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RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 62/276,788, filed Jan. 8, 2016, which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to sills for doors and windows, and, more particularly, to such sills with water drainage features for high differential-pressure (high DP) applications and to convertible sill assemblies. 
       BACKGROUND 
       [0003]    Door sills including water catchment and drainage features are known in the art for preventing water ingress in high differential pressure environments. Many such sills employ interior drainage channels and multiple chambers with drainage restrictions leading to an exterior weep. Some employ a column of standing water within the drainage pathway to resist water ingress from wind-driven rain and high differential pressures of the kind experienced in many coastal areas during tropical storms, typhoons, and hurricanes. In order to contain a column of water sufficient to resist differential pressures (DP) across the door of, for example, 35 or 50 psi, the sill must typically be relatively tall. Typically the height of such a high-DP sill at the threshold above the adjacent interior floor and exterior decking presents challenges for compliance with the American for Disabilities Act (ADA) or other handicap-accessibility or wheelchair-accessibility regulations, in that a tall threshold can impede entry and egress of persons with mobility impairment. 
         [0004]    To ease ADA compliance, some known sills employ a low-profile design that forms a DP-resistant water column within a drain trough or chamber that depends downwardly from an outermost edge of the sill, below the level of the floor or subfloor on which the threshold portion of the sill structure is supported. Such a drainage trough forms an exterior chamber in the drainage pathway of the sill and is positioned outboard of the exterior edge of the floor or subfloor on which the sill is supported. Weep openings along the bottom of the drain trough are sized relatively small so that a column of water is retained within the trough during high DP conditions to thereby resist ingress of water upwardly into the sill and into the building via the door seal or track of the sill. 
         [0005]    The present inventors have recognized certain disadvantages of low-profile sills with exterior drop-down drain troughs. For example, the downwardly depending trough, which can extend an inch or two below the bottom of the sill, requires clearance in the exterior decking or flooring to accommodate it. Not all installation locations allow for such clearance. The present inventors have therefore identified a need for improved door sills with water drainage features for high differential pressure environments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an isometric view of a door frame and sill assembly according to a preferred embodiment. 
           [0007]      FIG. 2  is an enlarged isometric view of the sill assembly of  FIG. 1 . 
           [0008]      FIG. 3  is an isometric section view of the sill assembly of  FIG. 2  with jamb members of the door frame omitted and showing detail of a removable drop-down drainage trough. 
           [0009]      FIG. 4  is a bottom view of the sill assembly of  FIG. 3  with the door frame and corner key components omitted, showing detail of drainage openings formed in interior walls of the sill body. 
           [0010]      FIG. 5  is an isometric view of the sill assembly of  FIG. 2  with door jamb and a left-side corner key omitted, and with the drop-down drainage trough/reservoir removed. 
           [0011]      FIG. 6  is an end elevation view of the sill assembly of  FIG. 2 , with the jamb members and left corner key omitted to show detail of the sill body and right corner key. 
           [0012]      FIG. 7  is an enlarged isometric detail view of a drainage trough of the sill assembly of  FIGS. 1-4 and 6 . 
           [0013]      FIG. 8  is an isometric view of the right-side corner key of the sill assembly of  FIGS. 5 and 6 , marked to show the location of a score or cutting region along which an end cap for the drainage trough can be removed when necessary. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0014]    With reference to  FIG. 1 , a door frame  10  according to a preferred embodiment includes left and right jambs  12 ,  14 , a head jamb  16 , and a sill assembly  20 . In combination, the side jambs  12 ,  14 , head jamb  16  and sill assembly  20  are sized to retain one or more door panels (not shown). The embodiment of the frame  10  depicted herein is a frame for a sliding glass door or other sliding patio door. However, some embodiments of the inventions described herein may be used in frames and sill assemblies for non-sliding doors, such as conventionally side-hinged entry doors, or for windows or other fenestration systems not specifically illustrated herein. Consequently, nothing in the detailed description should be construed as limiting the invention to frames and sills for sliding doors. 
         [0015]      FIG. 2  is an enlarged view of door frame  10  showing detail of sill assembly  20 . With reference to  FIG. 2 , sill assembly  20  includes a sill body  24  attached to left and right jambs  12 ,  14  via respective left and right corner keys  26 ,  28 . Left and right corner keys  26 ,  28  are preferably made of molded plastic for rot resistance and affixed to opposite ends of sill body  24  by screws  32  and/or adhesive or other means. Similarly, corner keys  24  and  26  are fixed to left and right jambs  12  and  14  by screws  36  or other means, holding all or a portion of jambs  12 ,  14  above the surface of sill assembly  20 . Sill assembly  20  includes a drainage trough  40  which depends downwardly from an exterior margin  44  of sill body  24  outside of the plane of the doors, as described below in greater detail with reference to  FIGS. 3-7 . End cap portions  46 ,  48  of corner keys  26 ,  28  are fitted against the ends of drainage trough  40  to form a container or reservoir within the trough as further described below. A tread bar  52  is fastened to a top surface  104  ( FIG. 3 ) of the sill body  24  to help prevent accidental slippage when the threshold is wet. 
