Patent Publication Number: US-2006005496-A1

Title: Torchless self-adhesive roofing product and method

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to roofing. More particularly, this invention relates to a self-adhesive waterproof membrane or roofing material, which is particularly suited for application to flat or slightly pitched roofs and which requires no torching operation for its installation. Such a roofing product is generally of the type employed on commercial, industrial, and large multi-unit residential structures. However, use of this roofing product and method on smaller structures and residences is not excluded from the present disclosure. Still more particularly, this invention relates to a roofing product and method having an installation that is substantially free of Volatile Organic Compounds (VOC&#39;s), and which is applied to a building substantially without the use of torching or molten tar. Rather, the roofing material is pressure-sensitive, and is pressed into place and is further secured with roofing fasteners. Thus, concerns of air pollution, worker safety, and possible structural fire, are substantially eliminated by use of this invention.  
      2. Related Technology  
      Generally, the roof structure of a building which employs a substantially flat or only slightly pitched roof includes a structural portion, which may include roof beams or trusses, possibly a grid of stringers carried on the beams or trusses, and a roof deck or sheeting which is carried on the stringers. The roof deck or sheeting may be carried directly upon the roof beams or trusses in some roof structures. Upon this structural portion is generally disposed an outwardly (i.e., upwardly) exposed water proof membrane (i.e., the roofing material). The water proof membrane structure prevents water (i.e., from precipitation) from penetrating the roof structure. Generally, the roof is provided with a system of drains, and possibly a system of gutters, along with drain pipes or down spouts, to carry precipitation water away.  
      Such a roof structure may be substantially flat, or may be slightly pitched. Further, such a roof structure frequently has plural vent pipes (i.e., for ventilating, heating, and air conditioning of the building, for example), ventilator fans, air conditioning units, heaters, electrical service conduits and cable ducts, electrical transformers and switch gear, and other utility devices and facilities mounted on the roof, and with portions of these facilities and devices passing through openings in the roof structure.  
      Historically, such flat or slightly pitched roofs have been of “built up” construction. That is, after the structural portion of the roof is completed, one or more layers of “tar paper” in the form of strips or sheets from a roll would be put down on the roof decking or sheeting, and one or more layers of roll sheet roofing material would be applied over the “tar paper.” The strips of roll roofing material are slightly overlapped at their edges, and the roof membrane may include several layers of such overlapped strips with the strips in each successive layer all running horizontally. The roll roofing material is generally applied with molten tar, in what is known as a “hot mop” process. As used herein, “tar” refers to any of various dark-colored viscid products obtained by the destructive distillation of certain organic substances, such as coal or wood, coal tar pitch, viscid asphaltic materials, etc., and is used without limitation on the invention.  
      Further, the conventional roll sheet roofing is usually about 3 feet wide (or about one meter if metric sized), is utilized at a roofing site in the form of a rolled elongate strip which may be 15 feet or more in length, and would generally be applied by a “hot mop” method as mentioned above. In such a “hot mop” method hot molten tar may be carried by hand in buckets up a scaffolding, or may be pumped from a tar kettle (i.e., a tar heater and pump unit) on the ground, in order to be delivered by a temporary pipe line arrangement to the roof. This hot tar is then mopped or otherwise spread on the seams and over the face of the sheet roll roofing to seal the seams and provide an additional water proof layer. Generally granular mineral material is spread over the surface of the roof to provide protection for the tar from ultraviolet radiation in sun light.  
      Some forms of conventional roll sheet roofing have granular material already applied over most of the outer face of the strip of roofing material, and the seams between adjacent strips of this roofing may be formed by a “torch down” method. In such a “torch down” method, after a strip of roofing is put down, a pre-applied strip of tar on the top elongate edge of this one strip of roofing is heated and softened with a large torch immediately before the side marginal edge portion of the next-successive strip of the roll sheet roofing material is put down on the roof structure.  
