Birds often find the warmth of a vent pipe inviting for nesting.
Because the vent pipe is located on the roof, you can’t see the clog directly. Instead, look for these "symptoms" inside your home: vent pipe blockage
In cold climates, water vapor can freeze at the top of the stack, gradually closing the opening with frost and ice. How to Clear a Vent Pipe Blockage Birds often find the warmth of a vent
Are you dealing with in a specific room, or is the slow drainage affecting the whole house? vent pipe blockage