         [0016]      FIG. 3  is an enlarged cut-away isometric section view of sill assembly  20  of  FIG. 2  with the right jamb  14  of frame  10  omitted for clarity. Sill body  24  is preferably formed of extruded aluminum or another metal or extruded plastic. Sill body  24  includes an upstanding inner wall  62  along an inner longitudinal marginal edge of sill body  24  and a door channel  64  formed between inner wall  62  and a longitudinal forward gutter wall  68  of sill body  24 . One or more rails  72  located within door channel  64  and extending upwardly from a floor  70  of sill body  24  may include an elongate track  74  for guiding a sliding door (not shown) that slides within the door channel  64 . Rails  72  and track  74  are preferably shorter than inner wall  62  so that the sliding door sits lower than inner wall  62  and slidably seals a bottom surface of the door against a resilient sealing strip  76  that is retained in a slot formed along a top edge of forward gutter wall  68 . Sill body  24  includes a raised sill cap  80  located externally (outward) of door channel  64  and supported above floor  70  by first and second spaced apart longitudinally-extending upstanding walls, including a first wall  82  (best illustrated in  FIG. 5 ) located outwardly of forward gutter wall and between forward gutter wall  68  and a second wall  84 . A brush seal  86  or other weather sealing strip is attached to an inward edge of sill cap  80  and bears against an external face of door (not shown), maintaining the seal against the door face as it is slidably opened and closed. First wall  82  is spaced apart from forward gutter wall  68  to form a gutter or catchment tray  88  that catches any water that may drip between brush seal  86  and the door. The space above floor  70 , below sill cap  80  and between first and second walls  82 ,  84  comprises a first chamber  90 . One or more first passages  92  are formed through first wall  82  between catchment tray  88  and first chamber  90 , allowing any water that may drip into catchment tray  88  to drain outwardly into first chamber  90 .  FIG. 4  is a bottom view of sill assembly  20  illustrating how first passages  92  are formed by milling or otherwise machining out a section of the floor  70  and a bottom section of the first wall  82  from below sill body  24 . Similarly one or more second passages  94  may be formed in second wall  84  allowing water to drain from first chamber  90  into a reservoir chamber  96  ( FIG. 3 ) formed between sill body  24  and drainage trough  40 . Additional passages  98  are similarly formed in forward gutter wall and rails  72 ,  74  for drainage of any water that may be deposited inwardly, for example during opening and closing of the door. Floor  70  is formed with a slight decline in the outward direction relative to a supporting bottom surface of sill body  24  to thereby facilitate gravity drainage of water through passages  92 ,  94 ,  98 . After passages  92 ,  94 ,  98  have been formed in sill body  94 , the floor of the passages may be sealed by plugs, adhesive film or other sealing material (not shown). Thus, a collection of one or more passages extend from catchment tray  88  outwardly through sill body  24  toward exterior margin  44  to an outlet of the sill body, so that the passages (e.g.,  92 ,  94 ,  98 ) allow water to drain from catchment tray  88  out of sill body through the outlet and, optionally, into the reservoir chamber  96  of drainage trough  40 , when drainage trough  40  is attached to sill body  24 . A series of weep holes  99  are drilled into or otherwise formed along the bottom surface of drainage trough  40  (generally after extrusion of drainage trough  40 ) for allowing water to slowly drain from reservoir chamber  96 . Weep holes  99  are sized small enough that surface tension prevents water from draining when sufficient back-pressure is present. This allows a column of water to form within reservoir chamber  96  during storm conditions. The weight of the water column in reservoir chamber  96  then opposes ingress of water and air (wind) through weep holes  99  and, after sufficient water builds up, the column provides sufficient head to cause drainage through weep holes  99  even during high DP conditions, as is known in the art. 
         [0017]    A threshold  100  of sill assembly  20  is formed in major part by a top surface  104  of sill cap  80 , which is inclined and textured to provide a non-slip tread surface while allowing water to run off. An auxiliary tread bar  52  may be fastened to top surface  94  of sill cap  80  via screws which are screwed into second wall  84  from above. An upstanding guide rail  106  for a screen door (not shown) may extend along an exterior margin  108  of sill cap  80  and sill body  24 . 
