CA1105299A - Insulation fastener system - Google Patents
Insulation fastener systemInfo
- Publication number
- CA1105299A CA1105299A CA312,494A CA312494A CA1105299A CA 1105299 A CA1105299 A CA 1105299A CA 312494 A CA312494 A CA 312494A CA 1105299 A CA1105299 A CA 1105299A
- Authority
- CA
- Canada
- Prior art keywords
- plate
- screw
- fastener
- fastener system
- drill
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Roof Covering Using Slabs Or Stiff Sheets (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A fastener system is disclosed that is adapted for attaching sheet insulation material to a corrugated sheet metal base, such as a roof deck, which includes a hold-down plate in the form of a regular polygon having at least five sides and a screw fastener. The hold-down plate is designed with circular ridges to absorb transient dynamic forces and with circumferen-tial linear ridges to provide rigidity. The preferred screw fastener is a drill screw in which the major diameter of the drill flights does not exceed the minor diameter of the screw flights.
A fastener system is disclosed that is adapted for attaching sheet insulation material to a corrugated sheet metal base, such as a roof deck, which includes a hold-down plate in the form of a regular polygon having at least five sides and a screw fastener. The hold-down plate is designed with circular ridges to absorb transient dynamic forces and with circumferen-tial linear ridges to provide rigidity. The preferred screw fastener is a drill screw in which the major diameter of the drill flights does not exceed the minor diameter of the screw flights.
Description
1~5~99 ~ACKGROUND OF THE INVENTION
Field of the Invention This invention relates to a fastener system of the type especially adapted for use in the attachment of sheet insulation material to a corrugated sheet metal base, such as a steel roof deck. More specifically, the invention is an improvement in the stress distribution or hold-down plates and fastener devices utilized in such systems.
Description of the Prior Art A variety of fasteners have been used to mechanically secure various materials to sheet metal bases. Generally, these devices include a rather long nail- or screw-threaded shaft which pierces the insulation and sheet metal and grips into the support underlying the sheet metal. Stress distribution or hold-down plates are either placed between the head of the screw and the insulation material or incorporated onto the head of the shaft itself in order to provide a bearing surface area and prevent the shaft head from tearing through the relatively soft insulation material when it is under stress.
The primary load which the insulation fastener must withstand, in the case of a component of a roof, is an uplifting force induced by winds which tend to unseat the insulation material upwardly away from the metal base. Resistance to the w;nd uplift force is, in fact, the primary criterion used by Factory Mutual System, an industry testing and underwriting organization, in granting approval to fastening systems for securing sheet insulation material to a roof.
The present invention presents markedly superior~wind uplift resistance than the stress distribution devices currently being utilized. Each of the prior art devices possesses substan-tial shortcomings in this respect. Those that are round tend to buckle prematurely under load. Those made of stiffer material llQ5299 or those with sharp corne~s tear through the insulation material before specified ~aximum loads are achieved. For these and other reasons, the prior art devices have not proved completely satisfactory in providing the required resistance to the insula-tion material against the uplift of the wind.
According to the present invention there is provided a fastener system particularly adapted for attaching sheet insulation material to a sheet metal base comprising: a hold-down plate in the form of a regular polygon having at least five sides; a hole through the center of the polygonal plate; at least one circular ridge on the plate concentric with the hole;
a plurality of ridges substantial parallel to and adjacent the perimeter of the plate; radial ridges extending between the outermost circular ridge and the perimeter of the plate; and a screw fastener having a shank portion adapted to be received by the hole and having a head portion adapted to seat on the surface of the plate surrounding the hole.
, j DESCRIPTION OF THE DRAWINGS
FI~. 1 is a view of a face of a stress distribution plate made according to the inventioni FIG. 2 is a sectional view of the plate taken through line 2-2 of FIG. l;
FIG. 3 is a side view of a preferred fastening device for use with the distribution plate of this invention; and FIG. 4 is a view of the plate of FIGS. 1 and 2 when positioned to secure insulation material to a sheet metal base.
Referring to FIG. 4, the environment of the invention is shown in which a layer of sheet insulation material 2 is secured to a corrugated sheet metal base 4 suitable for use as a roof for a building. The sheet insulation 2 is secured to the metal base 4 by means of hold-down plates 6 and fasteners 8.
The fasteners 8 pass through a central opening in the hold-down plates 6 and are driven through the metal base 4. In a typical insulation, after the insulation 2 has been secured in place, the roof is completed as by covering it with tar or other suit-able roofing material.
