We are in the process of renovating a two-story 1910’s foursquare in climate zone 4. We’re planning a re-roof later this summer, and I am working out what we’d like to do with our chimneys in preparation and could use some advice. Currently the attic is insulated at the roof deck with 7” closed-cell spray foam.
Chimney #1 is a single-wythe unlined brick chimney serving an old coal-burning fireplace on the first floor. Except where it penetrates the roof, it is entirely inside the thermal and air envelope of the house. I would like to seal and insulate it semi-permanently (with the option of reopening it in the future).
I was thinking of wrapping wire or rope around stone wool batts pushed down from the chimney top, with the wire/rope tied to a rod running across the top of the chimney, and then sealing the chimney top with a metal cover and caulk. Would this approach be feasible?
Chimney #2 is also an unlined single-wythe brick chimney. At some point in the past, its top was removed to a point below the roof line and was used as a chase for a B-vent for a gas furnace and hot water heater located in the basement, both now abandoned and removed. I would like to line this chimney and use it for a wood stove or masonry heater at some future point.
My question for this chimney is, would it be better to rebuild the removed masonry portion through the roof, or build a wood-framed chase on top of the existing chimney and apply thin brick veneer to it above the roofline?
Chimney #3 does not actually exist at this point. As part of the renovation I am adding a radon mitigation system to our basement and crawl space. The only space I could retrofit the 4” PVC pipe into passes through the interior space of the basement and first floor, but then exits the roof of a one-story bump-out along an exterior wall. We are adding 2” of polyiso and a peel-and-stick air barrier to the exterior walls, and I am considering framing a chase to enclose the radon pipe and keep it within the 2” of polyiso. If I did this, I’d probably want to continue the framed chase through the roof and apply a thin brick veneer above the roofline to be consistent with the other chimneys (below the roofline I would use the same lap siding as the rest of the house).
Are there any concerns with this approach I should be aware of?
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