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CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims domestic priority on co-pending U.S. Provisional Patent Application Ser. No. 60/969,859, entitled “Baffle Vent with Integral Drift Blocker” and filed on Sep. 4, 2007, the contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to attic vent baffles commonly used in residential building structures to allow ventilation flow from soffit vents into an attic space for venting from the attic, and, more particularly to a baffle vent with integral drift blocker that can be used in the manufactured housing industry. 
     BACKGROUND OF THE INVENTION 
     Attic ventilation systems are typically used in residential buildings to provide proper ventilation of the attic space, which is desired to help prevent formation of condensation along the interior surface of the roof. Condensation can damage the attic insulation and the wooden structure of the building itself. Proper ventilation also helps to prevent premature melting of snow accumulated on a building roof, which can lead to the formation of ice on the roof that presents a safety hazard and can also lead to roof damage. Such attic ventilation systems will utilize vents placed into the underside of the soffit, which projects outwardly from the roof of the building and forms the overhang at the perimeter of the building roof. The intent of these attic ventilation systems is for air to travel through the soffit vents into the attic space and be discharged through an attic vent, which is typically placed at the apex of the roof. 
     The use of insulation in the attic to provide a barrier to the transmission of heat between the occupied portion of the building structure and the unoccupied attic portion of the building can restrict, or even prevent, the flow of air from the soffits to the roof vent at the apex of the roof. The insulation can be packed along the joists of the roof trusses to the soffits and not allow a passageway for the movement of air past the insulation into the portion of the attic above the insulation. Known construction of the insulation material can include cellulose, rock wool, fiberglass and expanded foam, the latter being used most often in manufactured housing, i.e. housing constructed in a factory and transported to the job site instead of being constructed at the job site. To maintain a discrete passageway for the movement of from the soffit, past the insulation barrier, and into the upper portion of the attic for discharge through the roof vent, baffle vents have been provided for attachment to the interior side of the roof to keep the insulation separated from the interior surface of the roof deck. 
     One embodiment of a baffle vent can be seen in U.S. Pat. No. 7,094,145, granted on Aug. 22, 2006, to Palle Rye, et al, and assigned to Brentwood Industries, Inc. The Rye baffle vent is stapled to the interior surface of the roof sheeting between the roof rafters and includes a tail portion that is bent in the vicinity of the soffit to extend from the interior surface of the roof sheeting to engage the wall plate. This baffle vent thus forms a barrier that prevents the movement of insulation into the soffit area and restricting the flow of air into the insulation blanket and directs the air flow from the soffit over and above the insulation into the attic. The structure of the baffle vent incorporates a series of convolutions that are oriented parallel to the roof rafters to provide channels that define passageways for the movement of air past the insulation that is engaged against the baffle vent. In operation, the baffle vent utilizes the channels to keep the insulation away from the interior surface of the roof and establishes dedicated passages for the flow of air past the insulation along the interior surface of the roof sheeting. 
     Earlier configurations of baffle vents can be seen in U.S. Pat. No. 4,446,661, granted to Jan Jonsson, et al, on May 8, 1984, in which a corrugated sheet is fastened to the vertical surfaces of adjacent roof rafters to provide a plurality of longitudinally extending passageways for the movement of air past insulation in the roof. A major consideration in the design and manufacture of such baffle vents is the cost of such structures, particularly when taking into consideration the large square footage of the roofs of some residential buildings. Consequently, baffle vents have been fabricated extensively of foam or plastic material in narrow sheets that form self-supporting structures that can be handled and manipulated into position between the roof rafters for attachment against the interior surface of the roof sheeting. In U.S. Pat. No. 5,341,612, issued to Gary Robbins on Aug. 30, 1994, a baffle vent structure is formed of a thinner foam sheet material and includes a reinforced structure to prevent the vents from collapsing during shipping, handling and installation, as well as to prevent collapsing of the vents from compacted insulation which often is blown into attic areas of a building against the underside of the baffle vents. 
