Patent Publication Number: US-2012023825-A1

Title: Watertight patio door assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present case claims priority to Canadian Patent Application No. 2,710,278 filed 30 Jul. 2010 and to U.S. Provisional Patent Application No. 61/369,952 filed on 2 Aug. 2010. The entire contents of Canadian Patent Application No. 2,710,278 and of U.S. Provisional Patent Application No. 61/369,952 are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The technical field generally relates to patio door assemblies and more particularly to patio door assemblies having an improved watertightness between two adjacent door panels. 
     BACKGROUND 
     A patio door assembly generally comprises two or more door panels disposed parallel to one another and that are mounted in a door frame. At least one of the door panels is slidably movable with reference to an adjacent and laterally offset door panel. Often, a patio door assembly comprises two door panels, one being slidable and the other being fixed (stationary) within the door frame. Many other different configurations exist, however. For instance, a patio door assembly can have more than two door panels. 
     One of the performance ratings for a patio door assembly is its resistance to rain water infiltrations from the exterior side to the interior side under severe weather conditions involving heavy rain and high winds when it is in a closed position. One of the main challenges for the designers of a patio door assembly attempting to obtain the highest possible rating is to mitigate the water infiltration between two door panels. The vertically-extending clearance gap located between the innermost vertical frame members of the door panels creates a possible entryway for water. 
     Generally, one or more weatherstrips are provided to mitigate air and water infiltrations through the clearance gap. However, during severe weather conditions, high winds impinging on the door panels can increase the air pressure on the exterior side, thereby creating a pressure differential between the exterior side and the interior side of the patio door assembly. This pressure differential can increase the risks of having water infiltrations from the clearance gap as water tends to be pushed towards the interior side. The bottom area of the clearance gap is particularly prone to water infiltrations since rain water flowing down along the inward door panel during a rain storm can result in a constant presence of water at that location. When combined to an air pressure differential, preventing water infiltrations during severe weather conditions can be difficult to achieve. 
     Attempts have been made in the past to mitigate water infiltrations from the clearance gap by providing better weatherstrips, often weatherstrips subjected to a more intense compression force when the patio door assembly is closed. This, however, is generally detrimental to the easiness of opening and closing the door panel or panels. These weatherstrips are also more prone to wear and may lose their efficiency over time. 
     Overall, room for improvements thus exists in this area. 
     SUMMARY 
     In one aspect, there is provided a watertight patio door assembly having an exterior side and an interior side, the patio door assembly including: a quadrilateral door frame having a sill section, a head section and opposite first and second jamb sections; two adjacent and laterally offset door panels mounted in the door frame and lying in respective vertical planes that are parallel to one another, at least one of the door panels being slidably movable within the door frame, each door panel including vertical and horizontal frame members, the innermost vertical frame members of the door panels being adjacent to one another and having a clearance gap between them when the patio door assembly is in a closed position; a combined air and water passageway located within the sill section of the door frame, the passageway providing a continual fluid communication between a location at a bottom end of the clearance gap and the exterior side of the patio door assembly; and two spaced-apart sets of weatherstrips creating a vertically-extending buffer air space within the clearance gap, the buffer air space being immediately above the location at the bottom end of the clearance gap, a first one of the two sets of weatherstrips being proximal to an exterior edge of the clearance gap and being continually subjected to a substantially equal air pressure on opposite sides, any water reaching inside the buffer air space being channeled directly into the passageway and kept away from a second one of the two sets weatherstrips, which second set is distal from the exterior edge of the clearance gap. 
     In another aspect, there is provided an insert for use in a main section of a top-opened gutter extending longitudinally inside a sill section of a patio door frame, the insert including: a first elongated wall having a width substantially corresponding to the width inside of the main section of the gutter, the first wall including a notch made across a thickness of the first wall and extending widthwise adjacent to one end of the insert; and at least two spaced-apart second elongated walls extending perpendicularly from a first main face of the first wall, at least one of the second walls crossing the notch made through the first wall. 
     In another aspect, there is provided a method for improving watertightness between a sliding door panel and of a stationary door panel of a patio door assembly, the method including the simultaneous steps of: blocking at least some of the air and water using a first set of weatherstrips positioned adjacent to an inlet of a vertically-extending clearance gap located between adjacent vertical frame members of the door panels when the sliding door panel is in a closed position; maintaining a substantially equal air pressure on opposite sides of the weatherstrips of the first set when a pressure differential occurs between an interior side and an exterior side of the patio door assembly; and draining water toward the exterior side if any water passes through the first set of weatherstrips, the water being prevented from reaching a second set of weatherstrips located deeper into the clearance gap. 