      Understandably, such conventional roofing practices which involve the use of hot molten tar, and of large torches, frequently result in a worker being burned by the tar or torch. Further, as is well understood by anyone who has been within even a few hundred feet of such a roofing project, the use of hot molten tar releases large amounts of noxious VOC&#39;s into the atmosphere.  
      Still further, molten roofing tar is flammable, and roofing torches provide a ready ignition source. Consequently, the conventional torch methods of roofing installation have resulted in many roof fires, and in structure fires when a roofing fire spreads before it is contained. Even in cases in which a roof fire results but is stopped before it spreads to the structure, the roofers are at risk of injury as they attempt to put out the fire. In some areas, local fire departments and Fire Marshals require torch roofing projects to be carried out under a “hazard watch” condition, in which local fire stations are informed of the project, and have an emergency response plan worked out ahead of time for use in the event that a roof fire starts.  
      As a result, recently a new form of roll sheet roofing has come into use. This newer roll sheet roofing is intended to be pressure sensitive and “self adhesive.” That is, in much the same way that an adhesive bandage is applied to the skin by first removing a release sheet to uncover a layer of sticky pressure-sensitive mastic adhesive, such “self adhesive” roll sheet roofing materials are provided with a layer of sticky adhesive on the underside of the roofing material. This sticky adhesive is covered by an elongate strip of release sheet material, which may be a plastic film of a type that does not bond permanently to the adhesive material, for example. In the use of such a “self adhesive” roll roofing material, as each successive strip of roofing material is unrolled the release sheet is pulled off and the adhesive material on the underside of the strip secures it to the underlying roof structure. The adhesive material is capable of bonding to the underlying roof structure so that the successive strips are placed side by side and appear to form a lap joint between them.  
      That is, although experience has shown that this “self adhesive” roll sheet roofing material solves many problems of the old “hot tar” roofing materials and methods, it has new problems and deficiencies of its own. In other words, the “self adhesive” roofing materials have limitations with respect to the conditions under which they can be successfully applied. If the conditions of application are too cold (i.e., below about 55° F.) or too wet, then the self adhesive roofing materials will not adhere well to the underlying roof structure. This limitation is understandable in view of the fact that the adhesives generally utilized on the self adhesive type of roll roofing materials is viscous and must soften (i.e., become viscid) to engage and bond with the underlying roofing materials. Further, rain, snow or other precipitation falling on the roof before the seams have bonded may seep through the seams. The presence of such moisture further will delay or interfere with the bonding of the adhesives generally employed on self adhesive roofing materials. In such cases the self adhering roofing materials have been known to not satisfactorily adhere to the underlying roof structure. In the event of such a less than satisfactory adherence of the self adhering roofing materials, if a strong wind storm takes place while the roof materials are not securely adhered then some or all of the new roofing materials may be blown off of the roof. With the conventional self adhesive roofing materials, when an application must be made during ambient conditions that are too cold the hope is that the conditions will improve (i.e., become warmer) and that the new roof material will then adhere by action of its own adhesive before the new roof is exposed to a strong wind storm.  
      Further, the conventional self adhesive roofing materials provide only a single layer of coverage for the underlying roof structure with each layer of the material put on a roof. So, several layers may be necessary in order to achieve satisfactory weatherproofing.  
     SUMMARY OF THE INVENTION  
      In view of the deficiencies of the conventional related technology, it is an object of this invention to overcome one or more of these deficiencies.  
      Particularly, it is an objective for this invention to provide a self-adhesive roll roofing material that has improved moisture resistance at the seams, even when applied in cold conditions.  
