How can I repurpose a cast iron chimenea stack for my oven?

We are about to begin a Grande build. I have scrounged up a 30" tall, cylindrical cast iron chimenea smokestack that I want to use the same way. It has no wide circular flange at the bottom. What product should I use to affix the bottom of the stack to masonry?

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You will want something that includes a damper. The complication to my mind is that the chimenea smokestack is surely not a lightweight, so you’ll also need something that can stabilize 2 ½ feet of cast iron. (The chimenea does that when your find is used as intended.)

The other important feature is the interface with your oven chimney, as you’ve pointed out.

One thought: maybe get friendly with a local welding and metal shop, and have them cut out and weld a square steel plate to the bottom of your chimenea piece?

I’m all for scrounging and repurposing, and we have a few metal-heads on this forum, so hoping more-developed ideas from more-knowledgeable builders will show up here!

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I really like the idea of that welded-on square bottom plate. If nothing else, I could drill 4 holes in the corners of that plate and then into the masonry, and mount the stack onto the masonry using pot-metal lag shields and bolt-headed lag screws.

My welder is a grumpy old Ukrainian who learned his trade welding Soviet tanks long ago. No doubt he can do it - after declaring me nuts. Slava Ukraini!


No great project starts until the operator declares that you’re nuts. Lol!

Lags/lag shields should do the trick. You will also want to use high temp adhesive silicone (it is readily available through Amazon) to seal the plate to the chimney crown. Otherwise smoke will find its way out under the plate instead of up the pipe.

I think that’s going to be a unique stack for your oven. Wondering what it looks like, if you have a moment to share a photo.

Oh the story gets better. I also found an very ornate, columned, cast iron coal furnace door & hinged frame from the early 20th century, complete with fancy scroll-work and the maker’s name “Mueller” cast into it… Stripped it to bare metal, primed & repainted black with hi-temp auto engine paint, and even pin=striped & highlighted the scroll work in gold. That’ll be the door. Then there’s the custom-cut, pink granite front-arch keystone with MMXXIII incised into it, …
The welder’s right… we’re nuts.

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I think photos might not do it justice. Wow!

(But photos will be most welcome and eagerly anticipated.)

The project progresses. I have had a 3/8" steel plate welded to the bottom of my repurposed, cast iron 30" tall chimenea stack. I suspect it may weigh 35 40 lbs. Should I be concerned about that much added weight on the arched firebrick? I have built a 2-brick high chimney base from firebrick, and plan to add a 3rd layer of hard-fired solid paver- brick , upon which to bolt the stack base. Am I being over-cautious?

BTW, “it” means the stack & plate combined.

I wouldn’t worry. @BrickWood says (half in jest) that the arch can support the weight of a healthy child, which is true. The arch is inherently a strong structure provided you built it to spec. That’s why you see it in structures that have survived thousands of years.

Strong momentary force like a frontloader bucket smashed into the right spot might collapse it. But 40 pounds on top should not be a problem.

I’m glad your project is going well, and am eager to see a photo or two. Would you mind posting one so folks here can get their bearings? Thanks!

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I’ll have to get my tech-savvy son to post pix. This flip-phone-carrying geezer has NO idea how to do that. Son is impressed I can even hunt-&-peck this message.

Given that firebricks are about 8 lbs. each and given how many bricks are already in the arch, I’m guessing that adding and extra 40 lbs of pipe (equivalent to 5-6 bricks) is not a big issue.


Hope he’s also impressed you’re doing this great mod!

Yes, if he would be willing to do that, it works just as well as if you posted it personally. Thank you!

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