Abstract:
A latch is provided for use principally on a pivotal sash window of a double-hung sash window assembly. The latch comprises a latch-bolt slidably mounted within and biased relative to a housing, where the housing is mounted to the top rail of the sash window. The latch bolt is connected to a button for manual actuation of the latch bolt. The latch bolt, while maintaining the convenience and utility of a standard short throw latch, is contoured and designed to maintain engagement with the jam after the window has been deformed under high sustained wind loading typically experienced during extreme weather phenomena such as hurricanes and tornados. The engagement is assured in spite of twisting of the latch bolt within the corresponding opening in the jam.

Description:
FIELD OF THE INVENTION 
     This invention relates to a tilt latch mechanism for use in a pivotable sash window, and more particularly to a latch bolt designed to efficiently withstand high wind loading while simplifying installation into a window. 
     BACKGROUND OF THE INVENTION 
     One of the most valuable and cherished possessions, for many people, is unquestionably his or her own home, which is reflected by the fact that home improvement beyond the traditional contractor renovation has become a major industry. These home improvements include upgrades in older homes in the form of upgraded electrical service, copper plumbing, and particularly replacement windows. A longstanding reason for window replacement, in addition to improved curb appeal, had been the dramatic improvements in thermal efficiency of the double-paned window arrangement, which had already been incorporated into most new construction. 
     However, windows to be utilized for either new construction or as replacements have seen further improvement as a result of advances in building technology. Improvements to fenestration products have in part been driven by the need to meet more demanding national standards, and in some locations, local building codes which are even more stringent. 
     A major factor in devising such strict requirements is the ability of the windows to resist damage caused by storms, where storm damage to homes is typically attributable to the storm surge, flood damage, and wind damage. Damage attributed to hurricane Katrina striking the New Orleans area is estimated to be $81.2 billion dollars, and although much of that amount had been due to the flooding which resulted from the levee breaks, shattered windows from hurricane force winds is a significant contributor. Katrina had reached category five in intensity on the Saffir-Simpson Hurricane Scale, but then dropped to category three intensity once it made landfall, and maintained sustained winds between 110-130 mph. Hurricane Andrew, which in 1992 actually struck the Miami-Dade part of Florida at category five, had been the most costly natural disaster in American history, at roughly $26 billion. Victims of hurricane Andrew reported trying to ride out the storm while listening to the category five winds in excess of 156 mph shatter windows, with the glass being dispersed everywhere. 
     There were similar reports when hurricane Hugo struck South Carolina in 1989, devastating parts of historic Charleston. While the problem may be more often faced by residents of the southern and gulf states, it is not limited to those geographic areas. The “Great September Gale of 1815” was a category three hurricane that struck Long Island, New York, and broke through the barrier beach to create the inlet that still isolates Long Beach. Also, the New York Hurricane of 1893 directly struck New York City, and the Great New England Hurricane in 1938 killed over 682 people and cause over $4.7 billion in damage (2005 U.S. dollars). On average, a hurricane will make landfall in New England every 10-20 years, with last such case being Hurricane Bob in 1991, which killed ten people and caused 2.8 billion dollars in damage (2005 U.S. dollars). Window damage caused by weather phenomena, although very costly and common because of coastal hurricanes, is also problematic for many parts of the country that experience similar risk of damage during tornado season. 
     However, many if not most coastal areas now mandate that the windows installed be constructed to be both impact resistant and to satisfy other standards. One such standard includes a requirement that the window be able to withstand, for a set period of time, a certain design pressure (DP). A window with a DP30 rating, which would permit the window to maintain its integrity throughout the sustained winds of a category three hurricane, is rated to a pressure level equivalent to 110 mph wind speed, but is tested structurally at a pressure equivalent to 164 mph. Similarly, a window with a DP40 rating is rated to a pressure level equivalent to a 127 mph wind speed, but is tested at a pressure equivalent to a wind speed of 190 mph, and a DP50 rating requires satisfaction of even higher load requirements. Under high wind loading, it is not uncommon to see a window convex a couple of inches, but when properly designed, the window will regain its original form within the window frame. But this deformation under high wind loads creates another design consideration relating to the hardware. 
     A typical latch for a slidable sash window is shown by U.S. Pat. No. 4,901,475 to Simpson. A latch bolt is spring-loaded relative to its housing, and capable of movement between a retracted or unlatched position, and an extended or latched position. Only a relatively short throw is needed to retract the latch bolt and permit movement of the sash window. 
