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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims domestic priority on U.S. Provisional Patent Application Ser. No. 60/804,476, file Jun. 12, 2006, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Vent baffles are utilized in building structures to vent an area beneath the roof between a soffit and a peak of the building to prevent moisture buildup. Moisture in the roof can potentially damage attic insulation and the building structure itself. Proper ventilation aids in the prevention of premature melting of snow accumulated on a roof. Premature snow melting may lead to the formation of ice on the roof, which is a potential safety hazard and may also damage the roof. 
     Providing attic ventilation for cathedral ceilings presents unique challenges because drywall or alternative wall boards are secured directly to the inner sides of the roof rafters, leaving a relatively small space between the drywall or wallboards and the roof sheathing of the building. Accordingly, this space is relatively small and must accommodate venting structure and insulation. Conventional cathedral ceilings typically are constructed utilizing ventilation sheets mounted in an end-to-end configuration to the roof sheathing, insulation positioned over the ventilation sheets and drywall or other ceiling sheets mounted to a bottom of the rafters over the insulation. Such installation is labor intensive and misalignment of the vent sheets could potentially inhibit or block the desired flow of air in channels created by the vent sheets from the soffit area to the outlet or ridge of the building structure. Air flow may be blocked if insulation creeps between gaps created between misaligned end-to-end vent sheets, thereby defeating the purpose of or severely limiting the effectiveness of the vent sheets. 
     Cathedral ceilings may include an attic space near the soffit area of the building proximate the top of the wall and the lower edge of the roof. This area may be insulated by conventional blown insulation that rests on the floor of the attic. Such blown insulation is preferably protected from wind that blows into the soffit area of the building. Uncontrolled air currents circulating in the attic space can have a negative effect on the performance of the attic insulation by promoting increased convective heat transfer along the top surface of the insulation. A roof ventilation system for blocking air from disturbing the blown insulation and enhancing ventilation of the attic space in the soffit area is described in U.S. Pat. No. 7,094,145, granted to Palle Rye, et al on Aug. 12, 2006, from a patent application filed on Mar. 29, 2004, which is co-owned with the instant application and is incorporated herein in its entirety by reference. U.S. Pat. No. 7,094,145 describes a vent baffle and method of installation that may be utilized in the soffit area of a building structure; however, this vent baffle may also be utilized in building structures having a cathedral ceiling-type construction. 
     A roof constructed of a water impervious outer layer and a water impervious inner layer with an insulating layer therebetween is formed with ventilating channels in U.S. Pat. No. 2,855,869, granted to Carl Munters, et al on Oct. 14, 1958. These ventilating channels extend from the eaves to the wall header along the width of the roof to remove moisture from the insulating layer. The ventilation baffle in U.S. Pat. No. 4,096,790, granted on Jun. 27, 1978, to Laurence Curran, is secured to the tops of the rafters by the roof sheathing and includes a vertical flap that is secured to the sill at the top of the wall to prevent insulation from entering the soffit area from the interior of the building. 
     U.S. Pat. No. 5,596,847, issued on Jan. 28, 1997, to Michael Stephenson, discloses a polystyrene foam vent structure that is formed with longitudinal ribs, one of which includes a score line to permit the vent panel to be cut into a size that conforms to a smaller spacing of the roof rafters. The vent panel is placed on top of adjacent rafters to provide an air space past the insulation layer. A similar vent panel is taught in U.S. Pat. No. 6,347,991, issued to Blake Bogrett, et al, on Feb. 19, 2002, in which the PVC panel is formed with a central rib to be mounted on top of adjacent roof rafters to provide an air space past the insulation layer. This PVC vent panel is also formed with a hinged chute segment that can be folded downwardly to be affixed to the top sill or the wall to provide an insulation dam. Multiple fold lines in the hinged chute segment provide flexibility in the attachment of the insulation dam. 
     U.S. Patent Publication No. 2005/0072072 of Richard Duncan, et al, published on Apr. 7, 2005, discloses a baffle vent that is mounted between two adjacent rafters by a friction fit. This baffle vent is also formed with a central longitudinal rib and transverse thickened supports to provide lateral support and stability. A transversely extending perforation is located along one of the transverse supports to permit the baffle vent to be separated along the perforation to form a baffle vent having a shortened length. 
