During a hard rain last week, I noticed water leaking thru ceiling in Laundry room. I climbed into the attic and noted that the roof was not leaking. The water was leaking out from a bend in the exhaust stack from the water heater. I also noted that the same was happening from the gas exhaust stack from the AC / Gas Heater in the attic over the garage.
1. Should these be sealed to prevent gas from going into the attic/garage or does the upward flow prevent this? and
2. How do I seal these to prevent water from entering and leaking out on the ceiling? Roofs are steep.