FIG. 1 shows in more detail the preferred configura-tion of a hold-down plate 6 made in accordance with this inven-tion. The plate 6 is provided with a hole 10 located at its center adapted to receive a suitable fastening device 8. The diameter of the hole 10 is large enough to pass the shank 12 of the fastener 8, but small enough to retain the head portion 14 of the fastener 8. The plate is also provided with several con-centric circular impressions 16 located centrally in its face.
The plate 6 is also provided with a peripheral impression 18 located adjacent to and reinforcing the perimeter of the plate 6. Finally, the plate 6 is provided with several radial impres-sions 20 extending between the outermost circular impression and the perimeter of the plate. In the preferred embodiment, these radial impressions are equally spaced about the plate and connect the outermost circular impression with each corner of the hexa-gonal perimeteral impression.
FIG. 2 illustrates the preferred depth and spacing of the impressions 16 and 18 in relation to the external dimensions of the plate. The hole 10 must be surrounded by an adequate flat area 22 in order to properly seat the head 1~ of the fastening device 12. Outboard of this flat area 22, the circular and hexa-gonal impressions occupy a significant portion of the plate's 6 remaining surface area. The depth of the impressions depends upon the size of the plate and the thickness of the plate material.
Generally, the impressions have a depth of roughly ten times the thickness of the plate material.
The drill screw fastening device 8 is shown in greater detail in FIG. 3. Basically, the drill screw has a shank portion 12, a formed head portion 14, a pointed end 24, one or more drill flights 26 and threads 28. The drill screw 8 is designed so that it may be secured to a workpiece without predrilling a hole since the drill flights 26 will accomplish this function ahead of the time that the threads 28 engage the workpiece. In order to obtain maximum holding power, the drill screw 8 is designed so that the maximum diameter of the drill flights 26 is no greater than the minor diameter of the threads 28. It can be understood that by so designing the drill screw, the threads 28 will be able to obtain a maximum bite on the workpiece.
Although superficially it might appear that insulation fasteners are static devices, the dynamic characteristics of stress distribution plates are essential to their satisfactory performance. The nature of the typical service conditions in which these plates operate will clarify this consideration.
First, it must be remembered that the materials used as roofing insulation are generally quite soft and have a low 11~ 5 2 ~
modulus. Even with the protective coating typically affixed to the upper surface o~ the insulation, the composite material can withstand relatively little stress.
Second, the amplitude of the w;nd's upward force fluc-tuates greatly from time to time. Thus, the ability of a fastener system to secure insulation material under wind uplift loading is limited not only by its own static and dynamic strength, but also by the insulation material's dynamic strength and resistance to tearing. It ls in this aspect of the dynamic performance lO characteristics of the entire fastener system that the features of this invent;on interact so as to effect marked improvement in the prior art.
The important design criteria fundamental to the attain-ment of these improvements will be illustrated more clearly by reference to the preferred embodiment. The optimum stress dis-tribution plate must demonstrate a high resistance to buckling yet not have a tendency to tear the insulation material. Circular plates might acceptably prevent tearing of the insulation, but they will lack sufficient resistance to buckling under load.
Four-sided plates seem to possess greater stability under load, but tend to tear the insulation easily. The six-sided shape of the present invention improves both aspects. This shape retains a superior resistance to buckling, but the shallow corner angles reduce tearing of the insulation.
In order to improve rigidity, it is not sufficient merely to stiffen the plate and reduce its corner angles since the dynamic nature of the wind uplift force further complicates the design. As gusts of wind cause varying uplift forces, the stress distribution plate itself, the insulation material, and the threaded shaft's grip on the metal base are dynamically impact loaded, which must be accomodated. The present invention overcomes this problem by providing a plate with stiffness, but .
.
5~
controlled flexibility. The perimeteral and radial impressions give the plate adequate strength, stability and resistance to buckling. The circular impressions, however,enable the device to flex under dynamic loads and modulate the forces transmitted to the insulation, the drill screw fastener, and to the stress distribution plate itself. Thus, in service, the plate absorbs a portion of the loading energy, prevents its unmodulated trans-mittal to the insulation material or sheet metal base, and reduces the likelihood that the insulation will tear or break out, that the shaft will pull out of the sheet metal base, or that the plate itself will buckle. In the disclosed stress distribution plate, the interaction of shape, thickness, flexing impression and stiffening impression results in marked improvement in the gastener's resistance to wind uplift forces and permanence of installation.
