You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD 
       [0001]    The present disclosure relates to a roof tile attachment system and method that include the use of polymer adhesives and mechanical fasteners. 
       BACKGROUND 
       [0002]    Roof tiles are widely used as roof coverings on pitched roof decks in various parts of the world. Roof tiles are extremely durable and provide significant aesthetic and decorative effects to the structures to which they are applied. Roof tiles as described herein may be made of ceramic materials and also brick, stone, concrete, clay, or plastic, wood, metal, rubber or bituminous materials. 
         [0003]    Roof tiles have been installed using mortar or similar binders between the roof tile and a roof substrate, such as roofing felt. Using mortar is a slow procedure and labor intensive as the mortar must first be prepared, typically at ground level in buckets which must then be raised to the roof, and then the mortar is applied to the roof substrate. The mortar adds unnecessary weight to the roof. Occasionally, roof tiles are damaged during installation by dropped buckets of mortar. The set-up time of the mortar increases the time required to form the bond between the roof tile and the roof substrate. The installed roof tiles should not be moved until the mortar has set-up as movement of the roof tile affects the bond. Furthermore, the strength of the completed bond between the roof tile and the roof substrate is not extremely satisfactory. Typically, an approximate 22.7 kilogram (60 pound) load applied transversely to the roof tile will break the mortar bond between the roof tile and the roof substrate. During high wind loading conditions, such as that experienced during a hurricane or a tornado, the roof tiles frequently release from the roof structure. 
         [0004]    In very price sensitive housing construction markets in which roof tiles are used, the conventional method of attachment of the tiles to the roof substructure is with mechanical fasteners, typically nails. The mechanical fasteners are applied at the head of each tile and the tiles are installed in an overlapping manner to facilitate covering the mechanical fasteners. 
         [0005]    This method of attachment is economical although it has shortcomings. For example, during a wind event this method of attachment allows the “tail” or leading edge of the roof tile to lift and/or chatter causing damage in the mechanical fastener area. If severe enough and/or over time, the attachment fails and the tiles become airborne. 
         [0006]    It is known in the art that a polyurethane adhesive may be employed to attach roof tiles to a roof substrate and to each other. This adhesive method of attachment has primarily been used in areas prone to high wind events. It has been found that adhesive-attached tiles can withstand greater “lifting” forces than mechanical fastener-attached tiles, although the installation and material cost is greater. As a result of the higher cost, the house builders of very price sensitive housing have continued to install tiles with mechanical fasteners. 
         [0007]    It is desirable to have a roof tile attachment system and method for use in price sensitive housing construction that is able to withstand greater “lifting” forces than the conventional mechanical fastener method. It is also desirable to have a roof tile attachment system and method for upgrading an existing roof installation or repairing a roof installation to meet current code wind uplift standards. It is further desirable to have a tile attachment method that eliminates tile “chatter” during wind events. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is a roof tile attachment system and method. The roof tile attachment system and method can be used on new roof construction and on existing roofs. The roof tile attachment system and method is well-suited for use in price sensitive housing construction and is able to withstand greater “lifting” forces than the conventional mechanical fastener method of attaching roof tiles. The present invention is also suitable for upgrading an existing roof installation or repairing a roof installation to meet current code wind uplift standards. The present invention also eliminates tile “chatter” during wind events. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The objects, advantages, and features of the invention will become more apparent by reference to the drawings which are appended hereto and wherein like numerals indicate like parts and wherein an illustrated embodiment of the invention is shown, in which: 
           [0010]      FIG. 1  is a perspective view of the upper side of a typical roof tile that can be used with the roof tile attachment system and method of the present invention; 
           [0011]      FIG. 2  is a perspective view of the lower side of the typical roof tile shown in  FIG. 1 ; 
           [0012]      FIG. 3  is a perspective view of a pitched roof deck having a roof substrate applied to the roof deck; 
           [0013]      FIG. 4  is a perspective view of a portion of a roof assembly showing the deck with batten strips and roof tiles being installed; 
           [0014]      FIG. 5  is a side elevation view of a portion of the roofing system with each upper row of roof tiles overlapping a lower row of roof tiles; 
           [0015]      FIG. 5A  is an enlarged portion of  FIG. 5 ; and 
           [0016]      FIG. 6  is a side elevation view of a portion of an existing roofing system being repaired and/or upgraded. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The roof tile attachment system and method, generally designated as  100 , will now be described in greater detail with specific reference to the drawings. A typical roof tile, designated generally as  10 , is shown in perspective view in  FIGS. 1 and 2 .  FIG. 1  shows the upper side and  FIG. 2  shows the lower side of the roof tile  10 . The roof tile  10  shown in  FIGS. 1 and 2  was commercially available from Monier-Raymond Company (now MonierLifetile LLC). It is to be understood that the present invention is not limited to the roof tile design shown in the drawings, but is equally applicable to a variety of other shapes and types of roof tiles well known to those skilled in the art. For example, flat roof tiles and reverse curve roof tiles, in addition to other styles, can be used with the system and method of the present invention. Typically, the roof tiles  10  are made from cementitious or clay materials. It is also to be understood that the system and method of the present invention is not limited to clay or cementitious roof tiles  10  but is also applicable to roof tiles  10  made from other materials including, but not limited to, brick, stone, ferrous, plastic, wood, rubber, or bituminous materials. 
