  14   a  and  16   a  and the header base  18   a , respectively. A packaging material, such as the plastic wrap enclosure  26 , may be wrapped around the partially preassembled split jamb assembly  12  to establish a side of the cavity  22  opposite to the door  20 , and thereby retain the extensions  14   b ,  16   b , and  18   b  and other parts in the cavity  22 . Optionally, the extensions  14   b ,  16   b , and  18   b  may be secured to the partially preassembled split jamb assembly  12  and/or the door  20  using tape, staples, ties, straps, bands, and/or other temporary fasteners. Additionally or alternatively, the packaging material may press against the edges of the extensions  14   b ,  16   b , and  18   b  and other trim parts  24  opposite to the door  20  surface to secure the extensions  14   b ,  16   b , and  18   b  and trim parts  24  in place. 
     The packaging method may be accomplished using additional or fewer steps. Also, the steps may be performed in various sequences. 
     A method of installing the door kit  10  into a wall opening to establish a door unit in the wall opening will now be described in greater detail. After the packaging material  26  is removed, the extensions  14   b ,  16   b , and  18   b , the trim parts  24 , and other stowed parts (e.g., fasteners, adhesive, etc.) are removed from the cavity  22 . The partially preassembled split jamb assembly  12  is inserted into an opening of a wall doorframe  30 . Standard fasteners, adhesive, sealant, and/or other mechanical mechanisms and/or chemicals may be employed to secure the bases  14   a ,  16   a , and  18   a  to the sides and top of the wall doorframe  30 . Plumbing and/or shimming may also be performed to properly align the partially preassembled split jamb assembly  12 . The first side extension  14   b  is connected lengthwise to the first side base  14   a , the second side extension  16   b  is connected lengthwise to the second side base  16   a , and the header extension  18   b  is connected lengthwise to the header base  18   a . For example, the tongues  14   d ,  16   d , and  18   d  may be inserted into the grooves  14   c ,  16   c , and  18   c , respectively. The tongue-and-groove connections may involve frictional mating of parts. Brackets, fasteners, and/or adhesive may be employed to connect the extensions  14   b ,  16   b , and  18   b  to the bases  14   a ,  16   a , and  18   a , respectively. Optionally, trim  24  is then attached to the first split side jamb  14 , the second split side jamb  16 , and the split header  18 . In  FIG.  2   , the trim  24  in the form of brick molding is connected by fasteners such as nails or screws, adhesive, and/or sealant to the first side base  14   a  on one side of the wall doorframe  30  and to the first side extension  14   b  on the other side of the wall doorframe  30 . Trim  24  may similarly be connected to the wall doorframe  30  with respect to the second split side jamb  16  and the split header  18 . 
     The installation method may be accomplished using additional or fewer steps. Also, the steps may be performed in various sequences other than the sequence described above. For example, the split jamb assembly  12  may be secured to the wall doorframe  30  before or after the extensions  14   b ,  16   b , and  18   b  are connected to the base  14   a ,  16   a , and  18   a , respectively. 
     Another exemplary pre-hung door unit in kit form will now be described with reference to  FIGS.  4 - 6   . Comparable parts to those of the first embodiment illustrated in  FIGS.  1 - 3    are designated with like reference numerals with the addition of a one-hundred digit. For example, the pre-hung door unit in kit form is generally designated by reference numeral  110  in  FIG.  4   , and is also referred to herein as a door kit  110 . In its illustrated form, the exemplary door kit  110  is a pre-hung door unit in kit form that can be assembled into a door unit for or during installation into a framed opening, such as a framed opening of a wall of a residential or commercial building. 
     The door kit  110  includes a “split” jamb assembly generally designated by reference numeral  112  in a partially preassembled state. The split jamb assembly  112  includes a first split side jamb  114 , a second split side jamb  116 , and a split header  118 . The first split side jamb  114  includes a first side base  114   a  and a first side extension  114   b  that are separable and connectable to one another lengthwise. The second split side jamb  116  includes a second side base  116   a  and a second side extension  116   b  that are separable and connectable to one another lengthwise. The split header  118  includes a header base  118   a  and a header extension  118   b  that are separable and connectable to one another lengthwise. In  FIG.  4   , the header extension  118   b  is hidden behind the header base  118   a , and is better shown in  FIG.  5   . 
