Patent Publication Number: US-2013239502-A1

Title: Web or vapor retarder with tie-strap

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 12/511,645 filed Jul. 29, 2009, now assigned U.S. Pat. No. 8,438,810, which claims priority from and benefit of the filing date of U.S. provisional patent application Ser. No. 61/084,397 filed Jul. 29, 2008, and the entire disclosure of each of said prior applications is hereby expressly incorporated by reference into the present specification. 
    
    
     BACKGROUND 
       FIG. 1  illustrates a known (prior art) building roof structure R comprising a corrugated metal or other roof deck D supported on plurality of parallel, spaced-apart purlins, trusses or other structural members P that extend axially along respective longitudinal axes PX that each extend perpendicularly into and out of the page as shown in  FIG. 1 . Between each successive pair of purlins P, an open bay B is defined, and the roof deck D spans the bays B. It is known to insulate the roof deck D with a known roof insulation system  10 . Typically, as shown in  FIG. 1 , the known roof insulation system  10  comprises a vapor retarder facing or web or sheet S draped over the respective upper flanges or edges P 1  of multiple (at least two) successive purlins P so that the sheet S spans one or more bays B. The vapor retarder sheet S may be fixed to at least some or all of the purlins P over which it is draped using suitable fasteners, adhesive or other means (the vapor retarder sheet S is usually secured to the first and last purlins P over which it is draped). The vapor retarder sheet S is a single layer or multiple layer product, e.g., single-layer vinyl film/sheet or other film/sheet, or a laminated composite containing various combinations of aluminum foil, polymeric film/sheet, kraft paper, reinforcing yarns and fabrics. Vapor retarder sheets S vary in strength, color, light reflectivity, and their ability to retard moisture migration therethrough. An insulation space SP is thus defined between the inner face S 1  of the sheet S and the roof deck D (i.e., the sheet inner face S 1  is oriented toward the roof deck D), and fiber glass or other insulation I is laid or blown or otherwise installed in the insulation space SP and is supported on the inner face S 1  of the vapor retarder sheet S and/or laminated to the inner face S 1  vapor retarder sheet S. As noted, the vapor retarder sheet S inhibits migration of moisture into the insulation and improves aesthetics of the interior of the building. 
       FIG. 2  is identical to  FIG. 1 , except that a drawback of the system  10  of  FIG. 1  is illustrated. In particular, during installation or of the vapor retarder sheet S, the sheet can be pulled too tightly (over-tensioned) across one or more bays B, in a direction transverse to the purlin longitudinal axes PX, so that the height (relative to the roof deck D) and volume of the insulation space SP is diminished, leading to a reduction in the available space for insulation I and/or leading to undesired compression of any previously installed insulation I, both of which reduce the efficiency or “R-value” of the insulation I. Another, related deficiency of the known roof insulation system  10  is that the vapor retarder sheet S might not pulled tight enough (under-tensioned) across one or more bays B, which leads to a sagging appearance and/or can cause the insulation I to move away from the purlins P toward the middle of the bay B, leaving the lateral areas of each bay B adjacent the purlins P under-insulated. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  (prior art) illustrates a known building roof structure insulated using a conventional vapor retarder sheet; 
         FIG. 2  (prior art) shows the insulated rood structure of  FIG. 1  and a common defect with respect to the installation of the vapor retarder sheet and insulation; 
         FIG. 3  is an isometric view of a vapor retarder sheet system formed in accordance with the present development; 
         FIGS. 4  is a top view of the vapor retarder sheet system  FIG. 3 ; 
         FIG. 5  is a side view as taken along view line  5 - 5  of  FIG. 4 ; 
         FIG. 6  illustrates the known building roof structure of  FIGS. 1 and 2 , with a portion of the roof deck broken away, and shows a roof insulation system formed in accordance with the present development using the vapor retarder sheet system of  FIG. 3 ; 
         FIG. 7  is similar to  FIG. 6  but shows that the vapor retarder sheet of the present development can alternatively be affixed to the purlins of the roof structure; 
         FIG. 8  is an isometric view of the installed vapor retarder sheet system of the present development that is similar to  FIG. 6 , but not showing the roof deck or any installed insulation; 
         FIG. 9  is an isometric view of a vapor retarder sheet system formed in accordance with an alternative embodiment of the present development. 
     