     The nature of the construction and configuration of a cathedral ceiling requires air ventilation along the entire length of the cathedral ceiling area of the building structure or, at times, from the soffit area to the peak of the building structure. There is a need for a cathedral ceiling vent baffle that is inexpensively manufactured, effectively provides ventilation for the cathedral ceiling, provides a space for insulation between the drywall and roof sheathing of the cathedral ceiling, is quickly and easily installed, and is adaptable for a wide range of cathedral ceiling building configurations. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a ceiling vent baffle that can be used in the construction of cathedral ceilings. 
     It is a feature of this invention that the cathedral ceiling vent baffle provides ventilation for a cathedral ceiling while providing adequate space for the installation of insulation between the baffle vent and the ceiling structure affixed to the roof rafters. 
     It is an advantage of this invention that the ceiling vent baffle can be installed into a cathedral ceiling structure quickly and easily. 
     It is another feature of this invention that the cathedral ceiling vent baffle is adaptable for a wide range of cathedral ceiling building configurations. 
     It is still another feature of this invention that the cathedral ceiling vent baffle is formed with longitudinally extending ribs that interengage with the installation of the vent sheets to the roof sheeting. 
     It is another advantage of this invention that the interengaged longitudinally extending ribs of the first and second vent sheets limit the lateral movement of the first vent sheet relative to the second vent sheet. 
     It is yet another feature of this invention that the vent sheets are also formed with lateral stiffeners that are interengaged when the vent sheets are installed on the roof sheeting. 
     It is still another advantage of this invention that the interengaged lateral stiffeners limits the longitudinal movement of the first vent sheet relative to the second vent sheet. 
     Briefly stated, a preferred embodiment of the present invention is directed to a vent baffle assembly for a cathedral ceiling to provide air ventilation in a cathedral ceiling portion of a building structure having rafter beams and a roof sheathing. The vent baffle assembly includes a first vent sheet having a first end, a second end, a first side, a second side, a first longitudinal rib, a second longitudinal rib and a first lateral stiffener extending generally perpendicularly relative to the first and second longitudinal ribs. The first and second longitudinal ribs extend from the first end toward the second end. A second vent sheet includes a third end, a fourth end, a third side, a fourth side, a third longitudinal rib, a fourth longitudinal rib and a second lateral stiffener extending generally perpendicularly relative to the third and fourth longitudinal ribs. The third and fourth longitudinal ribs extend from the third end toward the fourth end. The first vent sheet is positioned between two adjacent rafter beams such that the first and second longitudinal ribs extend generally parallel to the rafter beams. The second vent sheet is positioned between the two adjacent rafter beams such that the third longitudinal rib engages the first longitudinal rib and the second longitudinal rib engages the fourth longitudinal rib to limit lateral movement of the first vent sheet relative to the second vent sheet. The first lateral stiffener engages the second lateral stiffener to limit longitudinal movement of the first vent sheet relative to the second vent sheet in an installed configuration. 