     Further details on these aspects as well as other aspects of the proposed concept will be apparent from the following detailed description and the appended figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an elevation view illustrating an example of a patio door assembly depicting the proposed concept. 
         FIG. 2  is an enlarged isometric view of the bottom center area of the patio door assembly shown in  FIG. 1 . 
         FIG. 3  is a cross-section view taken along line  3 - 3  in  FIG. 1 . 
         FIG. 4  is a view similar to  FIG. 1  showing the sliding door panel in a partially opened position. 
         FIG. 5  is a cross-section view taken along line  5 - 5  in  FIG. 4 . 
         FIG. 6  is an isometric view illustrating a portion of the bottom horizontal gutter shown in  FIG. 5 . 
         FIG. 7  is a cross-section view taken along line  7 - 7  in  FIG. 4 . 
         FIG. 8  is a cutaway view of some of the parts shown in  FIG. 2 . 
         FIG. 9  is an isometric view of the insert shown in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is an elevation view illustrating an example of a patio door assembly  10  depicting the proposed concept. This patio door assembly  10  is designed for use in an opening between the interior side and the exterior side of a building.  FIG. 1  illustrates the patio door assembly  10  as viewed from the exterior side of the building. The patio door assembly  10  includes a quadrilateral door frame  12 . The door frame  12  includes a sill section  12   a , a head section  12   b  and opposite first and second jamb sections  12   c ,  12   d . The lengthwise direction of the sill section  12   a  and the head section  12   b  of the door frame  12  define what is referred to hereafter as the longitudinal direction of the patio door assembly  10 . 
     The illustrated patio door assembly  10  includes only two door panels, one being a sliding door panel  14  and the other being a stationary door panel  16 . Other configurations and arrangements are possible as well. For instance, it is possible to construct a patio door assembly where the two door panels are slidable. It is further possible to construct a patio door assembly with three or more door panels. If desired, one or more of the door panels can tilted and/or otherwise moved with reference to an adjacent door panel in addition to a sliding movement. These are only a few examples of possible alternative configurations and arrangements for the patio door assembly. 
     Each door panels  14 ,  16  includes vertical and horizontal frame members inside which is positioned a windowpane. If desired, one or more of the windowpanes can be replaced by another kind of sheet or structure, whether transparent, translucent or opaque. 
     The sliding door panel  14  and the stationary door panel  16  are adjacent and laterally offset. They lie in respective vertical planes that are parallel to one another. The stationary door panel  16  is closer to the exterior side than the sliding door panel  14  in the illustrated example. The sliding door panel  14  is movable within the door frame  12  between a closed position and an opened position. In the illustrated example, both door panels  14 ,  16  have substantially the same dimensions and are slightly longer than half of the distance between the first and the second jamb sections  12   c ,  12   d . They thus slightly overlap at the center of the door frame  12 . 
       FIG. 2  is an enlarged isometric view of the bottom center area of the patio door assembly  10  shown in  FIG. 1 . As shown in  FIG. 2 , the innermost vertical frame members of the door panels  14 ,  16 , which are identified using reference numerals  20 ,  22 , respectively, are adjacent to one another when the sliding door panel  14  is in a closed position. The innermost vertical frame members  20 ,  22  are separated from one another by a vertically-extending clearance gap  24 . 
     The sill section  12   a  of the door frame  12  includes an exterior sill member  30 . The exterior sill member  30  extends in-between the jamb sections  12   c ,  12   d  of the door frame  12 . The exterior sill member  30  can be manufactured from an extruded workpiece, for instance a workpiece made of aluminum. A first exterior capping member  32  is connected over the exterior sill member  30  in front of the sliding door panel  14 . The first exterior capping member  32  extends between the innermost side of the stationary door panel  16  and the second jamb section  12   d  of the door frame  12 . It includes an inclined upper wall  34  and a front wall  36 . The upper wall  34  is inclined to redirect rain water away from the sliding door panel  14 . 
     A second exterior capping member  40  located below the stationary door panel  16  is also connected to the exterior sill member  30 . The second exterior capping member  40  extends between the innermost side of the stationary door panel  16  and the first jamb section  12   c  of the door frame  12 . The second exterior capping member  40  has a front wall  42  that is positioned flush with reference to the front wall  36  of the first exterior capping member  32 . 