      Accordingly, the present invention, as seen in a particularly preferred exemplary embodiment, provides a roll roofing product including an elongate strip of inorganic fibrous sheet material permeated with an asphaltic matrix; the elongate strip defines a pair of upper elongate longitudinal facial portions each about one-half as wide as the strip of sheet material. One of the pair of upper elongate longitudinal facial portions carries a covering layer of protective coarse granular material, and the other of the pair of upper elongate longitudinal facial portions carries a coating of fine-dimension granular material sufficient to prevent self adhesion of successive wraps of the strip of roofing material when rolled on itself. The elongate strip further defines a pair of lower elongate longitudinal facial parts each about one-half as wide as the strip of sheet material. And, one of the pair of lower elongate facial parts carries a coating of an asphaltic adhesive, while the other of the pair of lower elongate longitudinal facial parts carries a coating of fine-dimension granular material effective to prevent self adhesion of successive wraps of the strip of roofing material when rolled on itself.  
      Other objects, features, and advantages of the present invention will be apparent to those skilled in the art from a consideration of the following detailed description of a preferred exemplary embodiment thereof taken in conjunction with the associated figures which will first be described briefly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       FIG. 1  provides a fragmentary perspective view of a portion of a roof structure having self-adhesive roll roofing material applied thereto, and embodying the present invention;  
       FIG. 2  is a fragmentary cross sectional view of the roof structure seen in  FIG. 1 ;  
       FIG. 3  is a somewhat enlarged cross sectional end view of a roofing material embodying the present invention and which may be used in practice of the present inventive method; and  
       FIG. 4  provides a diagrammatic representation schematically depicting how rolled strip roofing materials are applied to a roof structure in the practice of the present invention according to a particularly preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF AN EXEMPLARY PREFERRED EMBODIMENT OF THE INVENTION  
      While the present invention may be embodied in many different forms, disclosed herein is a specific exemplary embodiment that illustrates and explains the principles of the invention. In conjunction with the description of this embodiment, a method of practicing the invention is described. It should be emphasized that the present invention is not limited to the specific embodiment illustrated.  
      Viewing  FIGS. 1 and 2  (which respectively provide a perspective view, and an elevation view, both of which are fragmentary and partially cross sectional), and referring first to  FIG. 1  for a general overview of the inventive roof structure, a typical flat or slightly pitched building roof structure  10  according to the present invention is depicted. It is to be noted that in  FIGS. 1 and 2 , the thickness of the roll roofing material to be further described below is illustrated with an exaggerated thickness for clarity of illustration. The roof structure  10  includes plural elongate and spaced apart roof beams or rafters  12 , cooperatively supporting a roof deck  14 . The roof deck  14  may be made, for example, of one or more layers of boards or plywood spanning the spaces between the rafters  12 , and supported on these rafters. Supported on the roof deck  14  is a waterproof membrane structure, generally referenced with the numeral  16 . This membrane structure  16  preferably includes a layer of partially overlapping (i.e., with a little more than a 50% overlap) strips of roll roofing material  18 . As will be seen, the roll roofing material  18  upwardly presents an elongate exposed surface portion which is coated with protective coarse granular material which protects the roofing material from deterioration by ultraviolet rays in sun light.  
      Downwardly, the roll roofing material  18  presents an elongate surface portion that is coated with an adhesive material effective to sealing bond the roofing material  16  to an adjacent strip of the roofing material, and also to sealingly bond the roofing material to the roof deck  14  as will be further explained. The remaining elongate surface portions of the roofing material  18 , both on the upper and lower faces, are coated with a fine granular material. That is, about half of the upper face and about half of the congruent lower face of the roll roofing material  18  is coated with the fine granular material. This fine granular material is effective to prevent wraps of the material from sticking to itself when rolled for shipping. However, an upwardly disposed surface portion of the roofing material strip (which surface portion is coated with this fine granular material) is nevertheless bondable to a successive strip of the roofing material by action of the adhesive carried on the lower face of that next-successive strip of roofing material. Importantly, as is seen in  FIGS. 1 and 2 , because of the overlap of adjacent strips of the material  18  being slightly more than one-half (i.e., slightly more than 50%) the roofing material  18  everywhere provided double thickness coverage for the roof deck  14 , as will be further explained.  