         [0018]    Drainage trough  40  is detachably connected to sill body  24  outwardly from second wall  84  so that drainage trough  40  can be removed at the job site when the installation site (flooring, external decking, etc.) cannot accommodate the downwardly-extending drainage trough  40 , or when high DP performance is not needed in the drainage system of sill assembly  20 , or when another system is provided for high-DP drainage performance. Drainage trough  40  is detachably connected to an underside of sill body  24  adjacent an exterior margin of sill cap  108 . Detachability of drainage trough  40  allows sill assembly  20  to be manufactured and sold with or without a drainage trough  40 , and may enable frame  10  and sill assembly  20  to be converted in the field to a very low profile sill assembly, on demand, by removing the drainage trough  40  from the sill assembly when desired.  FIG. 5  illustrates sill assembly  20  without drainage trough  40  attached. Thus, sill assemblies according to the present disclosure, such as sill assembly  20 , may provide a low-profile handicap-accessible or wheelchair-accessible threshold (e.g. ADA-compliant threshold) with high-DP drainage features, while providing for the ability to convert in the field for installation in places that do not have space for the downwardly-depending drainage trough  40  (or where such a tough and reservoir are not needed or desired). In one embodiment, sill assembly  20  provides high-DP performance, such as at least DP-35 or DP-50 or better, while the threshold of sill assembly rises to a height of no more than 0.75 inch, or not more than 1.0 inch (2.54 cm), above the surface of the supporting flooring or subfloor of the entryway and the underside of the sill body  24 . 
         [0019]    With reference to  FIGS. 3 and 5-7 , drainage trough  40  is formed separately from sill body  24  and is generally U-shaped or channel-shaped with spaced-apart upstanding inner and outer walls  122  and  124 . In other embodiments, other shapes, such as a V-shape or rectangular shape, may be employed. A first outwardly projecting lip  132  and first channel  134  are formed along an upper edge of inner wall  122  and extend along the entire length of inner wall  122  of trough  40 . Lip  132  and channel  134  are shaped to interlock and nest with a first protrusion  136  and first groove  138  formed along an outer margin of floor  70  of sill body  24 . A second outwardly-projecting lip  142  and second channel  144  are formed along an upper edge of outer wall  124  extend along the entire length of outer wall  124  of trough  40 . Second lip  142  and second channel  144  face away from first lip  132  and first channel  134 , and interlock with and nest in a second protrusion  146  and second grove  148  formed along an underside of sill cap  80  proximal of exterior margin  108  thereof. Second protrusion  146  and second groove  148  generally face toward first protrusion  136  and first groove  148 . Outward spring force generated by the resilient material of drainage trough  40  (preferably extruded aluminum or plastic) causes lips  132 ,  142  to firmly seat in the respective grooves  138 ,  148  for retaining drainage trough  40  on sill body  24 . 
         [0020]    As illustrated in  FIG. 6 , when corner keys  26  ( FIGS. 1 ) and  28  are installed, tabs or ridges  160  projecting from corner keys  26 ,  28  extend inwardly of the ends of the walls  122 ,  124  of drainage trough  40  and provide support for walls  122 ,  124 . In particular, an arc-shaped lower ridge  162  (best shown in  FIG. 8 ) projects from end cap  48  and lines and supports the end of a curved bottom wall portion  164  of drainage trough  40 . A second ridge  168  (best shown in  FIG. 8 ) projects from end cap  48  in a cantilever manner and extends from outer wall  124  of trough  40  toward inner wall  122  of trough  40  to impede movement of walls  122 ,  124  out of engagement with sill body  24  and thereby prevent trough  40  from inadvertently being dislodged from sill body  24 . 
         [0021]    With reference to  FIG. 8 , when drainage trough  40  is to be removed for conversion of the sill assembly  20 , end cap  48  of corner key  28  may be detached, cut away, or otherwise severed from the remainder of corner key  28  along a score line or cutting zone represented by dashed line  182 . In some embodiments, the end caps  46 ,  48  must first be removed in order to detach drainage trough  40  from sill body  24 . In other embodiments, end caps  46 ,  48  are removed simultaneously with drainage trough  40  in a break-away operation. In still other embodiments, end caps  46 ,  48  are broken off, severed, cut away, or otherwise removed after drainage trough  40  is detached from sill body  24 . 
         [0022]    Various other means and methods of removably or detachably attaching drainage trough  40  to sill body  24  are envisioned within the scope of the present disclosure. For example, in one alternative embodiment (not shown), drainage trough  40  may be co-extruded with sill body  24 , being connected thereto by a very thin wall section, such that drainage trough can be easily cut or torn away from sill body  24  to convert sill assembly  20  to a low profile sill. In still another embodiment, the drainage trough may be connected to sill body  24  by a snap-fit arrangement, adhesive, threaded fasteners or pinch connection. 
         [0023]    It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the claims.

Summary:
A sill assembly for a door or window frame includes an elongate sill body with a water catchment tray and one or more drainage passages extending from the catchment tray to an outlet, and a drainage trough mounted to an underside of the sill body and depending downwardly therefrom to define a reservoir that receives water that drains from the outlet of the drainage passages. The drainage trough includes weep holes which restrict outflow from the reservoir and is detachable from the sill body, which facilitates the manufacture of the sill assembly in different configurations to suit site requirements.