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CROSS REFERENCES  
       [0001]    This application is a continuation-in-part of co-pending U.S. application Ser. No. 10/411,535 filed Apr. 10, 2003. 
     
    
     
       TECHNICAL FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to door frames and, more particularly, to a modular sill assembly which may be vertically adjusted and adapted for a variety of doorway configurations.  
         BACKGROUND OF THE INVENTION  
         [0003]    In a standard threshold assembly, a sloping sill is attached to a base. The sill is oriented on the exterior of the door frame. A trim piece or nosing is generally attached to the opposite side of the base facing the interior of the door frame. Between the sill and trim piece, a riser or threshold cap is attached to the top of the base. The riser is positioned to underlie the door when it is in a closed position and form a seal with the bottom of the door.  
           [0004]    Several methods of attaching the riser to the base exist in the prior art. In particular, a number of these prior art designs provide for adjustment in the height of the riser relative to the base. These prior art designs tend to incorporate mechanisms, for example, corresponding nut and screw assemblies, that are fixed in position relative to the length of the base.  
           [0005]    The manufacture of the individual pieces comprising a sill assembly and the method of attaching the riser to the base have presented numerous design issues to the millwork industry. One particularly troublesome issue is the fact that, doorways, come in a large variety of configurations. For instance, a door frame may accommodate a door and a non-moving sidelight or a pair of opposing (“french”) doors and an astragal, which may or may not be attached to one of the opposing doors. Current sill designs can be used in a limited number of configurations and provide little flexibility in the available configurations. While manufacturers have attempted to design threshold assemblies that are adaptive in some aspects, none have produced a design that provides sufficient adaptability. As mentioned above, the prior art designs generally utilize attachment mechanisms that are fixed in position relative to the length of the base.  
           [0006]    Furthermore, these prior art designs utilize a large amount of custom hardware, particularly in their attachment mechanisms, such as specialized shoulder screws and push nuts. This custom hardware increases the cost of the sill assembly and requires that manufacturers stock a large amount of custom pieces for which they have no other use.  
           [0007]    An improved sill assembly would preferably have a modular design that is capable of ready adaptation to various doorway configurations, while requiring a minimal amount of custom hardware for assembly.  
           [0008]    The present invention is directed to overcoming one or more of the problems set forth above.  
         SUMMARY OF THE INVENTION  
         [0009]    An aspect of the present invention is to provide a modular sill assembly that is easily adapted to a variety of different doorway configurations.  
           [0010]    Another aspect of the present invention is to provide a modular sill assembly that utilizes a means of connecting a riser to a substrate that is easily adaptable to whatever length and arrangement is required by a particular doorway design.  
           [0011]    Yet another aspect of the present invention is to provide a modular sill assembly that utilizes a minimal number of custom parts for assembly, thereby enhancing interchangability of parts in the system.  
           [0012]    Another aspect of the present invention is to provide a modular sill assembly with a height-adjustable riser that can be adjusted without the need for a visible adjustment mechanism.  
           [0013]    In accordance with the above aspects of the invention, there is provided an adjustable threshold assembly that includes an elongated substrate base composed of a molded composite material; a sill plate connected with the substrate base; a riser having a top and two downwardly-extending legs defining an interior of the riser, said interior of the riser having a first flange and a second flange angling downward and toward one another; and means for supporting the riser on the substrate base including an adjusting screw and a corresponding T-nut, said adjusting screw having a head adjacent the substrate base and said T-nut slideably supported by the first and second flanges and wherein the riser is supported by the substrate base by threading the adjusting screw into the T-nut.  
           [0014]    In another embodiment, the adjusting screw is provided with an extended head that extends beyond the legs of the riser, thereby enabling adjustment of the screw by direct engagement and turning of the extended screw head.  
           [0015]    These aspects are merely illustrative of the innumerable aspects associated with the present invention and should not be deemed as limiting in any manner. These and other aspects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the referenced drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    Reference is now made to the drawings which illustrate the best known mode of carrying out the invention and wherein the same reference numerals indicate the same or similar parts throughout the several views.  
         [0017]    [0017]FIG. 1 is a perspective view of a doorway incorporating a sill assembly according to an embodiment of the present invention.  
         [0018]    [0018]FIG. 2 is a cross-sectional view of the sill assembly of FIG. 1 taken along line Z-Z.  
         [0019]    [0019]FIG. 3 is a partial section perspective view of an embodiment of a sill assembly illustrating a T-nut/screw fastening assembly.  
         [0020]    [0020]FIG. 4 is a cutaway view of an embodiment of a sill assembly  
         [0021]    [0021]FIG. 5 is a perspective view of an embodiment of a sill assembly for a doorway including an active door and sidelight or non-active door.  
