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  • Had an idea for vertical stack ventilation of chimney chase. Would this work?

    From cole_thompson@bf680a3126ec737c359611ab24e6ceb2@example.com to alt.home.repair on Fri Feb 20 14:45:02 2026
    From Newsgroup: alt.home.repair

    I have a wooden chimney chase like the one in the attached picture.

    I have an idea about an improvement that I tried to capture in a crude diagram that is also attached. I'll try to explain the idea:

    Last summer I did a lot of work removing all the siding (T1-11), and old asphalt paper moisture barrier, and carefully replaced framing wood that showed a little bit of termite damage. Pressure treated stuff (rated for above ground use) was used for replacement. Also, the ground around the chimney chase has been treated by a local professional, should be good against subterranean termites for 8 to 10 years. So, lots done.

    The termite guy had an observation I found interesting. He said that in our region, it always seems like the chimney chases are where the termites like to go. We talked and thought maybe it's because chimney chases are dead air, sealed up, and maybe they become moisture traps, due to hot/cold cycles, condensation, etc. Termites like moisture.

    My thought is that during the summer and warmer months, maybe it would help to promote "vertical stack ventilation", where air enters at the bottom of structure, heats up, then rises and escapes through some kind of storm-proof vent at the top. This should in theory dry things out nicely. In my small chimney chase, about 18 feet tall, there is no blocking wall or whatever on the inside of the chimney chase, it's all open space. I understand that in a multi-story building, there should be firewalls to prevent any vertical spread of flames inside the chimney chase, but that's not how mine was built, I guess.

    To make vertical stack ventilation possible, I think I would need an opening at the base of the chimney chase, well screened against critters. And it would be on me to ensure it had a tight hatch cover that would go on when the hot months were over.

    It seems like it should work to keep the chimney chase well dried out. But I'd be curious what people think. I don't have a lot of ego about this, so if I'm wrong, I'm wrong.
    https://www.homeownershub.com/img/3ebx
    https://www.homeownershub.com/img/3eby
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