    
    
     SUMMARY 
     In accordance with one aspect of the present development, a vapor retarder system includes a vapor retarder sheet. At least one tie-strap is located adjacent an inner surface of the sheet, and the tie-strap extends across a width of the sheet and is connected to the sheet at multiple connection locations that are spaced from each other along a length of the tie-strap. The sheet includes drape regions where the sheet is disconnected from the tie-strap between successive connection locations. 
     In accordance with another aspect of the present development, a roof structure includes a plurality of parallel, spaced-apart purlins, wherein bays are defined between each successive pair of the purlins. The roof structure further includes a vapor retarder system including a vapor retarder sheet draped over a plurality of the purlins so as to span multiple bays. The vapor retarder sheet includes a tie-strap located adjacent an inner surface of the sheet. The tie-strap is connected to the sheet at multiple connection locations that are spaced from each other along a length of the tie-strap. The sheet includes drape regions that are disconnected from the tie-strap between successive connection locations. The tie-strap is extended so that the connection locations are located adjacent respective ones of the purlins and the drape regions are located in respective bays between successive ones of said purlins. 
     DETAILED DESCRIPTION 
       FIG. 3  is an isometric view of a vapor retarder sheet assembly or system  100 S formed in accordance with the present development.  FIG. 4  is a top view of the vapor retarder sheet system  100 S of  FIG. 3 , and  FIG. 5  is a side view as taken along view line  5 - 5  of  FIG. 4 . Referring to all of  FIGS. 3-5 , the vapor retarder sheet system  100 S comprises a vapor retarder facing or web or sheet S′, that is identical to the conventional vapor retarder facing or web or sheet S disclosed above in connection with  FIGS. 1 and 2 , and further comprises at least one and preferably a plurality of tie-straps T that extend coextensive or at least substantially coextensive with a width SW of the sheet S′ which can vary, but is at least equal to the lateral spacing between two successive purlins P. The tie-straps T comprise or are defined from any suitable flexible fabric, cloth, yarn, film, web, strap or other flexible member that is connected to the vapor retarder sheet S′ at multiple connection locations C spaced along the length or longitudinal axis of each tie-strap T so that the tie-strap T lies adjacent the inner surface S 1 ′. Preferably, multiple (at least two) tie-straps T are connected to the vapor retarder sheet and lie adjacent inner surface S 1 ′ and are arranged in parallel (i.e., at least substantially parallel) spaced-apart relation to each other, spaced from each other at an interval L. The lateral spacing interval L can vary within a sheet system  100 S and can vary as between different sheet systems  100 S. 
     Each tie-strap T is connected to the inner surface S 1 ′ and/or other part of the sheet S′ at the connection locations C that are spaced from each other at a constant interval N along the length or longitudinal axis of each tie-strap T. Furthermore, each tie-strap T is connected in the same manner and at the same constant interval N so that the respective corresponding connection points C of the straps T are aligned with each other on respective strap-connection axes CX that extend transverse to the longitudinal axes of each tie-strap T. Each tie-strap T is preferably continuous, but those of ordinary skill in the art will recognize that each tie-strap T can be replaced by multiple separate tie-straps, each having a length of at least one interval N. 
     The vapor retarder sheet system  100 S can be rolled or folded as desired for storage and transport. When completely unfurled as shown in  FIGS. 3-5 , the tie-straps T are extended to a maximum extent, and the tie-straps T limit maximum extension of the vapor retarder sheet S′ to the width SW, which is less than a full unrestricted width of the sheet S′ if it was not connected to the one or more tie-straps T. Between successive connection points C, the vapor retarder sheet S′ defines a drape region DR ( FIG. 5 ) that is free of and not connected to the tie-strap(s) T so that it has a predetermined, select drape height DH (measured as the maximum possible distance between the plane of the fully extended tie-strap T and the inner surface S 1 ′) which is predetermined when the tie-strap(s) T are connected to the sheet S′. The drape height DH is controlled by the extent to which the length/width of the sheet S′ between any two successive connection points C is greater than the straight-line spacing interval N between the same two successive connection points C, i.e., the distance between the two successive connection points C is shorter by a first path that follows said tie-strap T as compared to a second path that follows said sheet S′. In one embodiment, the spacing interval N between connection points C is in the range of 24 inches to 72 inches (commonly 60 inches) and the drape height is in the range of 3 inches to 18 inches, but the present development is not limited to such dimensions. 
       FIG. 6  illustrates the known building roof structure R of  FIGS. 1 and 2 , which is not described again here, with portions of the roof deck D are broken away.  FIG. 6  shows a roof insulation system  100  formed in accordance with the present development using the vapor retarder sheet system  100 S. The vapor retarder sheet S′ is draped over the upper flange or edge P 1  of multiple (at least two) successive purlins P so that the sheet S′ spans one or more bays B, with the tie-straps T extending perpendicularly or otherwise transversely between the purlins P. The connection point interval N of the tie-straps T to the sheet S′ is selected to match the lateral spacing between successive purlins P (preferably at the centers of the upper edges/flanges P 1 ) so that the connection points C are located on or at least near the purlin upper flanges/edges P 1 , with the strap connection axes CX extending parallel with the purlin longitudinal axes PX. 
