Abstract:
A one-piece molded plastic flashing precisely fits outside corners of chimneys, dormers and roof offsets on pitched roofs ranging from 3/12 to 12/12 consisting of a horizontal roof plane, and a pair of vertical planes, angled with respect to one another to match with the pitch of the roof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     NONE  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Research and development of this invention and Application have not been federally sponsored, and no rights are given under any Federal program.  
       REFERENCE TO A MICROFICHE APPENDIX  
       [0003]     NOT APPLICABLE  
       BACKGROUND OF THE INVENTION  
       [0004]     1. Field of the Invention  
         [0005]     This invention relates to the prevention of leakage at the corner intersection of roof penetrations—such as at those locations where chimneys exit through the roof and where dormers meet the slanted plane of the roof. More particularly, the invention represents an improvement over the corner flashing shown in U.S. Pat. No. 5,077,943 to McGady, issued Jan. 7, 1992.  
         [0006]     2. Description of the Related Art  
         [0007]     As will be appreciated, at these intersections, a roofing contractor conventionally trims a piece of flashing into a corner so that a waterproof envelope is provided by the shingles of the laid roof. As will also be appreciated, to do it properly in the field takes time and skill—neither of which the typical installer possesses, usually being only paid piece-work, “by the square”. This oftentimes results in a flashing installation which is sloppily done. In fact, experience has shown that almost 90% of those roof leaks that develop occur not at the body of the shingles, but at these corners, when the flashing fails.  
         [0008]     McGady recognizes this problem in his above identified patent, and attempts to deal with it by having a corner flashing member adapted for adjustment in the field. This is done utilizing a “tuck”, said to cause the upstanding sides of the flashing member to tightly embrace the chimney or dormer above the roof line. Besides continuing to require a high degree of skill to overlap the sides in forming the tuck at a vertical corner, however, the suggestion there put forth provides only minimum protection at the point where the vertical planes and horizontal plane of the flashing intersect at the base. Analysis has shown that this is due to its triangular flap which contains no overlap whatsoever at the intersection. Since the McGady flashing unit is intended for fitting all roof pitches, extensive modification must be performed in the field—which the everyday worker normally does not possess. Even so, the intersecting point of the two vertical sections and the horizontal section continues as a “weak point” for possible water infiltration caused by the resulting seam at the juncture.  
       SUMMARY OF THE INVENTION  
       [0009]     As will become clear from the following description, the flashing of the present invention consists of one-piece molded plastic corner which precisely fits the outside corner of chimneys, dormers and roof offsets on pitched roofs ranging from 3/12 to 12/12 pitches. Because each flashing is molded to fit each particular roof pitch, an easy and water-tight installation is achieved, without any field modification or cutting—merely by selecting the appropriate one to match with the roof pitch. Including a horizontal plane, a front or rear vertical plane, and a side vertical plane, the angles between the planes change from roof-to-roof, as the roof pitch changes. With each plane being a minimum 5″×7″ in size, the overlapping of laid down shingles allows for an installation without gaps or seams which sits tightly on the roof. Requiring no field modification, the one-piece molded plastic corner flashing will be appreciated to meet all specifications of the National Roofing Contractors Association (NRCA). 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     These and other features of the present invention will be more clearly understood from a consideration of the following description, taken in connection with the accompanying drawings, in which:  
         [0011]      FIGS. 1-4  are perspective views helpful in an understanding of the McGady flashing installation, and how its “tucking” and “seaming” construction invites water leakage; and  
         [0012]      FIGS. 5   a - 5   e  are views helpful in an understanding of a one-piece molded plastic corner according to the present invention employed as a lower flashing for an installation;  
         [0013]      FIGS. 6   a - 6   e  are views helpful in an understanding of a one-piece molded plastic corner according to the invention employed as an upper flashing for an installation; and  
         [0014]      FIGS. 7 and 8  are perspective views from opposite positions of a chimney set-up helpful in understanding the installation of the one-piece molded plastic corner. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     In the prior art drawings of  FIGS. 1-4 , the McGady corner flashing  10  includes a base  11  with an integral upstanding corner  12  having a pair of sides  13  and  14  in right-angled relation. With the sides integrally joined at a corner  15 , the upstanding corner  12  is substantially in right angle relationship with the base  11 .  
