I’ve recently done a couple of inspections in which there was water entry into the bottom of chimneys that were vinyl-sided and configured as in the pics shown here. The water appears to run down the bottom panel (which was rotting in both cases), and into the basement. This appears to be a systemic design flaw.
My thought is that the water works its way around the edges of the siding in the corners and is caught and drawn in by the “J” channel border that was idiotically installed on the bottom of the course of the siding. With 2 stories of runoff, it certainly appears easy to see how water got in.
My question is how does one fix this with a minimum of surgery?
It seems to me a different configuration that replaces the “J” channels on the bottom and sides would make more sense, but that would involve re-siding the entire chimney, all 2-3 stories of it. It seems that re-configuring the bottom of the siding so water is run out, rather than in would solve most of the problem.