     It is yet another object of this invention to provide a ceiling vent baffle that can be utilized in cathedral ceiling construction and which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     These and other objects, features and advantages are accomplished according to the instant invention by providing a vent baffle assembly that provides air ventilation in a cathedral ceiling having rafter beams and roof sheathing. The vent baffle assembly includes a first vent sheet and a second vent sheet. The first vent sheet has first and second ends, first and second longitudinal ribs and a first lateral stiffener extending generally perpendicularly to the ribs. The second vent sheet includes third and fourth ends, third and fourth longitudinal ribs, and a second lateral stiffener extending perpendicularly to the ribs. The first vent sheet is positioned between adjacent rafters with the ribs oriented parallel to the rafters. The second vent sheet overlaps the first vent sheet with respective ribs interengaged to limit lateral movement of the first vent sheet relative to the second vent sheet. The first lateral stiffener engages the second lateral stiffener to limit longitudinal movement of the first vent sheet relative to the second vent sheet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a perspective view showing the interior surface of a starter vent sheet of the vent baffle assembly in accordance with a first preferred embodiment of the present invention; 
         FIG. 2  is an elevational view of the starter vent shown in  FIG. 1  with the interior surface being on the lower side of the figure as the starter vent would be installed, as depicted in  FIG. 8 ; 
         FIG. 3  is a plan view of the starter vent showing the interior surface as depicted in  FIG. 1 ; 
         FIG. 4  is a perspective view showing the interior surface of an intermediate vent of the vent baffle assembly in accordance with a first preferred embodiment of the present invention; 
         FIG. 5  is a plan view of the intermediate vent sheet shown in  FIG. 4 ; 
         FIG. 6  is a cross-sectional view of the intermediate vent sheet corresponding to lines  6 - 6  of  FIG. 5 ; 
         FIG. 7  is a cross-sectional view of the starter vent sheet corresponding to lines  7 - 7  of  FIG. 3 ; 
         FIG. 8  is a cross-sectional view of the intermediate vent sheet corresponding to lines  8 - 8  of  FIG. 5 ; 
         FIG. 9  is a partial vertical cross-sectional view through a roof, wall and ceiling of a building structure, showing the starter vent sheet of  FIG. 1  and a portion of an intermediate vent sheet of  FIG. 4  in an installed configuration proximate a soffit area of the building structure constructed with a cathedral ceiling; and 
         FIG. 10  is a vertical cross-sectional view through the roof and ceiling of the building structure, showing the starter vent sheet of  FIG. 1  and a portion of an intermediate vent sheet of  FIG. 4  in an installed configuration proximate a ridge board or peak of the building structure constructed with a cathedral ceiling. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Certain terminology is used in the following description for convenience only and is not limiting. The words, “right”, “left”, “up”, “down”, “top”, and “bottom” designate directions in the drawings to which reference is made. The words, “interior” and “exterior” refer to directions toward and away from, respectively, the geometric center of the cathedral ceiling vent assembly or designated parts or portions thereof. Furthermore, as used herein, the article, “a” or a singular component includes the plural or more than one component, unless specifically and explicitly restricted to the singular or a single component or unless a singular meaning is apparent from the context. The terminology includes the words above specifically mentioned, derivatives thereof and words of similar meaning. 
     Referring to the drawings in detail, wherein like reference numerals are used to identify like components throughout, there are shown in  FIGS. 1-10 , preferred embodiments of a cathedral ceiling vent baffle assembly. The vent baffle assembly of the preferred embodiments includes a starter vent sheet  10  and an intermediate vent sheet  12 . The intermediate vent sheet or sheets  12  and/or the starter vent sheet or sheets  10  are assembled in a cathedral ceiling portion of a building structure to vent air in a roof  14  of a building to generally limit or prevent moisture buildup proximate the roof  14 . Other configurations for the shape and design of the vent sheets  10 ,  12  will be appreciated by one of ordinary skill in the art. One such alternative design configuration is shown in  FIG. 5A  of Applicants&#39; provisional patent application U.S. Ser. No. 60/804,476, for which domestic priority is claimed. 
     Referring to  FIGS. 1-4 ,  8  and  9 , the starter vent sheet  10  includes a ribbed main body portion  10   a  and a tail portion  10   b . In use, the tail portion  10   b  is preferably secured to the building structure and the main body portion  10  provides ventilation along the underside of the roof  10  to create channels for airflow to draw moisture away from the roof  14 . The main body portion  10   a  is ribbed longitudinally to provide airflow channels and longitudinal stiffness, while the tail portion  10   b  is preferably comprised of generally planar sections of sheet-like material that is convenient for mounting to the building structure and may also be readily bent or formed for adapting to various shapes that are convenient during installation, as will be described in greater detail below. 
     The starter vent sheet  10  and intermediate vent sheet  12  are preferably constructed of a sheet of polymeric material having a thickness of approximately one one-hundredth to four one-hundredths of an inch (0.010″-0.040″). Sheet metals, thermoplastics and composite materials may all be utilized to form the starter vent sheet  10  or the intermediate vent sheet  12  or nearly any material that is able to take on the general shape of the starter and intermediate vent sheets  10 ,  12  and perform the typical functions of the starter and intermediate vent sheets  10 ,  12 . 