     Similarly, another latch for a tilt window is shown by U.S. Pat. No. 7,171,784 to Eenigenberg. The Eenigenberg latch has the same characteristic short throw to retract the latch bolt within the housing, but additionally offers structure permitting its use as a right-hand or a left-hand latch bolt. 
     Although the short throw characteristic of these tilt-window latches is very desirable, in terms of convenience to the user, and is satisfactory as far as the utility required for personal security, it is deficient maintaining latch integrity during severe weather conditions. Under the high wind loads experienced during a hurricane, the associated deformation to the window may cause the latch bolt to twist and thus the flat face of the bolt will not remain fully engaged with the jam. Also, the deformation, due to the convexing of the window from the winds, may reduce the amount by which any portion of the latch bolt remains engaged with the jam. 
     A simple solution to the problem would of course be to use a longer latch bolt, and to design the arrangement to have a longer throw, or travel distance, between the engaged and disengaged positions. However, that approach dilutes the advantageous nature of a quick release latch, where any user is able to easily open the window or rotate the window for cleaning, which generally occurs with far greater frequency than that for which such improved hurricane resistance characteristics are normally needed. This invention discloses a tilt latch capable of maintaining its integrity during high wind loading, while maintaining the convenience and overall utility of a short-throw latch bolt. 
     SUMMARY OF THE INVENTION 
     The latch of this invention is designed to be able to resist the “twist-out” effect that occurs when a window undergoes substantial deformation, which may occur as a result of the high sustained winds found in a hurricane, as well as the winds that may be found around the periphery of a tornado. The latch features disclosed herein may be utilized on any number of different latch types, but they are particularly useful for the sash window of a tiltable double hung window assembly. 
     The latch of this invention features a latch bolt, which is biased relative to the sash window, and is capable of resisting twist out effect without requiring large-scale changes to the latch bolt, which would affect its size and ease of use, particularly with regard to the throw of the latch. The throw of the latch bolt is unaffected by incorporation of the features of this invention. 
     The latch of this invention comprises a couple of different features. In order to successfully counter twist-out effect without modifying the size of the latch bolt and its throw, the nature of engagement of the face of the latch bolt tongue with the window jam becomes critical. Improvements to that engagement may be accomplished herein through a number of different embodiments. In one embodiment, an angled groove passes across the face of the latch bolt tongue in a direction roughly in line with the direction of the jam. The groove may begin at either the upper or the lower edge of the tongue, or may also alternatively begin at some position in between the upper and lower edges of the tongue. The angled groove feature has a combined effect, the first of which involves the creating an angled face on the tongue face, where the angle of the face may be designed for a particular size window so as to become flush with the jam, when the window and latch are experiencing high wind loads and deformation leading to twisting of the latch. In addition, the angled groove also creates lateral faces which may catch upon the window jam flange to aid the latch in resisting disengagement from the jam. 
     This angled groove may also, in another embodiment, be utilized in two places on the latch tongue. The tongue may have one angled groove beginning at some mid-point on the latch tongue front face and running towards the upper edge with progressively increasing depth, while another angled groove begins just below the first angled groove and runs down towards the lower tongue edge with progressively increasing depth. This tongue configuration would permit the latch bolt to be utilized in either a left-hand or a right-hand installation. 
     Another possible embodiment would have a groove which is not angled but rather parallels the front face of the latch bolt tongue. This parallel groove, similar to the angled groove, could run from top to bottom, bottom to top, or may alternatively run in either direction while beginning at some intermediate point between the upper and lower edge of the tongue. Additionally, the tongue of the latch bolt could have two such parallel grooves where one runs towards the top edge of the tongue, and the other runs down to the bottom edge of the tongue, with both grooves beginning at some intermediate point between the upper and lower edge of the tongue. 
     It should be apparent to one skilled in the art that although such a latch may typically be used for a tiltable sash window which rotates downward and inward (see  FIG. 1 ), it could also be used be used for a window that rotates clockwise and inwards or counterclockwise and inwards, in which case use of the terms up or down in describing the direction the groove runs on the tongue front face may presumably be replaced by left and right. The latch is not limited to a horizontal installation despite the fact that certain terminology herein suggests that such a situation is possible if not likely. 