      More particularly, viewing  FIG. 2  in detail, it is seen that the strips  18  of roofing material on their upper faces each have a width dimension composed of two adjacent parts  18   a  and  18   b,  each of which represents an elongate ribbon-like portion of the roofing material strip  18 . Although the invention is not so limited, according to a preferred embodiment of the invention, the parts  18   a  and  18   b  are about but not exactly of equal width. Further, according to the preferred embodiment, the part  18   a  (i.e., an underlying portion covered by a next successive strip  18  of roofing material) is about 20 and ½ inches wide, while the part  18   b  (i.e., the upwardly exposed overlying portion, covering over part of a preceding strip of the roofing material  18 ) is about 19 inches wide, and the strip of roofing material  18  most preferably has a width of about 39½ inches. The portion  18   a  also forms a Z-shaped lap joint feature, indicated in  FIG. 2  by the arrowed numerals  18   a ′, but is mostly covered over or lapped over by the portion  18   b  of a next successive strip  18  of the roofing material.  
      Conversely, the portion  18   b  substantially laps over the part  18   a  of a preceding strip of the roofing material  18 . As is seen in  FIG. 2 , the extent of overlapping of each strip  18  of the roofing material  16  with a preceding strip of the material  16  is preferably a little more than about ½ of the total width of the strip of roofing material  18 . That is, although the invention is not so limited, the most preferred embodiment of the inventive roofing material  18  utilizes an overlap fraction that is a little more than substantially one-half. Accordingly, each strip of the roofing material  18  most preferably overlaps a preceding strip of the material in a layer of the roofing material  18  making up a membrane  16  by about one-half (½) of the width of the strips  18 , and also very slightly overlaps another underlying strip of the material  18 , as is best seen in  FIG. 2 .  
      Turning now to  FIG. 3 , which presents a fragmentary end view of a roofing material strip  18  with portions of the width of this strip broken out for clarity of illustration, it is seen that the strip of roofing material  18  includes an elongate base sheet or strip  20  of inorganic fibrous material. The base sheet has a left-hand edge indicated with numeral  20 ′ and a right hand edge indicated with numeral  20 ″. As is seen in  FIG. 3 , the base sheet  20  has a width  18 ′ (which is about 39½ inches according to the preferred embodiment) and extends from side to side and from end to end of a strip  18  of the roofing material. That is, the base sheet  20  and the strip  18  of roofing material may be several feet long. This base sheet  20  may be made, for example, of felted, fine-dimension glass fibers, which are inter-tangled and compressed into a self-sustaining web. That is, although the sheet  20  is not woven, it does not fall apart easily, or even pull apart easily, because the fine-dimension glass fibers of this sheet are inter-tangled and pressed together. As is well understood in the pertinent arts, the sheet  20  may also be embossed, or needle-punched, for example, to improve its tenacity and cohesiveness.  
      Penetrated into and substantially through the sheet  20  is a matrix  22  of asphaltic material. This matrix of asphaltic material  22  adheres the fibers of the base sheet  20 , and unifies the base sheet  20  and matrix  22  into a unitary durable structure. As is seen in  FIG. 3 , a layer  24  of raw asphaltic adhesive material is carried on a lower facial portion of the base sheet  20 , and extends from the right-hand side edge  20 ″ over a little more than one-half the width of the base sheet  20 . This layer of raw asphaltic material  24  is preferably covered by a removable plastic sheet  26 . That is, the layer  24  of adhesive raw asphaltic material extends from one side edge  20 ″ of the base sheet  20  through a lateral dimension  28 , which is a little more than one-half (½) or more of the width of the strip  18  of roofing material. Most preferably, the lateral dimension  28  is at least one-half (½) inch more than the width of the facial portion  18   a.  Accordingly, the dimension  28  is most preferably at least about 20½ inches wide. The lateral dimension  28  may also be wider than 20½ inches.  