     Conventional residential construction affected at the job site will typically have the roof structure formed at the same time as the exterior shell of the building so as to get the building under roof to prevent the intrusion of foul weather into the interior of the building. The baffle vents described above are intended for use in such on-site construction techniques. Since the insulation is placed into the attic area long after the roof sheeting and shingles are added to the roof rafters, the baffle vents are formed to be placed between the roof rafters on the underside of the roof sheeting by attaching mounting flanged to either the vertical surfaces of the roof rafters, as is depicted in the aforementioned U.S. Pat. No. 4,446,661 to Jonsson, or the underside of the roof sheeting, as is depicted in U.S. Pat. No. 5,341,612 to Robbins. Generally, the baffle vents are installed as part of the installation of the insulation by contractors that specialize in the installation of insulation, rather than by the roofing contractor that will install the roof vent at the apex of the roof structure. 
     Manufactured housing is constructed in a factory setting where there is no pressing need to have the roof structure completed before the interior portions of the house are completed. As a result, the baffle vents can be installed on top of the roof rafters before the roof sheeting is fastened to the roof rafters. Generally, manufactured housing is formed with the interior drywall sheeting applied to the bottom side of the ceiling joists to form the inside ceiling of the housing before the roof is completed. The roof sheeting is then attached to the top surfaces of the roof rafters, followed by the application of the exterior roofing materials, typically fiberglass shingles. Insulation can then be installed between the joists on top of the drywall. While blanket fiberglass insulation or blown loose cellulose or fiberglass insulation can be used, expanded foam is often used in manufactured housing construction. The expansion rate of the foam places a substantial pressure on the baffle vent and will often collapse the passageways, resulting in the interruption of the air flow from the soffit past the insulation layer. 
     An example of a baffle vent that is adapted for use in the manufactured housing setting can be found in U.S. Pat. No. 5,596,847, granted to Michael Stephenson on Jan. 28, 1997. This baffle vent is formed with longitudinally extending ribs that are spaced on eight inch centers so that the single panel can be used on rafters whether spaced sixteen or twenty-four inches apart. A score line is formed on one of the interior ribs so that the excess eight inch strip can be removed if the baffle vent is used on rafters spaced at sixteen inched. In U.S. Pat. No. 4,096,790, issued on Jun. 27, 1978, to Laurence Curran, the baffle vent is formed to span across multiple roof rafters with a panel hanging down to engaged the wall plate and form a barrier to restrict the passage of insulation into the soffit area. In the Curran baffle vent configuration, mounting ribs are spaced at intervals corresponding to the roof rafter structure on which the baffle vent is to be applied. Thus, to be used with sixteen inch and twenty-four inch rafter spacings, the Curran baffle vent would have to be provided in two different models. 
     The Stephenson baffle vent configuration, and particularly in the Curran baffle vent configuration, the spacing of the longitudinally extending ribs provides a wide span between the ribs to define large passageways for the movement of air along the interior surface of the roof sheeting. Unfortunately, this wide expanse of unreinforced passageway, particularly when the baffle vent is manufactured from foam or a thin plastic material to maintain cost considerations, is subjected to collapse, especially when used with expanding foam insulation techniques. If the passageway collapses, the baffle vent is not functional to allow the passage of air from the soffit past the insulation layer to the upper portions of the attic structure. 
     Some configurations of manufactured housing are shipped over the highway with the roof structure, which is formed with at least two pivot devices on each side of the roof, collapsed to reduce the height of the transported structure. In such manufactured housing, the pitch of the roof structure is designed so that the attic portion of the building above the first floor can be utilized as an open storage area. Thus, the roof structure from the knee braces toward the center of the roof is open. The insulation is typically placed between the ceiling joists, trapped in the central portion of the building between the drywall panel forming the ceiling of the first floor and the floor decking placed on top of the ceiling joists at the central portion of the building. With the temperature differential between the roof area and the living space in the first floor of the building structure, condensation can accumulate beneath the attic flooring deck, which can eliminate the effectiveness of the insulation, leak into the ceiling of the first floor living space, and/or provide a medium for the growth of mold. 
     Accordingly, it would be desirable to provide a baffle vent structure that would be particularly adapted for use in the manufactured housing industry to establish and maintain passageways for the movement of air from the building soffit past the insulation layer into the upper attic area for discharge from the attic through a roof vent. It would also be desirable that the baffle vent be formed in a manner to resist a collapsing of the air flow passageways when expanded foam insulation material, or other similar insulation material that exerts a force onto the baffle vent, is installed against the baffle vent. Furthermore, it would be desirable to provide a vent structure that will assist in preventing the accumulation of condensation in the central portion of manufactured housing where the insulation is trapped between ceiling and floor panels on opposite sides of the ceiling joists. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to overcome the disadvantages of the prior art by providing a baffle vent structure that incorporates an integral drift blocker that can be oriented at an angle to the baffle vent structure. 
