Patent Application
20070175170
1. Field of the Invention
The present invention relates generally to mechanical fasteners, and more specifically, to a peel and stick type of coated mechanical fastener that secures a flexible sheet or membrane to the roof without penetrating the membrane and to a method of applying the same.
2. Prior Art
A roofing system generally includes a roof deck which is considered the structural supporting surface of a building extending between the surrounding exterior walls of the building. The roof deck may be constructed from plywood, metal decking or concrete or any other suitable material. Depending upon the construction, the roof deck may extend over the surrounding exterior walls or the roof deck may stop short of the exterior walls thereby forming a parapet wall, i.e., a low retaining wall at the edge of the roof deck. If desired, the roofing system may also include an insulation barrier formed from polyisocyanarate or any other suitable material applied over the roof deck.
To make the roof deck and building weather resistant a single-ply membrane roof is installed over the roof deck. The single-ply membrane roof refers to a water impermeable single sheet of polymeric material such as ethylene propylene diene rubber (EPDM) having a preapplied hot melt adhesive, chlorinated polyethylene, polyvinyl chloride, or chlorosulfanated polyethylene. The membrane roof has heretofore been installed on the roof deck using a variety of different methods.
For example, the field or interior of the membrane roof may be held to the roof deck by the use of ballast and/or penetrating or non-penetrating fastener means as known in the art. A large number of commercial and factory plant roofs are of a flat roof design wherein the roofing material itself is often of a built-up asphalt and in more modern systems of a single ply EPDM elastomeric sheet or membrane. Adhered roof membrane retention systems suffer from the cost penalty while mechanical fasteners and related fastening systems generally require fixation to the roofing substrate via mechanical fasteners. Mechanical fastening is extensively used in conventional single ply membrane roof assemblies. Low slope roof membranes like TPO or PVC are usually mechanically fastened at the roof to limit thermally induced lateral movement. Mechanical fastening reduces the bulk of material required in the roof and may also reduce or avoid the need for hot bitumen.
There are two basic kinds of mechanical fasteners, namely, membrane penetrating and non-penetrating ones. Each of these types of fasteners has a number of favorable features and each of them is also subject to various drawbacks and disadvantages.
Mechanical fastening systems of the penetrating type generally require fixation to the roofing substrate by a metal fastener with metal or rubberized nailing strips. Penetrating type fastening systems use various rigid and semi-rigid members to secure the membrane to the roof. These systems require openings to be formed in the membrane either for receiving a fastening plate or by the attaching anchoring members.
An example of a penetrating fastener means for retaining the field of a membrane roof installed to a roof deck is by utilizing a plurality of small, circular, metal plates having a hole in the center and a roofing screw or other suitable fastener. In order to anchor the membrane roof, the small, circular, metal plates are spaced apart in rows on the membrane roof and the fastener is driven through the hole in each plate, the membrane roof, any insulation material and then into the roof deck. The metal plates are then covered by overlapping roof membrane. An example of a non-penetrating fastener means would include totally adhering the field of the membrane roof to the roof deck.
An important consideration for a mechanically fastened membrane roof system is that the system withstand wind uplift forces. Consequently, in order to withstand wind uplift forces the membrane is typically fastened to the deck at close intervals over the entire membrane surface thereby minimizing the areas of membrane not secured to the roof deck. If the membrane sheets are secured only along the longitudinal edges the width of the membrane sheets should be restricted to a dimension of about 5-6 feet in order to ensure adequate resistance to uplift in the membrane between fastening locations.
Although the many known variations for attaching a membrane roof to a roof deck may perform satisfactorily under certain conditions, further improvements on attaching a membrane roof to a roof deck are desired as several problems occur in the mechanical fasteners in the prior art. Mechanically fastened membranes are subject to billowing from wind up lift forces which stress the membrane, plates and the fasteners. Mechanical fasteners that are adhered to the underside of the membrane may also create problems if the fasteners pull out of the deck and subsequently puncture the membrane. Mechanical fasteners that puncture the roof membrane may create weak points in a waterproofing system. Further, the possibility of cold surfaces at the inside ends of the plates along with fasteners raises the likelihood of condensation and corrosion.