     Those of ordinary skill in the art will recognize that the presence of the tie-straps T ensures that the vapor retarder sheet S′ is arranged in each bay B with the drape regions DR suspended or “pillowed” in the bays B and exhibiting the select, predetermined drape height DH when the tie-straps T are fully extended. The tie-straps T prevent over-tensioning of the vapor retarder sheet S′ between successive purlins P as described above in relation to  FIG. 2 . As such, the vapor retarder sheet S′ allows for consistently higher R-values as compared to prior systems. The vapor retarder sheet S′ may be fixed to some or all of the purlins P over which it is draped using suitable fasteners, adhesive or other means, after which the tie-straps T can be severed if desired to facilitate installation of fiber glass or other insulation I in the insulation space SP′ defined between the inner surface S 1 ′ of the vapor retarder sheet S′ and the roof deck D, or the tie-straps T can be left intact. In one example, the vapor retarder sheet S′ is connected to the first and last purlins P over which it is draped. 
     The vapor retarder sheet S′ is a single layer or multiple layer product, e.g., single-layer vinyl film/sheet or other film/sheet, or a laminated composite containing various combinations of aluminum foil, polymeric film/sheet, kraft paper, reinforcing yarns and fabrics. The retarder sheet S′ can vary in strength, color, light reflectivity, ability to retard moisture migration therethrough, and other attributes without departing from the overall scope and intent of the present development. 
     As shown in  FIG. 7 , in an alternative embodiment, the drape region DR of the sheet S′ can be affixed to the purlins P so that the drape region DR is pulled tight between the purlins or otherwise shaped as desired, e.g., with a substantially planar outer face DRF that lies at least substantially parallel to the fully extended tie-strap T as shown in  FIG. 7 . In such case, the drape height DH ( FIG. 6 ) of the sheet S′ must be dimensioned properly to ensure that sufficient material of the sheet S′ is present in the bay B to allow the drape region DR to be shaped as desired/required. 
       FIG. 8  is an isometric view of the installed vapor retarder sheet system  100 S of the present development that is similar to  FIG. 6 , but not showing the roof deck D or any installed insulation I. 
     In an alternative embodiment, the vapor retarder sheet S′ is replaced with an alternative sheet or web that can be any desired polymeric sheet/film, fabric, cloth, netting, laminate and/or other flexible material. In one such embodiment, as shown at W in  FIGS. 3 ,  6 , and  8  using a broken lead line, such an alternative web W is provided as a fall-protection member that will support a person or object that falls from the purlins P or other location above the web W. One suitable fall protection member is defined from or comprises a netting material. 
       FIG. 9  is an isometric view of a vapor retarder sheet system  200 S formed in accordance with the present development, which is identical to the system  100 S excepts as shown and/or described herein. The system  200 S differs from the system  100 S in that the flexible tie-straps T are replaced by rigid or semi-rigid tie-members or tie-straps T′ defined from wood, foam, polymeric members, corrugated cardboard or polymeric material or the like. In such case, the tie-straps T are connected to the vapor retarder sheet S′ (or fall protection web W) to lie adjacent the inner surface S 1 ′. Each tie-member T′ is connected to the inner surface S 1 ′ or other location of the sheet S′ at the connection locations C that are spaced from each other at an interval N along the length or longitudinal axis of each tie-member T′. Each tie-member T′ thus defines successive sections T 1 ′,T 2 ′,T 3 ′, etc. between the connection locations C. Furthermore, each tie-member T′ is connected in the same manner and at the same interval N so that the respective connection points C of the tie-straps T′ are aligned with each other on respective connection axes CX that extend transverse to the longitudinal axes of each tie-member T′. The tie-straps T′ comprises a hinge H adjacent each connection point C, e.g., a living hinge defined by a weakened/flexible zone in the case where each tie-member T′ is a continuous strip of material, or by a cut and/or break and/or space in the tie-member T′, or by connecting successive sections T 1 ′,T 2 ′,T 3 ′, etc. of the tie-member T′ with a separate hinge device which could be a flexible strip of fabric or other material. As described above for the system  100 S, between successive connection points C along the axis of each tie-member T′, the vapor retarder sheet S′ defines a drape region DR that is free of or not connected to the tie-member T′ so that it has a predetermined, select non-zero drape height DH ( FIG. 5 ) which is predetermined when the tie-straps T′ are connected to the sheet S′. The drape height DH is controlled by the extent to which the length of the sheet S′ between successive connection points C is greater than the straight-line spacing interval N between the connection points C. A greater drape height DH will allow for greater amounts of insulation Ito be installed in the insulation space SP′. 
     The development has been described with reference to preferred embodiments. Those of ordinary skill in the art will recognize that modifications and alterations to the preferred embodiments are possible. The disclosed preferred embodiments are not intended to limit the scope of the following claims, which are to be construed as broadly as possible, whether literally or according to the doctrine of equivalents.