     Also shown in  FIG. 2  is an upstanding screen rail  44  provided for the sliding screen (not shown). The screen rail  44  is made integral with the exterior sill member  30  and extends uninterruptedly between the first and the second jamb section  12   c ,  12   d . In the illustrated example, the screen rail  44  also includes a plurality of spaced-apart drain holes  46 , one of which is shown in  FIG. 2 . The drain holes  46  provide a passage for draining water present behind the screen rail  44  toward the exterior side. 
       FIG. 3  is a cross-section view taken along line  3 - 3  in  FIG. 1 . It shows that two spaced-apart and vertically-extending weatherstrips  50 ,  52  are provided between the corresponding surfaces of the innermost vertical frame members  20 ,  22  of the door panels  14 ,  16 . 
     In the illustrated example, both weatherstrips  50 ,  52  are connected to the innermost vertical frame member  22  of the stationary door panel  16 . They engage the corresponding surface on the innermost vertical frame member  20  of the sliding door panel  14  when it is in a closed position. The first weatherstrip  50  is proximal to the exterior edge of the clearance gap  24 . It mitigates air and water infiltrations under most weather conditions. The second weatherstrip  52  is positioned deeper in the first half of the clearance gap  24 . Two vertically-extending flanges  54 ,  56 , one provided on the sliding door panel  14  and one on the stationary door panel  16 , cooperate with one another to close the clearance gap  24  at its center when the sliding door panel  14  is closed. Two spaced-apart and vertically-extending weatherstrips  60 ,  62  are provided between the two door panels  14 ,  16  in the second half of the gap  24 . Other configurations and arrangements are possible as well. 
       FIG. 4  is a view similar to  FIG. 1  showing the sliding door panel  14  in a partially opened position.  FIG. 4  shows the patio door assembly  10  as viewed from the exterior side of the building. 
       FIG. 5  is a cross-section view taken along line  5 - 5  in  FIG. 4 . It shows details of the bottom horizontal frame member  70  of the sliding door panel  14  and the sill section  12   a  of the door frame  12 . The exterior side of the building is on the right side of the figure. 
     The sill section  12   a  of the door frame  12  includes an interior rail member  72  providing a track  74  for the sliding door panel  14 . The sliding door panel  14  engages the top of the track  74  using two or more spaced-apart supporting wheels  76 . 
     In the illustrated example, the interior rail member  72  is connected to an interior frame member  80  located at the bottom of the sill section  12   a  of the door frame  12 . The interior frame member  80  is connected to the exterior sill member  30  using a thermal barrier  82 . The thermal barrier  82  is made of a material having good mechanical properties and a thermal conduction coefficient lower than that of the materials it connects together. For instance, the thermal barrier  82  can be made of a polymer such as polyvinyl chloride while the exterior sill member  30  and the interior frame member  80  can be made of a metal such as aluminum. Other materials can be used as well. 
     Also visible in  FIG. 5  is a bottom horizontal gutter  90  that is positioned in the sill section  12   a  of the door frame  12  immediately above the thermal barrier  82 . The gutter  90  extends longitudinally from one side of the door frame  12  to the other. The gutter  90  has a main section  92  that is opened on the side opposite the thermal barrier  82 . Similar gutters are also provided in the head section  12   b  and in the jamb sections  12   c ,  12   d  of the door frame  12 , each having a main section opened towards the inside of the door frame  12 . 
       FIG. 6  is an isometric view illustrating a portion of the bottom horizontal gutter  90  shown in  FIG. 5 . The actual gutter  90  would be much longer than what is illustrated in  FIG. 6 . This figure also shows the gutter  90  from the end located near the first jamb section  12   c  of the door frame  12 . A small portion at the end of the gutter  90  was machined to fit with the abutting end of the corresponding vertical gutter (not shown) located in the first jamb section  12   c . The gutter  90  can be made of a material having a relatively low thermal conduction coefficient but relatively good mechanical properties. It can be made for instance of a polymer such as polyvinyl chloride. It can also be manufactured using an extrusion process and then machined thereafter. Other materials and manufacturing methods are also possible as well. 
     As shown in  FIGS. 5 and 6 , the main section  92  of the illustrated gutter  90  is somewhat U-shaped. It includes a bottom horizontal wall  94 , two obliquely-disposed walls  96 ,  98 , each being made integral with a corresponding longitudinal edge of the bottom horizontal wall  94 , and two vertical walls  100 ,  102 , each being made integral with a corresponding edge of one of the obliquely-disposed walls  96 ,  98 . A horizontal flange  104  is made integral with the vertical wall  100  on the interior side of the illustrated gutter  90 . A bottom member  106  is made integral with the horizontal flange  104  and creates a longitudinally-extending groove  108  facing the interior side. An upper flexible strip  110  is also made integral with the horizontal flange  104 . This upper flexible strip  110  can be made for instance of polyvinyl chloride that is softer than the rest of the gutter  90 . Other materials and configurations are possible. 