         [0018]    As shown in  FIGS. 1 and 2 , the roof tile  10  typically includes an interlocking connection at the first and second longitudinal edges  12  and  14 , respectively, of the roof tile  10 , to additionally form a water lock. The second edge  14  of the first roof tile  10  mates with the first edge  12  of an adjoining second roof tile  10  as shown in  FIG. 4 . This type of interlocking connection for roof tiles  10  is well known in the art. The roof tile  10  as shown in  FIGS. 1 and 2  includes a head portion  13  and a nose portion  15 . Preferably, the head portion  13  includes one or more head lugs  13   a  on the lower side of the roof tile  10  for reasons which will be explained below. The lower side of the nose portion  15  may include one or more nose lugs  15   a  on the lower side of the roof tile  10 . Typically, upon installation of the roof tiles  10 , the nose lugs  15   a  overlap a lower installed roof tile to form a weather barrier to help prevent free passage of wind, rain, etc. therebetween. Typically, the roof tile  10  includes at least one tile fastener hole  10   a  at the head portion  13  as shown in  FIGS. 1 and 2 . 
         [0019]    The roof tiles  10  are typically installed on a pitched roof deck, designated generally as  50 , as shown in  FIG. 3 . The roof deck  50  includes decking material  52 , typically plywood, nailed or glued to roof framing members  54 . The roof framing members  54  are typically truss rafters spaced on 61-centimeter or 41 centimeter (24-inch or 16-inch) centers. The decking material  52  is typically in 1.2 meter by 2.4 meter (4-foot by 8-foot) panels or sheets. The panels of decking material  52  are positioned end to end and side to side. It is also to be understood that the roof deck  50  may alternatively be constructed of concrete, metal or other material. 
         [0020]    Preferably, a roofing substrate  20  forming a waterproof coating is applied and preferably bonded to the upper surface of the decking material  52 . The roofing substrate  20  can be a roofing felt, commonly used in the roofing industry. The roofing felt is a roll goods membrane ( FIG. 3 ) that is fastened to the decking material  52 , typically with mechanical fasteners such as nails and/or bonded to the decking material with, for example, tar or bitumen. The roofing felt is typically applied along the length of the roof with an adjacent row of the felt overlapping the edge of the prior row of felt. The roofing substrate  20  protects against rain and moisture coming into contact with and passing through the pitched roof deck  50 . It is to be understood that in some circumstances the roofing substrate  20  may not be desired or necessary for the present invention. 
         [0021]    Referring to  FIG. 4 , typically, in high wind areas, tiles are installed direct to the deck without the use of batten strips. When batten strips are utilized, the batten strips  18  are secured, preferably by nails, to the decking material  52 . Batten strips  18  can be wooden, metal, or other construction materials such as are known to persons of skill in the art. Typically, the batten strips  18  are affixed to the roof deck  50  perpendicularly to the truss rafters  54 . Preferably, the batten strips  18  have a uniform width of between five to fifteen centimeters (two to six inches) and a thickness of approximately 2.5 centimeters (one inch). The spacing between the batten strips  18  is dependent on the dimensions of the selected roof tile  10 . It is to be understood that in some circumstances the batten strips  18  may not be desired or necessary for the present invention. 
         [0022]    Referring to  FIG. 4 , the roof tiles  10  are placed in rows beginning along the lower edge of the roof. The lower row of roof tiles  10  are preferably placed onto the lower batten strip  18  so that the head lug  13   a  of the roof tile  10  contacts the batten strip  18  (see  FIG. 5 ) and the roof tiles  10  are preferably interlocked with the adjacent roof tiles as shown in  FIG. 4 . The head portion  13  of the roof tiles  10  are preferably secured by inserting fasteners  16 , for example nails or screws, through the tile fastener holes  10   a  into the batten strips  18  and/or decking material  52 . It is to be understood that each individual roof tile  10  may be secured to the roof deck  50  with a fastener  16 ; however, this may not be required due to the interlocking and overlapping nature of the installed roof tiles  10  as further described below. 