     It is another object of this invention to provide a baffle vent structure that is adapted for use in manufactured housing structures. 
     It is a feature of this invention that the baffle vent is designed to be placed on top of the roof rafters prior to the installation of the roof sheeting member. 
     It is another feature of this invention that the drift blocker portion of the baffle vent structure is integrally formed with the main body portion of the baffle vent structure by a planar portion that will allow the drift blocker portion to bend relative to the main body portion. 
     It is an advantage of this invention that the drift blocker portion will fall into a generally vertical orientation when the main body portion of the baffle vent structure is installed on the roof rafters. 
     It is still another feature of this invention that the main body portion is formed with transversely extending ribs to stiffen the main body portion, while the integral drift blocker portion is formed with longitudinally extending ribs to stiffen the drift blocker portion. 
     It is another advantage of this invention that the planar transition portion between the main body portion and the drift blocker portion is devoid of stiffening ribs to allow the drift blocker portion to move relative to the main body portion. 
     It is yet another feature of this invention to provide a baffle vent structure that incorporates a return lip along the longitudinally extending edges of the main body portion to position the main body portion on the top of the roof rafters in a manufactured housing operation before the roof sheeting is applied on top of the baffle vent structure. 
     It is still another object of this invention to provide a baffle vent structure that can be manufactured in sheet form to span across several roof rafters in a manufactured housing operation. 
     It is another feature of this invention that the sheet form of the baffle vent structure incorporates multiple drift blocker portions attached to the main body portion of the baffle vent structure. 
     It is still another advantage of this invention that the drift blocker portions are formed with a gap between the multiple drift blocker portions to accommodate the roof rafters extending between the drift blocker portions beneath the main body portion of the baffle vent structure. 
     It is yet another advantage of this invention that each of the drift blocker portions is attached to the main body portion of the baffle vent structure by respective planar transition portions. 
     It is a further advantage of this invention that the drift blocker portions can contain the insulation materials within the manufactured building structure while the manufactured housing is being shipped from the factory to the job site. 
     It is yet another object of this invention to provide a deck baffle panel on the ceiling joists to provide air movement beneath attic flooring to allow moisture to move toward a roof vent. 
     It is a further feature of this invention that the deck baffle panel extends past the knee brace interconnecting the ceiling joists and the roof rafters. 
     It is still a further advantage of this invention that the deck baffle panel will draw an air flow from the baffle vent to extract condensation from beneath the attic flooring. 
     It is yet another advantage of this invention that the use of the deck baffle panel will allow the removal of moisture that facilitates the growth of mold beneath the attic flooring. 
     It is yet a further feature of this invention that the deck baffle panel is formed in the same configuration as the main body portion of the baffle vent structure. 
