Cob Flue Design for a Wood Stove?

Hi there!

My landmates and I are converting our barn into a multi-use space, and we just got a wood burning stove to heat it in the winter. I would like to add some thermal mass around the stove with cob and/or stone, to collect more radiant heat, and wondering what the best approach would be.

I’ve heard that it’s not recommended to put cob directly on the stove (touching it) because the radiant heat may cause the stove materials to warp and prematurely deteriorate. So, I’m thinking that we could build a cob bell shape or a trapezoidal shape around and behind the stove (with plenty of air space) to help collect extra heat and radiate it out into the space. I was also wondering if it would help to build a cob flue to collect more heat, rather than just use a metal one.

I have a very very basic sketch of one idea I have so far for designing the cob (see attached).

Some of the questions my group has:

Safety and Functionality -

Is a cob flue is safe and does it work well for smoke exhaust? I was thinking we could make a snake like flue shape internally to keep the smoke and heat from exhausting too quickly (to retain more heat). Would this snake-like shape create enough friction for trapping more heat? You can see my silly drawing attached see what I am thinking for the shape of the flue.

Chimneys need cleaning obviously. How would we clean a cob flue? And, would we be able to clean a snake-like one like the one I am proposing?

Chimney Exit
Current idea is to exit the flue out the highest point of the wall, does that work with this design? Our exterior wall is made of wood. We need to figure out how to get the smoke/heat out from the cob flue through a metal flue to the outside. Any combustibility issues we need to consider?

If we want to remove it later, or if the cob breaks down over time, does a cob flue design allow for it to be removable rather than permanent?

New to this group, and curious what info people might have regarding this idea. Thanks!!!

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