     OBJECTS OF THE INVENTION 
     It is an object of this invention to provide a latch to be installed on the top rail of a sash window of a tiltable double hung window assembly. 
     It is a further object of this invention to provide a latch in which the latch bolt may be toggled from the latched to the unlatched position with a short throw. 
     It is another object of this invention to provide a latch that can maintain positive contact with a window jam during sustained winds of a hurricane. 
     It is another object of this invention to provide a latch that can maintain positive contact with a window jam during sustained winds associated with the periphery of a tornado. 
     It is another object of this invention to provide a latch that can maintain positive contact with a window jam during load conditions imposed by pressure testing to simulate hurricane force winds. 
     It is another object of this invention to provide a latch that can maintain positive contact with a window jam under conditions in which the window experiences severe deformation. 
     It is another object of this invention to provide a window latch that can resist latch “twist-out” effect during high wind loading. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a tiltable sash window utilizing the latch of this invention, with part of the master window frame removed to reveal latch details. 
         FIG. 2  is an enlarged perspective view of the latch details of  FIG. 1 . 
         FIG. 3  is a perspective view of a 1 st  embodiment of the latch of the current invention. 
         FIG. 4  is a perspective view of a 2 nd  embodiment of the latch of the current invention. 
         FIG. 5  is a perspective view of a 3 rd  embodiment of the latch of the current invention. 
         FIG. 6  is a perspective view of a 4 th  embodiment of the latch of the current invention. 
         FIG. 7  is a perspective view of a 5 th  embodiment of the latch of the current invention. 
         FIG. 8  is a perspective view of a 6 th  embodiment of the latch of the current invention. 
         FIG. 9  is a perspective view of a 7 th  embodiment of the latch of the current invention. 
         FIG. 10  is a perspective view of a 8 th  embodiment of the latch of the current invention. 
         FIG. 11  is a perspective view of a 9 th  embodiment of the latch of the current invention. 
         FIG. 12  is a perspective view of a 10 th  embodiment of the latch of the current invention. 
         FIG. 13  is an enlarged perspective view of the 4 th  embodiment of the latch according to the invention. 
         FIG. 14  is an enlarged perspective view of an 11 th  embodiment of the latch according to the invention. 
         FIG. 15  is a side view of the first side of the 11 th  embodiment of the latch according to the invention. 
         FIG. 16  is a bottom view of the 11 th  embodiment of the latch according to the invention. 
         FIG. 17  is a side view of the second side of the 11 th  embodiment of the latch according to the invention. 
         FIG. 18  is an end view of the 11 th  embodiment of the latch according to the invention. 
         FIG. 19  is an exploded view of the parts comprising the 11 th  embodiment according to the invention. 
         FIG. 20  is an exploded view of the reverse side of the parts comprising the 11 th  embodiment according to the invention. 
         FIG. 21  is a bottom perspective view of the 11 th  embodiment of the latch according to the invention, before installation. 
         FIG. 22  is a perspective view of the 11 th  embodiment of the latch and the sash window frame, before installation of the latch. 
         FIG. 23  is a section cut through the 11 th  embodiment of the latch and sash window rail and stile, after installation of the latch. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The latch design features of the present invention may be incorporated for use into any one of the various different latch configurations of the prior art, as well as others which may be created. The advantageous nature of these design features, which may be incorporated in whole or in part, are best described in terms of one of the particular latch embodiments, which may be utilized in many different applications, but are particularly useful for a tiltable sash window of a double-hung sash window assembly. 
       FIG. 1  depicts a tiltable single-hung or double hung window assembly  70  with an upper sash window  81 , lower sash window  82 , and a master frame consisting of a sill portion  71 , a head jam  72 , and side jams  73 . Portions of the head jam  72 , and the side jams  78  have been cut away in the figure in order to illustrate the features of the jam with which the latch interacts. The lower sash window  82  is comprised of bottom rail  86 , top rail  87 , and stiles  84  and  85 , which support the edge of the glazing, or glass pane  83 . As is common for a tiltable double-hung sash window, the lower portion of the window has a connection to the frame (not shown) which is both pivotable and slidable with respect to the frame, and the upper portion of the window has a latch  90  with a tongue  91  which is also slidable with respect to the jam, but may also be retracted to permit the lower sash window  82  to rotate inward (see  FIG. 2 ). 
