US3670470A

US3670470A - Roof joint cover assembly

Info

Publication number: US3670470A
Application number: US99363A
Authority: US
Inventors: Wenzel W Thom
Original assignee: ARCHITECTURAL ART Mfg Inc
Current assignee: ARCHITECTURAL ART Mfg Inc
Priority date: 1970-12-18
Filing date: 1970-12-18
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20

Abstract

An expansion joint cover for effectively sealing the joint between two shiftable roof sections while permitting the natural expansion and contraction of the latter which employs a cover plate resiliently mounted on one of a pair of support members on opposite sides of the joint with a bolt and coil spring therearound so as to bias the cover into a sealing position on both supports, the bolt and spring being positioned proximal to the joint between the two sections and providing a balanced sealing action on the respective supports.

Description

United States Patent Thom [451 June 20, 1972 [541 ROOF JOINT COVER ASSEMBLY 3,447,273 6/1969 Thom ..52/39s x [72] Inventor: Wenzel W. Thom, Wichita, Kans.

Primary Examiner-Price C. Faw, Jr. Asslgneel architectural 8" Wichita, Attomey-Schmidt, Johnson, Hovey & Williams ans. 7

22 Filed: Dec. 18, 1970 [571 ABSTRACT [211 App) No; 99,363 An expansion joint cover for effectively sealing the joint between two shiftable roof sections while permitting the natural expansion and contraction of the latter which employs a [52] U.S. Cl ..52/395, 52/58, 52/467, cover plate resiliently mounted on one of a pair of support 2/573 members on opposite sides of the joint with a bolt and coil [51] I13. Cl. E0411 3/38, E04f 15/14 spring [herearound so as to bias the cover into a sealing posi- [58] FlEld of Search ..52/573, 467, 395, 393, 396, {ion on both supports, the bolt and spring being positioned 52/53, 463 proximal to the joint between the two sections and providing a balanced sealing action on the respective supports. [56] References Cited 15 Claims, 3 Drawing Figures UNITED STATES PATENTS 3,372,521 3/1968 Thom ..52/395 l '5'\'\''\' iifiij w ill" a? /.54

ROOF JOINT COVER ASSEIVIBLY This invention relates to the field of expansion joint covers and, more particularly, to animproved expansion joint cover for sealing the joint between two shiftable roof sections which provides increased sealing efficiency without interfering with the natural expansion and contraction of the roof sections.

The joints between a pair of horizontal roof sections and between a horizontal section and a vertical section such as a parapet wall, have conventionally been scaled against the elements by a variety of cover devices. These devices allow the various roof sections to shift back and forth and up and down relatively to each other during the expansion and contraction of the roof sections during varying temperature conditions with real success being obtained only at high cost.

For years, flexible flashing material has been bent to provide overlapping, interleaved units adapted to be nailed to respective roof sections and the roofing material laid over the nailed edges of the flashing units. During expansion and contraction of the roof sections, the interleaved portions of the units move relatively to retain the seal therebetween. Although this type of assembly enjoyed some commercial success, primarily because it was the only structure available for general use, fabrication and installation of the units was expensive and time consuming, and the structure was susceptible to damage by loads thereon, particularly if walked upon by workmen on the roof.

Other devices which allow for the expansion and contraction of the roof sections use an extruded cover plate assembly to span the distance between the roof sections and to seal the joint. One side of the plate is securely attached to one of the roof sections or to one of the supports for the cover while the opposite side engages a support on the other roof section in an overlapping relationship therewith. The cover plate, which has a limited degree of flexibility is mounted in covering position over the joint in a slightly flexed condition in such amanner that the natural flection of the cover provides the necessary clamping force and sealing on each of the supports for the respective roof sections. This arrangement, however, is not a satisfactory solution in all applications due to the limited range through which the cover may be flexed. if the cover is flexed too far in one direction it will lack the necessary clamping force to provide an efficient seal, or if the cover is flexed too far in the opposite direction, the cover may become permanently bent or even break. I

Other prior devices which allow for the contraction and expansion of the various roof sections have used leaf springs spanning the joint and joined to an overlying cover plate in an attempt to provide the necessary clamping force to efiect a seal between the cover and the respective supports for the cover assembly. The leaf springs have leg portions which engage opposite support members on respective roof sections defining the joint therebetween. Fastening means is used to connect the leaf springs to the cover member. This arrangement suffers from many practical fabrication, installation, operation and excessive cost problems with the most serious involving inability of the leaf spring construction to force the cover plate into positive sealing engagement with cover sup ports, particularly when the joint is of considerable width, under pressure sufiicient to assure a seal along the entire length of the joint under all conditions of movement of the roof sections. While this arrangement offers a greater degree of movement than does the other arrangement mentioned above, it still does not provide a satisfactory and balanced sealing action during the expansion and contraction movement of the various sections.