     The split jamb assembly  112  is partially preassembled for packaging and transportation, for example, to a retail or wholesale store or an installation site. As shown in  FIGS.  4  and  5   , when the split jamb assembly  112  is in the partially preassembled state, such as for packaging and/or shipping, the first and second side bases  114   a  and  116   a  are spaced apart from one another and are substantially parallel to one another. The header base  118   a  extends between and interconnects respective top end portions of the first and second side bases  114   a  and  116   a  to one another. The header base  118   a  is substantially perpendicular to the first and second side bases  114   a  and  116   a . By “substantially,” it is understood that the bases  114   a ,  116   a , and  118   a  may not be exactly 90 degrees, because the split jamb assembly  112  may be subject to plumbing and shimming during installment to fit the building doorframe. Manufacturing, packaging, and installation tolerances that may cause the first and second side bases  114   a  and  116   a  to be not exactly parallel to one another and cause the header base  118   a  to be not exactly perpendicular to the first and second side bases  114   a  and  116   a  are not unexpected. 
     Any suitable fastener, adhesive, sealant, or other adjoining mechanism(s) and/or chemical(s) may be used to connect the header base  118   a  to the first and second side bases  114   a  and  116   a . For example, L-shaped brackets and screws or nails (not shown) may be used to establish the connections of the partially preassembled split jamb assembly  112 . 
     Although not shown, the partially preassembled split jamb assembly  112  may also include a sill, which optionally may be a split sill including a sill base and a sill extension. The sill, if provided, typically is substantially perpendicular to the first and second side bases  114   a  and  116   a  and interconnects respective bottom end portions of the first side base  114   a  and the second side base  116   a  to one another. 
     As also shown in  FIGS.  4  and  5   , the door kit  110  further includes a door  120  having a rectangular shape. The door  120  is preferably an entryway door or interior door movable between an open position for providing a passageway between rooms and a closed position for separating rooms from one another. As packaged and transported, the door  120  is received within a space provided by the bases  114   a ,  116   a , and  118   a  of the partially preassembled split jamb assembly  112 . The door  120  preferably is pre-hung, such as by using one, two, three, or more hinges to connect a first side edge of the door  120  to the first side base  114   a . Optionally, an opposite second side edge of the door  120  may include a lockset that engages a strike plate and/or opening of the second side base  116   a.    
     As best shown in  FIGS.  4  and  5   , the thickness of the door  120  is less than the width of the first and second side bases  114   a  and  116   a  and the header base  118   a . Consequently, a cavity  122  bounded around its perimeter by the bases  114   a ,  116   a , and  118   a , bounded at one side by the door  120 , and bounded at the opposite side by packaging such as a plastic wrap or other enclosure  126  ( FIG.  6   ) is established. As discussed in further detail below, the cavity  122  provides space for storage of trim parts  124 , such as brick molding, as well as brackets, fasteners, and/or adhesive, during packaging, transportation, and storage of the door kit  110 . 
     The first and second side bases  114   a  and  116   a  and the header base  118   a  include respective grooves  114   c ,  116   c , and  118   c  that align with one another about the perimeter of the partially assembled split jamb assembly  112 . The first and second side extensions  114   b  and  116   b  and the header extension  118   b  include respective tongues  114   d ,  116   d , and  118   d  that are receivable in the grooves  114   c ,  116   c , and  118   c , respectively, in the same manner as shown in  FIG.  2    and described above in connection with the first exemplary embodiment. The tongue  118   d  of the header extension  118   b  is hidden in  FIG.  4    behind the header base  118   a , and is better shown in  FIG.  5   . In the door kit  110  in its unassembled state, the tongues  114   d ,  116   d , and  118   d  are not inserted into the grooves  114   c ,  116   c , and  118   c , i.e., the extensions  114   b ,  116   b , and  118   b  are unassembled relative to the bases  114   a ,  116   a , and  118   a . To assemble the extensions  114   b ,  116   b , and  118   b  relative to their bases  114   a ,  116   a , and  118   a , the tongues  114   d ,  116   d , and  118   d  are inserted into the grooves  114   c ,  116   c , and  118   c , respectively, after the door unit in kit form  110  has been delivered to its destination (e.g., building site) and unpackaged for installation. Optionally, the tongues  114   d ,  116   d , and  118   d  have widths slightly less than the width of the openings of the grooves  114   c ,  116   c , and  118   c , respectively, to establish frictionally mated tongue-in-groove connections. Brackets, fasteners, adhesives, sealants, and/or other adjoining mechanism(s) and/or chemical(s) may be employed to connect and/or secure the extensions  114   b ,  116   b , and  118   b  in an assembled state to the bases  114   a ,  116   a , and  118   a , respectively. Although not shown, it should be understood that reversing the tongues and grooves is possible, so that the bases  114   a ,  116   a , and  118   a  are provided with the tongues, and the extensions  114   b ,  116   b , and  118   b  are provided with the grooves. 
