Apparatus and method for extending the length of a vent pipe above the elevation of a building roof

Abstract

Apparatus and a method for extending the length of a vent pipe for a predetermined distance above the elevation of a building roof includes an elongated extension pipe connectable with the vent pipe, a flashing attachable to the roof while fitted as a sleeve over the extension pipe, and a vent cap fittable over the flashing and the extension pipe. The vent cap includes an opening for venting to external atmosphere gases received by the extension pipe from the vent pipe. The extension pipe and the vent cap are sized so as to maintain a venting pressure in the extension pipe not greater than the venting pressure in the extension pipe.

What is claimed is:  
     
         1 . Apparatus for extending the length of a vent pipe for a predetermined distance above the elevation of a building roof, said vent pipe having a known inside diameter, said apparatus comprising: 
 (a) an extension pipe characterized by: 
 (i) a lower end having a cylindrical outside diameter sized to fit snugly within said inside diameter of said vent pipe; and,  
 (ii) an elongated tubular portion extending upwardly from said lower end, said tubular portion having: 
 (A) an inside diameter greater than said inside diameter of said vent pipe; and,  
 (B) an outside diameter,  
 
   (b) a flashing, said flashing comprising a base attachable to said roof and a centrally positioned tubular portion extending upwardly from said base, said tubular portion characterized by: 
 (i) an inside diameter sized to fit as a sleeve over said extension pipe; and,  
 (ii) an outside diameter; said base including a centrally aligned opening having a diameter corresponding to said inside diameter of said tubular portion and extending lengthwise through said base for permitting said flashing to be lowered as a sleeve over said extension pipe; and,  
   (c) a vent cap comprising an inner wall and an outer wall with an annular space defined between said walls, said annular space having a closed top and an open bottom, said inner wall defining a centrally aligned opening extending lengthwise through said cap, and wherein: 
 (i) said inner wall has an outside diameter sized to slidingly fit within said inside diameter of said extension pipe;  
 (ii) said outer wall has an inside diameter sized to slidingly receive said outside diameter of said tubular portion of said flashing.  
   
     
     
         2 . Apparatus as defined in  claim 1 , wherein 
 (a) said tubular portion of said flashing has a tubular wall thickness substantially less than the tubular wall thickness of said upper end of said extension pipe;    (b) said inner wall of said vent cap has a wall thickness substantially less than the tubular wall thickness of said upper end of said extension pipe; and,    (c) said inner wall of said vent cap has a wall thickness substantially less than the tubular wall thickness of said upper end of said extension pipe.    
     
     
         3 . Apparatus as defined in  claim 2 , wherein said centrally aligned opening in said vent cap has a bottom diameter not less than said inside diameter of said vent pipe.  
     
     
         4 . Apparatus as defined in  claim 2 , wherein said centrally aligned opening in said vent cap has a bottom diameter greater than said inside diameter of said vent pipe.  
     
     
         5 . Apparatus as defined in any of the preceding claims, wherein said extension pipe includes a pipe coupling having a lower end and an upper end, the lower end of said coupling forming said lower end of said extension pipe, the upper end of said coupling connecting with said elongated tubular portion of said extension pipe.  
     
     
         6 . Apparatus for extending the length of a vent pipe for a predetermined distance above the elevation of a building roof, said vent pipe having a known inside diameter, said apparatus comprising: 
 (a) an elongated extension pipe connectable with said vent pipe to receive gases flowing upwardly from said vent pipe;    (b) a flashing attachable to said roof while fitted as a sleeve over said extension pipe; and,    (c) a vent cap fittable over said flashing and said extension pipe to shield the annular region between said flashing and said extension pipe from external precipitation, said vent cap including an opening for venting to external atmosphere gases received by said extension pipe from said vent pipe,    said extension pipe and said vent cap being sized so as to maintain a venting pressure in said extension pipe not greater than the venting pressure in said extension pipe.    
     
     
         7 . Apparatus as defined in  claim 6  wherein said opening in said vent cap has a bottom diameter not less than said inside diameter of said vent pipe.  
     
     
         8 . Apparatus as defined in  claim 6  wherein said opening in said vent cap has a bottom to diameter greater than said inside diameter of said vent pipe.  
     
     
         9 . On a building where a new roof is constructed atop an old roof, and where an existing vent pipe extending above the old roof is of insufficient length in relation to the new roof, a method of extending the length of the existing vent pipe above the elevation of the new roof, said method comprising: 
 (a) connecting an upwardly extending, elongated extension pipe with said vent pipe to receive gases flowing upwardly from said vent pipe, said extension pipe having sufficient length to extend from said vent pipe to a desired distance above said new roof;    (b) fitting a flashing as a sleeve over said extension pipe;    (c) attaching said flashing to said new roof when so fitted; and,    (d) fitting a vent cap over said flashing and said extension pipe to shield the annular region between said flashing and said extension from external precipitation, said vent cap including an opening for venting to external atmosphere gases received by said extension pipe from said vent pipe,    said extension pipe and said vent cap being sized so as to maintain a venting pressure in said extension pipe not greater than the venting pressure in said extension pipe.    
     
     
         10 . A method as defined in  claim 9 , wherein said extension pipe and said vent cap are sized so as to maintain a venting pressure in said extension pipe less than the venting pressure in said extension pipe.  
     
     
         11 . A method as defined in  claim 9  wherein said vent pipe and said extension pipe are generally cylindrical, said extension pipe having an inside diameter greater than the inside diameter of said vent pipe.  
     
     
         12 . A method as defined in any of  claims 9  to  11 , further comprising the step of cutting a top part away from said extension pipe leaving an upper rim of said extension pipe flush with an upper rim of said flashing.