Patent Abstract:
A roof curb is shipped in a disassembled state to an installer who assembles, sizes, locates and configures the curb to accommodate slope on any roof without welding or metal cutting. The curb includes an aluminum walls, each having a channel for receiving the bottom edge of a board, which may be taper cut according to the pitch of the roof to provide a level surface for supporting an appliance. Methods of making and installing the roof curb also are disclosed.

Full Description:
This application is a continuation of copending application Ser. No. 10/944,714, filed Sep. 21, 2004. 

   BACKGROUND OF THE INVENTION 
   Metal buildings having metal roofing have become popular for commercial, industrial and warehousing uses. These buildings often require roof openings for skylights, fans, air conditioning units and the like. The installation of such equipment requires a roof curb for support. 
   Traditionally, roof curbs have been designed specifically and custom made to provide a relatively horizontal mounting structure for a particular rooftop appliance given the shape and pitch of a particular roof. Designing and building these traditional roof curbs, often formed from a singular piece of metal to uniquely accommodate a particular roof pitch, has been a laborious and time consuming task for roof curb manufacturers and rooftop appliance installers. Further, because these roof curbs are installed in a metal roof system, the actual opening may vary with respect to the roof corrugations, seams or ribs, which may be ascertainable only shortly before installation. This untimely design-and-build practice delays appliance installation. 
   Manufacturers developed standardized roof curbs to help limit installation delays. See, for example, U.S. Pat. No. 4,559,753, issued Dec. 24, 1985, to Ralph H. Brueske, for Method of Installing a Prefabricated Curb Unit to a Standing Seam Roof, which describes a method of installing a metal roof curb in which the rims of the curbs are pre-welded to a roof panel, and the curb containing-panel is attached to a large opening cut into the roof. However, this method requires cutting a hole in the roof that is larger than the opening for the equipment that may be susceptible to leakage. 
   Prefabricated roof curbs tend to be quite large, thus have been difficult to ship in a cost effective and timely fashion, let alone by traditional rapid delivery methods. Consequently, roof curb manufacturers have had to ship their products by truck, which is slower and more expensive. 
   Traditional roof curbs include four coated steel curb walls positioned to define an open rectangular frame joined by factory welding at the corners. Because welding burns off the corrosion resistant coating of the steel, the manufacturer or installer must provide an additional coating of rust inhibitor paint to keep the roof curb from rusting when installed on the roof. Routine rust inhibitor paint coatings are required to protect the roof curb throughout the life of the product. Mechanical attachment, such as with threaded fasteners, may secure the corners without welding. However, on-site sizing and drilling of traditional roof curb panels creates exposure to corrosive weathering. 
   What is needed is a standardized, corrosion-resistant roof curb that can be shipped in a disassembled state, which an installer may assemble, size, locate and configure to provide an appropriate roof slope on any roof without welding. 
   SUMMARY OF THE INVENTION 
   The invention is a standardized, corrosion-resistant roof curb that can be shipped in a disassembled state, which an installer may assemble, size, locate and configure to provide an appropriate roof slope on any roof without welding. 
   The invention provides improved elements and arrangements thereof, for the purposes described, which are inexpensive, dependable and effective in accomplishing intended purposes of the invention. 
   Other features and advantages of the invention will become apparent from the following description of the preferred embodiments which refers to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in detail below with reference to the following figures, throughout which similar reference characters denote corresponding features consistently, wherein: 
       FIG. 1  is an environmental perspective view of an embodiment constructed according to principles of the invention; 
       FIG. 2  is an exploded environmental perspective view of the embodiment of  FIG. 1 ; 
       FIG. 3  is an environmental perspective view of a portion of the embodiment of  FIG. 1 ; 
       FIG. 4  is a cross-sectional detail view drawn along line IV-IV in  FIG. 2 ; 
       FIG. 5  is an environmental perspective view of another embodiment constructed according to principles of the invention; 
       FIG. 6  is an exploded environmental perspective view of the embodiment of  FIG. 5 ; 
       FIG. 7  is a flow chart of a method of making the embodiment of  FIG. 1 ; 
       FIG. 8  is a schematic representation of the embodiment of  FIG. 7 ; 
       FIG. 9  is a flow chart of a method of making the embodiment of  FIG. 5 ; 
       FIG. 10  is a schematic representation of the embodiment of  FIG. 9 ; 
       FIG. 11  is a flow chart of a method of installing the embodiment of  FIG. 1 ; 
       FIG. 12  is a schematic representation of the embodiment of  FIG. 11 ; 
       FIG. 13  is a flow chart of a method of installing the embodiment of  FIG. 5 ; and 
       FIGS. 14   a  and  14   b  are a schematic representation of the embodiment of  FIG. 13 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1-3 , an embodiment of a roof curb  100  configured according to the invention includes four walls  105  interconnected with four connection blocks  110 , defining a roof curb base  112 , for mounting on a roof R. Four composite boards  115  mount on walls  105  and support an appliance (not shown). 