     It is yet another object of this invention to provide a baffle vent for use in manufactured housing, 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 baffle vent incorporating an integral drift blocker portion that is connected to the main body portion of the baffle vent by a generally planar transition portion to allow the drift blocker portion to move relative to the main body portion. The main body portion is formed with transversely extending stiffening ribs, while the drift blocker portion is formed with longitudinally extending stiffening ribs with the transition portion being devoid of stiffening ribs to maintain flexibility in the transition portion. The baffle vent structure can be formed in large sheets that span several roof rafters with multiple integral drift blocker portions formed to be positioned between the roof rafters. A deck baffle panel is also provided in a configuration similar to the main body portion to be installed beneath attic flooring in manufactured housing to allow an air flow to remove moisture from beneath the attic flooring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages of this invention will become 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 top plan view of a baffle vent incorporating the principles of the instant invention, the depicted baffle vent being sized to fit between two adjacent roof rafters spaced on 16 inch centers, the integral drift blocker being oriented generally parallel to the convoluted body portion; 
         FIG. 2  is an end elevational view of the baffle vent depicted in  FIG. 1  looking in the plane of the body portion, the drift blocker being oriented in the general configuration corresponding to deployment; 
         FIG. 3  is a side elevational view of the baffle vent depicted in  FIG. 1 ; 
         FIG. 4  is a top plan view of an alternative embodiment of the baffle vent incorporating the principles of the instant invention, the integral drift blocker being oriented generally parallel to the convoluted body portion; 
         FIG. 5  is an end elevational view of the baffle vent depicted in  FIG. 4  looking in the plane of the body portion, the drift blocker being oriented in the general configuration corresponding to deployment; 
         FIG. 6  is a side elevational view of the baffle vent depicted in  FIG. 4 ; 
         FIG. 7  is a perspective view of the baffle vent structure shown in  FIG. 1 ; 
         FIG. 8  is an enlarged partial side elevational view of the body portion of the baffle vent; 
         FIG. 9  is a vertical elevational view of the baffle vent depicted in  FIG. 1  deployed between two adjacent roof rafters; 
         FIG. 10  is a vertical elevational view of the baffle vent depicted in  FIG. 4  deployed between two adjacent roof rafters; 
         FIG. 11  is an enlarged partial vertical elevational view of the baffle vent depicted in  FIG. 1  to show a feature that allows the drift blocker to be adjusted to accommodate rafter spacing less than the nominal intended spacing; 
         FIG. 12  is an enlarged partial vertical elevational view of the baffle vent shown in  FIG. 11 , but depicting the bending of the drift blocker to fit between narrowed rafter spacing; 
         FIG. 13  is a partial top plan view of another alternative embodiment of the baffle vent incorporating the principles of the instant invention, with the baffle vent formed in a sheet that would span several roof rafter spacings, the integral drift blockers being oriented generally parallel to the convoluted body portion; 
         FIG. 14  is a partial end elevational view of the baffle vent depicted in  FIG. 13  looking in the plane of the body portion, the drift blockers being oriented in the general configuration corresponding to deployment; 
         FIG. 15  is a partial cross-sectional view of a building structure taken through the soffit area and having a high roof pitch and with a baffle vent incorporating the principals of the instant invention installed therein; 
         FIG. 16  is a partial cross-sectional view of a building structure taken through the soffit area and having a low roof pitch and with a baffle vent incorporating the principals of the instant invention installed therein; 
         FIG. 17  is a partial cross-sectional view of a manufactured building structure taken through the soffit area and having a high roof pitch, the roof being pivotally collapsed for transport over the highway and having a baffle vent incorporating the principals of the instant invention installed therein, the ceiling joists also having a deck baffle vent positioned at the central portion of the building structure; 
         FIG. 18  is a partial cross-sectional view of the manufactured building structure shown in  FIG. 17 , but having the roof structure restored to the operative configuration; 
         FIG. 19  is a partial cross-sectional view of the manufactured building structure shown in  FIG. 18 , but having the soffit and roof structure completed; 
         FIG. 20  is a top plan view of the deck baffle vent utilized in the manufactured building structure shown in  FIGS. 17-19 ; 
         FIG. 21  is an end elevational view of the deck baffle vent shown in  FIG. 20 ; and 
         FIG. 22  is a cross-sectional view of the installed deck baffle vent corresponding to lines  22 - 22  in  FIG. 19 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1-12 , a baffle vent incorporating the principles of the instant invention can best be seen. The baffle vent  10  is preferably formed from polyvinyl chloride (PVC) film (not shown) having a thickness of about 12 to 16 millimeters through a conventional vacuum molding process in which the film is placed over a mold (not shown) and heated. A vacuum applied to the film draws the PVC film over a mold to cause the PVC film to assume the shape of the mold. The preferred embodiment of this baffle vent  10  would be formed in specific sizes that corresponding to conventional roof rafter spacing. The baffle vent  10  corresponding to 16 inch roof rafter spacing is depicted in  FIGS. 1-12 . The baffle vent  10  corresponding to a conventional 24 inch roof rafter spacing would preferably be formed with two more channels that would expand the overall width of the baffle vent  10 . 