     A press-molded thermoplastic material is the preferred material for the starter and intermediate vent sheets  10 ,  12  and the most preferred thermoplastic material is a polyvinyl chloride (PVC) material. The PVC material is preferred for construction of the starter and intermediate vent sheets  10 ,  12  due to its adaptability to the molding process, resistance to corrosion and relatively light weight. However, the starter and intermediate vent sheets  10 ,  12  are not limited to constructions utilizing the PVC material and may be constructed using nearly any material that is able to take on the general shape of the starter and intermediate vent sheets  10 ,  12  and withstand the normal operational environment of the starter and intermediate vent sheets  10 ,  12 . 
     The starter vent sheet  10  includes a first stiffened panel  1 , a second stiffened panel  2 , a first non-ribbed section  3 , a second non-ribbed section  4  (either of the non-ribbed sections could be planar or radiused slightly), and a mounting flange  5 . Each of these portions of the starter vent sheet  10  is preferably constructed of integrally molded PVC material. The first and second stiffened panels  1 ,  2  preferably comprise the main body portion  10   a  and the first and second non-ribbed sections  3 ,  4  and the mounting flange  5  preferably comprise the tail portion  10   b . The starter vent sheet  10  is not limited to inclusion of each of the above-listed portions nor to the first and second stiffened panels  1 ,  2  comprising the main body portion  10   a  or the first and second non-ribbed sections  3 ,  4  and mounting flange  5  comprising the tail portion  10   b . The starter vent sheet  10  may be otherwise configured to perform the normal operation of the starter vent sheet  10 , as would be obvious to one having ordinary skill in the art. 
     The first non-ribbed section  3  is preferably separated from the second non-ribbed section  4  by a first living hinge  16  that permits pivoting of the first non-ribbed section  3  relative to the second non-ribbed section  4 . Pivoting on the first non-ribbed section  3  relative to the second non-ribbed section  4  permits the starter vent sheet  10  to adapt its shape for insertion into the building structure. Preferably, the first non-ribbed section  3  is also connected to the second stiffened panel  2  by a second living hinge  17  to provide greater flexibility in the positioning of the starter vent sheet  10 . Mounting the tail portion  10   b  to the building structure and adapting the shape of the starter vent sheet  10  for installation into the building proximate a soffit area  48  of the building is described in detail in U.S. Pat. No. 7,094,145, which is incorporated herein by reference. 
     The first stiffened panel  1  and the second stiffened panel  2  are separated by a planar portion  18  that permits the second stiffened panel to bend relative to the orientation of the first stiffened panel. The planar portion  18  is preferably integrally molded into the main body portion  10   a . The first and second stiffened panels  1 ,  2  are preferably ribbed longitudinally such that they are relatively rigid in comparison to the tail portion  10   b , and in comparison to the planar portion  18 . The ribbed configuration of the stiffened panels  1 ,  2  defines longitudinal channels extending from end to end of the main body portion  10   a  in an installed configuration for the venting of air beneath the roof  14 , as would be understood by one having ordinary skill in the art. 
     The bending between the first stiffened panel land the second stiffened panel  2  and the pivoting between the second stiffened panel  2  and the first and second non-ribbed sections  3 ,  4  about the first and second living hinges  16 ,  17  is preferred so that the starter vent sheet  10  is adapted for installation into the soffit area ( FIG. 9 ) or onto a ridge board  20  proximate a peak of the roof  14  ( FIG. 10 ) or at nearly any location between the peak and the soffit area  48  of the roof  14  as required for the construction of a cathedral ceiling. In addition, the starter vent sheet  10 , based upon inclusion of the ribbed main body portion  10   a  and the first and second living hinges  16 ,  17 , permits installation of the starter vent sheet  10  at the ridge board  20  while providing continuous ventilation beneath the roof  14  along an entire length of the main body portion  10   a . The starter vent sheet  10  is not limited to inclusion of the first and second living hinges  16 ,  17  and may be constructed and adapted for mounting in the soffit area  48  and proximate the ridge board  20  of the building structure in alternative manners to permit continuous venting of moisture beneath the roof  14  in a cathedral ceiling portion of the building structure, as would be obvious to one having ordinary skill in the art. 
