GB1570058A

GB1570058A - Strip for fastening and sealing sheets of construction material

Info

Publication number: GB1570058A
Application number: GB1306478A
Authority: GB
Original assignee: Grefco Inc
Current assignee: Grefco Inc
Priority date: 1978-04-04
Filing date: 1978-04-04
Publication date: 1980-06-25

Description

(54) STRIP FOR FASTENING AND SEALING SHEETS OF CONSTRUCTION MATERIAL (71) We, GREFCO INCORPOR ATED, of 50 Monumenr Road, Bala Cynwyd, Pennsylvania 19004, U.S.A. a corporation existing by and under the laws of the State of Delaware, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is concerned with jointing strips for fastening and sealing sheets of building material placed in edge-abutting relation.

The widespread and growing use of building materials in sheet form in all phases of the building industry has necessitated the development of improved jointing strips for fastening the sheets together. Typically, the sheets are positioned over an underlying frame structure with the edges of adjoining sheets abutting to form a joint. In many applications the spacing of the underlying frame members is determined by the dimensions of the sheets so that the joints can be positioned directly over a frame member and so that the sheets can be fastened to the frame structure at the joint locations.

The use of building materials in sheet form has not been confined to interior applications, and with the development of suitable lightweight weather-proof coatings, the use of sheet material in the fabrication of exterior walls and roofdecks has become commonplae.

An example of such sheet material is disclosed in U.S. Patent Application Serial No. 702.966.

Such exterior applications, however, have required that the jointing strips perform a seal ing function as well as withstand the additional loadings caused by wind forces and forces induced by thermal expansion and contraction.

U.S. Patent Specifications Nos. 3,320,707 and 3,339,329 typify jointing strips currently used in the building industry for fastening and sealing sheet material placed in edgeabutting relationship. The jointing strip disclosed in U.S. Patent Specification No.

3,320,707 includes a deformable sealing pad, and overlying metal strip, and screws passing through the strip and pad into the underlying frame for forcing the pad into the joint formed by the lipped abutted sheets thereby capturing the sheets. A major problem with such a joint- ing strip is that, although the metal strip gives the superior hold-down performance needed for exterior applications, the exposed metal acts as an eilìcient, but unwanted, conductor of heat energy through the joint and past the wall or roof structure. During hot weather this conduction path can result in a significantly increased air conditioning load, while heat losses during the winter months will be reflected in greater heating costs.Such a jointing strip, then, is counter-productive, inasmuch as the corresponding sheet materials, especially those intended for roofdeck applications, are usually fabricated for maximum insulating properties.

Also, the direct exposure of metal parts to weathering can lead to corrosion which would necessitate maintenance at unacceptably short intervals during the life of the structure. Such corrosion can be particularly troublesome if dissimilar metals are used for the metal strip and the screws where the galvanic action can greatly accelerate the corrosion rate possibly causing a premature loss of hold-down capability.

A jointing strip utilizing an unexposed metal strip overlying the edges of the abutted sheets for superior hold-down performance but without the attendant heat conduction and corrosion problems of conventional devices would therefore be highly desirable.

With regard to the required sealing function, jointing strips such as disclosed in U.S. Patent Specification No. 3,320,707, depend upon deformation of the underlying sealing pad against the sheet edges to effect the primary moisture seal in exterior applications. This is not altogether satisfactory as deterioration of the pad material and lateral movements of the sheet material caused by thermal expansion and contraction can substantially diminish the sealing effectiveness of such conventional joint ing strips. Modifications of current jointing strips such as shown in Figure 4 of U.S. Patent Specification No. 3,320,707 and Figure 3 of U.S. Patent Specification No. 3,339,329 have attempted to maintain positive contact between the pad and the exterior facing surfaces of the sheet material in an effort to improve sealing performance.The modifications generally consist of extending the overlying metal or plastics hold-down strip beyond the channel formed by the abutted sheets and by providing that a part of the pad underlies these extensions to act as a gasket.

