With the pipe in a vertical position trace around the pipe using a pencil.
Getting a liitle water through my roof vents.
Each needs to be evaluated for risk to your home.
If your roof vent leaks during heavy rain the rain may be blowing up under the hood and into the vent.
Position the vent pipe up to the bottom of the roof.
Minimizing water intrusion through roof vents in high wind regions.
The main sources of water intrusion into houses aside from floods arise from windows and doors attic vents including the ones on the roof vents on gable end walls and soffits eave and gable end wall penetrations for utilities cracks in wall siding.
The penetration will be oval to have a round pipe exit vertically through a pitched roof you need an oval hole in the roof.
Place a deflector over the opening of the vent to keep rain from blowing through the opening.
There are professionals that will inspect your roof and look for a ridge vent leak for only a minimal cost.
And on occasion a hard driving rain with whipping wind will cause roof vents to leak water.
To describe practices for minimizing water intrusion through roof vent systems that can lead to interior damage and mold growth in high wind regions i e greater than 90 miles per hour mph basic gust design wind speed 1.
But some roof air vents sit fairly flat to the roof with a mushroom style hood and unprotected sides.
Most air vent styles prevent direct intrusion of water.
As well check shingle integrity.
They will look over all your metal flashing the number one cause for roof leaks.