      On the upper face of the strip  18  of roofing material as seen in  FIG. 3 , this material includes a layer  30  of coarse granular material extending from the right-hand side edge  20 ″ through a lateral dimension  32 . The lateral dimension  32  is preferably slightly more than the width of facial portion  18   b,  and is also may be slightly more than one-half the width of the strip  18  of roofing material. As is well understood in the pertinent arts, the layer  30  of granular material is adhered to the base sheet  20  and matrix  22  by the application of a thin coating of hot asphalt (not seen in the drawing Figures) and the immediate sprinkling of the granular material  30  onto and slightly into this asphalt coating (i.e., by use of a pressure roll). The layer  30  of coarse granular material provides full coverage with the coarse granular material through the width of portion  18   b,  and also on an additional margin of full coverage followed by a tapering off of the coverage of granular material  30  slightly onto the adjacent facial portion  18   a.    
      Thus, the coarse granular material  30  provides full coverage on facial portion  18   b,  and also a short distance onto the facial portion  18   a.  This marginal portion of facial portion  18   a  is effective to form the Z-shaped transition indicated in  FIG. 2  with the arrowed numeral  18   a ′, which is formed at the lap joint of adjacent strips of the roofing material  18 . Accordingly, most of the coarse granular material  30  (i.e., throughout the width dimension  18   b,  and through most of the dimension  32 ) is exposed upwardly when the strips  18  of roofing material are installed on a roof. A part of the layer  30  of course granular material is covered by the next successive strip of roofing material  18 . And, this layer  30  of coarse granular material not only protects the asphaltic matrix  22  from deterioration which would be caused by ultraviolet rays in sunlight, but is generally colored in various shades (and possibly is applied in a pattern of variegated colors) in order to give the roof  10  a pleasing aesthetic appearance. Most of the remainder of the upper face of the strip of roofing material  18  is covered with a fine-dimension granular material  34  extending through a lateral dimension  36 . This fine-dimension granular material covers most of the facial portion  18   a.    
      Further, in order to insure proper overlap of the roofing material strips  18  when installed on a roof, the layer  30  will include an elongate line of longitudinally extending visual guide markers (i.e., perhaps in the form of a dashed chalk line) the location of which is generally indicated by arrow  30 ′ on  FIG. 3 , and which is disposed the correct distance from edge  20 ″ in order to define the facial portion  18   b.  According to the illustrated exemplary preferred embodiment, the guide marks indicated by arrow  30 ′ are about 19½ inches from the side edge  20 ″. So, the facial portion  18   b  is intended to measure 19½ inches from side edge  20 ″ while the facial portion  18   a  measures about 20½ inches from side edge  20 ′ to the guide marks  30 ′.  
      However, on the upper face of the roofing material strip  18 , there is preferably a small exception to or exclusion of the coating  34  in a marginal edge portion (or selvage edge portion)  34 ′. In this selvage edge portion  34 ′ the fine-dimension granular material  34  preferably is partially removed and/or partially pressed into the base sheet  20  and matrix  22 . Accordingly, in this marginal edge portion  34 ′, which may be about an inch wide, for example, the thickness of the roofing material  18  is reduced or tapered toward the adjacent side edge  20 ′. In this selvage edge portion  34 ′ however, there remains sufficient fine granular material so that the selvage edge portion is not sticky and does not cause adherence of successive wraps of the material  18  when rolled for shipping. It is to be appreciated, however, that because of the reduced thickness of the selvage edge portion  34 ′ when the successive strips  18  of roofing material  16  are overlapped during installation on a roof, the underlying strip of material  18  provides an edge thickness at selvage edge portion  34 ′ that is rather thin (that is, thinner than the full thickness created by the combination of base sheet  20  and matrix  22  along with the upper and lower coatings of fine-dimension granular material  34  and  34 ″—coating  34 ″ being introduced below). This rather thin dimension at the side edge  20 ′ of the underlying strip of roofing material (i.e., at the edge of selvage edge portion  34 ′) is easily accommodated and bridged by the layer  24  of raw asphaltic material on the overlying strip  18  of roofing material, so that void spaces (which could harbor moisture and lead to blistering of the roof membrane  16 ) are substantially eliminated. Again, it is to be noted that the dimensions  32  and  36  are each about one-half (½) of the width of the strip  18  of roofing material, while the dimension  28  is preferably at least one-half (½) inch more than the width of the portion  18   a.    