     The intermediate sheet vent  12  is preferably comprised of a ribbed, generally rectangular sheet constructed of the PVC material. The preferred intermediate vent sheet  12  includes a first end  22 , a second end  24 , a first side  26 , and a second side  28 . The intermediate vent sheet  12  also preferably includes a longitudinal axis  30  and a lateral axis  32 . The first and second ends  22 ,  24  are spaced along the longitudinal axis  30  and the first and second sides  26 ,  28  are spaced along the lateral axis  32 . The intermediate vent sheet  12  also preferably includes a length dimension measured parallel to the longitudinal axis  30  from the first end  22  to the second end  24  and a width dimension measured along the lateral axis  32  from the first side  26  to the second side  28 . In the first preferred embodiment, the length dimension is approximately forty-eight inches (48″) and the width dimension is approximately fourteen and one-half inches (14½″). The starter vent sheet  10  also preferably has a width dimension that is the same or similar to the width dimension of the intermediate vent sheet  12  for insertion between adjacent rafters  46 , as will be understood by one having ordinary skill in the art. The intermediate vent sheet  12  is not limited to the above-listed length and width dimensions and may have nearly any length or width that is appropriate for a specific building structure, as will be described in greater detail below and will be understood by one having ordinary skill in the art. 
     The intermediate vent sheet  12  also preferably includes a plurality of intermediate longitudinal ribs  34  that extend generally parallel to the longitudinal axis  30  from the first end  22  to the second end  24  and a plurality of intermediate lateral ribs  36  that extend generally parallel to the lateral axis  32  from the first side  26  to the second side  28 . The intermediate longitudinal ribs  34  and the intermediate lateral ribs  36  preferably provide stiffness for the intermediate vent sheet  12 . In addition, the intermediate longitudinal ribs  34  define a plurality of vent channels  38  that extend generally parallel to the longitudinal axis  30  between the first and second ends  22 ,  24 . The vent channels  38  provide a pathway air flow parallel to the longitudinal axis  30  from the first end  22  to the second end  24  of the intermediate vent sheet  12  when the vent sheet  12  is mounted to the underside of the roof  14 , as will be described in greater detail below. 
     In addition, the intermediate lateral ribs  36  provide lateral stiffness for the intermediate vent sheet  12  and create edges  36   a  or discontinuities in the longitudinal direction, due to the transformation of the cross-section from flattened surfaces to rounded surfaces, as noted in a comparison between  FIGS. 6 and 8 . These edges  36   a  are engagable when a first intermediate vent sheet  12  is stacked with a second intermediate vent sheet  12 , or when the intermediate vent sheet  12  is stacked with a starter sheet  10 , as will be described in greater detail below, to restrict longitudinal movement of the intermediate sheets. The intermediate vent sheet  12  is not limited to inclusion of the intermediate lateral ribs  36  and the edges  36   a  having the particular shape and configuration shown in the attached figures and may have nearly any shape, size or configuration that permits the intermediate vent sheet  12  to perform its typical functions, as is described in greater detail below. 
     Referring to  FIGS. 1-3 , the first stiffened panel  1  and second stiffened panel  2  include a rib pattern that is generally identical to the rib pattern of the intermediate vent sheet  12 , including the intermediate longitudinal ribs  34  and the intermediate lateral ribs  36  having the discontinuities or edges  36   a . Accordingly, when the starter vent sheet  10  is mounted to the roof  14  proximate the soffit area  48  and/or to the ridge board  20 , the starter vent sheet  10  may be secured to or interlocked with an intermediate vent sheet  12  through the intermediate longitudinal ribs  34 , intermediate lateral ribs  36  and edges  36   a  of the main body portion  10   a  and the intermediate vent sheet  12 , as will be described in greater detail below. 
     Referring to  FIGS. 1-8 , the starter vent sheet  10  and intermediate vent sheet  12  include supplemental ribs  40  that preferably extend from sides of the intermediate longitudinal ribs  34  between adjacent intermediate lateral ribs  36 . The supplemental ribs  40  provide additional stiffness for the intermediate vent sheet  12 , the first stiffened panel  1  and the second stiffened panel  2 , and provide an additional locking or securing mechanism for securing the starter vent sheet  10  and/or the intermediate vent sheets  12  to each other in an assembled or installed configuration. The starter vent sheet  10  and intermediate vent sheet  12  are not limited to inclusion of the supplemental ribs  40  and may perform their function without inclusion of the supplemental ribs  40  or with additional alternatively configured supplemental ribs. However, the supplemental ribs  40  are utilized in the starter vent sheet  10  and intermediate vent sheet  12  to provide an additional engagement or securing feature between the intermediate vent sheets  12  and/or starter vent sheet  10  when they are engaged and installed in the roof  14 . 