     The tongue  91  of the latch  90  normally prevents the window from rotating inward, because, until the latch bolt is toggled, the front face  92  of the tongue  91  bears up against the bearing surface  75  of the side jam flange  74 . It is this connection, as previously discussed, which is critical to withstand the high wind loads. When substantial deformation to the window occurs as a result of high wind loading, causing the latch bolt to twist, the flat front face  92  of the tongue  91  will not remain fully engaged with the jam. The twisting will tend to result in only one edge of the front face  92  making contact with the bearing surface  75  of jam flange  74 , and additionally, the deformation due to the convexing of the window may further cause the tongue to be angled with respect to a vertical axis, such that only a portion of the bottom edge of the tongue maintains contact with the jam flange at the inner edge of the jam flange. These deformations make the latch subject to “twist-out” effect whereby the jam does not positively restrain the latch tongue, and the window may rotate under such loading. 
     A series of design modifications to the latch tongue found in this invention negate this effect, and are shown by the various exemplary embodiments of  FIGS. 3-12 . The advantageous nature of the design is illustrated by the latch embodiment 4 shown in  FIG. 6 , and also in  FIG. 13  but at a larger scale. However, each of the latch embodiments shown in  FIGS. 3-12  represent substantial improvements over a conventional latch in order to provide it with improved characteristics necessary to resist twist-out effect. 
     The latch  4  embodiment ( FIG. 13 ) comprises the latch body  420  which is a combination latch bolt and trigger, a spring  13  ( FIG. 19 ) and fixed member  14 . The fixed member  14  and latch body may be slidably interconnected ( FIGS. 15-17 ,  21 , and  23 ), whereby a portion of the fixed member extends beyond the latch body, and a portion of the latch body extends beyond the fixed member, and with other features co-acting, as will be described hereinafter. The fixed member  14  is set against the top rail  87  of the lower sash window  82 , and in conjunction with spring  13 , biases the latch body relative to the top rail  87  ( FIG. 23 ). The combination of latch body  420 , spring  13 , and fixed member  14  may be installed through a pair of openings  88  and  89  ( FIG. 22 ), which may be punched in the top rail and stile respectively. The size and position of the openings  88  and  89  may be coordinated to match the size of and spatial relationship between the tongue and latch bolt body. 
     The latch body  420  ( FIG. 13 ) may comprise a top plate  421  which may sit flush atop the top rail  87 . The top plate  421  may have rounded comers  422  for aesthetic appeal as well as for providing a safer end of the part as opposed to having a sharp edge. Protruding upward from the top plate is toggle button  424 . Immediately adjacent to toggle button  424  is a recess  425  which permits the button to have a larger surface area that may be contacted by the thumb or fingers of the user seeking to pivot the window, while permitting a reduced height toggle button that protrudes at an unobtrusive height above the top rail  87 . The top plate  421  may additionally have a raised area  423  if desired, as well as lateral extensions  426  and  427 . 
     The latch body  420  may further comprise a latch bolt housing  430  that may be either attached to or integral to the top plate  421 . The housing  430  may have a first side wall  451 , a second side wall  452 , and a bottom wall  453 , and the housing  430  has a first end  447  that may facilitate biasing of the latch bolt body relative to the window top rail  87 , as will be seen later, and a second end  448  which terminates in latch bolt tongue  432 . A portion of the fixed member  14  may be slidably retained by the walls of the housing ( FIGS. 15-17 ,  21 , and  23 ). The housing  430  may also have a plurality of protrusions  431  which may assist in retaining the latch bolt body within the top rail  87 . The latch bolt housing may also have one or more protrusions to co-act with features on the fixed member, such as protrusion  149  that may co-act with a correspondingly located protrusion  141  on the fixed member ( FIGS. 20 and 23 ) to limit biased travel of the latch bolt relative to the fixed member, and thus also limit its biased travel relative to the window stile. The protrusion  141 , which may be located on the underside of the top connecting wall  147 , may be sloped on one side and be flat on another side. The connecting wall  147  may span between first side wall  145  and second side wall  146  of the fixed member  14 . At a first end  143  of the fixed member ( FIG. 19 ), there may be a recess  149  in the top connecting wall  147 , and another recess  150  at a second end  144  of the fixed member  14 . There may also be an end wall  148  at the second end  144  of the fixed member  14 , which may be angled ( FIG. 20 ). The recess  150  may be formed in top connecting wall  147  at the second end of fixed member  14  or in the end wall  148 . Also, as seen in  FIG. 19 , first side wall  145  and second side wall  146  may have a plurality of openings  151  so as to create a plurality of cantilevered members  152  ( FIG. 20 ). The cantilevered members  152  may further comprise small protrusions  153  at the cantilevered end of the cantilevered members  152 , which, as seen in  FIG. 20 , may make slidable contact with the underside of the housing bottom wall  453 , once inserted therein ( FIG. 18 ). To accommodate retention of the biasing spring  13 , latch body  15  may have a post  450  ( FIG. 23 ), and fixed member  14  may have a similar post  154 . 
