Static structures (e.g. – buildings) – Cover with projecting restrainer; e.g. – snow stop – Rod-type with plural supports
Reexamination Certificate
2001-08-20
2003-03-25
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Cover with projecting restrainer; e.g., snow stop
Rod-type with plural supports
C052S024000, C052S026000, C411S432000
Reexamination Certificate
active
06536166
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a roof-mounted snow guard assembly to retain accumulated snow and prevent damage and injury caused by snow sliding off the roof surface, and more particularly, to an improved mounting block for securing such snow guard assemblies to a metal roof seam.
Snow guard assemblies have long been used for inhibiting and directing the movement of snow and ice across selected or pitched areas of roofs, as a preventive measure to mitigate the damage caused by migrating and falling snow and ice accumulations. An early application of snow guard assemblies is taught in U.S. Pat. No. 42,972 to Howe, which issued May 31, 1864. Recently, snow guard assemblies have increased in popularity, and currently several snow guard mounting assemblies serve to hold snowloads on roofs. Relevant examples include U.S. Pat. Nos. 5,613,328, and 5,732,513, each to Alley, each of which is herein incorporated in its entirety by reference.
Changing weather conditions, such as high winds or cyclically varying temperatures, create an environment which can induce physical changes in the accumulated snow, and give rise to the conditions tending to cause a snowpack to slide off of a sloped roof. Dislocated snow and ice often cause damage to surrounding property and, in some cases, the sliding snow can cause serious bodily injury. The problem of sliding snow is particularly prevalent on metal roofs. Metal roofs offer many structural advantages, such as strength and durability. However, because metal tends to absorb environmental heat, even a minimal amount of panel expansion or contraction exacerbates the conditions leading to snow slides. Furthermore, metal roofs generally afford little surface friction, which is also conducive to snow slides.
The increasing popularity of construction incorporating metal roof materials also poses particular problems with respect to attaching snow guard assemblies. A typical metal roof comprises a plurality of juxtaposed metal panels typically having substantially perpendicular edges that abut to form a joint therebetween. The perpendicular edges of the abutting panels are each crimped together and/or bent downwardly over each other forming a sealed seam which both connects the roofing panels and prevents fluid communication between and beneath the roof panels.
In snow guard assemblies for seamed metal roofs, the mounting block assembly is typically secured to the roof seam using a coupling means, such as screws or bolts. These screws or bolts generally pass through a sidewall of the mounting block seated around the seam, and extend inwardly, to contact the roof seam. However, screws and bolts tend to puncture, abrade, or otherwise damage the surface coating of the metal roof seam seal when tightened to securely fasten the mounting assembly. Holes or fissures thusly created destroy the hermeticity of the metal roof, especially upon removal of the snow guard, and allow water to permeate the seam even while the snow guard is still attached. The water tends to attack the exposed metal beneath the damaged surface coating, creating rust or seeping rust stains, which weakens the metal and diminishes the intrinsic aesthetic qualities of metal roofs.
Prior attempts to address this problem include using a mounting block capable of being attached to a metal roof without tearing, puncturing or otherwise destroying the hermeticity of the metal roof seam, as described U.S. Pat. No. 5,613,328. In order to attach the mounting block to the seam, a ball and set-screw is provided, such that the curved surface of the ball, rather than the end of the screw, engages a portion of the roof seam. As the screw is tightened to attach the mounting block, the ball forms a pocket in the engaged portion of the seam such that the mounting block can be secured to the roof without piercing or tearing the seam.
Although this method of attachment is an improvement over the prior art attaching means, drawbacks remain. For example, the entire holding force per coupling means is limited to the contact area between the seam and each ball, which is only a singular, independent contact surface. Because such a design requires that the entire contact force be applied through a single contact surface on each ball, 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. Thus, the net holding force available for holding the mounting block in place is significantly limited, and sliding will occur if the force of the snow load exceeds the friction force at that singular point of contact.
Yet another drawback of the ball and set-screw assembly relates to the occasional rotation of the ball element in conjunction with the turning of the set-screw, instead of gripping to form a stationary contact surface with the metal seam. This unwanted turning may give rise to damage on the contact surface of the seam, and effectively undermine the benefits of employing a ball and set-screw coupling means.
Another drawback associated with prior art mounting block assemblies for snow guard assemblies relates to corrosion caused by the contact between the metal seam and the metal groove in the mounting block coupled with the exposure to high degrees of moisture typical of roofs. The corrosion is a result of a galvanic reaction between the metal roof, typically copper, and the metal groove in the mounting block, typically aluminum. This can lead to many harmful conditions, both cosmetic and structural, including unsightly deposits on the roof panels and a weakened coupling between the seam and snow guard assembly. Additionally, the corrosion and moisture infiltration eventually degrade the hermeticity of the metal roof.
Efforts to combat the corrosion caused by the galvanic reaction include fabricating the mounting block using a non-reactive metal, such as stainless steel. However, using stainless steel instead of aluminum significantly increases overall manufacturing and consumer costs, and does not address the problem of moisture communication and physical harm to the surface of the seam caused by fastening with screws or bolts. Another attempt to combat reactivity involves using a non-corrosive insert as an interface in the metal groove of the mounting block, between the mounting block and the roof seam, as described in Applicant's pending application Ser. No. 09/397,938, the entirety of which is incorporated herein by reference. However, such non-reactive inserts do not afford the seam protection from invasive coupling means, since the coupling means penetrate the inserts and directly contact the seam.
Thus, it would be desirable to provide a snow guard assembly having a means for securing a mounting block assembly onto a metal roof seam which addresses each of the primary problems associated with the prior art. That is, it would be desirable to provide a snow guard assembly having a means for securing a mounting block assembly onto a metal roof seam which prevents physical breach of the seam integrity by a coupling means and which preferably eliminates the negative effects of galvanic reactions between the roofing material and the mounting block, to better preserve the hermeticity of the roof. Further, a cost effective means of achieving the aforementioned goals is also desired.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the drawbacks of the prior art, particularly to provide a cost effective snow guard assembly having a means for securing a mounting block assembly onto a metal roof seam which prevents physical breach of the seam integrity by a coupling means and which preferably eliminates the negative effects of galvanic reactions between the roofing material and the mounting block.
In accordance with one embodiment of the present invention, a snow guard assembly adapted to be attached to a metal roof seam by a mounting assembly is provided. The mounting assembly includes a mounting block having a seam
Burr & Brown
Friedman Carl D.
Katcheves Basil
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