BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are employed to indicate like parts in the various views:
FIG. 1 is a top perspective view of prior art shingles aligned in a shingle course;
FIG. 2 is a bottom perspective view of one embodiment of a roofing member of the present invention possessing thermal expansion relief characteristics depicted in an abutting relationship with an adjacent roofing member;
FIG. 3 is a close-up plan view of the roofing member generally in a region identified by the circled area in FIG. 2, showing a spacer tab and a corresponding depression;
FIG. 4 is a view similar to FIG. 3, with the spacer tab being partially displaced into the depression due to a compressive force being applied by the adjacent roofing member;
FIG. 5 is a view similar to FIG. 3, with the spacer tab being fully displaced into the depression due to a compressive force being applied by the adjacent roofing member;
FIG. 6 is a perspective view of the roofing member region depicted in FIG. 3;
FIG. 7 is a bottom plan view of another embodiment of a roofing member of the present invention possessing thermal expansion relief characteristics depicted in an abutting relationship with an adjacent roofing member;
FIG. 8 is a close-up plan view of the roofing member generally in a region identified by the circled area in FIG. 7, showing a spacer tab and a corresponding cutout; and
FIG. 9 is a view similar to FIG. 8, with the spacer tab being partially displaced into the cutout due to a compressive force being applied by the adjacent roofing member.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a roofing system formed by roofing members or shingles possessing thermal expansion relief characteristics. The roofing system provides a degree of “play” between adjacently mounted shingles on a roof structure. Specifically, as the shingles expand in size due to the temperature of the shingles becoming elevated, spacer tabs which are typically utilized to properly align and space apart shingles for installation are allowed to be displaced inwardly into the side regions of the shingles. This allows the side regions of the shingles to avoid the high compressive loads applied by thermally expanding adjacent shingles. In certain embodiments, the spacer tabs are configured to substantially only undergo elastic deformation when thermal expansion occurs, while in other embodiments, certain modes of failure result in the spacer tabs partially or fully breaking away from connection with the side regions of the respective shingle.
Turning to FIGS. 2-6, an embodiment of a shingle 200 possessing thermal expansion relief characteristics is depicted with a spacer tab feature 202 abutting an adjacent shingle 300. The shingle 200 has a main body 204 possessing a top surface 206, a bottom surface 208, and side regions 210 from which the spacer tab feature 202 extends. It should be understood that the shingle top surface 206 may take the same form as the top surface 103 of the prior art shingle 100 of FIG. 1, or any other form desired. The spacer tab feature 202 extends laterally outwardly from the side regions 210 adjacent to a depression feature 212 formed in the bottom surface 208 of the shingle 200. As used herein, the term “spaced tab feature” refers to one or more individual spacer tabs 214 each located on one of the shingle side regions 210. Similarly, the term “depression feature” refers to one or more individual depressions 216 or cavities each corresponding to one of the individual spacer tabs 214.
Each spacer tab 214 has a first longitudinal end 218 and a second longitudinal end 220 moving in the longitudinal direction of a sidewall 222 of the side regions 210. Each depression 216 is preferably located relative to the shingle sidewall and to one of the corresponding spacer tabs 214 such that the sidewall 222 is formed with a first smaller wall thickness at a location A directly between the depression 216 and the spacer tab first longitudinal end 218 and is formed with a second larger wall thickness at a location B directly between the depression 216 and the spacer tab second longitudinal end 220, as seen in FIG. 3. This design serves the purpose of creating a weak point in the sidewall 222 webbing at location A to control the initial structural failure mode of the sidewall 222 as the compression force due to thermal expansion of an adjacent shingle 300 increases against the spacer tab 214. At the initial failure mode, depicted in FIG. 4, the spacer tab 214 cantilevers into a first region 224 of the depression 216 while remaining attached to the sidewall 222 generally at location B. Specifically, the first longitudinal end 218 moves into contact with a depression sidewall 226 in the first region 224 while a portion of the spacer tab 214 remains outside of the depression 216 and extends outwardly from the plane of the sidewall 222 to remain in contact with the adjacent shingle 300. Thus, the initial failure mode provides displacement of the spacer tab 214 laterally into the shingle main body 204 without completely disconnecting with the shingle sidewall 222.
