Stretched cable membrane attachment system
In standard single ply membrane roofing, there is a great number of fasteners used. If the roof deck does not accept standard mechanical fasteners, the workload required to mechanically fasten a roof becomes quite immense. The stretched cable membrane attachment system is designed to improve efficiency in installing single ply roofing membrane, as well as improve wind uplift resistance for the roofing system. It consists of a cable that is attached at both ends to the roof substrate or decking and is then sealed from the elements by means of placing additional membrane over it and adhering it to the already installed membrane. One embodiment of the device has the means of installing a turn buckle to increase the cable tension or has the turn buckle as part of its integral design. In another embodiment, the cable can have multiple mechanical fastening points on the interior of its structure in addition to the endpoints.
This invention is based upon and claims the benefit of priority from U.S. Provisional Application Ser. No. 60/934,747 filed the 15 of Jun., 2007.
INTRODUCTIONThe title of the invention set forth in this document is “Stretched Cable Membrane Attachment System.” The inventor's name is Henry L. Hamlin III, residing in Macon, Ga. and with United States citizenship. The inventor's correspondence address is PO Box 7548, Macon, Ga. 31209.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot Applicable
REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIXNot Applicable
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a method and system of installing roofing membrane, particularly installation by use of a stretched cable and appropriate fasteners in place of standard screws and other fasteners.
2. Background
A typical single ply membrane roofing system for a low slope roof incorporates several different primary features. The deck is typically made of one of three materials: metal, wood, or concrete. Over the deck there is a layer of insulation and over the layer of insulation is a sheet of roofing membrane. The make up of a typical roof may vary but the one described is the most common method. There are multiple ways of fastening the materials to the deck but the prevailing method is to mechanically fasten. This method is cost efficient and saves on labor versus other methods such as fully adhering (whereas the entire membrane is effectively glued to the substrate beneath).
In the case of a metal or wood deck, fastening of the insulation and membrane is quite simple. One typically uses roofing screws that are long enough to penetrate to the decking with a circular stress plate situated beneath and centered around the head of the screw. Both the insulation and the membrane are fastened in this manner with fasteners that are similar. For the membrane, there is a specified number of fasteners per a specified length of membrane (typically spaced between every six inches to every twenty four inches linearly, dependant on factors such as the width of the roll of membrane and wind uplift requirements). For the insulation, there is typically a set number of fasteners per piece (dependant on the size of the insulation board). Over the areas where the membrane is fastened down to the deck, the next layer of membrane is overlapped onto the existing, thereby going over the existing set of fasteners and covering them with membrane. This overlapping membrane is then heat-welded or adhered to the existing layer beneath it. The entire roof is typically covered with membrane in this fashion.
At walls, flat perimeters, and various penetrations through the roof, the membrane must be terminated and waterproofed so as to prevent leakage and to fully secure the membrane. Typically, this is done with termination bar, a bar that is situated on top of the membrane and fasteners are placed through the bar, the membrane and on through to the substrate. Appropriate sealants are then used to seal up seams and vertical junctures so as to prevent water from reaching underneath the membrane.
The primary difficulty with mechanical fastening occurs when there is a type of deck that is considered non-nailable. The primary type of non-nailable deck is the concrete deck. In order to mechanically fasten to a concrete deck, a hole must first be pre-drilled and then a special type of fastener is inserted and attached. Whereas fastening a screw into a metal deck is a simple process, fastening into a concrete deck is a multi-step process and takes up considerably more time and is much more expensive. Since the same number of fasteners is typically required as with a nailable deck, the process tends to take much longer for the concrete, in turn increasing the total cost for the roof to be completed in both materials and labor.
There have been previous inventions that have attempted to solve this problem. One of interest would be U.S. Pat. No. 7,028,438, which is a roofing system that utilizes hold down straps for the insulation. In addition, others have used batten bars, which help to further secure the roofing membrane in locations of the membrane that are linearly between fasteners. U.S. Pat. No. 6,764,260 uses this method. These prior methods fail to sufficiently improve the process of mechanically fastening to a non-nailable deck.
