Furnace Vent Roof Leak

Cut away the old caulk from around the vent pipe.

Furnace vent roof leak.

Use the knife blade to scrape the pipe clean and smooth. And on occasion a hard driving rain with whipping wind will cause roof vents to leak water. This structure generally uses the furnace vent pipe through roofbecause the b venting pipe is designed in vertical manner. But some roof air vents sit fairly flat to the roof with a mushroom style hood and unprotected sides.

There are many possible parts of the roof potentially leaking but one of the most common ones is the area around the roof vent. When the vent is withdrawing air from the house it expels the gas outside through the vent. If your furnace exhaust pipe or flue pipe is leaking it can be a sign of a much bigger problem. Another problem is that flue pipes that go through the roof tend to be less efficient.

High efficiency furnaces take advantage of the heat in the combustion gases that are wasted in natural ventilation systems. If your roof vent leaks during heavy rain the rain may be blowing up under the hood and into the vent. I had a small leak from the vent pipe in the last rain so used some pl roof flashing sealant to fix it. Roof leaks around vent pipes is relatively common.

Here s what to look for. This old house general contractor tom silva shows how to create a watertight seal around a vent pipe. Steps for fixing a leaking rooftop vent pipe. Apply a thick bead of lap seal caulk around the seam between the vent pipe and old rubber gasket.

A roof that leaks around a vent pipe is a common cause of small water stains on a ceiling or water leaking into a home. Also known as the type b this vent is operating on the natural air convection. The roof vent pipe is installed cut through the roof and around the pipe attached to the roof is surrounded with rubber boot as insulation for the gap between the pipe and roof. If your furnace has an afue rating of 90 or lower it probably exhausts the gases though the flue pipe on your roof.