     Another vertical wall  112  is provided on the exterior side of the illustrated gutter  90 , as best shown in  FIG. 5 . This vertical wall  112  is made integral with the upper edge of the adjacent vertical wall  102  through a horizontal bridge wall  114 . Both adjacent vertical walls  102 ,  112  are spaced apart from one another. A small longitudinally-extending protrusion  116  is provided on a side of the vertical wall  102  facing the vertical wall  112 . An upwardly-projecting flange  118  is also made integral with the horizontal bridge wall  114 . This upwardly-projecting flange  118  supports a flexible strip projecting towards the exterior side. A horizontal flange  120  is made integral with the exterior side of the vertical wall  112 , near the bottom edge thereof. This horizontal flange  120  includes a bottom groove  122  located immediately adjacent to the vertical wall  112 . 
     A plurality of spaced-apart and square-shaped bottom drain holes  130  is provided through the obliquely-disposed wall  98  on the exterior side of the illustrated gutter  90 . The lower edge of the bottom drain holes  130  is positioned about the upper surface of the horizontal bottom wall  94 . This way, any water present therein can immediately exit the gutter  90  through one or more of the bottom drain holes  130 . There is also an exterior water guiding plate  132  made integral with the rest of the gutter  90  at the junction between the bottom horizontal wall  94  and the obliquely-disposed wall  98 . The water guiding plate  132  is configured and disposed to prevent water flowing out of the bottom drain holes  130  from reaching the thermal barrier  82 , as best shown in  FIG. 5 . 
     As can also be seen from  FIG. 5 , the gutter  90  is snap-fitted over an upstanding flange  140  of the exterior sill member  30 . The flange  140  fits inside the space formed between the two vertical walls  102 ,  112  on the exterior side of the illustrated gutter  90 . The horizontal protrusion on the vertical wall  102  engages an abutment point at the tip of the flange  140 . The parts are also connected together by a plurality of spaced-apart screws  142 , one of which is shown in  FIG. 5 . On the left side of the illustrated gutter  90 , the free end of the horizontal flange  104  engages the side of a vertical wall  150  of the interior rail member  72 . This vertical wall  150  includes a small lateral projecting flange  152  that is made integral therewith. This small lateral projecting flange  152  fits into the groove  108  ( FIG. 6 ) and the upper flexible strip  110  engages the surface of the vertical wall  150  above the flange  152 . 
       FIG. 5  also shows the first exterior capping member  32  that is connected to the exterior sill member  30  in front of the sliding door panel  14 . The bottom edge of its front wall  36  rests on the upper surface of the exterior sill member  30 . The first exterior capping member  32  further includes a rear horizontal wall  160  and an interior wall  162 . The interior wall  162  is made integral with the back of the front wall  36 . It has its free end designed to be inserted inside the bottom groove  122  on the exterior side of the gutter  90 . 
     The rear wall  160  of the first exterior capping member  32  includes an upper wall portion with two parallel horizontal grooves, each designed for receiving a corresponding weatherstrip  164 ,  166 . It also includes a bottom wall portion  168  engaging the upper surface of the bottom horizontal wall  94  of the gutter  90 . The bottom wall portion  168  includes a plurality of openings provided along its length to allow water passing from one side to the other. 
     As can be seen in  FIG. 5 , the vertical wall  100  on the interior side of the main section  92  of the gutter  90  is positioned under the sliding door panel  14  in the patio door assembly  10 . The top edge of this vertical wall  100  is also slightly higher than the lowermost edge of the bottom horizontal frame member  70  of the sliding door panel  14 . A weatherstrip  180  is provided between this lowermost edge and the interior side of the vertical wall  100  of the gutter  90 . This weatherstrip  180  mitigates air infiltrations from inside the gutter  90  to the space located right under the sliding door panel  14 . 
     As can be seen, any rain water flowing down along the exterior side of the sliding door panel  14  will tend to enter by gravity between the bottom horizontal frame member  70  and the rear wall  160  of the first exterior capping member  32 . The weatherstrip  164 , however, mitigates this water infiltration since it extends across the gap and redirects water over the top inclined wall  34  of the first exterior capping member  32 . Nevertheless, if some rain water passes the weatherstrip  164 , it will fall into the gutter  90 . 