   In practice, walls  105  are cut into standardized lengths that foster ready packaging in standard shipping containers along with other components described herein for conventional or overnight courier delivery. Aluminum extrusion stock permits on-site sizing of the standard pieces without local burning off of corrosion resistant coatings ordinarily required for steel stock. Using aluminum stock also eliminates routine rust inhibitor paint coatings that would be required to protect steel stock. 
   Referring also to  FIG. 4 , each wall  105  is constructed of extruded aluminum having a lower flange  120  and an upper channel  125 . Each flange  120  is inwardly-disposed to limit exposure of fasteners and other mounting mechanisms and sealing to the elements. Each flange  120  has chamfered ends  130  that promote flushness along the entire contacting surface of flange  120  with roof R. 
   Each channel  125  is configured to receive and retain a composite board  115 . Channels  125  are inwardly disposed so as to define, in conjunction with wall  105 , a generally uniform vertical wall  127  without ledges or partial enclosures that might find favor with unwanted insects and vermin. 
   Flange  120 , vertical wall  127  and channel  125  define a pocket  128  for receiving insulation, as described below. 
   Side walls  105   a  have an edge  107   a  that provides a continuous, water-tight seal with roof R. Top and bottom walls  105   b  have notches  109  for alignment with and accommodation of seams or ribs F extending from roof R, thus defining an edge  107   b  that also provides a continuous, water-tight seal with roof R. 
   Referring to  FIG. 3 , each connection block  110  is constructed from aluminum and has pre-drilled through bores  114  at predetermined locations. In practice, a roof curb installer introduces holes at the ends of walls  105  according to a template, as shown in  FIG. 8 , that register with through bores  114 . 
   Preferably, composite boards  115  are Trex® boards, which are constructed from a combination of reclaimed wood and plastic. The plastic component shields the wood component from moisture and insect damage, reducing or eliminating rotting or splintering. The wood component protects the plastic component from ultraviolet radiation damage from ordinary sunlight, ensuring integrity longer than would be expected from products constructed from purely plastic or purely wood. 
   As shown in  FIG. 2 , unique to roof curb  100  is a top support channel  135 . Top support channel  135  is similar to bottom support channel  140 , which is common to roof curb  100  and roof curb  200 , as shown in  FIG. 6 . Top support channel  135  and bottom support channel  140  each have generally perpendicular ribs  136  and  141 , respectively. Ribs  136 ,  141  strengthen and enhance top support channel  135  and bottom support channel  140  load bearing capabilities. 
   Top support channel  135  has flanges  137  and bottom support channel  140  has flanges  143  that mount onto structural members S supporting roof R. When installed, top support channel  135  and bottom support channel  140  each support a wall  105   b , and support members S support the remaining walls  105   a . 
   Referring to  FIGS. 5 and 6 , another embodiment of a roof curb  200  configured according to the invention provides for diverting water that otherwise might accumulate along the upper, laterally-extending intersection of roof R and roof curb  200 . The water diverting feature of roof curb  200  is intended for larger installations that would be susceptible to collecting large amounts of water. Roof curb  200  includes four walls  205  interconnected with four connection blocks  210 , defining a roof curb base  212 , that mounts on roof R. Four composite boards  215  mount on walls  205  and support an appliance (not shown). Roof curb  200  is similar to roof curb  100 , except as described below. 
   As shown in  FIGS. 5 and 6 , unique to roof curb  200  are a diverter plate  235  and a diverter angle  245 . Diverter plate  235  covers a portion of roof R removed so that ribs F in roof R do not prevent flush mounting of diverter angle  245  on roof R against roof curb  200 . Like top support channel  135 , diverter plate  235  has strengthening ribs  236  for supporting wall  205  and diverter angle  245 . 
   Diverter angle  245  has upstanding flanges  247  that define an impervious dihedral angle  249 . Angle  249  is such that flanges  247  provide a flow path for water to pass around roof curb  200 , rather than collect against the upwardly disposed wall  205 , which, over time, might cause local corrosion or sealant failures. Diverter angle  245  is sealingly connected to diverter plate  235 . In operation, water flowing down roof R toward roof curb  200  would encounter then flow along flanges  247 , then onto the portion of roof R lateral to roof curb  200 , thereby bypassing roof curb  200  and continuing to flow down roof R. 
   Referring to  FIG. 7 , an embodiment of a method of making  300  roof curb  100  configured according to the invention includes: a step  305  of determining curb size; a step  310  of cutting extrusions; a step  315  of cutting bottom extrusion; a step  320  of cutting steel channels; a step  325  of drilling corner connections; a step  330  of applying corner block mastic; a step  335  of assembling extrusion corners; a step  340  of determining composite board dimensions; and a step  345  of cutting composite boards. 
