My house is 7 years old. Our furnace is in our basement and the exhaust pipe runs from the basement, up through the first floor, on into the attic, and out the roof. We noticed recently that some water stains are appearing on our ceiling, and after further investigation, we're noticing that water is some how getting into the pipe and flowing down. However, the pipe does have a crown over it, but there is still a gap between the end of the pipe and the crown. It's what the builders had used, and it's what every other house in our neighborhood looks like. Is it possible, and normal, for water to get in this pipe when it rains heavy? I've already gotten up on top the roof and sealed off around where the pipe exits the roof, but it's still getting in and this is the only possible way. Please, I'm asking for someone to ease my mind.

Regards,
Justin

If it is PVC pipe it should be glued and not leak out of the pipe from inside of the pipe.

Water could be getting into the house around that pipe at the roof line an running down the outside of that pipe on to the ceiling.

A couple of things, if the furnace is a 90% efficiant then it could be the pvc pipe is not glue and sealed completely, However if it's an 80% furnace with metal vent and your sure
the flashing is sealed, (question does it only leak when it rains?) if so it's coming in through the penetration somehow, if it leaks at random with no rain be sure the vent is the proper size (4") from furnace does it get bigger more than 2 sizes this could cause sweating that could run down the inside of your vent. Are there multiple vents tied to the furnace vents? If so you need to have it checked for proper sizing.