Insulating Outside of Masonry Chimney
I’m wondering about the efficacy of insulating the outside of a masonry chimney. The attic/loft will be used as semi-conditioned living space, and I am concerned about 1. keeping the chimney from sucking all of the heat out of this area and 2. potentially improving the efficiency of the house overall. I’ve been thinking that I might be able to insulate around the chimney in the loft space– roughly 9′ of chimney– and that at that point, the cinder block will actually represent a small but appreciable r-value, perhaps even as high as r-10. (This page– http://www.sizes.com/units/rvalue.htm –lists 8″ block as having an r-value of more than 1) It seems that the chimney mass might function better as well, leading to some synergistic gains. I’m not sure what one would use, though rigid fiberglass and rigid mineral wool seem like possibilities. Fire concerns might dictate building a chase 2″ away from the chimney and insulating that, which would allow for a wider array of insulation materials.
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