Although both the penetrating and non-penetrating type fastening systems do work satisfactory for some applications, it is desirable to have a non-penetrating system that provides a reliable and secure attachment between the roof deck and the roofing membrane. Therefore, there is a need in the roofing industry for a non-penetrating mechanical fastening system that provides for a proper dependable attachment between the roof deck and the roofing membrane.
One object of the present invention is to provide an inexpensive mechanical fastener of improved durability and improved resistance to wind uplift forces. Yet another object of the present invention is to provide a mechanical fastener that does not penetrate the roofing membrane or roof deck in order to prevent leaking in the roof structure. Another object of the present invention is to provide an improved method of securing a membrane roof to a roof deck in a manner which reduces labor and material costs. It is a further object of the present invention to provide an improved mechanical fastener that provides a strong and improved attachment between the roofing membrane and roof deck. Yet another object of the present invention is to provide a method of installing a membrane roof to a roof deck that is simple and economical.
Accordingly, a mechanical fastener for a roofing structure is provided, the mechanical fastener comprising a metal plate, the metal plate having a top side and a bottom side, and an adhesive layer on the bottom side of the metal plate. The mechanical fastener can have a coated layer on the top side of the metal plate.
The mechanical fastener further comprises a removable film covering the bottom of the metal plate having the adhesive layer. The metal plate can be disc shaped, square, reef or any other shape known in the art. The adhesive of the adhesive layer is selected from the group consisting of a butyl compound or other waterproofing compound such as single component PVAc (polyvinyl acetate) water-resistant adhesive, water-resistant polyvinyl acetate adhesive, EVA (ethylene vinyl acetate)-hot melt adhesives, pressure sensitive hot melt adhesive atactic polypropylene (APP) base pressure sensitive tapes, polyurethane adhesives, thermoplastic adhesive film based with co-polyamides, thermoplastic adhesive film based with mixed polyolefin and co-polyamide, animal base adhesive, asphaltic base adhesive styrol or verstat acrylate types, and neoprene rubber cementic base adhesive.
The mechanical fastener further comprises a hole at the center of the metal plate extending from the top side to the bottom side of the metal plate, and a fastening device can be provided through the hole. The fastening device can comprise a screw, nail, or any other similar device.
Additionally, a method of applying a mechanical fastener to a roof deck is provided, the method comprising peeling a film off a bottom side of a metal plate, the bottom side having an adhesive layer, and attaching the bottom side of the metal plate having the adhesive layer onto a roof deck.
The method further comprises heat welding a roofing membrane on a coated top side of the metal plate and the roof deck. The method further comprises fastening a fastening device through the metal plate and into the roof deck. The fastening device extends through a hole provided at the center of the metal plate.
The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.
These and other features, aspects, and advantages of the apparatus and methods of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:
FIGS. 2(a)-2(c) illustrate a second embodiment of the metal plate of the present invention;
FIGS. 3(a)-3(b) illustrate a method of application of the first embodiment of the present invention to a roof deck; and
FIGS. 4(a)-4(b) illustrate a method of application of the second embodiment of the present invention to a roof deck.
Although this invention is applicable to numerous and various types of roofing structures, it has been found particularly useful in the environment of the attachment of roofing membranes to a roof deck. Therefore, without limiting the applicability of the invention to the above, the invention will be described in such environment.
With reference now to the drawings, the metal plate mechanical fastener of the present invention will be described.
The use of the adhesive layer in accordance with the present invention provides a water resistant, strong and uniform adherence of the bottom side 102 of the metal plate 100 to a roof deck. The entire surface of the bottom side 102 is covered with a plastic film 103, which covers and protects the adhesive layer from drying before application of the metal plate to the roofing membrane. The film 103 is removed during application of the metal plate 100. The non penetrating metal plate 100 provides a quick and easy installation of the metal plate 100 to a roof deck. The bottom side 102 having the adhesive layer is attached to a top of a roof deck and/or insulation board, and a roofing membrane may be welded on the top side 101 of the metal plate 100 having a coated layer, which will be described in more detail later.