     As indicated above, the split jamb assembly  112  of the door kit  110  is partially preassembled for packaging and transportation to a delivery site (e.g., a retailer, wholesaler, or installation site). The first and second side extensions  114   b  and  116   b  and the header extension  118   b  of the door kit  110  are not preassembled with the first and second side bases  114   a  and  116   a  and the header base  118   a , respectively. The extensions  114   b ,  116   b , and  118   b  are removably secured to outer surfaces of the bases  114   a ,  116   a , and  118   a  for shipping and preferably until unpacking for installation at the installation site. Packaging the first split side jamb  114 , the second split side jamb  116 , and the split header  118  in their unassembled states reduces the overall thickness of the split jamb assembly  112  and the door kit  110  as a whole for transportation and storage. 
     An enclosure  126  is placed around the partially preassembly split jamb assembly  112  and the extensions  114   b ,  116   b , and  118   b  and other trim parts  124 . In an exemplary embodiment, the enclosure  126  is a plastic wrap or seal, desirably is a transparent material such as a plastic sheath wrapped around the door kit  110  for packaging purposes and having sufficient strength to withstand shipping and handling during transportation without tearing the plastic wrapping/sheath. Part of the enclosure  126  faces the side of the door  120  against which the trim parts  124  are stowed to establish a side of the cavity  122  and retain the trim parts  124  in the cavity  122  for safe transport. Alternatively, the enclosure  126  may be a shipping container, such as a cardboard box. 
     The extensions  114   b ,  116   b , and  118   b  may be secured adjacent to the outer surface of the bases  114   a ,  116   a , and  118   a , respectively, using temporary fasteners, such as staples, tape, ties, adhesive, etc. Additionally or alternatively, the enclosure  126 , particularly plastic wrap, around the edges of the door kit  110  may secure the extensions  114   b ,  116   b , and  118   b  to the bases  114   a ,  116   a , and  118   a . The plastic wrapping/sheath enclosure  126  may be stapled, tied, or otherwise secured about the door kit  110 , and thus may be easily removed at the place of installation. Preferably, the extensions  114   b ,  116   b , and  118   b  are placed in direct contact with the outer surfaces of the bases  114   a ,  116   a , and  118   a . Optionally, a protective sheet such as foam or cardboard may be interposed between the extensions  114   b ,  116   b , and  118   b  and the outer surfaces of the bases  114   a ,  116   a , and  118   a  to protect the adjacent surfaces from scuffing and marring. 
     The first and second split side jambs  114  and  116 , the split header  118 , and the additional trim parts  124  made be made of the same materials as one another or may be made of different materials. Similarly, the bases  114   a ,  116   a ,  118   a  may be made of the same material or different materials than the extensions  114   b ,  116   b , and  118   b . Suitable materials include wood, metal such as steel, plastics, and wood composites. Fire resistant materials are especially useful. Various types of materials may be used for making the door  120 , such as wood doors, composite doors, fiber-reinforced doors, steel doors, etc. The door  120  may be solid core or hollow core. 
     Removably securing the extensions  114   b ,  116   b , and  118   b  to outer surfaces of the bases  114   a ,  116   a , and  118   a  and stowing other parts (e.g., the trim parts  124 , fasteners, adhesive, lockset, strike plate, etc.) that do not form part of the partially preassembled split jamb assembly  112  within the cavity  122  provides several advantages. The overall thickness of the door kit  110  is significantly reduced (compared to the extensions assembled with respect to the bases), thereby simplifying shipping and substantially reducing storage space requirements for transport and inventory. The securing of the extensions  114   b ,  116   b , and  118   b  adjacent to the outer surfaces of the bases  114   a ,  116   a , and  118   a  and the stowing of other parts  124  within the cavity  122  also reduces instances of accidental loss of the unassembled parts. Further, the door  120  can be pre-hung to the partially preassembled split jamb assembly  112  of the door kit  110  by hinges connecting the door  120  to one of the side bases  114   a  or  116   a , so that installation is simplified. 