As can be seen in FIG. 6, the first longitudinal end 218 of the spacer tab 214 has a sloped intersecting edge 228 with the shingle sidewall 222. This slope provides a tapered length for the spacer tab 214 longitudinally along the sidewall 222 such that the spacer tab length increases moving in the direction of the shingle bottom surface 208. The sloped intersecting edge 228 aids in guiding the initial failure mode at location A on the sidewall 222 webbing so that the spacer tab 214 laterally pivots directly into the depression 216 without pivoting upwardly or downwardly towards the shingle top surface 206 or bottom surface 208. If the sloped edge 228 were instead vertically aligned and perpendicular to an intersecting edge 230 of the bottom surface 208 and the sidewall 222 of the shingle 200, the extra material strength added by a surface webbing 232 of the shingle main body 204 above the depression 216 would cause uneven failure of the sidewall 222 near the spacer tab first longitudinal end 218, and thus undesirable upward or downward pivoting of the spacer tab 214.
With reference to FIGS. 4 and 5, as the shingles 200, 300 continue in thermal expansion beyond the point where the initial failure mode depicted in FIG. 4 occurs, such as on a hot day with significant sun exposure, the compressive forces on the spacer tab 214 are transferred to the shingle main body 204, specifically to the depression sidewall 226 and to the shingle sidewall 222 in the region of location B. Continued expansion beyond this point causes a second structural failure mode depicted in FIG. 5. Specifically, the second longitudinal end 220 of the spacer tab will break away from the shingle sidewall 222 at location B, causing the adjacent shingle 300 to push the spacer tab 214 into the depression 216 beyond the first region 224 and into a retaining region 234 of the depression 216. In this way, the depression 216 both serves to control the failure modes of the spacer tab 214 and compression loads that are transferred to the shingle main body 204 over a range of thermal expansion of adjacently mounted shingles, as well as serving as a retainer for the spacer tab 214 that has broken away from the shingle sidewall 222. The particular depth of the depressions 216 measured along the sidewall 226 perpendicularly to the plane of the shingle bottom surface 208 is a matter of design choice, and in one embodiment, is at least as large as the height of the spacer tabs 214, enabling the depressions 216 to accept the spacer tabs 214 therein when the shingle bottom surface 208 rests on top of a flat roof structure and the spacer tabs 214 experience an inwardly compressive load that results in the initial and second failure modes described herein.
Turning to FIGS. 7-9, another embodiment of a shingle 400 possessing thermal expansion relief characteristics is depicted with a spacer tab feature 402 abutting the adjacent shingle 300. In a similar form to the embodiment of the shingle 200 illustrated in FIGS. 2-6, shingle 400 has a main body 404 possessing a top surface 406, a bottom surface 408, and side regions 410 from which the spacer tab feature 402 extends. The shingle top surface 406 may take the same form as the top surface 103 of the prior art shingle 100 of FIG. 1, or any other form desired. The spacer tab feature 402 extends laterally outwardly from the side regions 410 adjacent to a cutout feature 412 formed in at least one of the side regions 410 and preferably extends from the top surface 406 through the main body 404 to the bottom surface 408. As with the embodiment of shingle 200 illustrated in FIGS. 2-6, the term “spaced tab feature”, as used herein, refers to one or more individual spacer tabs 414 each located on one of the shingle side regions 210. Similarly, the term “cutout feature” refers to one or more individual cutouts 416 each corresponding to one of the individual spacer tabs 414.