     The baffle vent  10  is formed with a convoluted body portion  20  having a series of parallel, longitudinally extending flat ridges or plateaus  22  preferably separated by a semi-circular valley  25  defining an overall depth of the baffle vent  10 . The ridges  22  are spaced at four inch centers to provide a uniform configuration that will correspond to both 16 and 24 inch rafter spacings. Each valley  25  between the longitudinally extending ridges  22  is preferably formed in a semi-circular configuration to provide strength in cross-section to resist the expansive forces of the insulation materials, such as expanding foam insulation. Thus, each valley  25  has a rounded bottom surface  26  that is spaced vertically approximately one inch from the top surface  23  of the adjacent ridges  22 . 
     Each valley  25  extends along the circular arc having a preferred radius of approximately seven-eighths of an inch from the center of the rounded bottom surface  26  through an angular deflection of approximately 68.5 degrees in each direction from the center of the bottom surface  22 , measured from the tangent at the center of the rounded bottom surface  26 , whereupon the valley  25  begins a reverse bend along a radius of approximately three-eighths of an inch to join with the horizontal, flat top surface  23  of the ridge  22  on either side of the valley  25 . 
     The above-described pattern is repeated on four inch intervals measured from the center of the flat top surface  23  of one ridge  22  to the center of the flat top surface  23  of the next adjacent ridge  22 , and consequently from the center of the rounded bottom surface  26  of each valley  25  to the center of the rounded bottom surface  26  of the next adjacent valley  25 . With this particular configuration of ridges  22  and valleys  25 , the baffle vent  10  can also mate with any oddly spaced roof rafter, so long as the spacing from the next adjacent roof rafter is a multiple of four inches. As an example, the end roof rafter on a roof structure is not always placed at the same sixteen or twenty-four inch spacing as the remaining roof rafters, because the overall length of the roof is not divisible by four feet. In such situations, the end rafter will typically have an end spacing of eight, twelve or twenty inches. The baffle vent  10  can easily accommodate such an odd end spacing with a ridge  22  that will mate with the top surface of the end roof rafter. 
     The configuration of the end elevation of the baffle vent  10 , as is best seen in  FIG. 2 , is such that the arched valleys  25  are supported by the adjacent ridges  22  that are pressed against the underside of the roof sheeting and present an arch to resist the forces exerted by the insulation that is pushing the baffle vent  10  against the underside of the roof sheeting. The arched shape provides a strong geometric configuration that is resistant to collapse. 
     The body portion  20  of the baffle vent  10  is also preferably formed with transversely extending strengthening ribs  29  uniformly spaced longitudinally along the length of the body portion  20 . The configuration of the ribs  29  are best seen in  FIGS. 3 and 8 . These strengthening ribs  29  substantially increase the ability of the body portion  20  to maintain its shape irrespective of the loading placed on the body portion. For example, where the body portion  20  extends along the roof rafters above the insulation layer and the insulation is not exerting any pressure on the body portion  20 , the strengthening ribs  29  prevent the baffle vent  20  from sagging between the rafters. Furthermore, the strengthening ribs  29  increase the resistance of the valleys  25  to the pressure exerted by the insulation to keep the valleys from collapsing upwardly against the roof sheeting. 
     The embodiment of the baffle vent  10  shown in  FIGS. 1-3  is formed to provide a side edge  12  along each transverse side of the baffle vent  10  that will be positioned approximately midway across the roof rafter when the roof rafters maintain the intended spacing. Accordingly, the next baffle vent  10  can be positioned with the side edge thereof adjacent the side edge  12  of the adjacent baffle vent  10  to provide all the baffle vents with an approximately ¾ inch mounting area  14  that can be stapled to the roof rafters on which the baffle vent  10  is mounted. 
     The embodiment of the baffle vent  10  shown in  FIGS. 4-6  is formed with a wider mounting area  14  that is intended to cover the entire top surface of the roof rafter on which the baffle vent  10  is mounted. Furthermore, each side edge  12  is formed with a return lip  15  that will serve to “capture” the roof rafter. The adjacent baffle vent  10  will simply be positioned with the mounting area  14  positioned on top of the previously mounted baffle vent  10  with the return lip  15  extending into the adjacent valley  25 . The advantage of forming the baffle vent  10  with a return lip  15  is that the baffle vent  10  can likely be mounted on top of the roof rafters without stapling the baffle vents  10  to the roof rafters. Once the roof sheeting is installed on top of the roof rafters and the baffle vents  10 , the nails fixing the roof sheeting to the roof rafters will permanently secure the baffle vent  10  to the roof rafters. This feature of enabling the baffle vents  10  to be supported on the roof rafters without stapling until the roof sheeting is installed is particularly important in the production of manufactured housing, which is done indoors in a factory setting where wind in not typically a factor during the manufacturing process. 