     In the illustrated example, the lowermost edge of the bottom horizontal frame member  70  of the sliding door panel  14  includes a bottom drip projection designed to form water drops and mitigates the risks that water reaches the weatherstrip  180  located under the sliding door panel  14  through a capillary action or the like. The water drops will also tend to contact the second weatherstrip  166 , either as the water drops form or as the water drops fall. 
     As best shown in  FIG. 5 , any water present inside the gutter  90  will be directed to the bottom drain holes  130  on its exterior side and will eventually enter a chamber  190  located within the exterior sill member  30  through holes  192  located adjacent to the upstanding flange  140 . As aforesaid, the water guiding plate  132  prevents the water from reaching the thermal barrier  82  as it exits the gutter  90  through its holes  130 . Once inside the chamber  190  of the exterior sill member  30 , water flows towards the exterior side of the sill section  12   a  since the bottom wall  194  of the chamber  192  is designed with a slight inclination. Water exits the chamber  190  through one or more outlet drain holes  196 . In the illustrated example, the outlet drain holes  196  are hidden under an L-shaped flange  198  extending above them. This configuration improves the visual aspect of the patio door assembly  10  but also mitigate the tendency of water flowing over the exterior sill member  30  to enter the chamber  190  at the outlet drain holes  196 . Other configurations and arrangements are possible as well. 
       FIG. 7  is a cross-section view taken along line  7 - 7  in  FIG. 4 . It shows the details of the bottom horizontal frame member  200  of the stationary door panel  16 . The exterior side of the building is on the right side of the figure. This figure shows many of the parts that are shown in  FIG. 5 , including the gutter  90  and the exterior sill member  30 . It also shows how the stationary door panel  16  is connected to the door frame  12  in the illustrated example. The stationary door panel  16  includes a bottom frame extension  202  located under its bottom horizontal frame member  200 . The bottom frame extension  202  overlaps the exterior side of the main section  92  of the gutter  90  and engages the upper surface of the exterior sill member  30 . A plurality of screws  204  is provided between the bottom frame extension  202  and the exterior sill member  30 . 
     As can be seen from  FIG. 7 , the exterior side of the main section  92  of the gutter  90  is positioned under the stationary door panel  16 . The interior side of the stationary door panel  16  is within the interior of the building. Since the inside of the main section  92  of the gutter  90  is in continual fluid communication with the exterior side of the patio door assembly  10  through the bottom drain holes  130 , the chamber  190  and its opposite holes  92 ,  196 , the top of the main section  92  of the gutter  90  all along the stationary door panel  16  is closed by an insert  210 . This way, air from the exterior cannot enter directly inside the building. The insert  210  has a length substantially corresponding to the length of the stationary door panel  16 . The insert  210  seals a bottom space  212  inside the main section  92  of the gutter  90  from the interior of the building. However, air and water are still able to circulate within the bottom space  212  under the insert  210 . 
     In the illustrated example, the insert  210  includes a main wall  220  and four spaced-apart elongated spacer walls  222  connected to the main wall  220 , two being on the sides and two being near the center. The bottom edges of the spacer walls  222  near the center engage the bottom of the main section  92  of the gutter  90  when the insert  210  is connected thereto. The insert  210  engages the gutter  90  with a light interfering engagement. 
       FIG. 8  is a cutaway view of some of the parts shown in  FIG. 2 . The insert  210  ends at the location shown in  FIG. 8 .  FIG. 8  illustrates that the main wall  220  of the insert  210  includes a notch  230  extending transversally across the entire width of the main wall  220 . This notch  230  is longitudinally positioned adjacent to the innermost end of the insert  210 , leaving only a small portion of the main wall  220  at the end. This small wall portion is wider in a widthwise direction than in a longitudinal direction with reference to the insert  210 . 
     The illustrated insert  210  further includes two upwardly-projecting weatherstrips  232 ,  234 , each extending substantially horizontally on a respective side of the notch  230 . In the illustrated example, the weatherstrip  234  is larger than the weatherstrip  232 . The weatherstrip  232  includes one row of flexible pile fibers. The weatherstrip  234  includes a plurality of rows of flexible pile fibers. Other configurations and arrangements are possible as well. 