   Referring also to  FIG. 8 , step  305  involves determining a curb size to ascertain a curb length for walls  105   a , as shown in  FIG. 1 , and a curb width for walls  105   b , top support channel  135  and bottom support channel  140 , as shown in  FIG. 2 . 
   Step  310  involves cutting the side extrusions or walls  105   a  according to the curb length of step  305 . Preferably, a roof curb assembler uses a 12-inch compound-sliding miter-saw with a carbide tooth blade for cutting aluminum. Mitering the interfaces among walls  105  promotes relative flushness as well as flushness with respect to roof R. 
   Step  315  involves cutting the top and bottom extrusions or walls  105   b  according to the curb width of step  305 . Step  315  differs from step  310  in that a roof curb assembler must cut walls  105   b  so as to accommodate seams or corrugations in roof R. 
   Step  320  involves cutting top support channel  135  and bottom support channel  140  according to the curb width of step  305 . Preferably, a roof curb assembler uses an angle grinder with cutoff blade. Top support channel  135  and bottom support channel  140  also may require notching to accommodate roof support structures. 
   Step  325  involves aligning a template relative to and drilling pilot holes through walls  105  so as to register with through bores  112  in connection blocks  110 . A roof curb assembler temporarily maintains relative positioning of the template and walls  105  with a locking C-clamp. The roof curb assembler drills two 5/16-inch diameter holes at each end of each of walls  105 . 
   Step  330  involves applying a 5/16-inch diameter bead of gun grade sealant, preferably Panlastic, to the top, bottom and corner of each of corner blocks  110  with a caulking gun. This provides roof curbs  100  and  200  with an integral water-tight seal that is superior to post-installation sealant treatments common to other roof curbs. 
   Step  335  involves driving ¼-inch×½-inch phillips head bolts through the holes in walls  105  and corner connection blocks  110 . Tightening the bolts urges walls  105  and corner connection blocks  110  to come together, and urges the mastic applied to corner connection blocks  110  at step  330  to flow into any gaps, thereby sealing the joint. 
   Step  340  involves determining the slope or pitch of roof R, and an appropriate measurement for the “X” dimension shown in  FIG. 8 , corresponding to the pitch so that composite boards  115  provide a generally level mounting area for an appliance (not shown). The “Y” dimension is fixed, preferably at 5-½ inches. Preferably, stock Trex® boards  115  for cutting are 5/4-inch×6-inches. 
   Step  345  involves using a circular, table or radial-arm saw equipped with a wood-cutting carbide blade to cut stock Trex® boards  115  as required to fit tightly in channels  125 . 
   Referring to  FIG. 9 , an embodiment of a method of making  500  roof curb  200  configured according to the invention includes: a step  505  of determining curb size; a step  510  of cutting extrusions; a step  515  of cutting bottom extrusion; a step  520  of cutting steel channels; a step  523  of cutting diverter plate; a step  525  of drilling corner connections; a step  530  of applying corner block mastic; a step  535  of assembling extrusion corners; a step  540  of determining composite board dimensions; and a step  545  of cutting composite boards. 
   Referring also to  FIG. 10 , method of making  500  is substantially identical to method of making  300  except for an additional step  523 . Step  523  involves cutting diverter plate  235  according to the curb width determined at step  505 , which is similar to step  305 . A roof curb assembler must cut diverter plate  235  so as to accommodate seams, corrugations or ribs F in roof R. Specifically, holes in diverter plate  235  must align with ribs F. 
   Referring to  FIG. 11 , an embodiment of a method of installing  400  roof curb  100  configured according to the invention includes: a step  405  of marking roof for cutout; a step  410  of placing walkboards for support; a step  415  of cutting panel; a step  420  of installing side support channels; a step  425  of installing rear support channel; a step  430  of applying mastic for curb; a step  435  of installing curb base; a step  440  of cleaning area; a step  445  of applying sealant; a step  450  of applying mastic; a step  455  of installing composite boards; a step  460  of applying foam tape and sealant at board joints; a step  465  of cutting out insulation; and a step  470  of installing retainers. 
   Referring also to  FIG. 12 , step  405  involves placing roof curb  100 , as assembled above, onto the portion of roof R where an appliance is desired. Bottom wall  105   b  should vertically register with supporting structural purlin. A minimum 6-inch distance should exist between top wall  105   b  and the upper supporting structural purlin. A roof curb installer then traces along the interior of flanges  120  of roof curb  100  with a standard lead or grease pencil. 
   Step  410  involves disposing boards or paneling, having sufficient strength to maintain a roof curb installer&#39;s weight on roof R, just outside of the tracing generated in step  405 , proximate to where the roof curb installer will cut roof R. 
