Patent Publication Number: US-5251416-A

Title: Insulated panelized roofing system

Description:
TECHNICAL FIELD 
     This invention relates to the art of roofing, and more particularly to the application of protective outer surfaces on commercial roofs. 
     BACKGROUND ART 
     As is well known to those skilled in the roofing art, the three leading generic types of commercial low-slope roof constructions are the torched on single-ply roof, the EPDM single-ply roof, and the built-up roof (BUR) construction. Generally speaking, the torched on single-ply roof construction comprises applying an insulation board cover to a steel deck or other suitable roof substrate and then securing an asphalt-coated polyester mat to the insulation boards by utilizing a hot torch flame to heat the underside of the membrane prior to adhering it to the insulation. The EPDM single-ply construction is very similar except that the thin EPDM membrane is glued to the insulation boards. Also, ballasting with heavy rock and spot attachment with fasteners are two other methods used to attach the EPDM membrane to the deck. Finally, the BUR roof construction normally provides for applying multiple reinforcement layers of asphalt saturated paper or fiberglass or spunbond polyester with hot-mopped asphalt applied between the layers in order to form a waterproof barrier over the roof substrate. 
     Unfortunately, all of the roof constructions described above suffer from inherent shortcomings which include lack of safety due to the requirement for open-flame torches, labor-intensive roof installation requirement, heavy and unwieldy roll roofing materials, splitting and blistering of the roof membrane, lap and seam failures, lack of puncture and tear resistance, failure in high winds, and non-uniform material qualities. In an effort to overcome some of these problems which have long plagued the commercial roofing industry, the panelized roofing system was developed. Quite a number of panelized roof systems are now known and they vary substantially in both their construction features and performance capabilities. Representative panelized roofing systems include the STRUCTODEK FS manufactured by Wood Fiber Industries of Chicago, Ill., the NORD BOARD system distributed by Nord Bitumi of Springfield, N.J., the INSULROOF distributed by American Roofing Corporation of Countryside, Ill., the panelized roofing system distributed by AB Mataki of Sweden, and panel systems disclosed in U.S. Pat. No. 4,680,909 to Stuart and U.S. Pat. No. 4,738,067 to Froseth. However, although potentially an improvement over conventional roofing systems, the panelized roofing systems have suffered from numerous shortcomings including relatively high cost, difficulty in cutting the panel boards, the requirement of open-torch flame application, easily damaged insulation boards, and physical irritation caused by fiberglass or rock wool insulation materials. 
     Applicant attempted to meet the long-felt need for a panelized roofing system with the novel roofing system described in applicant&#39;s recently issued U.S. Pat. No. 4,965,977. This roofing system has been found to be a vast improvement in the art, and applicant&#39;s new insulated panelized roofing system is a modification thereof to provide even greater flexibility in roof system constructions. 
     DISCLOSURE OF THE INVENTION 
     In accordance with the present invention, applicant provides an improved panelized roof system construction for application over a roof substrate comprising a plurality of roof panels which are positioned on the substrate in abutting relationship so as to cover the top surface thereof. The panels are formed from a foam insulation board having a mat of synthetic fiber reinforced rubber sheet, preferably EPDM, bonded to the top surface of the board so as to render the foam insulation board substantially waterproof. Fasteners are positioned along the sides of the panels and closely adjacent to the joints formed between the abutting panels with the fasteners penetrating the panels so as to secure them to the roof substrate therebeneath. Rubber strips, reinforced with a synthetic fiber scrim, are applied with adhesive or adhesive tape so as to overlap both the joints between the panels and the fasteners adjacent to the edges thereof and to form a water-tight seal thereover. Additional top surfacings applied in the field include but are not limited to gravel, ceramic granules, pavers and reflective roof coatings. Thus, the panelized roof system construction may further include a hot-mop applied bitumen layer applied over said plurality of panels and reinforced rubber strips and a surface ply layer applied over said bitumen layer. The surface ply layer may be a bitumen-saturated polyester mat, a bitumen-saturated fiberglass mat, a modified bitumen cap membrane, or a granular surface fiberglass cap membrane. 
     Thus, a panelized roof system is provided which can be easily and safely installed and possesses enhanced performance characteristics. 
     It is therefore the object of this invention to provide an improved panelized roof system which is less labor-intensive than roofing systems known heretofore. 
     It is another object of the present invention to provide a panelized roof system which does not require use of open-torching on the roof and thereby eliminates the exposure of roof workers to hot materials and the heating equipment therefor which would normally be maintained on the roof. 
     It is another object of the present invention to provide a panelized roof system which results in reduced application problems such as blistering, fishmouths and wrinkles and which may be easily flashed as required. 
     It is yet another object of the present invention to provide a panelized roofing system which possesses inherent high elongation, flexion, puncture and tear resistance tensile characteristics and which is lightweight and easily fashioned around roof projections and irregularities. 