         [0023]    According to one embodiment of the present invention, during a new roof installation, a polymer adhesive  30  is preferably applied on a portion of the upper surface of the head portion  13  of the first (lower) row of roof tiles  10  on the roof deck  50 . Referring to  FIG. 4 , the polymer adhesive  30  is preferably applied as a bead or stream at a location where the second row of installed roof tiles  10  will overlap the first row, preferably located approximately at the position of the tile fastener holes  10   a . It is to be understood that the bead can be continuous or interrupted across the tile width. It is also to be understood that the adhesive need not be applied to every roof tile  10  in a row, especially when the roof tiles  10  include interlocking edges  12  and  14 . 
         [0024]    With reference to  FIGS. 4 and 5 , the roof tiles  10  in the second row are placed with the head lug  13   a  contacting the respective second batten strip  18  and the lower surface of the nose portion  15  contacting the polymer adhesive  30  during the reactivity period of the polymer adhesive  30 . Fasteners  16  are preferably installed to secure the head portion  13  of the second row of roof tiles  10  to the roof deck  50  and the polymer adhesive  30  adheres the overlapping portions of the roof tiles  10  to each other. As before, it is to be understood that each individual roof tile  10  may be secured with a fastener  16  to the roof deck  50  or alternatively, a portion of the roof tiles  10  in the row may be individually secured with a fastener  16 . The additional courses or rows of roof tiles  10  are similarly placed and secured onto the roof deck  50  as shown in  FIG. 5 . 
         [0025]    The present invention is also suitable for upgrading or repairing an existing tile roof system in which the roof tiles were originally installed using only mechanical fasteners. Upgrading may be necessary or desirable due to changing weather patterns, re-zoning and/or revisions to code wind uplift standards. In some instances, an insurer may require the upgrade or repair of the existing tile roof system. In other instances, a repair may be desired to eliminate roof tile “chattering” during wind events. Typically, mechanically fastened roof tiles become loose during the life of the roof system. Chattering is caused by tile movement resulting from wind lifting the nose portion  15  of an upper row of tiles from the head portion  13  of the lower row. The tiles “chatter” as they lift and fall back into contact with each other. Over a period of time, the chattering tiles may fracture at the point of attachment or further loosen the mechanical fastening of the tiles; thus, reducing the integrity of the roof system. 
         [0026]    In this embodiment of the present invention, it is to be understood that the entire roof can be upgraded or a portion of the roof.  FIG. 6  illustrates an existing roofing system being repaired and/or upgraded. Preferably, the nose portion  15  of the tile is lifted, preferably manually, a small distance to allow an amount of polymer adhesive  30  to be applied beneath the raised tile  10  in the overlapping region of the adjacent rows of roof tiles. The nose portion  15  of the tile is then lowered back onto the head portion  13  of the lower tile and the polymer adhesive  30  adheres or bonds the two together, thus, eliminating relative movement and chatter between the two. It is to be understood that in lifting the nose portion  15  of the tile, it may result in concurrently lifting the nose portion  15  of a plurality of tiles in the same row and the polymer adhesive  30  may be applied in a continuous bead or intermittently as desired. 
         [0027]    In this embodiment of the present invention, the nose portion  15  of the roof tile  10  is lifted, preferably in the range of 6.4 millimeters (mm) (0.25 inch) to 25 mm (1.0 inch), more preferably in the range for 6.4 mm (0.25 inch) to 19 mm (0.75 inch), and most preferably approximately 12.7 mm (0.50 inch), and the adhesive  30  is applied within the gap between the overlapping roof tiles  10 . In a preferred embodiment, the adhesive  30  is applied through a small flexible tubing  32 , preferably having a diameter of 6.4 mm (0.25 inch), inserted within the gap between the overlapping, lifted roof tile  10  and the underlying tile  10 . The tiles  10  are brought back into contact with each other during the reactivity period of the adhesive. 
         [0028]    It is to be understood that some portion or all of the overlapping tiles may be adhered depending on the circumstances and the desired result. 
         [0029]    If desired, the polymer adhesive  30  can be applied in a continuous line across the width of the roof tile  10  to form a continuous barrier to the ingress of water between the overlapping rows of roof tiles. Alternatively, a nominal amount of the polymer adhesive  30  can be applied to the upper surface of the lower roof tile  10  or to the lower surface of the upper roof tile prior to installation of the upper roof tile  10 . The amount of polymer adhesive  30  applied being dependent on various design criteria, including but not limited to, adhesive properties of the polymer adhesive  30 , code wind uplift standards and roof tile shape. 