      Finally, the remaining portion or part of the lower face of the strip  18  of roofing material is coated also with a layer  34 ″ of substantially the same fine-dimension granular material used on the upper facial part  18   a  (there indicated with numeral  34 ). Actually, the layer  34 ″ of fine-dimension granular material is applied to the combination of the base sheet  20  and matrix  22  before the layer of adhesive material  24  is applied, and the width of this layer  34 ″ of fine-dimension granular material as applied is almost one-half of the width dimension  18 ′. Accordingly, because the layer  24  of adhesive material is more than one-half the width of the strip  18  it slightly overlaps this layer  34 ″ of fine-dimension granular material. Further, the strip  26  of removable plastic film is also slightly wider than is the layer  24  of adhesive material, both to extend slightly beyond the edge  20 ″ and to extend slightly beyond the coating  24  onto the coating of fine granular material  34 ″. Thus, a marginal edge portion  26 ′ of the plastic film  26  lies atop of the fine-dimension granular material of layer  38  and is not adhered. So, this loose marginal edge portion  26 ′ of the film  26  is easily lifted up manually in order to start pealing of the film  26  off of the adhesive layer  24  (as will be further explained below).  
      Turning now to  FIG. 4 , a step in the method of applying successive strips  18  of roofing material  18  in order to provide a waterproof membrane  16  on a roof structure deck  14  is illustrated. As is seen along the right-hand side of  FIG. 4 , a preceding strip  18  of the roofing material has been applied to the roof structure, and upwardly presents facial portions  18   a  and  18   b.  The preceding strip of material  18  is preferably secured to the roof deck  14  by three spaced apart elongate longitudinal lines of plural roofing nails or fasteners  38  (only the heads of which are visible in the drawing Figure), each line of fasteners being generally indicated by the numerals  38 ′. These fasteners  38  are driven through the roofing material  18  in facial portion  18   a,  and the two outside lines of fasteners are preferably on 12 inch centers. On the other hand, the center line of fasteners  38  is preferably on  18  inch centers. The left hand one of the three lines  38 ′ of fasteners  38  is preferably spaced laterally about  3  inches from the side edge  20 ′, while the center line of fasteners  38  is spaced laterally about 9½ inch from the edge  20 ′. On the other hand, the right hand line  38 ′ of fasteners  38  is preferably spaced laterally about 3 inches from the adjacent edge of the coarse granular material  30  (i.e., from the adjacent edge of the portion  18   b ). Each successive strip  18  of roofing material is similarly secured to the roof deck  14 . As will be seen, the adhesive material  24  also has a role to play in securing the roofing material strips  18  to the roof deck  14 .  
      Next, as is illustrated in  FIG. 4 , a successive strip  18  of roofing material is applied by unrolling this strip from a roll of the material (translational movement of the roll and unrolling being indicated respectively by the associated horizontal arrow and by arcuate arrow  40 ). The unrolling strip  18  of roofing material is placed on the roof deck  14  such that the portion  18   a  of the preceding strip is covered, and the layer  24  of adhesive is applied onto this facial portion  18   a  over the fine dimension granular material  34  of that preceding strip of roofing material  18 , and also extends beyond the selvage edge portion  34 ′ and edge  20 ′ to present a portion  24 ′ onto the roof deck  14 . Recalling the explanation above, the roofing installer will use the index or guide line  30 ′ in order to insure that the facial portion  18   b  is exposed, and the correct extent of facial portion  18   a  is covered by the next successive strip of roofing material  18 . As a result, and as seen in  FIG. 4 , the adhesive  24  is presented to and sealingly bonds to an elongate stripe  24 ′ of the roof deck  14  immediately adjacent to the side edge  20 ′.  