     Some of the objects of the invention having been stated, other objects will become evident as the description proceeds, when taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a panel according to the present invention; 
     FIG. 2 is a top view of a roof substrate with panels secured thereto in accordance with the present invention; 
     FIG. 3 is a top view of a roof substrate with the roof panels secured thereto and the seams between abutting panels taped according to the present invention; and 
     FIG. 4 is a cross-sectional view taken along lines 4--4 of FIG. 3. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring now to the drawings, FIG. 1 shows a panel 10 made in accordance with the present invention. Panel 10 comprises a foam insulation board 12 with a mat 14 of synthetic fiber reinforced rubber sheet bonded to the top surface so as to render foam insulation board 12 substantially waterproof. The rubber sheet can be bonded to the synthetic fiber thereby forming the mat using heat or bonding adhesives. The attachment of the rubber sheet to the synthetic fiber to form the mat may be partial (spot or strip) or total. The attachment of the mat 14 of synthetic fiber reinforced rubber sheet to the insulation board 12 may be partial or total. As a matter of choice, panel 10 may be formed from two sections of foam insulation board 12, which are joined together by mat 14 of synthetic fiber reinforced rubber sheet which extends across and is bonded to the top surface of both sections of foam insulation board 12 to form a fold line F. Thus, foam insulation board 12 may be folded back upon itself for ease of transportation and installation. The primary advantage of this construction, however, is that the amount of taping is greatly reduced. This optional feature will be discussed in more detail below. It is presently contemplated that foam insulation board 12 may be a polyisocyanurate foam insulation board, phenolic foam insulation board, extruded polystyrene board, expanded polystyrene (EPS) board, or a urethane board, although most suitably polyisocyanurate and phenolic insulation board are the preferred materials for the panelized roof system of the invention. Although other materials are contemplated as within the scope of the invention, synthetic fiber reinforced rubber sheet mat 14 most suitably is formed from either polyester, polyamide, polypropylene, and KEVLAR® fibers (KEVLAR® is a registered trademark of DuPont for its aramid pulp, wherein the aramide is poly paraphenyleneterephthalamide) or combinations thereof, and the preferred fiber is polyester in the form of a spunbonded non-woven sheet material such as LUTRADUR® manufactured by Freudenberg Spunweb Company of Durham, N.C. Also, although other panel fabrication techniques are possible, most suitably synthetic fiber portion SF of mat 14 is laminated to foam insulation board 12 during the process of extruding the board, and then the rubber sheet portion R of mat 14 is adhered to the top surface of the synthetic fiber to form the mat also in a controlled environment. 
     Panel 10 most suitably comprises a 4×8 foot section of foam insulation board 12 about 1/2 to 1 inch thick although it is contemplated that panel 10 may range in size from about 4×8 feet to 4×20 feet. If panel 10 is provided with a fold line F in the medial portion thereof, folded foam panels 10 may range in size from 4×4 feet to 4×10 feet. Synthetic fiber portion SF of mat 14 is most suitably formed from a spunbond or needle punch material weighing between about 3 to 12 ounces per square yard and bonded to a rubber sheet portion R that is about 20-90 mils thick. Foam insulation board 12 when bonded to synthetic fiber reinforced rubber sheet mat 14 forms a roof insulation panel which is itself waterproof without the application of additional layers of bitumen and/or membranes thereon. 
     Waterproof panels 10 are secured to roof substrate S therebeneath (see FIGS. 2-4) by fasteners 16. Roof substrate S may include plywood decks, wood plank decks, steel decks, structural concrete, and poured lightweight concrete-over-steel decks. Applicant contemplates that conventional fasteners known to those skilled in the art should be used to secure panels 10 to roof substrate S and that a minimum of 6 fasteners 16 will be required for a 4×8 foot panel 10. Most suitably, fasteners 16 will be positioned along the lengthwise sides of panel 10 and penetrate therethrough about 2 inches from the joints J formed by abutting side edges of panels 10. If the roof constructed from the panelized roof system of the present invention is expected to be exposed to unusually high winds, additional fasteners may be placed in the center of panel 10 to secure it to roof substrate S and protect panels 10 from the wind forces. Normally, however, applicant contemplates that fasteners 16 will only have to be secured adjacent to the two lengthwise sides of panels 10 to safely secure the panelized roof system to the underlying roof substrate S. 
     After panels 10 have been secured to roof substrate S with fasteners 16 as described hereinabove, the joints J defined between abutting panels 10 are taped with reinforced rubber strip 18 which is most suitably about 8 inches in width so as to cover both joints J and fasteners 16 on each side of the joints. To apply reinforced rubber strips 18, the joints J to be covered are first prepared by cleaning and application of adhesive or adhesive tape. Then reinforced rubber strips 18 are adhered over joints J defined between panels 10 and fasteners 16 adjacent to the edges of abutting panels 10. Reinforced rubber strips 18 most suitably are reinforced with a woven or non-woven sheet formed from polyester, polyamide, polypropylene, or KEVLAR® fibers and mixtures thereof, and most preferably the reinforcement comprises a polyester, woven scrim. 
     Reinforced rubber strips 18 have a thickness of about 20-90 mils. Once reinforced rubber strips 18 are applied to joints J between abutting panels 10, strips 18 adhere to panel 10 and form a waterproof seal over joints J between abutting panels 10 as well as fasteners 16 securing panels 10 to underlying roof substrate S (see FIG. 4). The panelized roof system as now described is waterproof, and no further layers are required in most circumstances. 
     It will thus be seen that there has been described above an improved panelized roof system which provides for a high-performance panelized roof system which is safer and easier to install than any roofing system known heretofore. Additionally, as an optional feature, each panel may be constructed so as to be easily folded back upon itself about a medial transverse fold line in order to facilitate transportation and installation of the panel. 
     It will be understood that various details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation--the invention being defined by the claims.