     A method of packaging the door kit  110  will now be described in greater detail. The partially preassembled split jamb assembly  112  including the first and second side bases  114   a  and  116   a  substantially parallel to one another and the header base  118   a  substantially perpendicular to and interconnecting the first and second side bases  114   a  and  116   a  is provided. Fasteners, adhesives, sealants, and/or other adjoining mechanism(s) and/or chemical(s) may be used to connect the bases  114   a ,  116   a , and  118   a  to one another and form the partially preassembled split jamb assembly  112 . Optionally, a sill or sill base may be included in the partially preassembled split jamb assembly  112 . The door  120  is arranged within a space defined by the first and second side bases  114   a  and  116   a  and the header base  118   a  of the partially preassembled split jamb assembly  112  so that the door  120 , the first and second side bases  114   a  and  116   a , and the header base  118   a  collectively establish the cavity  122 . The extensions  114   b ,  116   b , and  118   b  are removably secured adjacent to outer surfaces of the bases  114   a ,  116   a , and  118   a  so that the first and second side extensions  114   b  and  116   b  and the header extension  118   b  are unassembled with respect to the bases. 
     As best shown in  FIG.  6   , the packaging material  126 , such as plastic wrap, may be wrapped around the partially preassembled split jamb assembly  112  to establish a side of the cavity  122  opposite to the door  120 , and thereby retain the trim parts  124  in the cavity  122 . The packaging material  126  may also serve to removably secure the extensions  114   b ,  116   b , and  118   b  to the outer surfaces of the bases  114   a ,  116   a , and  118   a , respectively. That is, the packaging material  126  may press against the outer surfaces of the extensions  114   b ,  116   b , and  118   b  and other trim parts  124  opposite to the door  20  surface to removably secure the extensions and trim parts in place. Additionally or alternatively, tape, staples, ties, straps, bands, and/or other temporary fasteners may be used to temporarily secure the extensions  114   b ,  116   b , and  118   b  adjacent to the bases  114   a ,  116   a , and  118   a , respectively, and to removably secure the trim parts  124  against the door  120  in the cavity  122 . 
     The packaging method may be accomplished using additional or fewer steps. Also, the steps may be performed in various sequences. 
     A method of installing the door kit  110  into a wall opening to establish a door unit in the wall opening will now be described in greater detail. After the packaging material/enclosure  126  is removed, the extensions  114   b ,  116   b , and  118   b , the trim parts  124 , and other stowed parts (e.g., fasteners, adhesive, etc.) are separated from the bases  114   a ,  116   a , and  118   a  and removed from the cavity  122 . The partially preassembled split jamb assembly  112  is inserted into an opening of a wall doorframe  30  ( FIG.  3   ) in the same manner described above in connection with the first embodiment and  FIG.  2   . Standard fasteners, adhesive, sealant, and/or other mechanical mechanisms and/or chemicals may be employed to secure the bases  114   a ,  116   a , and  118   a  to the wall doorframe  30 . Plumbing and/or shimming may also be performed to properly align the partially preassembled split jamb assembly  112 . The first side extension  114   b  is connected lengthwise to the first side base  114   a , the second side extension  116   b  is connected lengthwise to the second side base  116   a , and the header extension  118   b  is connected lengthwise to the header base  118   a . For example, the tongues  114   d ,  116   d , and  118   d  may be inserted into the grooves  114   c ,  116   c , and  118   c , respectively. The tongue-and-groove connections may involve frictional mating of parts. Brackets, fasteners, and/or adhesive may be employed to connect the extensions  114   b ,  116   b , and  118   b  to the bases  114   a ,  116   a , and  118   a , respectively. Optionally, trim  124  is then attached to the first split side jamb  114 , the second split side jamb  116 , and the split header  118 . The trim  124  in the form of brick molding is connected by fasteners such as nails or screws, adhesive, and/or sealant to the first side base  114   a  on one side of the wall doorframe  30  and to the first side extension  114   b  on the other side of the wall doorframe  30  in a manner similar to that shown in  FIG.  3   . 
     The installation method may be accomplished using additional or fewer steps. Also, the steps may be performed in various sequences other than the sequence described above. For example, the split jamb assembly  112  may be secured to the wall doorframe  30  before or after the extensions  114   b ,  116   b , and  118   b  are connected in an assembled state to the base  114   a ,  116   a , and  118   a , respectively. 