         [0030]    According to one embodiment of the present invention, the polymer adhesive  30  may be a foamable or a non-foamable polymer adhesive. Preferably, the polymer adhesive  30  is a plural component, liquid polyurethane foam. The significant advantage of the plural component polyurethane foam is being able to walk on the installed roof tiles  10  shortly after the roof tiles  10  have been installed without affecting the bond between the roof tiles  10 . The reactivity period or rise time of the plural component liquid polyurethane foam  30  of the present invention is preferably about one-half to about ten minutes and most preferably about one and one-half to about four minutes. It is important that the roof tile  10  be properly placed during the reactivity period to achieve the required bonding of the upper roof tile  10  to the lower roof tile  10 . During the reactivity period, the liquid polyurethane foam  30  is an expanding foam, which will fill gaps and imperfections. The resulting foam provides excellent bonding between the roof tiles  10  due to the adhesive properties of the urethane. It has been found that a reactivity period of less than about one-half minute makes it difficult to timely install the roof tiles  10  during the reactivity period. 
         [0031]    The foamable liquid polyurethane  30  is preferably a froth foam. Froth foam chemistry is well known in the art of urethane foams. The froth foam may be formed by using blowing agents such as hydrogenated chlorofluorocarbon R22 (HCFC-R22), hydrogenated fluorocarbon 134A (HFC-134A), or chlorofluorocarbon R12 (CFC-R12). Preferably, the froth foam  30  is formed by using the hydrogenated blowing agents HCFC-R22 or HFC-134A, and not CFC-R12 due to CFC-R12&#39;s reported deleterious effects to the earth&#39;s ozone layer. 
         [0032]    Preferably, the froth foam  30  has a consistency similar to a foamy shaving cream. The froth foam is preferable over other types of foams because it can be neatly and accurately dispensed without blowing or overspraying onto other areas of the roof deck  50  or adjacently installed roof tiles  10 . The preferred liquid polyurethane  30  with its shaving cream consistency does not run when placed onto a steeply pitched roof, but remains where it is installed on the roof tile  10 . This ensures that the adhesive bond will be formed at the appropriate location of the roof tiles  10 . Additionally, the froth foam  30  begins expanding immediately upon application and results in a firm bond between the overlapping portions of the roof tiles  10 . 
         [0033]    The liquid polyurethane  30  preferably has a density of about 0.016 to about 0.13 grams per cubic centimeter (about one to about eight pounds per cubic foot). It may be desirable to minimize the density of the liquid polyurethane  30  to minimize the weight on the roof while still providing an excellent bonding of the roof tiles  10  to each other. It has been found to be most preferable to have a foam density of about 0.024 to about 0.032 grams per cubic centimeter (about one and one-half to about two pounds per cubic foot). The application rate of the liquid polyurethane  30  is preferably about 0.45 to about 2.7 kilograms per minute (about one to about six pounds per minute) and most preferably about 0.9 to about 1.4 kilograms per minute (about two to about three pounds per minute). 
         [0034]    The adhesive  30  is only required between a portion of the opposing overlapping tile areas to obtain the benefit. It is not intended or necessary for the adhesive to “spill over” and adhere the tiles to the roof substrate. 
         [0035]    A test was conducted according to Southern Building Code Congress International (“SBCCI”) SSTD 11-99, Determining Wind Resistance of Clay and Concrete Tile to determine the effectiveness of the present invention. The test was run using high profile tiles, each tile installed with two screws over 2.5 centimeter×5 centimeter (1 inch×2 inch) batten strip and a 2.5 centimeter×15 centimeter (1 inch×6 inch) bead of polymer adhesive at the tile overlap. The polymer adhesive was allowed to cure. This was compared to a similarly installed tile having no polymer adhesive at the tile overlap. An eyebolt was attached to the center of the roof tile by a small hole drilled through the roof tile. An upward load was hydraulically applied transversely to the roof tile until there was a failure of the roof tile attachment. The tile with polymer adhesive achieved a resistance value of 83 Newton-meters (61 ft-lbs). whereas the tile without polymer adhesive had a resistance value of 40.4 Newton-meters (29.8 ft-lbs). The addition of the polymer adhesive resulted in a 104% increase in resistance. 
         [0036]    It should be understood that the invention consists of a method of bonding roof tiles utilizing urethane foam and the invention should not be unduly limited to the foregoing set forth for illustrative purposes. Various modifications and alterations of the invention will be apparent to those skilled in the art without departing from the true scope of the invention.

Summary:
Methods of attaching roof tiles are disclosed. The methods may be used to attach a new roof or to upgrade an existing roof. The methods include the use of mechanical fasteners and polymer adhesives, including foamable adhesives.