SUMMARY OF THE INVENTIONThe goal of this invention is to improve the efficiency of attaching single ply membranes to roof decks, as well as to improve wind uplift resistance and durability of the membrane roof in general. The stretched cable membrane attachment system is designed around the concept of using a cable to secure the roof membrane to the deck. In its ideal form, the cable would have multiple fasteners that are further apart than one would normally space them but of sufficient spacing to provide the appropriate fastening strength. The cable would be fastened down to the roof deck and then the next roll of membrane would be heat welded over the fasteners and cable to the existing layer of membrane, thus sealing in the fasteners. The reason the fasteners could be spaced further apart is that the cable itself would provide additional holding strength in between the fastener locations without having to go through the extra effort and complications of using additional fasteners.
The roofing system that this patent application is proposing is the use of a stretched reinforced cable in mechanically fastened membrane roofing systems. The cable would be of a type with tensile strength such that it could be tightened and be capable of withstanding wind uplift and movement of the building due to temperature changes and other environmental factors. The cable would be fastened at its appropriate fastening points and then another layer of membrane, either from the very same roll of material or from the subsequent roll that would be used, would be placed over the cable and fasteners then heat welded or adhered to the material on the other side of the cable. This would effectively seal in the cable and all its parts within the membrane, thus protecting it from the outside elements.
One feature of the stretched cable membrane attachment system would be that each cable could include multiple fastening locations in addition to the fasteners at the ends of the cable. These additional fastening locations could be spaced throughout the length of the cable at spacings appropriate to the particular roofing application and the materials involved. These fastening points would not have to be as close as the spacings one would use if only using fasteners due to the presence of the cable between the fasteners helping to hold the roof securely to the building. In these fastening points, mechanical fasteners could be inserted and the cable could be attached to the roof deck. The fasteners used could be standard mechanical fasteners with the type dependant on the type of roof deck as well as the particular building and application.
The distance apart of each of the interior fastening points would be determined by the size of the roof for which it would be used, as well as the particular type of materials used. For smaller roofs, it might not be necessary to fasten at any interior point, only at the endpoints of the cable. Larger roofs' fastening requirements might necessitate a much greater number of fasteners.
The stretched cable membrane attachment system could have at some interior point within its length a turn buckle that would be used to tighten the cable prior to fastening any existing interior fastening points and after fastening the two end fastening points. For field use, the cable could be manufactured such that it had multiple fastening points at particular spacings. One would cut the cable for roof installation such that each cut piece had one end with a fastening point and one end without a fastening point (and multiple points within its length). Therefore, the end without a fastening point would be placed in the turn buckle and the other end would serve as an endpoint for the cable to be installed. Another piece of cable could be cut and one of its ends placed in the other end of the turn buckle, thus making a single cable with two fastening endpoints, interior fastening points, and a turn buckle at some point along its length. The length of the cable, as well as the tightness of the cable, could then be fine tuned by turning the turn buckle to an appropriate tightness. Tightness of the cable would be determined by several factors, including the wind uplift resistance desired, the size of the roof, and thermal or other environmental movements that might be expected from the building in question.
There are multiple methods of using the stretched cable membrane attachment system. One way is to lay out membrane over the entire roof and seal its seams together by the appropriate method (typically adhering with some type of mastic or heat welding). One would leave excess materials at the perimeter of the roof. Next, one would install the cable at all perimeters of the roof then fold the excess membrane over the cable and adhere the upper layer of the excess membrane to the upper layer of the installed membrane, thus sealing in the cable. If cables were needed for fastening within the perimeter of the roof, one could attach the cable and tighten it if needed then adhere a layer of membrane over the cable. The additional layer of membrane would then be adhered all around the cable to the installed membrane already on the roof, thus sealing the cable in the membrane.
An alternate method of installation would be to fold the membrane at the seams over the cable. After the cable is fastened and, if necessary, tightened, there exists a layer of excess membrane that extends past the point at which the cable is fastened. This excess membrane would be folded over the cable and welded (either by heat or other means of adherence) to the secured membrane on the roof. The entire cable would be sealed in this manner from end to end. This procedure would seal the cable entirely in membrane, thus waterproofing it and protecting both the fasteners and the cable from the elements with minimal seams, fastening points, and other areas of potential leakage.
