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 fig5 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 fig5 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.