   Step  415  involves drilling ½-inch starter holes in roof R at each corner of the tracing of step  405 , then using a double-cut shear, which minimizes shavings and chips, to cut roof R along the tracing. A roof curb installer will need a reciprocating saw to cut through corrugations in roof R. 
   Step  420  involves sizing and temporarily clamping in place side support channels on top of any insulation and between the upper supporting structural purlin and lower supporting structural purlin, just outside of the lateral edges of the hole in roof R generated at step  415 . 
   Step  425  involves sizing and temporarily clamping in place a bottom support channel between the side support channels installed in step  420 , just outside of the bottom edge of the hole in roof R generated at step  415 . 
   Step  430  involves inserting lockseam plugs on the bottom corrugations occurring along the bottom edge of the hole in roof R generated at step  415 . Once installed, the lockseam plugs may be filled with mastic. A roof curb installer applies ⅛-inch×½-inch Panlastic tape over the lockseam plugs around and aligned with the edges defining the hole in roof R. The tape should be butted, not lapped, at corners. Finally, the roof curb installer applies a continuous bead of sealant on top of the tape. 
   Step  435  involves positioning roof curb  100  over the prepared hole in roof R and securing flanges  120  of roof curb  100  to the support channels with self-drilling ¼-inch×⅞-inch metal screws at six-inch intervals. 
   Step  440  involves sweeping or vacuuming away all metal chips and shavings. 
   Step  445  involves applying a continuous bead of sealant around the intersection of roof R and roof curb  100 . 
   Step  450  involves applying gun grade mastic in the outer corner of channels  125  of walls  105  and to the butt ends of composite boards  115 . 
   Step  455  involves attaching composite boards  115  to walls  105  with self-drilling ¼-inch×⅞-inch metal screws, and to adjoining composite boards  115  with self-drilling #6×2-inch screws. 
   Step  460  involves applying sealant along the joint between walls  105  and composite boards  115 . The roof curb installer then applies foam tape on the top surfaces of the composite boards  115 . 
   Step  465  involves trimming a four-inch wide roll of insulation from building scrap. The roof curb installer places the insulation in pocket  128  in walls  105  defined by channel  125 , vertical wall  127  and flange  120 , as shown in  FIG. 4 . Temporary adhesive may aid in retaining the insulation in pocket  128 . The roof curb installer then slits the building insulation from each roof curb corner inwardly, then removes the insulation from the facing. The roof curb installer folds the facing up each inner side of roof curb  100  and secures the folds thereto with retainers and self-drilling screws. The roof curb installer then tapes each corner to seal vapor retarder completely. 
   Referring to  FIG. 13 , an embodiment of a method of installing  600  roof curb  200  configured according to the invention includes: a step  605  of marking roof for cutout; a step  607  of marking roof for diverter plate; a step  615  of cutting panel; a step  620  of installing side support channels; a step  625  of installing rear support channel; a step  627  of preparing diverter plate; a step  628  of installing diverter plate; a step  630  of applying mastic for curb; a step  635  of installing curb base; a step  637  of preparing diverter angle; a step  638  of installing diverter angle; a step  640  of cleaning area; a step  645  of applying sealant; a step  650  of applying mastic; a step  655  of installing composite boards; a step  660  of applying foam tape and sealant at composite board joints; a step  665  of cutting out insulation; and a step  670  of installing retainers. 
   Referring also to  FIGS. 14A and 14B , method of installing  600  is substantially identical to method of installing  400  except for steps  607 ,  627 ,  628 ,  637  and  638 . Step  607  involves placing diverter plate  235  adjacent to the top edge of the tracing generated in step  605 , which is similar to step  405 , and tracing around diverter plate  235 . 
   Step  627  involves attaching corrugation plugs to diverter plate  235  over the holes aligned with ribs F in roof R. The roof curb installer applies tape Panlastic over the side and outer edges of diverter plate  235 , being careful to butt and not lap the ends, so that a minimum of ¼ inch is exposed around the panel cut out. The roof curb installer applies gun grade mastic over the tape Panlastic. 
   Step  628  involves placing diverter plate  235  in the cutout in roof R so that corrugation plugs snugly fit in the corrugations in roof R. Self-drilling threaded fasteners secure diverter plate to roof R. Mastic must be applied around holes on the bottom side of the panel strips. 
   Step  637  involves applying a 5/16-inch bead of mastic to the back and ⅛-inch×1½-inch tape Panlastic to bottom of diverter angle  245 , then positioning diverter angle  245  against roof curb  200  on roof R. 
   Step  638  involves securing diverter angle  245  to roof curb  200  and roof R with self-drilling threaded fasteners. 
   The invention is not limited to the particular embodiments described herein, which should be understood to be merely illustrative of the invention defined by the following claims.

Technology Classification (CPC): 4