Accordingly, it is the primary object of this invention to provide an expansion joint cover assembly for sealing the joint between a pair of roof sections which provides greater sealing efficiency at a practical cost than that obtainable from prior devices during the natural contraction and expansion of the roof sections.

Another important object of this invention is to provide such a cover assembly which utilizes means other than the natural flection of a cover plate to yieldably bias the cover into its sealing position.

Another important object of this invention is to provide such a cover assembly which utilizes spring means for biasing the cover plate into sealing engagement with opposed support members comprising a series of bolts projecting downwardly from the cover plate and extending through a support bracket on one of the support members and a coil spring surrounding each bolt and trapped between the bracket and retainer on a corresponding bolt to firmly force the cover plate down against the support members and assure a uniform clamping force and a balanced sealing action on both roof section support members of the cover assembly.

4 Still another important object of this invention is to provide a cover assembly as described above having a separate cover element for spanning the distance between a pair of upright support units on opposite sides of the joint wherein the element is yieldably biased into engagement with the supports by coil spring operated attaching means mounted on the element in a position proximal to the joint.

A further important object of the invention is to provide such a cover assembly which may be economically extruded by conventional procedures and which provides a maximum degree of strength, weather-sealing characteristics, and installation efficiency.

In the drawing:

FIG. 1 is a fragmentary, perspective view of two embodiments of a roof joint cover embodying the principles of my invention, shown in their normal operative relationship in sea]- ing relationship to a joint defined by two roof sections and overlying a joint between the roof sections and a parapet;

FIG. 2 is an enlarged cross-sectional view of the embodiment of the roof joint cover adapted for covering the joint defined by two spaced, proximal roof sections, and taken along line 22 of FIG. 1; and

FIG. 3 is an enlarged cross-sectional view of a second embodiment of the roof joint cover designed for closing the joint between a parapet and adjacent roof sections, and taken along line 33 of FIG. 1.

One embodiment of the roof joint cover assembly which utilizes the principles of my invention is designated in FIGS. 1 and 3 by the numeral 10 and is used to cover a joint 12 defined between a horizontal roof section 14 and a vertical section 16 such as a parapet wall.

The roof section 14 is conventionally provided with a wooden stringer 18 having an outwardly and downwardly sloping outboard surface 20, and the upper, horizontal surface 22extending from joint 12 toward the corresponding surface 20. A layer of roofing material 24 is normally provided on roof section 14 and is laid down on the roof so that one margin thereof extends upwardly along surface 20 in contact therewith, presenting an edge 26 adjacent the horizontal surface 22.

Assembly 10 includes an elongated and generally inverted T-shaped support member or component 28 having a base portion 30 mounted atop the horizontal surface 22 of stringer 18 along the length of joint 12 and secured to the stringer by a plurality of screws 32 spaced along the length of base portion 30. Component 28 also includes an upwardly extending segment 34 having a channel-shaped terminal end 36 which removably receives an elongated, deformable sealing strip 38 therein.

An elongated flexible sealing element 40, disposed along the length of joint 12, is sandwiched between base portion 30 of support 28 and the horizontal surface 22 of stringer 18 with a portion 42 thereof extending across joint 12 and engaging surface 44 of parapet wall 16 to effect a secondary weatherproof seal therewith.

A flashing section 46 is provided on the outermost extremity of base portion 30 of component 28 remote from joint 12 and adapted to be bent down into sealing engagement with the roofing material and firmly held thereagainst by a plurality of spaced screws 32 driven into stringer 18. As is most apparent from FIG. 3 upon installation of the cover assembly 10, flashing section 46 extends generally downwardly toward roof section 14 and away from joint 12 over the edge 26 of roofing material 24 and along the latter in spaced, overlying relationship therewith, and terminates in a sealing rib 48. Rib 48 assures that an effective weatherproof seal is provided between roofing material 24 and flashing member 46 when rib 48 is positioned in tight engagement with roofing material 24.