         [0016]     As U.S. Pat. No. 5,077,943 describes, the base  11  is rectangular with parallel top and bottom edges, and parallel opposite sides intersecting at corners. The upper left-hand corner of the base  11  is notched out to provide a rectangular recess with edges which intersect at a corner spaced from the top, bottom and side edges of the base. The upstanding corner  12  forms a continuous junction with the base member that is coextensive with the recess, and the base  11  is “L”-shaped with leg portions radiating from sides  13  and  14  of the upstanding corner  12 . Composed of a bendable plastic material, the flashing  10  is selected of a thickness so as to be sufficiently flexible in conforming with the corner to be sealed, regardless of the inclination of the base  11  when placed on a roof deck.  
         [0017]     As shown in  FIG. 3 , the flashing  10  is applied to the lower corners of a chimney  16  at an inclined roof deck  17 , with the base  11  of the flashing  10  mounted on the deck to extend laterally and below the chimney. The upstanding sides  13  and  14  of the corner flashing  10  overlie or underlie flashing strips  18  and  19  at the corner, in allowing roof shingles  20  to be applied in conventional overlapping relation to cover the deck and extend up the roof line to intersect with the chimney.  
         [0018]     As respects the matter of “tucking”, McGady continues to incline the roof deck mounted base  11  of the right-hand bottom corner flashing  10 , as well as the side  13  of the upstanding corner  12  in allowing the side  14  to tightly abut the flashing  18 . To draw the side  13  into tight abutment with the flashing  19 , the corner  15  between the sides  13  and  14  is bent over the side  14  in forming this tuck,  21 . Such tuck overlaps the side  14  and is secured in position by a fastener, such as a nail  22  driven through the top end of the tuck into the chimney. The left-hand bottom corner flashing, in similar manner, has the side  14  of the corner tilted away from the flashing  19 , so as to form the tuck and drawing it against the flashing  19 .  
         [0019]     As McGady describes, the tuck  21  overlaps the side  14  to be nailed to the side wall of the chimney  16 . Alternately, the tuck is said to be overlappable of the side wall  13  so as to be securable to the front or bottom end wall of the chimney  16 . With this one flashing unit said to be fittable to all roof pitches, an actual installation requires field modification to fit the particular roof pitch encountered. Such modification must be performed by the installer—who, as was previously mentioned, is more trained in laying shingles down in courses, then he/she is in bending and trimming planes of flashing.  
         [0020]     More importantly, however, McGady&#39;s corner flashing in this respect offers minimal protection at the point where the vertical planes and horizontal plane of the flashing intersect at the base, and due to the triangular flap that contains no overlap at this intersection. In essence, a “hole”  100  is created at the intersection of the base  11  and the sides  13  and  14 , sufficient to drip water through the roof when caught at the fold  101  between the tuck  21  and the side  14 . Such fold catches rain, sleet and snow, for example, and directs it down along the inside of the tuck through the hole  100 , its weakest point. Because there is no overlap, not only is there a leakage, but a failure to meet National Roofing Contractors Association&#39;s installation specifications. (The same will also be understood as to any rain, sleet or snow entering from behind the fold.) These problems are eliminated, however, in accordance with the teachings of the present invention. In particular,  FIG. 5   a  is a perspective view of a one-piece molded plastic corner according to the invention, with  FIGS. 5   b - 5   e  respectively illustrating views taken in the direction of the arrows A, B, C and D in  FIG. 5   a.  As shown, the corner is molded of three planes—a horizontal roof plane  30 , a front vertical plane  31  and a side vertical plane  32  (which, if rotated counter-clockwise 90° places the vertical wall  31  as a side wall and the vertical wall  32  as a front wall, see  FIGS. 7 and 8 ). Molded of 1/16″ to ⅛″ thick plastic, and with each plane being a minimum of 5″×7″ in size, an easy and water-tight installation can be achieved by installing the flashing of a size to fit each particular roof pitch. Thus, for a one-piece molded plastic corner with a 12″×12″ base  30  and vertical planes 7″ wide and 6″ high, a corner flashing for a 5:12 pitch roof would have the following angles:  
                                                       Angle 40    67°           Angle 41   113°           Angle 42    23°           Angle 43    90°.                      
 
