Patent application title: ROOF TILE ATTACHMENT METHOD
Robert L. Ferrante (Davie, FL, US)
David H. Faulkner (Bradenton, FL, US)
E. Richard Huber (Spring, TX, US)
Pat L. Murray (Spring, TX, US)
3M Innovative Properties Company
IPC8 Class: AE04D134FI
Class name: Processes barrier construction cover
Publication date: 2011-06-23
Patent application number: 20110146199
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
7. A method for in situ installation of a plurality of rows of individual roof tiles to a roof substrate on a pitched roof, the method comprising the steps of: attaching a first row of individual roof tiles to the roof substrate; applying a polymer adhesive on an upper surface of a head portion of a first row roof tile, wherein the polymer adhesive comprises a foamable liquid polyurethane, wherein the foamable liquid polyurethane is a froth foam; placing a second row roof tile in overlapping contact with the first row roof tile such that the overlapping portion of the second row roof tile contacts the applied polymer adhesive on the first row roof tile during the reactivity period of the polymer adhesive; and attaching a head portion of the second row roof tile to the roof substrate with a mechanical fastener.
8. The method of claim 7, wherein the froth foam comprises a blowing agent selected from the group consisting of hydrogenated chlorofluorocarbon R22, hydrogenated fluorocarbon 134A, and chlorofluorocarbon R12.
9. The method of claim 7, wherein the adhesive has a density of 0.016 to 0.13 grams per cubic centimeter.
10. A method of upgrading a tile roof comprising a first rows of tiles, and a second row of roof tiles, wherein each tile comprises a nose portion and a head portion, wherein the head portion of a first tile in the second row of tiles is attached to roof with a mechanical fastener, and the nose portion of the first tile overlaps the head portion of a second tile in the first row of tiles, the method comprising the steps of: lifting a nose portion the first tile; applying a polymer adhesive in an overlapping region between the first tile and the second tile, wherein the polymer adhesive comprises a foamable liquid polyurethane, wherein the foamable liquid polyurethane is a froth foam; lowering the nose portion of the first tile back onto the head portion of the second tile; and adhering the first tile to the second tile with the polymer adhesive.
11. The method of claim 10, wherein the froth foam comprises a blowing agent selected from the group consisting of hydrogenated chlorofluorocarbon R22, hydrogenated fluorocarbon 134A, and chlorofluorocarbon R12.
12. The method of claim 10, wherein the adhesive has a density of 0.016 to 0.13 grams per cubic centimeter.
 The present disclosure relates to a roof tile attachment system and method that include the use of polymer adhesives and mechanical fasteners.
 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.
 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.
 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.
 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.
 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.
 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
 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
 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:
 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;
 FIG. 2 is a perspective view of the lower side of the typical roof tile shown in FIG. 1;
 FIG. 3 is a perspective view of a pitched roof deck having a roof substrate applied to the roof deck;
 FIG. 4 is a perspective view of a portion of a roof assembly showing the deck with batten strips and roof tiles being installed;
 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;
 FIG. 5A is an enlarged portion of FIG. 5; and
 FIG. 6 is a side elevation view of a portion of an existing roofing system being repaired and/or upgraded.
 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.
 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 13a 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 15a on the lower side of the roof tile 10. Typically, upon installation of the roof tiles 10, the nose lugs 15a 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 10a at the head portion 13 as shown in FIGS. 1 and 2.
 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.
 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.
 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.
 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 13a 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 10a 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.
 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 10a. 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.
 With reference to FIGS. 4 and 5, the roof tiles 10 in the second row are placed with the head lug 13a 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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's reported deleterious effects to the earth's ozone layer.
 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.
 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).
 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.
 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.
 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.
Patent applications by David H. Faulkner, Bradenton, FL US
Patent applications by Pat L. Murray, Spring, TX US
Patent applications by Robert L. Ferrante, Davie, FL US
Patent applications by 3M Innovative Properties Company
Patent applications in class Cover
Patent applications in all subclasses Cover