     The baffle vent  10  is also formed with an integral drift blocker  30  that is positionable between the roof rafters on which the baffle vent  10  is mounted. The drift blocker  30  is formed from same PVC film that the body portion  20  is manufactured from, and is formed in the same vacuum molding process. The drift blocker  30  is a generally planar member that projects from the body portion  20  between the mounting areas  14 . A transition portion  32  extends from the transversely convoluted body portion  20  to the planar configuration of the drift blocker  30 . The transition portion  32  is preferably smooth, formed without any ribs  29 , to allow the drift blocker  30  to bend about the transition portion  32 . Without the strengthening ribs  29 , the thin film transition portion  32  is quite flexible. 
     The drift blocker  30 , however, is preferably formed with longitudinally (vertically) extending strengthening ribs  35  to provide resistance to the pressure exerted by the insulation. Transversely extending strengthening ribs, such as the ribs  29  in the body portion  20 , would not be satisfactory as the transverse lines formed by such strengthening ribs would define a fold line, whereas the vertical strengthening ribs  35  in the drift blocker  30  would provide satisfactory results. Preferably, the vertical strengthening ribs  35  would extend along the entire transverse width of the drift blocker  20 . Either embodiment of the body portion  10  would be formed with an integral drift blocker  30 , as can be seen in  FIGS. 1-10 . 
     Referring now to  FIGS. 11 and 12 , the drift blocker  30  is preferably formed with a cut or separation line  37  at each transverse edge of the transition portion  32  where the transition portion  32  joins the convoluted body portion  20 . This cut or separation line  37  is only intended to extend approximately 1½ to 2 inches from the edge of the drift blocker  30 . This separation line  37  enables the drift blocker  30  to be folded along the transverse edge thereof when the spacing between the inside vertical faces of the roof rafters on which the baffle vent  10  is mounted is less than the nominal 14½ inches. A representative folding of the drift blocker  30  is depicted in  FIG. 12 . 
     Yet another embodiment of the instant invention can be seen in  FIGS. 13 and 14 . Rather than form the individual baffle vent  10 , as depicted in  FIGS. 1-6 , a sufficiently wide vacuum forming machine could form the baffle vent  40  in a continuous manner from a continuous roll of PVC film fed into the vacuum machine. Such a continuous baffle vent  40  would have a practical transverse width of about eight feet, which would correspond to four rafter spacings at 24 inches, or five rafter spacings at 16 inches. The practical considerations relate to handling abilities; however, an eight foot width would present an optimum maximum transverse width for use in the manufactured home industry. In this alternative embodiment, the drift blockers  45  project from the convoluted body portion  42  with a spacing therebetween corresponding to the roof rafters on which the continuous baffle vent  40  are to be mounted. With the spacing of the drift blockers  45  being a critical factor, an eight foot wide continuous baffle vent  40  for use with a 16 inch rafter spacing would have five drift blockers  45 , while the 24 inch rafter spacing version would have only four drift blockers  45 . 
     As best seen in  FIGS. 15 and 16 , the typical roof structure  50  is formed with ceiling joists  55  that function as attic floor joists and are oriented horizontally to support a ceiling structure  56  attached to the underside of the joists  55 . The roof rafters  52  are typically connected to the ends of the ceiling joists  55  and project upwardly therefrom at a prescribed angle to meet at an apex, forming with the ceiling joists  55  a conventional triangular configuration. The roof sheeting  53  is then fastened to the top surfaces of the roof rafters  52  to form the roof structure  50 . The ceiling joists  55  and the roof rafters  52  may be supplied as a pre-assembled roof truss assembly having internal braces (not shown), or alternatively may be assembled at the construction site, and spaced at sixteen or twenty-four inch centers. 