         [0022]    [0022]FIG. 6 is a cross-sectional view of another embodiment of a sill assembly incorporating an alternate riser support arrangement.  
         [0023]    [0023]FIG. 7 is a cross-sectional view of yet another embodiment of a sill assembly incorporating a second alternate riser support arrangement.  
         [0024]    [0024]FIG. 8 is a cross-sectional view of an alternate embodiment of a sill assembly incorporating the riser support arrangement of FIG. 6.  
         [0025]    [0025]FIG. 9 is a cross-sectional view of yet another embodiment of a sill assembly incorporating the riser support arrangement of FIG. 6. 
     
    
     DETAILED DESCRIPTION  
       [0026]    [0026]FIGS. 1-4 illustrate a sill assembly shown generally at  10  including a substrate  12 , a sill  14 , a riser  16 , and a trim piece  18 . FIG. 1 illustrates a sill assembly  10  of this design installed in a door frame  20  between the door jambs.  
         [0027]    The substrate  12  shown in FIGS. 1-4 is generally rectangular in shape with a number of grooves formed therein. In the embodiment shown, the top surface  26  of the substrate  12  includes a first sill groove  28 . The bottom surface  30  of the substrate  12  includes a second sill groove  32 . The first and second sill grooves  28 ,  32  aid in securing the sill  14  to the substrate  12 . The substrate  12  is also provided with a first trim groove  34  in the top surface  26  and a second trim groove  36  in the bottom surface  30 . These grooves aid in securing the trim piece  18  to the substrate  12 . The top surface  26  of the substrate  12  also includes a T-shaped slot  38  that extends along the entire length of the substrate  12  and opens to the top surface  26 . In a preferred embodiment, the substrate  12  is manufactured from a composite material that is processed to form the desired cross-section for the substrate.  
         [0028]    The riser  16  includes a top surface  40  and first  42  and second  44  legs extending generally downward from the top surface. The top surface  40 , first leg  42  and second leg  44  define an interior  46  of the riser  16 . A first flange  48  and a second flange  50  are located within the interior  46  of the riser  16 . In the embodiment shown, the first flange  48  emanates from the first leg  42  and the second flange  50  is supported by the top surface  40  of the riser. However, the flanges  48 ,  50  may be supported by the first and second legs, respectively, the top surface  40 , or the top surface  40  and second leg  44 , respectively. Advantageously, the first and second flanges  48 ,  50  angle downward and toward one another forming a generally V-shaped structure with an opening  60  at the vertex of the flanges. An extension  52 ,  54  is located at the end of each flange  48 ,  50 . Preferably, the extensions  52 ,  54  are made of a softer durometer material than the rest of the riser  16 , such as a plastic material. The riser  16  itself is preferably made of an extruded plastic material, although a number of extrudable materials are suitable. In a preferred embodiment, the extensions  52 ,  54  are co-extruded with the rest of the riser. The riser  16  also includes a sealing leg  56  extending out and downward from the top surface  40  of the riser  16 . The sealing leg includes a sealing extension  58  that extends into the space between the sealing leg  56  and first leg  42 . The sealing leg  56  and extension  58  engage the sill in manner described below in order to form a weather seal for the sill assembly.  
         [0029]    During installation, the riser  16  is positioned on top of the substrate  12  with the opening  60  at the vertex of the flanges located generally above the T-shaped slot  38 . A T-nut  62  having a flange  64  is inserted into the T-shaped slot  38  with first and second lateral extensions  66 ,  68  of the slot accommodating the flange  64 . A corresponding screw  70  is inserted between the flanges  48 ,  50 , with the flanges supporting the head of the screw  70  and the threaded portion of the screw extending through the opening  60  between the flanges. The extensions  52 ,  54  of the flanges engage the screw  70  to restrict both vertical and lateral movement of the screw, thereby eliminating any need for a push nut or similar structure to secure the screw. This, in turn, eliminates the need to use special fasteners, for example, screws having shoulders designed to accommodate push nuts. Any standard screw of suitable length may be used instead. In order to secure the riser  16  to the substrate  12 , the screw  70  is inserted into the T-nut  62 , and the screw  70  is tightened. The height of the riser  16  relative to the substrate  12  is adjustable by varying the extent to which the screw  70  is tightened into the T-nut  62 . The riser  16  is preferably provided with a number of access holes  72  in the top surface  40  through which a screwdriver may be inserted in order to tighten the screw  70 . Caps  73  are provided to cover the access holes  72  and present a finished appearance. At least two T-nuts with corresponding screws are generally necessary to securely fasten the riser to the substrate in a level manner. In a preferred embodiment, a T-nut with a corresponding screw is positioned approximately every ten inches along the sill assembly.  