Each spacer tab 414 has a free end 418 and a fixed end 420, with the fixed end 420 configured to provide resistance to the compression force provided by a sidewall 302 of the adjacent shingle 300 undergoing thermal expansion. The thickness of the spacer tab 414 at the fixed end 420 is ideally sufficient to resist laterally inward deflection of the tab 414 when being contacted by the sidewall 302 of an adjacent shingle 300 at the time of installation, but of a thickness that allows the tab 414 to elastically deflect as the compressive loads on the tab 414 provided by the thermally expanding adjacent shingle increase to prevent bowing of the shingle 400 and adjacent shingle 300.
As seen in FIG. 9, as the compressive load applied to the spacer tab 414 increases by the sidewall 302 of the adjacent shingle 300, the tab 414 continues to deflect into the corresponding cutout 416 until the free end 418 of the tab 414 contacts an inner wall 422 of the cutout 416. Ideally, the spacer tab 414 and the corresponding cutout 416 are sized and configured to enable a sufficient amount of rotation of the spacer tab 414 into the cutout 416 to handle the expected range of thermal expansion of the shingles 300, 400. The spacer tab 414 may optionally be configured to eventually undergo structural failure at the fixed end 420 if thermal expansion continues beyond the condition depicted in FIG. 9. Alternatively, the spacer tab 414 may be configured to avoid such failure, and instead resiliently return to the position depicted in FIG. 8 when temperatures of the shingles 300, 400 have lowered from the temperatures at which significant or maximum thermal expansion takes place.
It should be understood that the adjacent shingle 300 described herein may take the form of shingle 200 of FIGS. 2-6 or shingle 400 of FIGS. 7-9, such that all shingles in a given installed course possess the thermal expansion relief characteristics described herein. Alternatively, shingle courses may be installed utilizing rows of shingles that have only some of the shingles in the given row possessing the thermal expansion relief characteristics of shingles 200 and/or 400. As one example, a given row may alternate single 200 or shingle 400 with an adjacent shingle 300 lacking at least the depression feature 212, and optionally the spacer tab feature 202.
The shingles 200 and 400 of the present invention are preferably formed from composite materials. Suitable materials include, but are not limited to, rubber (e.g., ground up tire rubber), polymers such as polyolefins (e.g., various grades of polyethylene, recycled or virgin), fillers (e.g., glass, stone, limestone, talc, mica, cellulosic materials such as wood flour, rice hulls, etc.), asphalt embedded mats, or tile. In one embodiment, the composite material makeup includes at least a polymer component and a filler component. Coloring agents may also be added to the mixture so that the composite product more closely resembles a particular type of shingle. For example, for a composite slate product, a gray color may be added to the mixture. Similarly, for a composite wood shake product, a brown color may be added to the mixture. Other additives or processing methods may be added or applied to improve reflection, heat deflection or other weathering characteristics, (e.g., UV inhibitors and stabilizers). These material combinations form the shingles 200 and 400 into semi-rigid objects.
The shingles 200 and 400 may be made and cut, or molded, to shape using various fabrication techniques. For example, one manner of making the starter block relies on the use of a mixer and extruder. The ingredients that are used to form the starter block are mixed in the mixer (e.g., a kinetic mixer) and then passed through the extruder. The mixture emerging from the extruder may be sliced into small pellets by a rotary knife so that the material can be more easily conveyed through piping under air pressure or suction to a storage location for use when needed (e.g., in a storage bin). Thereafter, the pellets are extracted from storage and fed to an injection-molding machine along with coloring agents where the material is injected in one or more molds that have been cast or machined, such as by digitized molding, to have the desired shape of the shingle. After curing and sufficient cooling, the molded shingle is removed from the mold and bundled or otherwise packaged with like shingles for shipment or storage.
As can be seen, the shingles 200, 400 of the present invention provide a roofing system with thermal expansion relief characteristics to reduce the compressive loads induced by adjacent shingles on one another. While particular embodiments of the invention have been shown, it will be understood, that the invention is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. Reasonable variation and modification are possible within the scope of the foregoing disclosure of the invention without departing from the spirit of the invention.
Patent Application
20080034699