     Another exemplary pre-hung door unit in kit form will now be described with reference to  FIGS.  7 - 10   . Comparable parts to those of the second embodiment illustrated in  FIGS.  4 - 6    are designated with like reference numerals with the addition of a two-hundred digit. For example, the pre-hung door unit in kit form is generally designated by reference numeral  210  in  FIG.  10   , and is also referred to herein as a door kit  210 . In its illustrated form, the exemplary door kit  210  is a pre-hung door unit in kit form that can be assembled into a door unit for or during installation into a framed opening, such as a framed opening of a wall of a residential or commercial building. 
     The door kit  210  includes a “split” jamb assembly generally designated by reference numeral  212  in a partially preassembled state. The split jamb assembly  212  includes a first split side jamb  214 , a second split side jamb  216 , and a split header  218 . The first split side jamb  214  includes a first side base  214   a  and a first side extension  214   b  that are connected to one another lengthwise by at least one first joint member, such as a hinge,  214   c . The second split side jamb  216  includes a second side base  216   a  and a second side extension  216   b  that are connected to one another lengthwise by at least one second joint member  216   c . The split header  218  includes a header base  218   a  and a header extension  218   b  that connected to one another lengthwise by at least one third joint member  218   c.    
     The split jamb assembly  212  is partially preassembled for packaging and transportation, for example, to a retail or wholesale store or an installation site. As shown in  FIG.  8   , when the split jamb assembly  212  is in the partially preassembled state, such as for packaging and/or shipping, the first and second side bases  214   a  and  216   a  are spaced apart from one another and are substantially parallel to one another. The header base  218   a  extends between and interconnects respective top end portions of the first and second side bases  214   a  and  216   a  to one another. The header base  218   a  is substantially perpendicular to the first and second side bases  214   a  and  216   a . By “substantially,” it is understood that the bases  214   a ,  216   a , and  218   a  may not be exactly 90 degrees, because the split jamb assembly  212  may be subject to plumbing and shimming during installment to fit the building doorframe. Manufacturing, packaging, and installation tolerances that may cause the first and second side bases  214   a  and  216   a  to be not exactly parallel to one another and cause the header base  218   a  to be not exactly perpendicular to the first and second side bases  214   a  and  216   a  are not unexpected. 
     Although not shown, the partially preassembled split jamb assembly  212  may also include a sill, which optionally may be a split sill including a sill base and a sill extension. The sill, if provided, typically is substantially perpendicular to the first and second side bases  214   a  and  216   a  and interconnects respective bottom end portions of the first side base  214   a  and the second side base  216   a  to one another. 
     As also shown in  FIGS.  7  and  8   , the door kit  210  further includes a door  220  having a rectangular shape. The door  220  is preferably an entryway door or interior door movable between an open position for providing a passageway between rooms and a closed position for separating rooms from one another. As packaged and transported, the door  220  is received within a space provided by the bases  214   a ,  216   a , and  218   a  of the partially preassembled split jamb assembly  212 . The door  220  preferably is pre-hung, such as by using one, two, three, or more hinges to connect a side edge of the door  220  to the second side base  216   a . Optionally, an opposite side edge of the door  220  may include a lockset that engages a strike plate and/or opening of the first side base  216   b.    
     As best shown in  FIG.  10   , the thickness of the door  220  is less than the width of the first and second side bases  214   a  and  216   a  and the header base  218   a . Consequently, a cavity  222  bounded around its perimeter by the bases  214   a ,  216   a , and  218   a , bounded at one side by the door  220 , and bounded at the opposite side by packaging such as a plastic wrap enclosure  226  is established. As discussed in further detail below, the cavity  222  provides space for storage of trim parts  224 , such as brick molding and jamb doorstops, as well as brackets, fasteners, and/or adhesive, during packaging, transportation, and storage of the door kit  210 . 