Field of the Invention This invention relates to a fastener system of the type especially adapted for use in the attachment of sheet insulation material to a corrugated sheet metal base, such as a steel roof deck. More specifically, the invention is an improvement in the stress distribution or hold-down plates and fastener devices utilized in such systems.
Description of the Prior Art A variety of fasteners have been used to mechanically secure various materials to sheet metal bases. Generally, these devices include a rather long nail- or screw-threaded shaft which pierces the insulation and sheet metal and grips into the support underlying the sheet metal. Stress distribution or hold-down plates are either placed between the head of the screw and the insulation material or incorporated onto the head of the shaft itself in order to provide a bearing surface area and prevent the shaft head from tearing through the relatively soft insulation material when it is under stress.
The primary load which the insulation fastener must withstand, in the case of a component of a roof, is an uplifting force induced by winds which tend to unseat the insulation material upwardly away from the metal base. Resistance to the w;nd uplift force is, in fact, the primary criterion used by Factory Mutual System, an industry testing and underwriting organization, in granting approval to fastening systems for securing sheet insulation material to a roof.
The present invention presents markedly superior~wind uplift resistance than the stress distribution devices currently being utilized. Each of the prior art devices possesses substan-tial shortcomings in this respect. Those that are round tend to buckle prematurely under load. Those made of stiffer material llQ5299 or those with sharp corne~s tear through the insulation material before specified ~aximum loads are achieved. For these and other reasons, the prior art devices have not proved completely satisfactory in providing the required resistance to the insula-tion material against the uplift of the wind.
According to the present invention there is provided a fastener system particularly adapted for attaching sheet insulation material to a sheet metal base comprising: a hold-down plate in the form of a regular polygon having at least five sides; a hole through the center of the polygonal plate; at least one circular ridge on the plate concentric with the hole;
a plurality of ridges substantial parallel to and adjacent the perimeter of the plate; radial ridges extending between the outermost circular ridge and the perimeter of the plate; and a screw fastener having a shank portion adapted to be received by the hole and having a head portion adapted to seat on the surface of the plate surrounding the hole.
, j DESCRIPTION OF THE DRAWINGS
FI~. 1 is a view of a face of a stress distribution plate made according to the inventioni FIG. 2 is a sectional view of the plate taken through line 2-2 of FIG. l;
FIG. 3 is a side view of a preferred fastening device for use with the distribution plate of this invention; and FIG. 4 is a view of the plate of FIGS. 1 and 2 when positioned to secure insulation material to a sheet metal base.
Referring to FIG. 4, the environment of the invention is shown in which a layer of sheet insulation material 2 is secured to a corrugated sheet metal base 4 suitable for use as a roof for a building. The sheet insulation 2 is secured to the metal base 4 by means of hold-down plates 6 and fasteners 8.
The fasteners 8 pass through a central opening in the hold-down plates 6 and are driven through the metal base 4. In a typical insulation, after the insulation 2 has been secured in place, the roof is completed as by covering it with tar or other suit-able roofing material.
FIG. 1 shows in more detail the preferred configura-tion of a hold-down plate 6 made in accordance with this inven-tion. The plate 6 is provided with a hole 10 located at its center adapted to receive a suitable fastening device 8. The diameter of the hole 10 is large enough to pass the shank 12 of the fastener 8, but small enough to retain the head portion 14 of the fastener 8. The plate is also provided with several con-centric circular impressions 16 located centrally in its face.
The plate 6 is also provided with a peripheral impression 18 located adjacent to and reinforcing the perimeter of the plate 6. Finally, the plate 6 is provided with several radial impres-sions 20 extending between the outermost circular impression and the perimeter of the plate. In the preferred embodiment, these radial impressions are equally spaced about the plate and connect the outermost circular impression with each corner of the hexa-gonal perimeteral impression.
FIG. 2 illustrates the preferred depth and spacing of the impressions 16 and 18 in relation to the external dimensions of the plate. The hole 10 must be surrounded by an adequate flat area 22 in order to properly seat the head 1~ of the fastening device 12. Outboard of this flat area 22, the circular and hexa-gonal impressions occupy a significant portion of the plate's 6 remaining surface area. The depth of the impressions depends upon the size of the plate and the thickness of the plate material.
Generally, the impressions have a depth of roughly ten times the thickness of the plate material.
The drill screw fastening device 8 is shown in greater detail in FIG. 3. Basically, the drill screw has a shank portion 12, a formed head portion 14, a pointed end 24, one or more drill flights 26 and threads 28. The drill screw 8 is designed so that it may be secured to a workpiece without predrilling a hole since the drill flights 26 will accomplish this function ahead of the time that the threads 28 engage the workpiece. In order to obtain maximum holding power, the drill screw 8 is designed so that the maximum diameter of the drill flights 26 is no greater than the minor diameter of the threads 28. It can be understood that by so designing the drill screw, the threads 28 will be able to obtain a maximum bite on the workpiece.