Assembly also includes a second elongated support member or component 50 of generally L-shaped configuration mounted on the inner surface 44 of parapet wall 16 facing toward joint 12 and secured to wall 16 along the length thereof by a plurality of screws 56. A pair of elongated sealing strips 58, similar to the sealing strips 38, are sandwiched between component 50 and parapet wall 16 on both sides of screws 56 with strips 58 providing an effective weatherproof seal between parapet wall 16 and component 50. Component 50 is mounted on parapet wall 16in a position generally above the plane of the surface 22 with the foot portion or bracket 60 of component 50 being adjacent the plane of the surface 22 and extending outwardly from component 50 toward joint 12 in substantial alignment with terminal end 36 of segment 34 of component 28. Component 50 is provided with a generally inverted L-shaped projection 62 having a horizontal portion 64 extending generally outwardly from component 50 toward joint 12 and a vertical portion 66 extending downwardly from the .extremity of portion 64 remote from joint 12 toward bracket 60, thereby defining a channel 68 between projection 62 and support component 50.

A generally Z-shaped cover 70 having a central portion 72 and a pair of skirts 74 and 76 on opposite extremities of central portion 72 thereof spans joint 12 and is disposed in overlying relationship to component 28 with the lower surface 78 of a part of the central portion 72 adjacent skirt 74 engaging sealing strip 38 atop terminal end 36 and supported thereby. Skirt 74 of the cover 70 remote from joint '12 extends generally downwardly toward roof section 14 into overlying relationship with a portion of the segment 34 of support component 28. The other skirt 76 adjacent joint 12 extends generally upwardly into the channel 68 between projection 62 and component 50 with a cross-sectional bead-shaped terminal end 80 of skirt 76 being complementally received within an elongated, transversely circular slot 82 in the horizontal portion 64 of projection 62. Skirt 76 is secured to projection 62 and the other portion of the cover 70 adjacent skirt 76 is supported by virtue of the fact that the distance across the opening of slot 82 is smaller than the cross-sectional diameter of the bead-shaped terminal end 80. As may be appreciated from HO. 3, the configuration of slot 82 and terminal end 80 of skirt 76 allows the latter to swing relative to projection 62 and support 50 while securely holding skirt 76 in its upwardly extending position within channel 68.

A series of connectors 84 are provided for securely attaching cover 70 to the foot portion or bracket 60 of component 50 and to yieldably bias cover 70 downwardly toward bracket 60. Each connector 84 comprises a bolt 86 having a head 88 on one extremity thereof and a T-nut 90 having a flange 92 on one extremity thereof. The bolts 86 project downwardly through respective openings therefor in cover plate 70 with the heads 88 thereof engaging the top surface of plate 70 and the terminal ends of the same located above joint 12-but in proximal relationship thereto. Each bolt 86 extends through an opening 94 therefor in bracket 60 of component 50 with a respective T-nut 90 being threaded or otherwise affixed to the lower end of the bolt. A portion of each nut 90 extends through opening 94 with flange 92 thereof positioned beneath the bracket 60. The diameter of opening 94 is greater than the diameter of the nut 90 thereby allowing the latter to rock back-and-forth and from side-to-side within opening 94 and connector assembly 84 to swing relative to bracket 60. An E-retainer on the upper end of each T-nut 90 and of greater efl'ective diameter than the opening 94 therebelow maintains the nut in position on bracket 60 during installation so that each bolt 86 may readily be threaded into a corresponding nut notwithstanding the fact that the latter is hidden from view after the cover plate is positioned over the joint.

Biasing of the cover 70 downwardly toward bracket 60 is achieved by the provision of a coil spring 96 mounted over each nut 90 with one end of spring 96 engaging a corresponding flange 92 and the opposite end thereof contacting the bottom surface 98 of bracket 60, thereby causing nut 90 as well as cover 70 to be biased downwardly toward joint 12. The biasing force of springs 96 serves to force cover 70 into a tight sealing engagement with the sealing strip 38 of component 28 and to force the outer surface of the bead-shaped terminal end into a tight sealing engagement with the surfaces of the bead-shaped slot 82 adjacent the outer opening of slot 82.