These modifications are far from being totally satisfactory for several reasons. First, the extending portions of the hold-down strip must be made relatively stiff to compress the underlying pad. The force required to compress these outlying pad portions is unavailable to compress the pad directly over the joint resulting in a decrease in the localized clamping pressure. Decreases in the localized clamping pressure can result in unacceptable lateral movement of the sheets during wind-induced flexing.

Second, the required stiffness of the holddown strip extensions prevents these appendages from adequately conforming to sheet thickness variations (waviness) along the joint.

Portions of the pads underlying the "low spots" may remain uncompressed and provide leakage paths past the intended secondary moisture barrier.

Therefore, a jointing strip for edge-abutted sheets of building material that could accommodate variations in sheet thickness without significantly decreasing the localized clamping pressure would be highly desirable and would certainly find immediate acceptance in the building industry.

The jointing strip of the invention is provided for sealingly joining two edge-abutted sheets of building material and for attaching the sheets to an underlying frame member positioned beneath the joint, the abutting edges being rabbeted to form a joint channel.

In accordance with the invention, the jointing strip comprises a compressible resilient pad member for being drawn into said channel, the pad member extending in the longitudinal direction along the channel and having a transverse dimension for providing an interference fit with the sides of the channel; a resilient capping strip permanently adhered to the pad member, said capping strip also extending longitudinally along the channel and having transverse edges extending past the pad member for contacting the outwardly-facing surfaces of the sheets when the pad member is drawn into the channel, the extending edges being sufficiently flexible in both the transverse and the longitudinal directions to sealingly conform to the outwardly-facing surfaces; a metal strip embedded in the pad member and extending longitudinally of the channel, the strip being oriented to overlie the junction when the pad member is drawn into the channel; and means for securing the metal strip to the underlying frame member, the pad member being drawn into the channel upon actuation of the securing means, and the rabbeted surfaces of the sheets being captured between the portion of the pad underlying the metal strip and the frame member. The pad member may be fabricated from a semi-rigid insulating foam material; the capping strip may have an arcuate undeformed transverse shape for providing initial contact between the extended edges and the sheet surfaces when the pad member is only partially drawn into the channel; and the securing means may include screw means positioned at discrete intervals in the longitudinal direction along the strip.Preferably, the pad member is fabricated from foamed polyvinyichloride (PVC); the capping strip is fabricated from solid PVC; holes are provided in the pad member exposing the metal strip at the discreet intervals; and means are provided to seal the holes after the actuation of the securing means.

One construction of jointing strip and modifications thereof in accordance with the invention will now be described by way of example with reference to the accompanying drawing, in which: Figure 1 is a perspective view of the jointing strip Figure 2 is a cross-sectional view of the jointing strip in an installed position Figure 3 is a cross-sectional view on the line 3-3 of Figure 1 Figure 4 is a cross-sectional view on the line 4-4 of Figure 1 Figure 5 is a cross-sectional view showing a modification of the jointing strip of Figure 1, and Figure 6 is a cross-sectional view showing a further modification of the jointing strip of Figure 1.

Referring now to Figure 1, jointing strip 10 is provided for sealingly joining two edgeabutted sheets of building material, such as a perlite-foam composite, as seen at 12 and 14 in Figure 2. Sheets 12 and 14 are supported at the joint by rafter member 16, which can be of steel, wood or any other suitable material. The abutting edges 18 and 20 of sheets 12 and 14 respectively are rabbeted or mitered to provide a joint channel 22.

The jointing strip 10 includes a pad member 24 which when the jointing strip is installed extends longitudinally of channel 22.

As best seen in Figure 2, the transverse dimension of pad 24 is sized to provide an interference fit with the walls 26 and 28 of channel 22, thereby providing a moisture barrier for exterior uses of the jointing strip 10.