         [0030]    The slot  38  allows the T-nut  62  to be positioned anywhere along the length of the substrate  12 . Similarly, the flanges  48 ,  50  permit lateral movement of the screw  70  along the length of the riser  16 , although such movement does require some force due to the restriction of the extensions  52 ,  54 , to allow the screw  70  to be positioned anywhere along the length of the riser. This feature allows the position of the T-nut and screw fastening assemblies to be varied along the length of the riser/substrate subassembly. This arrangement enhances the modularity of the sill assembly by permitting greater interchangeability of parts.  
         [0031]    The sill  14  features a sloping top surface  74  having a number of ridges designed to enhance traction. On the underside of the sill  14  are located a front support  76  and a rear support  78 . Each of the supports  76 ,  78  is provided with a lateral extension  80 ,  82 . The front extension  80  is arranged to engage the second sill groove  32  in the substrate, while the rear extension  82  engages the first sill groove  28  to connect the sill  14  with the substrate  12 . The sill  14  also includes a sealing lip  84  which engages with the sealing leg  56  and extension  58  to form a weather seal. The remaining features of the sill  14  are generally known in the art and, therefore, will not be described in more detail.  
         [0032]    The trim piece  18  is preferably made from a material similar to that used for the riser  16 . Furthermore, both the riser  16  and trim piece  18  are provided with an identical finish in order to provide the sill assembly with aesthetically pleasing visible surfaces. The trim piece includes first and second connecting extensions  86 ,  88  which engage with the first and second trim grooves  34 ,  36  in the substrate, respectively, to secure the trim piece to the substrate.  
         [0033]    It is envisioned that each of the primary pieces of the sill assembly, the substrate, riser, sill and trim piece, will form a modular system in which these pieces may be interchanged. The easy adaptability of the system will decrease manufacturing costs and the amount of inventory a manufacturer must carry. Furthermore, because the screws used in the assemblies are standard, the amount of custom hardware necessary to assemble the product is minimized.  
         [0034]    [0034]FIG. 5 illustrates an embodiment of the sill assembly in a doorway having a door and a sidelight. The sill assembly  10  lies in a door frame (not shown in detail). A mullion  90  is positioned in the door frame between a door (not shown) and a sidelight  94 . A riser  16  attached to a substrate (not shown), as described above, extends under the door between one outer jamb and the mullion  90 . Between the mullion  90  and the other outer jamb, a sidelight adapter  96 , or fixed sill, is attached to the substrate to provide a level surface for installing the sidelight  94 . Like the other pieces of the system, the sidelight adapter  96  is intended to be extruded in a few standard lengths and cut to length at the installation site. A mullion adapter  98  is attached to the substrate between the riser  16  and the sidelight adapter  96  and provides a level surface for mounting the mullion  90 . This eliminates the need to cut the profile of the sill assembly into the mullion  90 .  
         [0035]    The above components are also suitable for use in patio or french doors. These doorways usually include dual opposing doors separated by an astragal. One of the opposing doors is generally kept fixed most of the time and is referred to as the non-active door. The astragal may be attached to one of the opposing doors but is usually attached to the non-active door. In this arrangement, a fixed sill can be attached to the substrate underneath the non-active door and the astragal, while a riser  16  can be positioned underneath the operating door. The modular design of the sill assembly allows the riser  16  and fixed sill to be easily configured whether the non-active door is on the right or left side of the doorway.  
         [0036]    [0036]FIG. 6 illustrates an alternate arrangement for supporting a riser  116  in a modular sill assembly. In the embodiment shown in FIG. 6, the remaining elements of the modular sill assembly are largely identical to the first embodiment shown in FIGS. 1-4. The sill includes a substrate  112 , a sill  114 , and a trim piece  118 . However, in the embodiment illustrated in FIG. 6, an adjusting screw  170  used to support the riser  116  is inverted relative to the arrangement shown in FIGS. 1-4. This allows the head of the adjusting screw  170  to serve as a pedestal that rests on the top surface of the substrate  112 . Alternately, the head  171  of the adjusting screw  170  may be inserted into the T-slot  138  of the substrate  112 . A T-nut  162  is secured between first  148  and second  150  flanges of the riser  116 . First  152  and second  154  extensions on the riser flanges engage the T-nut  162  to restrict both vertical and lateral movement of the nut. The first and second flanges  148 ,  150  and first and second extensions  152 ,  154  are spaced slightly wider than their counterparts in the embodiment shown in FIGS. 1-4 to accommodate the slightly wider diameter of the T-nut  162 . The T-nut  162  is threaded onto the adjusting screw  170 . A pair of tracks  155 , which extend along the length of the underside of the riser  116 , engages the flange  164  of the T-nut  162  and hold it a slight distance from the underside of the riser  116 . By moving the T-nut  162  slightly away from the underside of the riser  116 , the available room for raising the adjustment screw  170  is increased, thereby increasing the adjustment range of the system. In a preferred version of the embodiment, the adjusting screw  170  is provided with a slot (not shown) at the end opposite the head  171  and which faces upward. The slot allows easy adjustment of the riser height by turning the adjustment screw  170  and thereby moving the T-nut  162  upwards or downwards relative to the screw. Access holes (not shown) in the top of the riser  116  provide access to the adjusting screw  170 .  