Upon shifting of the roof section 14 upwardly relative to parapet wall 16, the bead-shaped configuration of terminal end 80 and slot 82, as well as the space between nut and the edges of opening 94, allow cover 70 to swing and slightly rotate clockwise about the pivot point corresponding to the bead-shaped terminal end 80 with connector assembly 84 rocking generally in a clockwise manner within opening 94. As may be appreciated, the upward shifting of roof section 14 as well as any other relative shifting of the roof sections does not prevent spring 96 from forcing cover 70 into a tight sealing engagement with the sealing strip 38 and the bead-shaped portion of terminal end 80 of cover 70 into tight sealing engagement with the surfaces of slot 82. It may also be appreciated that cover assembly 10 provides a more efficient clamping force and sealing action on support 28 as well as allowing a greater degree of relative upward and downward shifting of the two

roof sections

14 and 16 than that which is obtainable from using a flexible cover which depends upon the natural flection of the cover to provide the necessary clamping force.

In use,

components

28 and 50 and cover 70, due to their uniform cross-sectional configuration, may be extruded from aluminum or any other material which offers the desired degree of strength and production economy and cut to a variety of different standard lengths.

Components

28 and 50 are mounted along the length of joint 12 on their respective roof sections with component 28 being mounted over the sealing material 40.

Sealing rib 48 of flashing member 46 is shifted into tight engagement with the roofing material 24 by hammering or the like, and a splice cover 100 is positioned over abutting ends of

adjacent components

28 and 50, secured thereto by a plurality of screws (not shown), at each point of juncture between one component and the next succeeding component along the length of joint 12 in order to cover the breaks between the succeeding

components

28 and 50 and to properly seal joint 12 along its entire length. A plurality of covers 70 are inserted into channel 68 of their respective components 50 with skirts 76 being inserted into slots 82 and the central portion 72 being positioned over and engaging support 28. A splice cover 102 is also positioned over each point of juncture between abutting ends of and is secured to the covers 70 by a plurality of connectors 78 provided at spaced intervals along the length of the covers 70.

The second embodiment of the roof joint cover assembly illustrated in FIGS. 1 and 2 of the drawing is generally designated by the numeral and specifically adapted for use in covering a joint 112 defined between two horizontally spaced roof sections 114 and 116. Roof section 114 and 116 are provided with

wooden stringers

118 and 119 respectively each having an outwardly and downwardly sloping outboard surface 120, and an upper, horizontal surface 122 extending from joint 112 toward the corresponding surface 120. A layer of roofing material 124 lies on each roofing section 114 and 116 and extends upwardly along surface. in contact therewith, presenting an edge 126 adjacent the horizontal surfaces 122. Assembly 110 includes elongated and generally inverted T-shaped support members or

components

128 and 150 with each component 128 being mounted on stringer l 18 along joint 112 and component 150 being mounted on stringer 119 along joint 112.

Components

128 and 150 are both provided with base portions 130 and flashing members 146 which are similar in every major respect to those for the support component 28 of the first embodiment of the invention described above and thus need not be further described here. In the same manner, screws 132 are employed to secure

components

128 and 150 to respective stringers.

A flexible, elongated sealing element 140 spans the distance across joint 112 and is sandwiched at opposite sides thereof between the base portions 130 and their

respective stringers

118 and 119. The sealing element 140 preferably formed of extruded vinyl material similar to elements 40, also provides a secondary weatherproof seal for joint 1 12.

Components

128 and 150 are each provided with an upstanding segment 134 having a channel-shaped terminal end 136 and a sealing strip 138 therein similar to that of the support component 28 previously described in detail. Component 150, however, is provided with a bracket 160 extending outwardly therefrom at a position adjacent the terminal end 136 of the latter toward support component 128 and in substantial alignment with the terminal end 136 of segment 134 of component 128.

A generally channel-shaped cover 170 having a central portion 172 and a pair of skirts 174 and 176 spans the distance across joint 112 and is disposed in overlying relationship to

components

128 and 150 with the lower surface 178 of cover 170 engaging respective sealing strips 138. Skirt 174 of cover 170 adjacent stringer 118 extends generally downwardly toward roof section 114 in overlying relationship with a portion of segment 134 of component 128 while the opposite skirt 176 extends generally downwardly toward roof section 116 in overlying relationship with a portion of segment 134 of component 150. A rib 171 extends longitudinally of cover 70 and projects downwardly therefrom adjacent the free extremity of bracket 160 for strengthening cover 70.