     The roof rafters  52  will extend downwardly past the ceiling joists  35  to form the eaves or soffits  51 , which are formed with vents  51   a  to allow air to flow into the soffits  51  from the outside. The roof rafters  52  and the ceiling joists  55  typically rest on the wall plate  59 . After the roof sheeting  53  is attached to the roof rafters  52 , the roofing surface, usually fiberglass shingles  57 , is attached to the upper side of the roof sheeting  53  to complete the construction of the roof structure  50 . One of ordinary skill in the art will recognize that a roof vent (not shown) is usually placed at the apex of the roof  50  to permit the movement of air from the attic. 
     Insulation  60  in the desired form is placed between and above the ceiling joists  55  to insulate the living area beneath the ceiling joists  55 . The ceiling material  56  will retain the insulation in the attic. Preferably, the insulation  60  extends to the joinder of the roof rafters  52  and the ceiling joists  55  without extending into the soffits  51 . The baffle vent  10  described above is positioned between the insulation  60  and the underside  54  of the roof sheeting  53 , as will be described in greater detail below. Air can then flow from the outside through the vents  51   a  in the soffit  51  through the valleys  25  in the baffle vent  10  defining passageways through the insulation  60  barrier along the underside  54  of the roof sheeting  53  into the attic above the insulation  60 . The air can then be discharged through the roof vent (not shown). 
     For the preferred use in manufactured housing, the baffle vent  10  is placed on top of the roof rafters  52  before the roof sheeting  53  is placed on the rafters  52 . The baffle vent  10  need only extend along the roof sheeting  53  for a length that is greater than the height of the insulation  60  along the roof sheeting  53 . For most insulation  60  configurations, a length of 39 inches is more than sufficient to extend into the attic above the insulation  60 . The baffle vent  10  formed according to the principles of the instant invention does not require fastening to the tops of the roof rafters  32  when being installed, unless the configuration of the roof rafters mandates stapling to retain the baffle vent  10  in place until the roof sheeting  53  is applied. Once the baffle vent  10  has been mounted on top of the roof rafters  52 , the roof sheeting  53  can then be installed on top of the baffle vent  10  and on top of the roof rafters  52  beyond the baffle vent  10 . The fasteners used to attach the roof sheeting  53  to the roof rafters  52  will easily pass through the baffle vent  10  and retain the baffle vent  10  in the desired location. 
     As can be seen in a comparison of  FIGS. 15 and 16 , the baffle vent  10  can be used with a variety of roof structures irrespective of the pitch at which the roof is formed. For high pitched roofs, such as is depicted in  FIG. 15 , the vertical distance between the top of the roof rafter  52  and the wall plate  59  is greater than the corresponding vertical distance for a lower pitch roof structure  50 . The longitudinal length of the drift blocker  30  will enable the bottom edge of the drift blocker  30  to be stapled to the wall plate  59  to secure the drift blocker  30  to the roof structure  50  and prevent the intrusion of insulation  60  into the soffit area  51 . The same drift blocker  30  will extend further down the wall plate  59  in the lower pitch roof structures  50 , as is represented in  FIG. 16  to enable the drift blocker  30  to be stapled to the wall plate  59 . Preferably, the drift blocker  30  will be stapled along the top edge of the wall plate  59 , which provides some excess length of the drift blocker  30  when used on low pitch roofs  50 ; however, the excess length of the drift blocker  30  can be cut off with a knife if the excess length is not desired. 
     Some manufactured housing building structures are formed with sufficiently a high roof pitch that transport over the highway is problematic due to the height of the roof structure  50  above the ground and the transport width of the building structure. With such manufactured housing configurations, the roof structure  50  is formed with a first pivotal connection  62  in the roof rafters  52  to enable the soffit area  51  to be flipped onto the roof structure  50 , as is depicted in  FIG. 17 . A second pivot connection  63  in the roof rafters enables the upper portion of the roof structure  50  to be lowered toward the ceiling joists  55 . A third pivot connection  64  allows the knee brace  65  to be folded up against the roof rafters  52  for transport over the highway. In this configuration of manufactured housing, the baffle vent  10  can still be utilized, installed as described in detail above. 
     Restoration of the roof structure  50  is represented in  FIGS. 18 and 19 . In  FIG. 18 , the soffit  51  is lowered into place, the upper portion of the roof rafters  52  are raised to the proper orientation, and the knee braces  65  are positioned to support the rafters  52 . Pieces of roof sheeting are placed over the pivot area and the pivot areas are then shingled to complete the roof structure  50 . The soffit is completed with the soffit vent  51   a  in place. 