     Latch bolt tongue  432  may be attached to or be integral to the housing  430  and top plate  420 . Latch bolt tongue  432  may have a top surface  433  and bottom surface  434 , which need not be, but is however shown as being generally parallel in the latch  4  embodiment, and the other embodiments. The top surface of the latch bolt tongue, as seen in  FIGS. 15 and 17 , may be formed so as to create a gap  454  with the top plate  420 . This gap may be used to receive a first portion of the window top rail  87  for installation of the latch ( FIG. 23 ), or alternatively, the recess  149  in fixed member  14 , if the recess is of an appropriate depth, may work in conjunction with the top plate  420  to receive the portion of window top rail  87 . The opposite end of the latch may retain a second portion of the top rail  87  using recess  150  and top plate  420 . Furthermore, as to the latch bolt tongue  432 , top surface  433  and bottom surface  434  need not be flat, and may conversely be curved in one or more directions. The latch bolt tongue  432  may also have a back face  435  that is slanted with respect to front bearing face  436 , which extends between top surface  432  and bottom surface  433 . The slanted face  435  and front bearing face  436  may form a sharp edge or may alternatively be formed so as to have a chamfered tip  37 , or even a rounded tip. One end of the front face  436 , as it meets the tip- either chamfered, rounded or a sharp edge- is its outer end  429 , and is opposite the inner end  428 . Outer end  429  and inner end  428  need not be parallel, and they need not form a linear edge. 
     Front bearing face  436 , which will normally be flush against the bearing surface  75  of side jam flange  74 , may be interrupted by a step feature, which, for embodiment 4 may comprise lower angled groove  438 . Lower angled groove  438  may be created by the lower groove face  439  which is angled with respect to front bearing face  436  and thus would also form a first lateral face  440  and second lateral face  441 . The groove face in this embodiment is flat, however, it could also be curved in this and any other embodiment. These lateral faces may similarly be flat, or they may be curved, or they may initially be flat and thereafter transition into a curved portion, essentially forming a fillet radius between a flat portion of the lateral face and the groove face. Also, these lateral faces  440  and  441  may be perpendicular to front bearing surface  436 , or they may be angled with respect to front bearing surface  436  and may thus be so designed to catch a lip or recess formed at the junction of bearing surface  75  and side bearing surface  76  of side jam flange  74 . The lateral faces may also be generally triangular in shape. In other embodiments described in subsequent paragraphs, when the groove face may have a different orientation with respect to the tongue front bearing face, these lateral faces may then be generally rectangular in shape, trapezoidal in shape, or possibly an irregular shape. 
     The step feature of the latch 4 embodiment may also comprise the front bearing face  436  being interrupted by an upper angled groove  442 , which is similarly created by upper groove face  443 , and first and second lateral groove faces  445  and  445 , respectively. The front bearing face  436  being interrupted by lower angled groove  438  and upper angled groove  442  results in the front bearing surface  436  resembling an “H” shape, where the connecting portion or surface  446  would normally be in contact with the bearing surface  75  of side jam flange  74 . 
     When the window  70 , and consequently the latch  4 , is subjected to the high wind load conditions, the design of the latch bolt tongue  432  enables the latch to resist the “twist-out” effect and remain positively engaged with the side jam flange  74  for a combination of reasons. 
     First, as the latch experiences twisting due to the wind loading, the connecting surface  446  that had been bearing upon bearing surface  75  of window  70 , is now angled away from the bearing surface  75 , but the angled groove face of the tongue  432  may now be flush to bearing surface  75 . It can be appreciated by one skilled in the art, that the size and shape of a particular window will affect the magnitude of loading and twisting to the latch  4  installed in such a window, because the increased surface area of a larger window will produce higher loads under a 30, 40, or a 50 pound per square foot wind load condition, than a smaller window, and this load must be reacted by the latch  4 . Therefore, the relative angle between the groove face  439  or  443 , and the front bearing face of the tongue  436  (and more particularly connecting surface  446 ) may be increased or decreased for a particular window latch to accommodate such loading and twisting for a particular window design. In fact, that relative angle should necessarily be different and be custom designed for each particular window configuration. 