A series of connector assemblies 184 similar to assemblies 84 of the first described embodiment also each include a bolt 186 having a head 188, a nut 190 having a flange 192, and a coil spring 196 surrounding a respective nut between flange 192 and bracket 160 to securely attach cover 170 to bracket 160 of component 150 and thereby firmly bias cover 70 downwardly against respective sealing members 138 of

components

128 and 150 in such a manner as to compress the latter and effect a weatherproof seal therebetween. Each bolt 186 extends downwardly toward joint 112 from a position on cover 170 disposed generally centrally of the latter, over joint 112, and within the vertical extensions of the boundaries of joint 112. The bolts 186 extend downwardly through cover 170 and a respective opening 194 within bracket 160 of component 150. Each nut 190 is threaded onto the lower end of a corresponding bolt 186 with a portion of each nut extending through opening 194 while the remainder thereof projects downwardly toward joint 112 in disposition such that flange 192 thereon is positioned beneath bracket 160. The diameter of each opening 194 is greater than the diameter of a respective nut 190, thereby allowing each of the same to rock backand-forth and from side-to-side within a respective opening 194 and the connector assembly 184 to swing relative to bracket 160.

As may be appreciated, the provision of a connector assembly 184 mounted centrally on cover 170 enablesthe latter to provide an effective seal between cover 170 and supports 128 and 150 by allowing a balanced pivotal action about the point where each bolt 186 is circumscribed by an opening 194 within bracket 160. In this regard, it may be seen that if roof section 116 shifts upwardly with respect to roof section 114, the extremity 195 of cover 170 overlying roof section 116 shifts upwardly with respect to connector assembly 184 a distance equal to that which connector assembly 184 is shifted upwardly with respect to the extremity 197 of cover 170 overlying roof section 1 14. This pivotal action provides a balanced clamping force and sealing action on the

respective supports

128 and 150 as well as allowing a greater degree of relative upward and downward shifting of the two roof sections 114 and 116 than that which would be obtained by using a flexible cover which depends upon the natural flection of the cover to provide the necessary clamping force.

Components 128 and and cover are similar to that of

components

28, 50 and cover 70 previously described and may be constructed by the same material and by the same procedures.

Components

128 and 150 and cover 170 are provided with splice covers 200 and 204 respectively, similar to

covers

100 and 102 of the first described embodiment and are mounted on their

respective stringers

118 and 119 by the same procedure as used to mount their respective counterparts with the exception that the central portion 172 of cover 170 is mounted over and engages both

supports

128 and 150.

A particularly important feature of both embodiments of the invention is the use of coil springs for biasing the cover plates toward respective support members and disposed in essentially central locations transversely of respective cover plates to assure firm sealing engagement thereof with the sealing elements on the cover plate supports regardless of the degree or direction of movement of the roof sections. After the coil springs are placed in compression by tightening of

bolts

86 and 186, firm, uniform pressure is exerted on the respective cover plates throughout their lengths. In addition, although the normal spacing between connectors 84 or 184 is about 18 inches, it can be appreciated that such space can readily be varied at will to accommodate a particular structural condition.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A roof joint cover assembly for structural sections cooperable to present a roof for a building and including a pair of spaced sections defining a joint therebetween, said assembly comprising:

a first component adapted to be secured to one of the structural sections adjacent the joint defined thereby and including a first part configured to generally complementally engage a surface portion of said one structural section, and

a second part joined to said first part and extending away from the latter in a direction toward the joint;

a second component adapted to be secured to the other structural section of the pair thereof and having a segment extending away therefrom, said segment being provided with a terminal edge remote from the other structural section terminating in substantial alignment with said second part of the first component;

a cover plate overlying said parts of the first component in spaced relationship therefrom and engaging the terminal edge of said segment of the second component and the first part of said first component;

connector means on the cover plate and extending through the second part of said first component for pivoting movement relative thereto; and

resilient means on the connector and engaging said second part of the first components for biasing the cover plate into tight engagement with said first part of the first, component and the segment of said second component.

2. The invention of claim 1, wherein said cover plate is channel-like in configuration with the skirts on opposite sides thereof extending generally downwardly toward said roof in overlying relationship with corresponding portions of the segment of said second component and the first part of said first component.

3. The invention of claim 1, wherein said first and second components are of generally inverted T-shape configuration and are each provided with an integral flashing member on their respective extremities remote from said joint, said flashing members extending generally downwardly toward said roof and outwardly from said joint along corresponding structural sections in spaced overlying relationship therewith.

4. The invention of claim 1, wherein said second part of the first component is provided with a surface remote from said one structural section in substantial parallelism with the latter and with said outer edge of the segment of said second component, said surface being adapted to engage said cover plate.