     Referring to  FIGS. 1-10 , in operation, the starter vent sheet  10  is preferably initially mounted in the building structure by positioning the second non-ribbed section  4  on a top plate  42  such that the mounting flange  5  is positioned on an inner surface of the top plate  42  at the top of a wall stud  54 . The mounting flange  5  is secured to the inner surface of the top plate  42 , preferably by stapling, and the first non-ribbed section  3 , second stiffened panel  2 , and first stiffened panel  1  bend inwardly toward the roof  14  prior to insertion between two adjacent roof rafters  46 . Further bending the main body portion  10   a  relative to the already secured mounting flange  5  about the first living hinge  16 , the second living hinge  17  and the planar portion  18 , the first and second stiffened panels  1 ,  2  are positioned between the adjacent roof rafters  46 , generally in the installed configuration shown in  FIG. 9 . 
     The width dimension of the starter vent sheet  10  is preferably slightly larger than a space between the adjacent roof rafters  46 . Specifically, a majority of building structures having cathedral ceiling constructions utilize sixteen inch (16″) on center rafters including two inch (2″) wide roof rafters  46  having a nominal width of about 1⅝ inches, resulting in a fourteen inch (14⅜ ″) space between the adjacent roof rafters  46 . Accordingly, the preferred fourteen and one-half inch (14½ ″) width dimension of the starter vent sheet  10  and the intermediate vent sheets  12  results in an interference fit of the starter vent sheet  10  and the intermediate vent sheet  12  between the adjacent roof rafters  46 . This interference fit permits an operator to push or urge the first and second stiffened panels  1 ,  2  and the intermediate vent sheet  12  into the space between the adjacent roof rafters  46  against the roof sheathing  56 . When the first and second stiffened panels  1 ,  2  and the intermediate vent sheet  12  are released by the operator or installer, the first and second stiffened panels  1 ,  2  and intermediate vent sheet  12  are retained between the adjacent roof rafters  46  by an inherent spring action of the first and second stiffened panels  1 ,  2  and intermediate vent sheet  12 . If necessary in some installations, a staple can be placed through a rib  34  or  36  into the roof sheathing to help retain the vent baffle  10  in place between the rafters  46 . 
     The operator may install the starter vent sheet  10  by securing the mounting flange  5  to the top plate  42 , urging the first and second stiffened panels  1 ,  2  into the space between the adjacent roof rafters  46  and releasing the first and second stiffened panels  1 ,  2  such that they are retained between the roof rafters  46  typically without the need for fastening. The starter vent sheet  10  is not limited to having a width dimension of fourteen and one-half inches (14½ ″) or to being force fit between the adjacent roof rafters  46  for an interference fit and being secured therebetween without the need for fasteners. For example, the width dimension of the starter vent sheet  10  may be identical or slightly smaller than the spacing between the roof rafters  46  and the first stiffened panel  1  may be fastened, preferably by stapling, to a roof sheathing  56  of the roof  14 . In addition, the mounting flange  5  is not limited to being secured by stapling to the inner side of the top plate  42  and the tail portion  10   b  of the starter vent sheet  10  may be secured by stapling or otherwise fastening the second non-ribbed section  4  to a top surface of the top plate  42  or otherwise securing the tail portion  10   b  to an outside surface of the top plate  42  proximate the soffit vent  48 . In addition, the tail portion  10   b  may be secured by flaps (not shown) that extend onto adjacent ceiling rafters  46  and secure the tail portion  10   b  to the building structure such that air flow through the soffit vent  48  generally does not displace the tail portion  10   b  or second stiffened panel  2 . 