     As indicated above, joint members (e.g., hinges)  214   c ,  216   c , and  218   c  movably (e.g, pivotally) connect the extensions  214   b ,  216   b , and  218   b  to the side bases  214   a ,  216   a , and  218   a , respectively, for permitting movement of the extensions  214   b ,  216   b , and  218   b  between an extended (or deployed) position shown in  FIG.  7    and a stowed position shown in  FIG.  8   . In the extended (or deployed) position, the extensions  214   b ,  216   b , and  218   b  are edge-to-edge and having outer surface that are coplanar with the side bases  214   a ,  216   a , and  218   a , respectively. In the stowed position, outer surfaces of the extensions  214   b ,  216   b , and  218   b  and positioned adjacent to outer surfaces of the side bases  214   a ,  216   a , and  218   a . The stowed position is preferred for packaging and transportation of the door kit  210  to a delivery site (e.g., a retailer, wholesaler, or installation site). Packaging the first split side jamb  214 , the second split side jamb  216 , and the split header  218  in their stowed state reduces the overall thickness of the split jamb assembly  212  and the door kit  210  as a whole for transportation and storage. 
     The joint member (e.g., hinges)  214   c ,  216   c , and  218   c  may be a thin resilient material, such as a strap, bendable metal strip, or a tape, connecting the extensions  214   b ,  216   b , and  218   b  to the side bases  214   a ,  216   a , and  218   a , respectively. The hinges  214   c ,  216   c , and  218   c  alternatively may be a conventional mechanical hinge, such as a bi-fold metal hinge. The extensions  214   b ,  216   b , and  218   b  may be secured to their corresponding side bases  214   a ,  216   a , and  218   a  via interlocking mechanisms, such as snap locks, tongue-and-groove connections, and the like. 
     Referring to  FIG.  9   , the first split side jamb  214 , the second split side jamb  216 , and the split header  218  may be provided with respective jamb doorstops  224  as separate trim pieces. The jamb doorstops  224  prevent the door  220  from swinging through the split jamb assembly  212  and damaging the doorjamb hinges (not shown). The jamb doorstops  224  include a bump  224   a  that mates into a corresponding groove of the side bases  214   a ,  216   a , and  218   a  for fitting and optionally attachment purposes. The mating of the bump  224   a  to the groove may involve a frictional fit. 
     An enclosure  226  is placed around the partially preassembly split jamb assembly  212  and the extensions  214   b ,  216   b , and  218   b  and other trim parts  224 . In an exemplary embodiment, the enclosure  226  is a plastic wrap or seal, desirably is a transparent material such as a plastic sheath wrapped around the door kit  210  for packaging purposes and having sufficient strength to withstand shipping and handling during transportation without tearing the plastic wrapping/sheath. Part of the enclosure  226  faces the side of the door  220  against which the trim parts  224  are stowed to establish a side of the cavity  222  and retain the trim parts  224  in the cavity  222  for safe transport. Alternatively, the enclosure  226  may be a shipping container, such as a cardboard box. 
     The extensions  214   b ,  216   b , and  218   b  in their stowed positions may be secured adjacent to the outer surface of the side bases  214   a ,  216   a , and  218   a , respectively, using temporary fasteners, such as staples, tape, ties, adhesive, etc. Additionally or alternatively, the enclosure  226  is wrapped around the edges of the door kit  210  to secure the extensions  214   b ,  216   b , and  218   b  in the stowed positions. The plastic wrapping/sheath enclosure  226  may be stapled, tied, wrapped, or otherwise secured about the door kit  210 , and thus may be easily removed at the place of installation. Preferably, outer surfaces of the extensions  214   b ,  216   b , and  218   b  are placed in direct contact with the outer surfaces of the bases  214   a ,  216   a , and  218   a . Optionally, a protective sheet such as foam or cardboard may be interposed between the outer surfaces of the extensions  214   b ,  216   b , and  218   b  and the outer surfaces of the bases  214   a ,  216   a , and  218   a  to protect the adjacent surfaces from scuffing and marring. 
     The first and second split side jambs  214  and  216 , the split header  218 , and the additional trim parts  224  made be made of the same materials as one another or may be made of different materials. Similarly, the bases  214   a ,  216   a ,  218   a  may be made of the same material or different materials than the extensions  214   b ,  216   b , and  218   b . Suitable materials include wood, metal such as steel, plastics, and wood composites. Fire resistant materials are especially useful. Various types of materials may be used for making the door  220 , such as wood doors, composite doors, fiber-reinforced doors, steel doors, etc. The door  220  may be solid core or hollow core. 