     Referring back  FIG. 3 , the stippled lines  250  extending parallel to the door panels  14 ,  16  show the approximate location of the longitudinal sides of the main section  92  of the bottom horizontal gutter  90 . The stippled lines  252  show the approximate location of the notch  230 . As can be seen, the notch  230  is located immediately under the buffer air space within the clearance gap  24  between the first vertically-extending weatherstrip  50  and the second vertically-extending weatherstrip  52 . The first weatherstrip  232  of the insert  210  ( FIG. 8 ) is in registry with this first vertically-extending weatherstrip  50 . The second weatherstrip  234  of the insert  210  intersects the second vertically-extending weatherstrip  52  and also reaches the third weatherstrip  60 . The weatherstrips  232 ,  234  engage the bottom side of the bottom horizontal frame members  70 ,  200  of the two door panels  14 ,  16 , as best shown in  FIG. 7 . 
       FIG. 9  is an isometric view of the insert  210  shown in  FIG. 8 . The insert  210  is shown at the end where its notch  230  and its weatherstrips  232 ,  234  are located.  FIG. 9  illustrates the opposite flexible strips  260 ,  262  obliquely projecting from the longitudinal edges of the main wall  220  of the insert  210 . The flexible strips  260 ,  262  are configured and disposed for engaging the inside of the main section  92  of the gutter  90 . 
     In use, during severe weather conditions, the first set of weatherstrip  50 ,  232  acts as a baffle to decrease the velocity of air and water entering the clearance gap  24  between the door panels  14 ,  16 . They are continually subjected to a substantially equal air pressure on opposite sides since the buffer air space is in a continual fluid communication with the exterior through the passageway at the bottom. Any water reaching inside the buffer air space is channeled directly into the passageway and kept away from the second set of weatherstrips  52 ,  234  since water is prevented from passing on the other side of the notch  230  because the notch  230  extends the full width of the main wall  220 . Nevertheless, one can use a notch having a smaller width and create a barrier at each end of that notch. The second set of weatherstrip  52 ,  234  essentially mitigates the air infiltration inside the building. 
     As can be appreciated, the above-described arrangement can greatly improve watertightness between the door panels  14 ,  16  during severe weather conditions without the need of a complex arrangement and/or weatherstrips impairing the movement of the sliding door panel  14 . 
     The proposed concept also provides a method of improving weathertightness between a sliding door panel  14  and of a stationary door panel  16  of the patio door assembly  10 . The method includes the simultaneous steps of:
         blocking at least some of the air and water using a first set of weatherstrips  50 ,  232  positioned adjacent to an inlet of the vertically-extending clearance gap  24  located between the adjacent vertical frame members  20 ,  22  of the door panels  14 ,  16  when the sliding door panel  14  is in a closed position;   maintaining a substantially equal air pressure on opposite sides of the weatherstrips  50 ,  232  of the first set when a pressure differential occurs between an interior side and an exterior side of the patio door assembly  10 ; and   draining water toward the exterior side if any water passes through the first set of weatherstrips  50 ,  232 , the water being prevented from reaching a second set of weatherstrips  52 ,  234  located deeper into the clearance gap  24 .       

     Draining water may include collecting water at the bottom of the air space located in the clearance gap  24  between the first and the second sets of weatherstrips  50 ,  232 ,  52 ,  234 . 
     The present detailed description and the appended figures are meant to be exemplary only, and a skilled person will recognize that changes can be made. The following paragraphs give examples of such changes but they are only a subset of all the possible changes and are presented in no particular order. 
     As aforesaid, the number of door panels in the patio door assembly is not limited to two. For instance, one can design a patio door assembly with a central stationary door panel and two opposite sliding door panels, one on each side of the stationary door panel. Using more than three door panels is also possible. 
     The reference to a “slidable” door panel does not exclude the fact that the same door panel can also be otherwise movable within the door frame. For instance, the door panel could also have a tilted position. 
     The various features of the illustrated examples can be combined differently and the shapes and/or the number of the parts can be different compared to what is shown and described. The proposed concept is not limited to the illustrated examples. 
     Materials can be different from those specifically mentioned in the present specification. 
     It should be noted that the word “building” is used herein in a broad generic manner and may possibly cover constructions that are not always necessarily referred to as buildings by some persons. Likewise, the word “exterior” generally designates the side from which water impinges on the patio door assembly. In certain cases, the patio door assembly as suggested herein can be located inside a building. 
     The bottom drain holes of the gutter can have a shape different than that shown and described. 
     Still many other variants of the proposed concept will be apparent to a skilled person, in light of a review of the present specification.