     Secondly, and perhaps more significant for the latch  4  to resist the high wind-loading, is the fact that lower angled groove  438  creates the lateral groove face  441 , and similarly the upper angled groove  442  creates lateral groove face  445 . When high sustained winds would create deformation that would tend to pull the tongue from the opening in the jam and permit the window to unexpectedly rotate, these lateral faces  441  and  445  may engage the side bearing surface  76  (see  FIG. 2 ) of side jam flange  74  of window  70  to resist such loading. 
     While it would be apparent to one skilled in the art that loading of the window  70  will only produce twisting in one particular direction, so that having both the lower and upper angled grooves  438  and  443  on the latch  4  as installed in  FIG. 2 , would not be necessary, it is nonetheless beneficial. Having the tongue designed and manufactured as shown with both lower groove  438  and upper groove  443  allows the latch bolt to be utilized in either of the left-hand or the right-hand latch positions of the window  70 . 
     The advantageous nature of constructing the tongue  432  of a window latch  4  as shown in  FIGS. 6 and 13 , may also be recognized in the other possible embodiment as shown in FIGS.  3 - 5  and  FIGS. 7-12 . In the latch embodiment 1 of  FIG. 3 , the tongue  132  has a step feature in the form of a single groove  138 , and unlike embodiment 4, the groove  138  is not angled with respect to the front bearing face of the tongue and actually parallels the front bearing face. Although this embodiment would not have an angled bearing surface to be flush with bearing surface  75  (see  FIG. 2 ) of side jam flange  74  of window  70  as with embodiment 4, it would still be capable of meshing with the side bearing surface  76  to resist the tendency of the wind loading to pull the tongue from the opening. 
     The embodiments 7 and 8, shown in  FIGS. 9 and 10 , may each have a parallel groove,  738  and  842  respectively, as with embodiment 1, but for embodiments 7 and 8 the parallel grooves  738  and  842  do not run vertically across the entire front bearing face, as there are connecting surfaces  736  and  836  respectively, which are comparable to connecting surface  436  of embodiment 4. Embodiment 9 incorporates a combination of both an upper and a lower groove, such that it may, like embodiment 4, be utilized in either of the left-hand or the right-hand latch positions of the window  70 . 
     Embodiments 2 and 3 each have a single angled groove  242  and  328  respectively, and permit a similar response by the latch tongue to wind loading as with embodiment 4. However, embodiments 2 and 3 do not have a bearing surface, comparable to surface  446  of embodiment 4, which normally is flush to the bearing surface  75  of side jam flange  74  of window  70 . The angled groove  242  of embodiment 2 begins at the tongue bottom surface, and can have some initial depth or may essentially have no depth or a zero depth where the groove begins at the bottom surface, but in either case the groove will have increasing depth with increasing distance from the bottom surface. Angled groove  328  may be similarly formed, but would actually begin at the tongue top surface and have increasing depth with increasing distance from the top surface. 
     Embodiment 5, shown in  FIG. 7 , is essentially configured like embodiment 4, except that it has only one angled groove  538 , and thus would not be capable of installation in either the left-hand or right-hand latch positions as would be embodiment 4, nor would embodiments 2 and 3 have that left-hand right-hand installation advantage. However, utilizing only the single angled groove of embodiment 5 permits the groove to run across a greater vertical distance on the tongue for a given angle, which results in an increase in the depth of the lateral face which may engage the side bearing surface  76 . 
     One additional embodiment that would be advantageous in resisting high sustained wind loading, is shown by embodiment 10 in  FIG. 12 . Embodiment 10 has a surface  1038  that is offset from and parallel to face  1036 . Surface  1038  begins at the inner end of face  1036  so as to create a lateral face  1041 , which may engage the side bearing surface  76  of side jam flange  74  of window  70 , as already discussed. 
     Other modifications, substitutions, omissions and changes may be made in the design, size, materials used or proportions, operating conditions, assembly sequence, or arrangement or positioning of elements and members of the preferred embodiment without departing from the spirit of this invention as described in the following claims.