Although superficially it might appear that insulation fasteners are static devices, the dynamic characteristics of stress distribution plates are essential to their satisfactory performance. The nature of the typical service conditions in which these plates operate will clarify this consideration.
First, it must be remembered that the materials used as roofing insulation are generally quite soft and have a low 11~ 5 2 ~
modulus. Even with the protective coating typically affixed to the upper surface o~ the insulation, the composite material can withstand relatively little stress.
Second, the amplitude of the w;nd's upward force fluc-tuates greatly from time to time. Thus, the ability of a fastener system to secure insulation material under wind uplift loading is limited not only by its own static and dynamic strength, but also by the insulation material's dynamic strength and resistance to tearing. It ls in this aspect of the dynamic performance lO characteristics of the entire fastener system that the features of this invent;on interact so as to effect marked improvement in the prior art.
The important design criteria fundamental to the attain-ment of these improvements will be illustrated more clearly by reference to the preferred embodiment. The optimum stress dis-tribution plate must demonstrate a high resistance to buckling yet not have a tendency to tear the insulation material. Circular plates might acceptably prevent tearing of the insulation, but they will lack sufficient resistance to buckling under load.
Four-sided plates seem to possess greater stability under load, but tend to tear the insulation easily. The six-sided shape of the present invention improves both aspects. This shape retains a superior resistance to buckling, but the shallow corner angles reduce tearing of the insulation.
In order to improve rigidity, it is not sufficient merely to stiffen the plate and reduce its corner angles since the dynamic nature of the wind uplift force further complicates the design. As gusts of wind cause varying uplift forces, the stress distribution plate itself, the insulation material, and the threaded shaft's grip on the metal base are dynamically impact loaded, which must be accomodated. The present invention overcomes this problem by providing a plate with stiffness, but .
.
5~
controlled flexibility. The perimeteral and radial impressions give the plate adequate strength, stability and resistance to buckling. The circular impressions, however,enable the device to flex under dynamic loads and modulate the forces transmitted to the insulation, the drill screw fastener, and to the stress distribution plate itself. Thus, in service, the plate absorbs a portion of the loading energy, prevents its unmodulated trans-mittal to the insulation material or sheet metal base, and reduces the likelihood that the insulation will tear or break out, that the shaft will pull out of the sheet metal base, or that the plate itself will buckle. In the disclosed stress distribution plate, the interaction of shape, thickness, flexing impression and stiffening impression results in marked improvement in the gastener's resistance to wind uplift forces and permanence of installation.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fastener system particularly adapted for attach-ing sheet insulation material to a sheet metal base comprising:
a hold-down plate in the form of a regular polygon having at least five sides; a hole through the center of the polygonal plate; at least one circular ridge on the plate concentric with the hole; a plurality of ridges substantial parallel to and adjacent the perimeter of the plate; radial ridges extending between the outermost circular ridge and the perimeter of the plate; and a screw fastener having a shank portion adapted to be received by the hole and having a head portion adapted to seat on the surface of the plate surrounding the hole.
a hold-down plate in the form of a regular polygon having at least five sides; a hole through the center of the polygonal plate; at least one circular ridge on the plate concentric with the hole; a plurality of ridges substantial parallel to and adjacent the perimeter of the plate; radial ridges extending between the outermost circular ridge and the perimeter of the plate; and a screw fastener having a shank portion adapted to be received by the hole and having a head portion adapted to seat on the surface of the plate surrounding the hole.
2. A fastener system according to claim 1 wherein the screw fastener is a drill screw.
3. A fastener system according to claim 2 wherein the maximum diameter of the flights of the drill portion of the drill screw is not greater than the minor diameter of the threads of the drill screw.
4. A fastener system according to claim 1 wherein there are at least two concentric circular ridges.
5. A fastener system according to claim 1 wherein a radial ridge extends to each corner of the plate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84007177A | 1977-10-06 | 1977-10-06 | |
| US840,071 | 1977-10-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1105299A true CA1105299A (en) | 1981-07-21 |
Family
ID=25281375
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA312,494A Expired CA1105299A (en) | 1977-10-06 | 1978-10-02 | Insulation fastener system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1105299A (en) |
-
1978
- 1978-10-02 CA CA312,494A patent/CA1105299A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |