Static structures (e.g. – buildings) – Cover with projecting restrainer; e.g. – snow stop – Rod-type with plural supports
Reexamination Certificate
1999-06-30
2001-07-10
Stephan, Beth A. (Department: 3635)
Static structures (e.g., buildings)
Cover with projecting restrainer; e.g., snow stop
Rod-type with plural supports
C052S024000, C052S026000
Reexamination Certificate
active
06256934
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a snow guard system capable of being attached to a roof, which is used to prevent snow from sliding off the roof, and more particularly to an improved clamping means for securing such snow guard systems to a roof seam.
2. Related Art
Sliding snow and/or ice from roofs can be hazardous to people, the surrounding landscape, property, and building components. The problem of sliding snow or ice is particularly prevalent in connection with raised seam metal roofs, where there is relatively little friction between the roof and the snow or ice.
As shown in
FIG. 1
, conventional snow guard systems
200
have long been used for controlling movement of snow and ice across selected areas of roofs by preventing sliding of snow and ice down the pitch of the roof. Recently, these snow guard systems have increased in popularity, and currently several snow guard mounting systems serve to hold snowloads on roofs. For example, one such snow guard system is discussed in Applicants pending application Ser. No. 09/280,635, entitled “SNOW GUARD SYSTEM HAVING A FLAG TYPE ATTACHMENT,” which is incorporated herein by reference in its entirety.
Since the advent of snow guard systems, inventors have adopted a number of means for securing the snow guards to a roof. For example, see U.S. Pat. No.3,8880,405. With the advent of raised seam metal roofs, it has become particularly problematic to attach conventional snow guards thereto. A typical metal roof comprises a plurality of metal roofing panels that are laid side by side to cover the width of a roof section. Each panel usually includes substantially perpendicular edges running along both the left and right sides thereof. The roofing panels are located such that their substantially perpendicular edges are abutting, thereby forming a seam therebetween. The substantially perpendicular edges of the abutting panels are each typically crimped together and/or bent downwardly over each other to form a joint. The joint seals the adjoining panels, thereby preventing fluid communication to the roofing substructure below the roofing panels, as well as to the area between each roofing panel. Various metal roof installers have devised unique patterns for the joints, and as a result a wide variety of joints exist.
As shown in
FIG. 1B
, in snow guard assemblies used on seamed metal roofs, the assembly is typically attached to the roof seam using a mounting block
18
secured by an attachment means. For instance, one possible attachment method is via screws or bolts.
However, both screws and bolts require puncturing the roofing seam
12
to hold the assembly in place. Once the snow guard assembly is removed, any holes created by the screws or bolts remain, thereby destroying the hermeticity of the metal roof. Moreover, such holes allow water to contact the roof substructure even while the snowguard is still attached.
To solve this problem, the Applicant had previously developed an attachment device capable of being attached to a metal roof without tearing, puncturing or otherwise destroying the hermeticity of the metal roof seam
12
. This attachment device is described in detail in Applicant's U.S. Pat. No. 5,613,328, the entirety of which is incorporated herein by reference.
According to the teachings of this patent, as shown in
FIGS. 2A and 2B
, a device was provided capable of being attached to a metal roof seam
12
. This device includes a mounting block
18
having a first side wall
52
and a second side wall
54
, a base
53
and a top
51
. A groove
24
located in the base
53
of the block
18
allows the block
18
to be located on the metal roof by placement of the groove
24
about a segment of the seam
12
. A first threaded hole
62
is located in the block between the first side wall
52
and the groove
24
. In order to attach the mounting block
18
to the seam
12
, a ball
100
and first set screw
102
is provided. The ball
100
has a substantially curved surface
101
. A first set screw
102
is translocatable within the first threaded hole
62
. This first set screw
102
has a first terminal end
104
juxtaposed with the ball
100
such that the curved surface
101
of the attached mechanism
100
and
102
is diametrical thereto and is pivotable thereabout. As shown in
FIG. 2A
, the first set screw
102
further has a second terminal end
106
drivable into the first threaded hole
62
. As shown in
FIG. 2B
, driving the first set screw
102
into the first threaded hole
62
would cause the substantially curved surface
101
of the ball
100
to engage a first portion
105
of the seam
12
of the metal roof. Consequently, rotational movement of the curved surface
101
of the ball
100
is precluded relative to the first portion
105
of the seam
12
as the ball engages the seam
12
. As a result, the first set screw
102
pivots about the curved surface
101
of the ball
100
. Moreover, further driving of the first set screw
102
causes the first engaged portion
105
of the seam
12
to be driven towards the portion of groove
24
diametric thereto, thereby forming a pocket in the first engaged portion
105
of the seam
12
. As a result, the mounting block
18
could be secured to the roof without piercing or tearing the seam
12
.
Although this method of attachment represented a vast improvement over the prior attachment methods, there is still room for improvement.
For example, in the ball and screw arrangement, the entire holding force per attachment mechanism is limited to the force which can be applied through an individual contact surface. That is, the contact area between the seam
12
and each ball
100
is limited to only a singular, independent contact surface
101
. Because such a design requires that the entire contact force be applied through a single contact surface
101
on each ball
100
, the total amount of static holding force (which is equal to the summation of the holding forces of each individual contact surface), is determined by the number of balls engaging the roof seam
12
. Since the holding force per attachment mechanism is limited to (the force transmitted through) the singular contact surface
101
, the net holding force available for holding the mounting block in place is significantly limited.
Moreover, providing only a single contact surface results in a relatively unstable connection since sliding will occur if the force of the snow load exceeds the friction of force at that singular point of contact. Thus, if too few attachment mechanisms (i.e., ball
100
and set screw
102
) are employed, the mounting block will be susceptible to separating from the seam under heavier snow loads and sliding along the seam when the force of the snowload exceeds the friction of force between the contact surface and the seam.
Thus, it would be desirable to apply a greater amount of pressure to the seam per attachment mechanism thereby eliminating the need to employ an excessive number of attachment mechanisms. It would also be desirable to distribute the contact load through a greater number of points over the length of the seam to prevent sliding. Accordingly, a need exists for an attachment mechanism that will decrease the amount of holding force applied through each contact surface, while maintaining enough pressure per attachment mechanism to hold the mounting block
18
in place when particularly heavy snowloads are applied.
SUMMARY OF THE INVENTION
It is an object of the present invention to improve upon the prior art snow guard systems desired above.
These objects are achieved by replacing the ball with a clamping pad having multiple contact surfaces. This clamping pad is advantageous in that each contact area serves to deform a roof seam thereby increasing the effective contact area between the roof seam and clamping pad. By increasing the effective contact area between the roof seam and the clamping pad the sliding resistance of the clamping pad along the seam is significantly increased. Preferably, the
Burr & Brown
Dorsey Dennis L.
Stephan Beth A.
LandOfFree
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