5. The invention of claim 4, wherein said surface of the second part of the first component and said terminal edge of the segment of said second component are each provided with a compressible sealing member extending along their respective lengths and disposed to engage said cover plate and effect a seal therebetween.

6. The invention of claim 1, wherein said connector means includes a bolt having a head thereon and a nut threaded on said bolt below said second part of said first component, said resilient means on the connector means including a coil spring surrounding said bolt and engaging said nut and said second part of the first component.

7. The invention of claim 1, wherein both of said components and said cover plate are elongated and extend along the length of the joint, said connector means being provided at spaced intervals along the length of the cover plate.

8. The invention of claim 1, wherein said first component is generally L-shaped and is provided with a finger unit extending generally outwardly from said first part of said first component toward said joint and downwardly toward said second part of said first component, said finger unit and said first part defining a channel within said first component.

9. The invention of claim 8, wherein said second component is generally of inverted T-shaped configuration and provided with an integral flashing member on an extremity remote from said joint, said flashing member extending generally downwardly toward said roof and outwardly from said joint along its corresponding structural section in spaced overlying relationship therewith.

10. The invention of claim 9, wherein said cover plate is generally of Z-shape configuration with a first skirt on one of the extremities of said plate extending generally downwardly toward said roof in overlying relationship with a portion of the segment of said second component and with a second skirt on another extremity of said plate extending generally upwardly into said channel between said finger unit and the first part of said first component with the terminal end of said second skirt engaging the inner surface of said first component at the point of juncture of said finger unit with the first part of said first component.

11. The invention of claim 10, wherein said second skirt is provided with a bead on the terminal end thereof adapted to be complementally received within a corresponding beadshaped slot provided within the inner surface of said first component at the point of juncture of said finger unit with the first part of said first component, the distance across the opening of said slot being smaller than the cross-sectional diameter of said bead in order to secure the terminal end of said second skirt to said first component while permitting pivotal movement relative thereto.

12. The invention of claim 10, wherein said first part of said first component is provided with compressible sealing means extending along the length thereof and adapted to engage said one structural section and effect a seal between the latter and said first component 13. The invention of claim 12, wherein said terminal edge of the segment of said second component is provided with compressible sealing means extending along the length thereof and disposed to engage said cover plate and effect a seal therebetween.

14. The invention of claim 10, wherein said connector means includes a bolt having a head thereon and a nut threaded on said bolt below said second part of said first component, said resilient means on the connector means includes a coil spring surrounding said bolt and engaging said nut and said second part of the first component.

15. The invention of claim 10, wherein both of said components and said cover plate are elongated and extend along the length of the joint, said connector means being provided at spaced intervals along the length of the cover plate.

Claims

1. A roof joint cover assembly for structural sections cooperable to present a roof for a building and including a pair of spaced sections defining a joint therebetween, said assembly comprising: a first component adapted to be secured tO one of the structural sections adjacent the joint defined thereby and including a first part configured to generally complementally engage a surface portion of said one structural section, and a second part joined to said first part and extending away from the latter in a direction toward the joint; a second component adapted to be secured to the other structural section of the pair thereof and having a segment extending away therefrom, said segment being provided with a terminal edge remote from the other structural section terminating in substantial alignment with said second part of the first component; a cover plate overlying said parts of the first component in spaced relationship therefrom and engaging the terminal edge of said segment of the second component and the first part of said first component; connector means on the cover plate and extending through the second part of said first component for pivoting movement relative thereto; and resilient means on the connector and engaging said second part of the first components for biasing the cover plate into tight engagement with said first part of the first component and the segment of said second component.

11. The invention of claim 10, wherein said second skirt is provided with a bead on the terminal end thereof adapted to be complementally received within a corresponding bead-shaped slot provided within the inner surface of said first component at the point of juncture of said finger unit with the first part of said first component, the distance across the opening of said slot being smaller than the cross-sectional diameter of said bead in order to secure the terminal end of said second skirt to said first component while permitting pivotal movement relative thereto.

12. The invention of claim 10, wherein said first part of said first component is provided with compressible sealing means extending along the length thereof and adapted to engage said one structural section and effect a seal between the latter and said first component

13. The invention of claim 12, wherein said terminal edge of the segment of said second component is provided with compressible sealing means extending along the length thereof and disposed to engage said cover plate and effect a seal therebetween.