Gas vents 12 inches 305 mm in size or smaller with listed caps shall be permitted to be terminated in accordance with figure g2427 6 5 provided that such vents are at least 8 feet 2438 mm from a vertical wall or similar obstruction.
													
																	Vent height above roof. 
									
	
		
	
																	Where a roof is to be used for assembly or as a promenade observation deck sunbathing deck or similar purposes open vent pipes shall terminate not less than 7 feet 2134 mm above the roof. 
																	The slope is about 4 high for every 12 horizontal. 
																	So 28 inches plus 24 inches is a chimney height of only 52 inches. 
																	Open vent pipes that extend through a roof shall be terminated not less than 6 inches 152 mm above the roof. 
															
													
									
	
		
	
																	This reduces the actual required height by 12 inches from our previous calculation of 64 inches. 
																	Upc i 906 1 and 906 2. 
																	Above the roof surface with a listed cap or listed roof assembly. 
																	Please note that this rule doesn t generally apply to pellet and gas vent systems. 
															
													
									
	
		
	
																	Per the 10 and 2 rule once you are at the level of the peak you only need to be 2 feet above it. 
																	You are letting air into the plumbing system of the house. 
																	Above the roof plumbing vent height. 
																	I have a main vent and a sink vent and both are only 6 high above the roof. 
															
													
									
	
		
	
																	The 6 you describe should be just fine.