Pad member 24 should be compressible but resilient. A semi-rigid foamed insulating material such as foamed polyvinylchioride is a suitable material for pad member 24. The insulating properties of foamed polyvinylchloride are highly desirable for use with sheet materials having similar insulating properties, especially when intended for roofdeck applications.

As an alternative semi-rigid insulating material, honeycombed polyvinylchloride can be used for the pad member, as is shown in Figure 5. Elongated honeycombed structures can be easily produced from materials such as PVC by techniques well known in the plastics extrusion art.

As can best be seen in Figure 6, the sides 66 and 68 of pad member 24 can be tapered to insure an interference fit with walls 26 and 28 as well as to facilitate alignment of the pad member 24 in the channel 22 during installation.

The jointing strip 10 also includes a capping strip 30 which is fixedly adhered to pad member 24. The strip 30 also extends longitudinally of channel 22 and has transversely extending edges 32 and 34 for contacting the outwardly-facing surfaces 36 and 38 of the sheets 12 and 14, respectively, when the jointing strip 10 is installed.

Extending edges 32 and 34 are so fabricated as to be sufficiently flexible in both the longitudinal and transverse direction to sealingly conform to sheet surfaces 36 and 38 for reasonable variations in sheet thickness and for usual surface waviness. This biaxial conformability characteristic is accomplished by making edges 32 and 34 thin and using a resilient material for the capping strip 30. The thin edges 32 and 34 will ensure conforming contact without placing an appreciable bending load on the capping strip 30, which load would otherwise decrease the clamping pressure.The resilience of the edges also will allow minor vertical movements in the various components without breaking the sealing contact and, together with the resilience of pad member 24, will allow the jointing strip 10 to be reuseable after repair or replacement of a defective sheet in an assembled wall or roofdeck.

As herein embodied, solid PVC is used for the capping member 30 especially when foamed PVC is chosen as the material for pad 24 to facilitate adherence between pad 24 and the capping strip 30 when the jointing strip 10 is fabricated. It is intended that the capping strip 30 can be permanently adhered to pad 24 using any standard fabrication technique, such as buy adhesives.

It is preferred that the centerline thickness 40 of capping strip 30 (see Figure 3) is greater than the thickness of edges 32 and 34, to provide increased structural rigidity in the region where the capping strip 30 is affixed to pad 24. And it is also preferred that the capping strip 30 have an arcuate shape to provide initial contact between edges 32 and 34 and surfaces 36 and 38 before the pad member 24 is completely seated in channel 22. This ensures contact along the entire length of edges 32 and 34 when the jointing strip 10 is completely installed, particularly when sheets 12 and 14 have non-uniform thicknesses.

As the capping strip 30 is fixedly adhered to pad member 24, these components constitute a single unit which dispenses with the need for handling and assembling several elongated parts during installation. The resulting onepiece construction may yield significant savings in both fabrication and installation costs over the jointing strips currently in use in the building industry. Savings in fabrication costs would be particularly significant if pad member 24 were formed by foaming a suitable material directly onto the capping strip 30 while the latter was being extruded. But a capping strip formed separately and fixedly adhered to the pad by a laminating process is acceptable nonetheless.

The jointing strip 10 also includes a metal strip 42 embedded in pad member 24. Metal strip 42 also extends longitudinally of channel 22 and is oriented in pad 24 to overlie the junction of sheets 12 and 14 when the jointing strip 10 is installed, as can be seen in Figure 2. Strip 42 can be fabricated of galvanized steel or any other suitable metal. Strip 42 can be implanted during the fabrication of pad 24 by any suitable technique such as by making pad 24 in two pieces and laminating the pieces together with strip 42 sandwiched inbetween. If, as it is preferred, pad 24 is of a foamed material, strip 42 can be encapsulated during the foaming procedures by techniques well known in the art.

Means 44 are provided for securing metal strip 42 to rafter 16. It is intended that the pad member 24 be drawn into channel 22 by the actuation of the securing means 44 and that the rabbeted surfaces 46 and 48 of sheets 12 and 14, respectively, are captured between the portion 50 of pad 24 underlying strip 42 and the rafter member 16.

The securing means 44 includes screws 52 positioned at intervals along strip 42. Screws 52 should be of a length to engage rafter 16 with pad member 24 completely outside channel 22 in order to facilitate drawing pad member 24 into the channel and causing edges 32 and 34 to contact surfaces 36 and 38, respectively.

It is preferred that holes 54 be provided in the pad member 24 and the overlying capping strip 30 at the aforementioned intervals along strip 42. The holes 54 should expose metal strip 42 for insertion and actuation of screws 52. And it is also preferred that the jointing strip 10 further include means 56 to seal holes 54 after the activation of securing means 44. Acceptable sealing means 56 would include plug members 58 fabricated from a suitable material such as PVC and sized for an interference fit in holes 54. Alternatively, a standard caulking compound can be used for sealing means 56. Such compounds are well known in the building art.

By plugging or caulking individual screw holes 54 from the top, their location can be easily ascertained at such time in the future when the roof must be repaired by removing and replacing damaged sheets. The plugs or caulking can be removed and screws 52 backed out using conventional tools such as a reversible screw gun.

As embodied herein, and as best seen in Figure 5, the jointing strip 10 further includes material formed on the undersides 60 and 62 of edges 32 and 34, respectively, for promoting sealing upon contact with sheet surfaces 36 and 38. Preferably, butyl mastic tape is used for the material at 60 and 62. This tape can be protected until installation by a peelable protective release paper covering, a technique well known in the art. It is also preferred that sealing material be formed on the underside of pad 24 to insure sealing contact with rabbeted surfaces 46 and 48 and that butyl mastic tape also be used for the sealing material at 64.

WHAT WE CLAIM IS: 1. A jointing strip for sealingly joining two edge-abutted sheets of building material and for attaching the sheets to an underlying frame, the sheets having outwardly-facing surfaces and being oriented with the abutted edges positioned over a frame member, the abutted edges being rabbeted to form a channel along the junction of the sheets, the joining strip comprising:: (a) a compressible resilient pad member for being drawn into said channel, said pad member extending longitudinally of the channel and having a transverse dimension for providing an interference fit with the sides of the channel when said pad member is drawn into the channel; (b) a resilient capping strip permanently adhered to said pad member, said capping strip extending longitudinally of the channel and having edges extending in the transverse direction past said pad member for contacting the outwardly-facing surfaces of the abutted sheets when said pad member is drawn into the channel, said extended edges being sufficiently flexible in both the transverse and longitudinal directions to sealingly conform to the outwardly-facing surfaces when said extended edges have been made to contact said outwardlv-facing surfaces;; (c) a metal strip embedded in said pad member and extending longitudinally of the channel, said metal strip being oriented to overlie the junction when said pad member is drawn into the channel; and (d) means for securing said metal strip to the frame member, said pad member being drawn into the channel upon actuation of said securing means, the rabbeted surfaces of the sheets being captured between the portion of said pad underlying said metal strip and the frame member.

2. The jointing strip of claim 1 in which said pad member is constructed of a seini- rigid insulating foam material.

3. The jointing strip of claim 2 wherein said foam material is foamed polyvinylchloride.

4. The jointing strip of claim 1 in which said pad member is constructed of a semirigid insulating honeycombed material.

5. The jointing strip of claim 4 wherein said honeycombed material is polyvinylchloride.

6. The jointing strip of any preceding claim wherein said pad member has tapered sides to tighten said interference fit when said pad member is drawn into the channel.

7. The jointing strip of any preceding claim wherein said capping strip has an arcuate undeformed transverse shape for providing initial contact between said extended edges and said outwardly-facing surfaces when said pad member is partially drawn into the channel.

8. The jointing strip of any preceding claim wherein the thickness of said capping strip varies in the transverse dlrection, said thickness being the greatest at the center and the least at the periphery of said extended edges.

9. The apparatus of any preceding claim wherein said capping strip is fabricated from polyvinylchloride.

10. The jointing strip of any preceding claim wherein said securing means includes screw means positioned at intervals along said metal strip.

11. The jointing strip of claim 10 wherein holes are provided in said capping strip and said pad member, said holes being located at said intervals and exposing said metal strip for engagement by said screw means, and said jointing strip further comprising means for sealing said holes after the actuation of said securing means.

12. The jointing strip of claim 11 wherein said sealing means includes plug members.

13. The jointing strip of claim 11 wherein said sealing means includes a caulking compound.

14. The jointing strip of any preceding claim further comprising sealant material formed on the undersides of said extended edges for adhering to said outwardly-facing surfaces upon contact between said extended edges and the outwardly-facing surfaces when said pad is drawn into the channel.

15. The jointing strip of claim 14 wherein said sealant material is butyl mastic sealant tape.

16. The jointing strip of any preceding claim further comprising sealant material formed on the underside of said pad member

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. an interference fit in holes 54. Alternatively, a standard caulking compound can be used for sealing means 56. Such compounds are well known in the building art. By plugging or caulking individual screw holes 54 from the top, their location can be easily ascertained at such time in the future when the roof must be repaired by removing and replacing damaged sheets. The plugs or caulking can be removed and screws 52 backed out using conventional tools such as a reversible screw gun. As embodied herein, and as best seen in Figure 5, the jointing strip 10 further includes material formed on the undersides 60 and 62 of edges 32 and 34, respectively, for promoting sealing upon contact with sheet surfaces 36 and 38. Preferably, butyl mastic tape is used for the material at 60 and 62. This tape can be protected until installation by a peelable protective release paper covering, a technique well known in the art. It is also preferred that sealing material be formed on the underside of pad 24 to insure sealing contact with rabbeted surfaces 46 and 48 and that butyl mastic tape also be used for the sealing material at 64. WHAT WE CLAIM IS:

1. A jointing strip for sealingly joining two edge-abutted sheets of building material and for attaching the sheets to an underlying frame, the sheets having outwardly-facing surfaces and being oriented with the abutted edges positioned over a frame member, the abutted edges being rabbeted to form a channel along the junction of the sheets, the joining strip comprising:: (a) a compressible resilient pad member for being drawn into said channel, said pad member extending longitudinally of the channel and having a transverse dimension for providing an interference fit with the sides of the channel when said pad member is drawn into the channel; (b) a resilient capping strip permanently adhered to said pad member, said capping strip extending longitudinally of the channel and having edges extending in the transverse direction past said pad member for contacting the outwardly-facing surfaces of the abutted sheets when said pad member is drawn into the channel, said extended edges being sufficiently flexible in both the transverse and longitudinal directions to sealingly conform to the outwardly-facing surfaces when said extended edges have been made to contact said outwardlv-facing surfaces;; (c) a metal strip embedded in said pad member and extending longitudinally of the channel, said metal strip being oriented to overlie the junction when said pad member is drawn into the channel; and (d) means for securing said metal strip to the frame member, said pad member being drawn into the channel upon actuation of said securing means, the rabbeted surfaces of the sheets being captured between the portion of said pad underlying said metal strip and the frame member.

for adhering to the rabbeted surfaces of the channel when said pad is drawn into the channel.

17. The jointing strip of claim 16 wherein said sealant material is butyl mastic sealant tape.

18. A structure for use in the building industry, the structure being attached to an underlying frame, the structure comprising: (a) at least two sheets of a building material laid edge-toedge on the frame, said abutted edges being positioned over an underlying member of the frame, said sheets having outwardly-facing surfaces and said abutted edges being rabbeted to form a channel along the junction od said sheets; and (b) a jointing strip as claimed in any preceding claim.

19. A jointing strip substantially as hereinbefore described with reference to and as shown in the accompanying drawings.