It is well known to use battens in roof construction. Battens are generally metal strips or bars which are used to secure or hold down materials upon building roofs. In constructing roofs, one or more flexible cover membranes, such, as for example, thermoplastic or elastomeric sheets, are placed over a rigid substrate so as to form a part of the roof structure. The flexible membranes serve to seal the roof structure against liquid penetration and also may serve to provide an insulating effect. Such membranes are secured in place by means of batten strips or bars which are placed at spaced intervals over the flexible membrane. Headed fasteners, such as, for example, screws or nails, are then passed downwardly through the batten strips or pre-punched holes therein and the flexible membranes so as to secure the battens and membranes to the roof substrate. The batten strips should be of such nature as to permit a pointed mechanical fastener to pass therethrough without destroying the hold-down effectiveness of the batten bar. Under certain conditions wind can uplift the membrane causing it to pull, upwardly away and thereby, in turn, causing the batten strip to rip or tear about the fastener with the headed fasteners thereby passing through the batten strip so as to no longer secure either the batten strip or the membrane to the roof substrate. The batten bars, to be satisfactory, must exhibit high pull-through resistance, that is, good tear or split resistance at points where pointed mechanical fasteners penetrate the bars.
Batten bars can also be used in accordance with this invention to secure a layer or layers of insulation to a roof substrate or upon vertical building walls. They also can be used to secure flashing upon buildings and in other fastening applications where strips or bars are employed. For example, "batten strips" can be used as termination bars in order to secure membranes to the edges of vertical parapet walls to rough structure along the periphery of the roof. Thus, as used herein the term "batten strip" is not limited to roof battens but includes fastening means in building construction applications where strips or bars are useful in fastening building members.
Roofing batten bars should not unduly curl, kink or distort when penetrated by means of a fastener. Metal batten bars made of sheet metal have been used, but such bars are relatively heavy constituting a relatively dead weight upon the building roof and can be difficult to penetrate by means of a threaded mechanical fastener unless pre-drilled openings are provided therein. Metal bars are also known to corrode and diminish the soundness of the roof structure. Aluminum batten bars have also been used, but are more expensive and unless quite thick are subject to curling, kinking or distortion when penetrated by means of a threaded fastener. Wood battens decay.
Plastic batten strips have also been proposed. U.S. Pat. No. 4,718,211 discloses batten bars of a particular configuration made having plastic. Likewise, U.S. Pat. No. 4,445,306 discloses an elongated fastening bar made of plastic which has a flat batten surface and a convex top surface. The batten strips and fastening bars disclosed in these patents have a thickness at one point of approximately 1/4 inch and have pre-drilled holes therein so as to receive the fasteners.