A method of application of the first embodiment of the metal plate of the present invention is illustrated in FIGS. 3(a)-3(b). As shown in
The film 103 is then removed from the bottom side 102 of the metal plate 100, and the bottom side 102 is attached to the top surface 302a of the insulation 302. The adhesive layer on the bottom side 102 of the metal plate 100 attaches the metal plate 100 to the insulation 302, or roof deck 301 if insulation 302 is not used. The top side 101 has a coated layer, as described earlier.
As shown in
After the roof membrane assembly 303 is placed on top of the metal plate 100, the roof membrane assembly 303 is then bonded to the roof deck 301 or insulation 302 using any suitable technique well known in the art. In a preferred embodiment, the roof membrane assembly 303 is heat welded to the roof deck 301 or insulation 302 by using a conventional electric heat welder (not shown) which applies heat through a single nozzle to the overlapping roof membrane assembly 303 and compresses the roof membrane assembly 303 to aid in making a good bond or weld. Thus, the metal plate 100 provides a non-penetrating and leak-proof attachment between the roof deck 301 and the roof membrane 303.
FIGS. 4(a)-4(b) shows a method of application of the second embodiment of the metal plate 200 as illustrated in
Further, at least one fastening device 204 is secured through a center 205 of the metal plate and into the roof deck 401 and the insulation 402. The fastening device 204 may include a plurality of conventional threaded fasteners and seam discs for securing the metal plate to the roof deck, a plurality of conventional threaded fasteners and one or more batten bars or, if desired, a suitable combination of the foregoing.
As shown in
The fastening devices 204 can be installed in the roof deck 401 or insulation 402 at a spacing ranging from approximately every 6 inches to every 16 inches depending upon the wind uplift forces experienced by the roof membrane assembly 403. Under typical conditions, the preferred fastening device 204 spacing is about every 12 inches regardless of the fastening device used. It will be appreciated that because the distance between fastening devices 204 can be substantially increased over distances typically used in the past because of the adhesion provided on the metal plates, the time and labor typically required for the installation of the fastening devices is greatly reduced, and since this is a manual on site operation, a large amount of the installation cost is saved.
The present invention provides several advantages that solve the problems with prior art methods. Some of the advantages include providing a mechanical fastener having self adhere coated metal plates that increase adhesion from both the top side and bottom side of the metal plate. The metal plates have the advantage of not interrupting the component layers in the roof assembly since they are peel and stick.
Further, the peel and stick coated metal plates of the present invention have the advantage of performing the dual functions of securement from top to end layer due to the coated top side of the metal plate, which will weld to the bottom surface of the roof, whereas the peel and stick side of the plate will adhere to the cap sheet of the under layer of the roof. Thus, the first overlap or seam area is locked from the bottom of the plate due to adhesion and from the top of the plate due to the coated metal welding. This increases the peel strength and ply adhesion of the metal plates, which help increase the win up lift rating. Additionally, the peel and stick coated metal plates help to control condensation in a roof, due to the gum effect of the adhesive barrier. Even in the penetrating type metal plates used with the fastener, the adhesion is located as a sandwich between the cap and fastener bottom, and provides thermal insulation, as the melted adhesive adheres to the fasteners.
The above description of the present invention is only the preferred embodiment of the invention. Embodiments may include any currently or hereafter-known versions of the elements described herein. Different adhesives may be used on the bottom side of the metal plates, different size metal plates may be used, and different types of coatings may be used on the top side of the metal plates. Also, different types and sizes of fasteners may be used where appropriate. Further, the metal plates are not limited to mechanical fasteners between the roof deck and roof membrane assembly, buy may also be used as a patch between two or more roof membranes.
While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.