      Further, considering  FIG. 4  in detail, and recalling that the layer  30  of coarse granular material of the preceding strip  18  of roofing material is a little more than one-half the width of the strip, while facial portion  18   b  is a little less than one-half the width  18 ′, it will be seen that the side edge  20 ″ of the successive strip  18  is positioned such as to allow adhesive  24  to somewhat overlap the layer  30 . Most preferably, there is about one and one-half inch of overlap of the adhesive  24  onto the layer  30  of course granular material. The adhesive  24  is sufficiently flowable and is such a tenacious adhesive that the course granular material  30  extending beyond the facial portion  18   b  and onto facial portion  18   a  does not prevent the adhesive  24  from being sealingly effective and effecting a bond in this part of the overlap joint. Of course, in the facial portion  18   a  which is covered only with the layer of fine granular material  34 , the adhesive  24  is effective to sealingly bond the successive strips  18  of roofing material tenaciously to one another.  
      This method of installation of the roofing material  18  leaves substantially all of the area of layer  30  of coarse granular material (i.e., facial portion  18   b ) exposed on each of the preceding strips  18 , and completely covers the fasteners  38 . Thus, moisture from atop the installed strips  18  of roofing material making up membrane  16  would have to permeate between the strips  18  from the right hand side edge  20 ″ of a successive strip about one-half of the width of the strip in order to reach the left hand side edge  20 ′ of the preceding strip  18 . So, the waterproof membrane  16  provides double layer coverage of the roof deck  14 , and very good resistance against water penetration of the roof  10 . Preferably, after each successive strip . 18  of the roofing material is unrolled, partially overlapping the preceding strip of roofing material, and is fastened by fasteners  38 , then a weighted roller is used over the membrane  16  in order to press the adhesive layer  24  firmly upon the facial portion  18   a  of the preceding strip, and to bond the adhesive  24  onto the roof deck  14  in stripe  24 ′ as well. This pressing action employs the self-adhesive or pressure-sensitive nature of the adhesive  24  of the roofing material  18  to interbond the successive strips  18  of roofing material.  
      It is to be noted that during the unrolling of the succeeding strip  18  of roofing material  16 , the protective plastic film  26  is pulled away, as is indicated by arrow  26 ′ on  FIG. 4 . Simultaneously, the roll  18  of roofing material is rolled forward, again as is indicated by arrow  40 . As the roofing material  18  is applied from roll  18 ′ by forward motion of this roll, successive fasteners  38  are driven through the material as was explained above. Thus, the strips  18  of roofing material are secured to the roof structure  10  by fasteners, as well as by the adhesive  24  in stripe area  24 ′ in order to firmly secure the membrane  16  to the deck  14  of the roof structure. Also, the adhesive layer  24  is utilized in stripe area  24 ′ to effect waterproof interbonding of successive strips of the material  18  to the roof deck  14 , such that any moisture which might be able to penetrate under a lap joint between successive strips of the material  18  is not allowed to reach the roof deck  14  itself. That is, a stripe or area of water resistant sealing bond is effected at stripe area  24 ′ between the adhesive  24  of a successive strip  18  of the roofing material and the edge  20 ′ of an underlying strip  18  of the roofing material, and to the roof deck  14  as well. So, the roofing material  18  effects not only double layer coverage of the roof deck  14 , but also provides a duality of sealing bonds. The first sealing bond is formed between successive strips of the material  18  which overlap and interbond to one another to form the membrane  16 . And, the second sealing bond is formed by a successive strip of the material  18  interbonding with the roof deck  14  adjacent to the side edge of an underlying strip of the material  18 . Thus, a redundancy of sealing bonds are formed by the roofing material  18  with successive strips of itself, and with the roof deck  14 , in order to better prevent water penetration of the roof  10 .  
