This invention relates generally to roofing apparatus, and, more particularly, to a motorized roofing apparatus adapted to apply a continuous, even coating of solvent material between the overlapping edges of sheets of roofing material and ensure that such edges are urged together to create a weather-tight seal therebetween.
A variety of new roofing materials have been developed in recent years which are intended for gently sloping or flat roofs commonly found in industrial or commercial buildings. Normally, roofing materials are commercially available in rolls and are applied to the roof by first rolling out one strip or sheet of roofing material and then a second sheet so that its edge overlaps the edge of the first sheet. The overlapped edges of the sheets are then sealed together to form a weather-tight lap joint.
In applying bituminous roofing materials, it is customary to spread liquid or molten tar between the edges of overlapping sheets to create a seal therebetween. This operation is usually done manually with one or more workmen lifting the edge of the overlapped sheet and another applying the molten tar with a brush. In some instances, a portable roofing apparatus may be used to apply the tar or adhesive. Known portable roofing apparatus for applying tar typically include a wedge-shaped applicator adapted to be inserted beneath the edge of an upper, overlapping sheet of roofing material. A nozzle is mounted to the applicator and connects to one end of a delivery line, which is connected at its other end to a container of tar or adhesive. Pressing a trigger forces the tar or adhesive from the container through the delivery line and to the nozzle in the wedge-shaped applicator where it is deposited beneath the edge of the overlapping roofing sheet. The apparatus is advanced along the roof by hand and the upper, overlapping sheet is pressed into engagement with the sheet beneath by stepping on it, or otherwise applying weight such as by placing a sandbag on the upper roofing sheet over the lap joint. See for example U.S. Pat. Nos. 3,099,582 and 3,016,040.
Heat-fusible roofing materials have been developed and used in recent years, and are generally made as a single-ply sheet or multi-ply sheets including a core of plastic and/or bitumen layers encased within polyethylene. The lap joints formed by roofing sheets made of this material are sealed or fused by first applying heat to both the overlying sheet and the one beneath, and then pressing the two sheets together. Several machines for applying the heat-fusible roofing material have been developed to avoid a time-consuming and costly manual application operation using hand held torches or burners to heat the roofing sheets. See for example U.S. Pat. Nos. 4,259,142; 4,087,309; 4,204,904; and 4,239,581. Each of these patented machines generally comprise a frame, a handle assembly mounted to the frame, one or more burners mounted to the frame for heating the overlapping edges of the roofing material, and a continuous roller or other element mounted to the trailing end of the frame for applying pressure to the overlapping edges after they are heated to help create a seal therebetween.
As an alternative to heat-fusible roofing materials, a single-ply thermoplastic roofing membrane has been developed which is sealed by spreading a solvent material between the overlapping edges of roofing sheets without the application of heat. This material provides high tensile strength, good puncture and tear resistance, minimum shrinkage and is typically lighter than traditional bituminous roofing materials and the heat-fusible multi-ply roofing material. While providing many operational advantages, single-ply thermoplastic roofing material is typically installed manually by lifting the overlapped edge of one sheet and then applying the solvent material with a brush to the edge of the sheet beneath. The lap joint formed by the overlapping sheets is sealed by the application of pressure to the upper or overlying sheet, allowing the solvent to chemically react with the sheet material and in effect fuse the overlapping edges of the upper and lower sheets together. Pressure is usually applied to the upper sheet by stepping on it or placing a sandbag or other weight on the upper sheet.
Creating a good seal at the lap joint formed by overlapping roofing sheets is critical to obtain a weather-tight roof. It has been found that one major cause of bad seals between roofing sheets is the presence of surface irregularities in the roof such as valleys, ridges and bumps. Particularly with the thin, flexible single-ply roofing sheets, of either the heat-fusible or solvent-fusible type, the lower sheet forming the lap joint tends to follow the contours or surface irregularities of the roof so as to present an upper surface having ridges, valleys and bumps for engagement with the overlapping upper sheet. Unless the upper sheet is forced into the ridges and valleys of the lower sheet, gaps are formed in the seal therebetween. These gaps prevent the solvent from creating a bond between the sheets, and the result is a seal which is not weather-tight.
Prior methods and apparatus for forcing or pressing the upper sheet against the lower sheet of a lap joint are unsatisfactory in the installation of either heat-fusible or solvent-fused single-ply roofing material. The application of solvent or adhesive to the roofing sheets by handbrush, or by hand-operated machines such as described above, require the workman to either step on the upper sheet or apply a weight such as a sandbag to effect a seal of the roofing sheets. These manual methods are labor intensive, time consuming and can leave gaps in the overlapping sheets. The manner in which the lap joint of heat-fusible roofing sheets is sealed by a machine such as described above, usually involves the application of pressure to the roofing sheets after they are heated by a single, cylindrical-shaped roller mounted at the trailing end of the machine. The roller is continuous and rigid from end to end. It has been found that cylindrical rollers fail to force the upper roofing sheet into the valleys or along the ridges which may be present in the lower roofing sheet due to the surface irregularities of the roof on which it is placed. Since the cylindrical roller is rigid from end to end, it cannot follow the roof contours or bumps and other irregularities which may be present along the width of the lap joint. Therefore, machines adapted to seal lap joints of heat-fusible roofing sheets which include a continuous rigid roller must be used on roofs which are substantially planar and have little or no bumps, valleys, ridges or other surface irregularities.
In forming the lap joints between heat-fusible or solvent-fused roofing sheets, not only must the upper sheet be placed into direct contact with the lower sheet, it must also be held in place for a sufficient time to allow the heat or solvent to fuse the sheets together and create a weather-tight seal therebetween. A single continuous roller may be ineffective in holding the upper roofing sheet into engagement with the lower sheet for a sufficient time period where the operator advances the roller too quickly along the roof, or in cooler weather when the roofing sheets are less flexible and tend to maintain their own shape instead of conforming to the slope of the sheet beneath.