         [0037]    [0037]FIG. 7 illustrates a slightly different version of the embodiment of FIG. 6. While the riser support arrangement is identical to that shown in FIG. 6, the substrate  212  of this embodiment is not provided with a T-slot. The T-slot is not required for the alternate riser support arrangement, and elimination of the slot reduces the overall cost of producing the substrate.  
         [0038]    The embodiments illustrated in FIGS. 6 and 7 include a sill sealing lip  184  provided with a ridge  185  running along the entire length of the sealing lip. The ridge  185  engages the sealing leg  156  and sealing extension  158  of the riser  116  to create an improved seal between the two pieces. A series of secondary ridges  187  are utilized on both sides of the sealing lip  184  to help secure the engagement of the sealing lip  184  and the sealing leg  156  regardless of the adjusted height of the riser  116 .  
         [0039]    In yet another alternate embodiment as shown in FIG. 8, the substrate  312  is provided with a hole  313  extending perpendicularly therethrough. The axis of the hole  313  is coextensive with the center of and communicates with T-slot  338 . The remainder of the embodiment is similar to that illustrated in FIG. 6. The hole provides access to the head of the adjusting screw  170  from the underside of the substrate  312 . This arrangement allows adjustment of the riser height without the need for access holes in the top surface of the riser when the threshold assembly is installed into a door frame prior to the frame being installed at the construction site, for example, in the case of pre-hung door frames that are assembled at a factory prior to shipment to a distributor or directly to a construction site. Elimination of access holes in the top surface of the riser provides a more aesthetic assembly and also eliminates a possible entry point for moisture into the interior of the assembly. As with the embodiments shown in FIGS. 6 and 7, this arrangement can also be provided without the T-slot  338 .  
         [0040]    [0040]FIG. 9 illustrates an alternate embodiment of the riser. In FIG. 9, adjusting screw  470  is provided with an oversized head  471 . The oversized head  471  extends beyond the second leg  444  of the riser  416 . In order to accommodate the oversized head  471 , the first  442  and second  444  legs of the riser  416  are slightly shorter than those of the risers in the above-described embodiments. The legs of the riser  416  do not extend entirely to the top surface of the substrate, thereby leaving a gap between the bottom of the legs and the top of the riser. This gap accommodates the oversized head  471  of the adjusting screw  470  and allows the screw to extend beyond the legs. Alternatively, a slot is provided in the second leg  444  of the riser  416  to accommodate the oversized head  471 . Depending on the configuration of the riser  416 , a corresponding slot in the first leg  442  of the riser  416  may also be necessary to fully accommodate the oversized head  471 . These arrangements allow direct manipulation of the oversized head  471  of the adjustment screw  470  and, consequently, adjustment of the riser height. The trim piece  418  is removed in order to gain access to the adjustment screw  470 . The trim piece  418  may also be made from a flexible plastic material that will allow it to be partially pulled away from the riser to expose the oversized head  471  of the adjusting screw  470  without the need to remove the trim piece from the assembly. In this embodiment, access holes in the top surface of the riser are not necessary. This provides a smooth and unblemished top surface for the riser, which provides improved aesthetics for the assembly.  
         [0041]    Other objects, features and advantages of the present invention will be apparent to those skilled in the art. While preferred embodiments of the present invention have been illustrated and described, this has been by way of illustration and the invention should not be limited except as required by the scope of the appended claims and their equivalents.

Summary:
An adjustable sill assembly includes a substrate base; a sill plate connected with the substrate base; a riser having a top and two downwardly-extending legs defining an interior of the riser, said interior of the riser having a first flange and a second flange angling downward and toward one another; and means for supporting the riser on the substrate base including an adjusting screw and a corresponding T-nut, said adjusting screw having a head adjacent the substrate base and said T-nut slideably supported by the first and second flanges and wherein the riser is supported by the substrate base by threading the adjusting screw into the T-nut. In another embodiment, the adjusting screw is provided with a head that extends beyond at least one of the downwardly-extending legs of the riser to allow engagement and turning of the adjusting screw from the side of the riser.