      Moreover, it will be appreciated that the adhesive material  24  which is exposed when plastic film  26  is peeled off is effective to bond the successive layer of roofing material to the preceding layer over the entire length of the strip  18 , as well as from side to side of the facial portion  18   a  having a width somewhat greater than the dimension  36 . This bonding of adhesive layer  24  to facial portion  36  forms an interbonding of successive strips of the roofing material  16 . The result is that moisture atop the applied roofing material  16  would have to penetrate between the successive layers or strips  18  about one-half of the width of the strips  18  in order to reach the roof structure  10 . Because the raw asphaltic adhesive material  24  is such a tenacious adhesive, and because it remains viscid (i.e., it can soften or re-flow) and can re-bond each time it gets hot (i.e., from sunshine on a warm day), the roof  10  has somewhat of a self-healing nature, and remains water proof for many years after the roofing material  18  is installed to form the membrane  16 . The fine granular material  34  on facial portion  36  does not prevent the adhesive  24  from interbonding. Further, the thickness of adhesive layer  24  is sufficient to bridge the thickness of the strips  18  at their side edge  20 ′ (i.e., at the selvage edge portion  34 ′) so that the creation of void spaces adjacent to this side edge is avoided. Such void spaces could possibly trap moisture which would expand when heated by the sun and cause the roofing membrane  16  to bubble or blister on a hot day. However, the present inventive roofing material prevents such bubbling.  
      Further, because of the combination of a considerable width of the interbonding area (adhesive  24  to granular material  34  and underlying base sheet  20  and matrix  22  over lateral dimension  28 —which is preferably about 20½ inches wide). And this width combined with the viscid (or hot re-flow or re-softening) characteristic of the raw asphaltic adhesive  24 , along with the secure attachment of the membrane  16  to the roof deck by fasteners  38 . And combined with the additional sealing attachment effected as well by the adhesive  24  in bonding stripe area  24 ′, it is to be understood that differential thermal expansions and contractions between the roof structure  10  and the membrane  16  are well resisted or tolerated, and do not lead to separations of the strips  18  and leaking of the roofing membrane  16 .  
      Those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. Particularly, the extent of overlap of successive strips of a roll roofing material according to this invention need not be the one-half overlap described according to the most preferred embodiment. That is, an overlap of successive strips of one-third or less of the width dimension of each strip may be found to be acceptable and to make a successful roof structure in certain locations, and according to the desired service and life for a particular roof. However, in that case, the double-coverage feature of the most preferred exemplary embodiment would not be obtained. To recap that most preferred embodiment once again, the width dimension is 39½ inches, and the portions  18   a  and  18   b  respectively have widths of 20½ inches and 19 inches. The width of the layer  30  of coarse granular material is somewhat more than 19 inches, and the width of layer  34  (including selvage edge portion  34 ′) makes up the remainder of the upper face of the roofing material strip  18 . On the underside of the roofing material strip  18 , the width  28  of adhesive layer  24  is preferably 20½ inches, and the width of fine granular material layer  34 ″ is 19 inches. Thus, the stripe area  24 ′ of adhesive  24  presented to the roof decking  14  and sealingly interbonding with this roof decking is at least one-half (½) inch, nominally is about one inch, and may alternatively be about 1½ inches, in view of the tolerances obtainable in the manufacture of roofing materials. Because the foregoing description of the present invention discloses only a particularly preferred exemplary embodiment of the invention, it is to be understood that other variations are recognized as being within the scope of the present invention. Accordingly, the present invention is not limited to the particular embodiment which has been described in detail herein. Rather, reference should be made to the appended claims to define the scope and content of the present invention.