It is also possible for the membrane itself to be manufactured with the cable already sealed up within it along one side of its seams. There would have to holes through which the fasteners could pass, though these would be covered up when the next roll of membrane were laid down. The membrane would be fastened and tightened as usual (there could be holes also for the tightening of a turn buckle if it were needed) then the next roll of membrane would be laid with one side of the seam laying over the already installed cable and the other seam (which would have a cable sealed within it) ready to be installed to the roof. The side without a cable would be heat welded over the already installed cable from the prior installed roll of membrane such that the holes that would be used for fastening or tightening the turn buckle could be sealed within and protected from the elements.
The stretched cable membrane attachment system is designed to be used on either flat horizontal surfaces or flat vertical surfaces, such as walls. In order to use the system on vertical surfaces, the membrane would be turned either up a wall rising above the level of the roof or down the wall beneath the level of the roof. Then, the cable would be attached in the same manner as on a horizontal flat surface. On a completely flat roof with no walls around it, one could turn the membrane down the wall and beneath the level of the roof then fasten the cable around the perimeter of the building to the upper part of the wall. Then, the excess membrane could be turned up such that it covered the cable and then heat welded or adhered to the membrane on the roof or a higher part of the building's outer wall.
In addition to using the stretched cable system for attachment of the membrane at the perimeter or interior of the roof, it is also designed to be used around roof penetrations. Typically, there is either a pre-formed boot that fits around a round penetration (such as a pipe) or one might use a non-reinforced membrane that is much more pliable. The membrane or boot is made of material that is compatible with and capable of welding to the existing reinforced membrane layer on the roof. This material comes up the side of the penetration and must be terminated and waterproofed at this point. With the stretched cable system, the cable could be stretched taut around round penetrations with the membrane folded over just as described previously. For square or rectangular penetrations, the cable would be fastened or attached in the manner previously described for flat surfaces. Then, either the excess portion of the membrane would then fold over the cable and be welded to the secured section of the membrane or an additional layer of membrane could cover the cable, thus sealing in the cable and fasteners in the same manner as for the horizontal portions of the roof.
In the previously mentioned description, the invention has been described with particular embodiments. However, those skilled in the art may utilize other embodiments and modifications. The invention as described is not limited solely to the preferred embodiments as depicted.
Claims
1. A method and device for securing a roofing membrane to a flat or low slope roof by means of securing a cable which consists of two endpoints which both have a place through which a mechanical roofing fastener can be placed and a length of cable between the two endpoints, wherein the cable is mechanically fastened over a layer of membrane and to the roofing deck or substrate and another layer of membrane is installed over the cable and its endpoints then adhered by standard non-penetrative means to the layer of membrane beneath the cable.
2. The method and device as described in claim 1 whereby the cable has a means of connecting a turn buckle linearly along the length of the cable and between the two endpoints such that the act of turning the turn buckle increases the tension of the cable when the two endpoints are secured to the roofing substrate or decking and the turn buckle is afterward sealed by a layer of roofing membrane with the cable and its endpoints.
3. The method and device as described in claim 1 whereby there exists at least one additional fastening point within the length of the cable through which a standard mechanical fastener can be used to secure the device to the roofing substrate or decking.
4. The method and device as described in claim 1 whereby the cable and its endpoints are manufactured and sealed within one side of a roll of roofing membrane.
5. The method and device as described in claim 1 whereby the membrane that is fastened over the cable is material from the same roll or piece of membrane and is that excess which lies on one side of the cable which is then folded over the cable and adhered to itself, thus sealing in the cable device with the single piece of membrane, which is already mechanically fastened to the roofing substrate or deck.
Type: Application
Filed: Jun 16, 2008
Publication Date: Jan 1, 2009
Inventor: Henry Lee Hamlin, III (Macon, GA)
Application Number: 12/214,070