     Intermediate vent sheets  12  are subsequently engaged, preferably with at least one of the plurality of intermediate lateral ribs  36  or supplemental ribs  40  in engagement between the same features of the main body portion  10   a  or subsequent intermediate vent sheets  12 , thereby securing the starter vent sheet  10  or intermediate vent sheets  12  together extending upwardly on an underside of the roof  14 . Each of the main body portion  10   a  and the intermediate vent sheets  12  is preferably engaged between the adjacent roof rafters  46  by the interference fit such that one side of the main body portion  10   a  or intermediate vent sheets  12  is in contact with the roof sheathing  56  and air flow or vent channels  38  are created between the intermediate longitudinal ribs  34  and the roof sheathing  56  for carrying moisture away from the roof sheathing  56 . 
     Referring to  FIG. 10 , when installation of the intermediate vent sheets  12  reaches a point in the roof  14  where the next intermediate vent sheet  12  being installed would impact the ridge board  20 , peak or other feature between the rafters  46  of the roof  14 , another starter vent sheet  10  is obtained. The starter vent sheet  10  is engaged with the roof  14  and ridge board  20  preferably by stapling the mounting flange  5  to an underside of the ridge board  20  or stapling the second non-ribbed section  4  to a side surface of the ridge board  20  facing the roof sheathing  56 . The starter vent sheet  10  is then bent about the first and second living hinges  16 ,  17  to position the starter vent sheet  10  and, specifically, the first non-ribbed section  3 , the second stiffened panel  2  and the first stiffened panel  1  in an installed position, as is shown in  FIG. 10 . Accordingly, the intermediate longitudinal ribs  34  in the second stiffened panel  2  create air flow channels or vent channels  38  with the roof sheathing  56  to permit air flow. 
     Referring to  FIGS. 8 and 9 , when an entire area between the soffit vent  48  and peak or ridge board  20  of a bay between adjacent roof rafters  46  is assembled with starter and intermediate vent sheets  10 ,  12 , thereby creating generally continuous airflow or vent channels  38  between the soffit vent  48  and the ridge board  20  or peak of the building structure, insulation is inserted into the bay between the adjacent roof rafters  46  on the installed starter and intermediate vent sheets  10 ,  12 . The insulation may be of a conventional bat, foam or celluloid-type to fill a volume between the starter and intermediate vent sheets  10 ,  12  and a ceiling board  60  or a wall board  62  that is mounted to the wall stud  54  and/or roof rafters  46  to create a wall or cathedral ceiling of the building structure. One skilled in the art will note that the vent structure can be formed with a starter vent sheet  10  at the soffit area  48  and at the ridge pole  20  with the gap between the two starter vent sheets  10  being covered by one or more intermediate vent sheets  12 . If the area to be vented is sufficiently small, and the starter vent sheets  10  are sufficiently long, no intermediate vent sheets  12  may be necessary. 
     When the cathedral ceiling vent assembly comprised of the starter vent sheets  10  and intermediate vent sheets  12  are completely installed in a cathedral ceiling area of a roof  14  of a building structure, air venting may occur between an outlet and the soffit vent  48  of the building structure along the entire length of the roof  14 . The cathedral ceiling vent assembly of the present application generally prevents moisture from collecting beneath the roof  14  and provides insulation for cathedral ceilings of a building structure. The starter vent sheet  10  and intermediate vent sheet  12  are relatively simple for an operator to install, resilient, stiff, resistant to crushing during installation and are resistant to most types of corrosion due to being constructed of the PVC material. 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.

Summary:
A vent baffle assembly provides air ventilation in a cathedral ceiling having rafter beams and roof sheathing. The vent baffle assembly includes a first vent sheet and a second vent sheet. The first vent sheet has first and second ends, first and second longitudinal ribs and a first lateral stiffener extending generally perpendicularly to the ribs. The second vent sheet includes third and fourth ends, third and fourth longitudinal ribs, and a second lateral stiffener extending perpendicularly to the ribs. The first vent sheet is positioned between adjacent rafters with the ribs oriented parallel to the rafters. The second vent sheet overlaps the first vent sheet with respective ribs interengaged to limit lateral movement of the first vent sheet relative to the second vent sheet. The first lateral stiffener engages the second lateral stiffener to limit longitudinal movement of the first vent sheet relative to the second vent sheet.