     Arranging the extensions  214   b ,  216   b , and  218   b  in their stowed positions adjacent to outer surfaces of the bases  214   a ,  216   a , and  218   a  and stowing other parts (e.g., jamb doorstops and other trim parts  224 , fasteners, adhesive, lockset, strike plate, etc.) within the cavity  222  provides several advantages. The overall thickness of the door kit  210  is significantly reduced (compared to the extensions assembled with respect to the bases), thereby simplifying shipping and substantially reducing storage space requirements for transport and inventory. The securing of the extensions  214   b ,  216   b , and  218   b  adjacent to the outer surfaces of the bases  214   a ,  216   a , and  218   a  and the stowing of other parts  224  within the cavity  222  also reduces instances of accidental loss of the unassembled parts. Further, the door  220  can be pre-hung to the partially preassembled split jamb assembly  212  of the door kit  210  by one or typically two, three, or more hinges connecting the door  220  to one of the side bases  214   a  or  216   a , so that installation is simplified. 
     A method of packaging the door kit  210  will now be described in greater detail. The partially preassembled split jamb assembly  212  including the first and second side bases  214   a  and  216   a  substantially parallel to one another and the header base  218   a  substantially perpendicular to and interconnecting the first and second side bases  214   a  and  216   a  is provided. Fasteners, adhesives, sealants, and/or other adjoining mechanism(s) and/or chemical(s) may be used to connect the bases  214   a ,  216   a , and  218   a  to one another and form the partially preassembled split jamb assembly  212 . For packaging, the door  220  is arranged within a space defined by the first and second side bases  214   a  and  216   a  and the header base  218   a  of the partially preassembled split jamb assembly  212  so that the door  220 , the first and second side bases  214   a  and  216   a , and the header base  218   a  collectively establish the cavity  222 . The extensions  214   b ,  216   b , and  218   b  are moved into the stowed positions and their outer surfaces are secured adjacent to outer surfaces of the bases  214   a ,  216   a , and  218   a . The packaging material  226 , such as plastic wrap, may be wrapped around the partially preassembled split jamb assembly  212  to establish a side of the cavity  222  opposite to the door  220 , and thereby retain the trim parts  224  in the cavity  222 . The packaging material  226  may also serve to further secure the extensions  214   b ,  216   b , and  218   b  in place relative to the bases  214   a ,  216   a , and  218   a , respectively. 
     To install the door kit  210  into a wall opening, the packaging material/enclosure  226  is removed, the extensions  214   b ,  216   b , and  218   b  are moved from their stowed position to their extended or deployed positions relative to the side bases  114   a ,  116   a , and  118   a , respectively. The split jamb assembly  112  is inserted into an opening of a wall doorframe  30  in the same manner described above in connection with the first embodiment and  FIG.  2   . Standard fasteners, adhesive, sealant, and/or other mechanical mechanisms and/or chemicals may be employed to secure the bases  214   a ,  216   a , and  218   a  to the wall doorframe  30 . Plumbing and/or shimming may also be performed to properly align the partially preassembled split jamb assembly  212 . Optionally, the trim  224  is then attached to the first split side jamb  214 , the second split side jamb  216 , and the split header  218 . Trim in the form of brick molding is connected by fasteners such as nails or screws, adhesive, and/or sealant to the first side base  214   a  on one side of the wall doorframe  30  ( FIG.  2   ) and to the first side extension  214   b  on the other side of the wall doorframe  30 . 
     The packaging and installation methods may be accomplished using additional or fewer steps. Also, the steps may be performed in various sequences. 
     The structures, methods, and other features of the embodiments described above may be combined with one another and modified by persons skilled in the art having reference to this disclosure. 
     The enclosures  26 ,  126 ,  226  described herein may be made of packaging films such a polyvinylchloride (PVC), polystyrene (PS), polyethylene (PE), polyethylene terephthalate (PET), low density polyethylene (LDPE), and high density polyethylene (HDPE), all preferably +/−0.5 mil thick. An exemplary commercial enclosure material is U25112 Unisource Defiance VMC Stretch Film 30X9000FT 50GA LLDPE CST MG C1S 20/SK. Other enclosure materials that may be used include metal (e.g., steel) banding/strapping (e.g., 0.014 to 0.025 inch thick), polyphenylene ether, and corrugated cardboard. 
     Although the above exemplary embodiments have been described in connection with door kits and door units, a person of ordinary skill in the art having reference to this disclosure will understand that the principles described herein may be applied to a window kits and window unit. 
     The foregoing detailed description of the certain exemplary embodiments has been provided for the purpose of explaining the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. This description is not necessarily intended to be exhaustive or to limit the invention to the precise embodiments disclosed.