         [0021]     For a 6:12 pitch roof, on the other hand, these angles would change thusly:  
                                                       Angle 40    63°           Angle 41   117°           Angle 42    27°           Angle 43    90°.                      
 
         [0022]     To construct this one-piece molded plastic corner for 7:12, 8:12, 9:12, 10:12, 11:12 and 12:12 pitch roofs, all that would be required would be to continually decrease the angle  40  and increase the angles  41  and  42  in approximately 3°-4° increments each. Correspondingly, to construct the corner flashing for 4:12 and 3:12 pitch roofs, the angle  40  and the angles  41  and  42  would be successively increased and decreased, respectively in 3°-4° increments. Beginning with the most common roof of 5:12 pitch, the one-piece molded plastic corner flashing of the invention can be selected in this manner, just by custom fitting the angle selections as indicated above. The arrows  105  in  FIG. 5   a  signify a “roof pitch down” position, for this lower corner flashing unit  72  of the invention.  
         [0023]     As will be readily appreciated by those skilled in the art, comparable selections can be made for custom fitting the corner flashings as upper flashings ( FIGS. 6   a - 6   e ), just as the corner flashing of  FIGS. 5   a - 5   e  are usable as lower flashings. With a base  50 , a rear vertical plane  51  and a side vertical plane  52 , the same utilization would follow for the upper flashing unit rotated clockwise 90° as in  FIGS. 7 and 8 . The arrows  106  in  FIG. 6   a  signify the “roof pitch down” position for this upper corner flashing unit  73 .  
         [0024]     When so selected, an appearance of the roof  70 , a chimney  71 , the two lower corner flashing units  72  and the two upper corner flashing units  73  is as shown in the perspective views of  FIGS. 7 and 8 . With the same 12″×12″ dimension for the horizontal roof planes, and with the same 7″ wide and 6″ high dimensions for the vertical planes, the corner flashing of the invention can be custom fitted to any roof pitch just by selecting the proper angulations  40 ,  41 ,  42  and  43 . Being pre-formed in one-piece construction, the corner flashing units of the invention will be seen to sit tight on the roof at all times, simply by using the corner flashing unit that conforms to the roof pitch. Because these units require no field modification, possess no gaps, no seams or tucks, the leakage which continues to characterize the McGady construction is obviated, and no problem with NRCA specifications is presented. Once selected to match the specific roof pitch, the corner flashing unit of the invention requires no trimming whatsoever, and no bending or sealant to make them water-tight. All that is required is a placement about the chimney, to be then overlain with the shingles to complete the roof installation. No particular skill is required, other than to put the corner flashing in place.  
         [0025]     While there have been described what are considered to be preferred embodiments of the present invention, it will be readily appreciated by those skilled in the art that modifications can be made without departing from the scope of the teachings herein. Thus, although 4° angular increments are specified in fitting the corner flashing unit of the invention to different pitched roofs, it will be understood that the exact incremental angles are selected to substantially match exactly to the different pitches of the roof that is installed. In particular, in accordance with the invention, a water-tight flashing follows so long as angles 
 
 40 + 42 = 43 ; 
 
 42 + 43 = 41 ; 
 
and 
 
 angle  43  equals 90°. As will be apparent, angle  42  is that angle of the horizontal plane along the downwardly pitched roof, while angles  40  and  41  are that of the leading and trailing edges of the vertical planes intersecting the horizontal plane. The 90° angle  43  will be seen to be that between the two vertical planes. For at least such reason, therefore, resort should be had to the claims appended hereto for a true understanding of the invention.