I have a 1932 Bungalow with a chimney from the basement thru the roof. This is only used for furnace exhaust now, I guess I still need it in there. I have only been living in the home for one year and I have noticed the paint and plaster bubbling and peeling along the walls that box the chimney in, and yellow spots on the ceiling. I went up on the roof and noticed that there is no flashing around the penetration. THere is a lot of roofing caulk though and I added some more in some areas that are showing light thru, but I figure I will need to flash this in good before the rainy season. What should I use and how should I do it?