Every Virginia (VA) roof has at least one venting pipe and they are needed for so many things in a house that you probably have several coming through your roof. Anything that would create excess smell, humidity, or heat is usually vented out in order to preserve the house in the best condition.
When water goes down the drain from showers, sinks, and toilets, there is a U in the pipe and then a split, with one pipe taking the grey water or waste away and the other pipe exiting through the roof. This allows sewer gases to exit the system, and the water in the U keeps the smell out of your house. A dryer will have a vent to take excess moisture and heat out of the house, while stoves will have vents to remove heat and smells. Stoves also have a grease collection system built into the range hood so that grease won’t buildup in the vent and then lead to a fire. Your gas furnace or water heater also usually is vented.
Every time you cut a hole for a vent pipe, you have the potential to compromise the integrity of the roof. Vent pipes have rubber ‘boots’ that surround them like a turtleneck and extend out into a square base that integrates into the shingles or other roofing materials.
If you are experiencing a leak, either the pipe joints have become disconnected or somehow rain is getting past the flashing and into your house. Many times the vents don’t have caps on them, but you can install a mushroom type of cap to keep rain from traveling down the inside of the pipe. When your venting pipe is well connected along its length and well sealed where it meets the roof, it should give you few problems.