     As is depicted in  FIGS. 17-19 , but particularly in  FIG. 19 , the central portion of the attic area between the ceiling joists  55  and the roof rafters  52 , and inwardly from the knee brace  65 , is often configured in manufactured housing to be used as an attic storage area. To permit this use of the central portion of the attic area, the top surface of the ceiling joists  55  are capped with a floor  66  that traps the insulation  60  between the ceiling joists  55  and between the floor  66  and the ceiling panel (typically drywall)  56 . The attic floor  66  extends only to the knee brace  65  as there is no need to continue the flooring  66  outwardly of the knee brace  65 . The differential in temperature between the attic area above the floor  66  and the living area of the first floor below the ceiling panel  56 , once the building structure has been erected and people are living therein, tends to create condensation which collects beneath the floor  66 . Once sufficient condensation has been accumulated, the insulation  60  can become wet and moisture can leak through the drywall ceiling panel  56 . Also, the moist environment between the floor  66  and the ceiling  56  is conducive to the growth of mold. 
     The placement of a deck baffle panel  70  over the ceiling joists  56  before the flooring material  66  is affixed to the ceiling joists  56  will provide a barrier for the passage of condensation from the flooring material  66  into the insulation  60 . Furthermore, the deck baffle panel  70  will establish channels  72  for the passage of air beneath the flooring deck  66  to remove the moisture into the attic area outwardly of the knee brace  65 . The flow of air from the baffle vent  10  on the roof rafters  52  to provide a passageway from the soffit  51  past the insulation  60  into the roof vent (not shown), will draw an air flow from the deck baffle vent  70  to extract the condensation from beneath the floor  66 . 
     As can be seen in  FIGS. 19-22 , the deck baffle vent  70  is formed in the same convoluted configuration described above with respect to the body portion  20  of the baffle vent  10 , with flat ridges  71  separated by semi-circular valleys  72 . The deck baffle vent  70  is preferably formed in continuous sheets that are eight feet wide, although individual baffle vents, as depicted in  FIGS. 1 and 4  could also be utilized. Preferably, the deck baffle vent  70  will terminate outwardly of the knee brace  65  to provide a passageway for the movement of air beneath the floor  66  into the attic area outwardly of the knee brace where this air can be mixed with the flow of air flowing from the soffit  51  to the roof vent (not shown) and expelled from the building structure. 
     While PVC film is the preferred material from which the baffle vent  10  is formed through the thermal molding, vacuum forming manufacturing process, one of ordinary skill in the art will recognize that other materials may be used in the manufacture of the baffle vent  10 . Sheet metals, thermoplastics, and composite materials composed of fibers impregnated with thermoplastic materials can all be used to form the vent baffle  10 . Sheet metals such as galvanized steel, stainless steel, aluminum and copper can be formed into vent baffles for use in the present invention. Thermoplastic materials which can be used in the present invention in addition to PVC film are, for example, polystyrenes, acetyls, nylons, acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), polyphenylene oxides, polycarbonates, polyether sulfones, polyaryl sulfones, polyethylene, polystyrene, terephthalates, polyetherketones, polypropylenes, polysilicones, polyphenylene sulfides, polyionomers, polyepoxides, polyvinylidene halides, and derivatives and/or mixtures thereof. The particular material used may depend upon the desired end use and the application conditions associated with that use, as is well known in the art. 
     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 baffle vent incorporates an integral drift blocker portion that is connected to the main body portion of the baffle vent by a generally planar transition portion to allow the drift blocker portion to move relative to the main body portion. The main body portion is formed with transversely extending stiffening ribs, while the drift blocker portion is formed with longitudinally extending stiffening ribs with the transition portion being devoid of stiffening ribs to maintain flexibility in the transition portion. The baffle vent structure can be formed in large sheets that span several roof rafters with multiple integral drift blocker portions formed to be positioned between the roof rafters. A deck baffle panel is also provided in a configuration similar to the main body portion to be installed beneath attic flooring in manufactured housing to allow an air flow to remove moisture from beneath the attic flooring.