Chimney material other than stainless steel and ceramic liner

[eorl]

Hello all,

I am in the process of constructing my 42" Pompeii design wood fire oven. One of the big issue I am facing is that in my country I am not able to find stainless steel chimney pipes or ceramic/terracota flue liner.

I looked into getting a 304 stainless steel pipe but they are all 3mm thick which makes them very bulky and also very expensive. On top of that I need to buy a 20ft pipe most of which will be wasted. I also looked into ceramic/terracotta flue liners but they are also not available.

Can someone here guide me if I can make a chimney out of firebricks. My current plan is to pour a RCC structure on top of the throat opening and then form a firebrick chimney 8" wide using that as support on top of the vent opening. Then put 2" insulation blanket around the chimney and then Portland cement mortar on top for finish.

Questions I have :
1. Will this work ?
2. For 42" Igloo design with 20"X18" opening what should be vent size on the throat ?
3. Should I plaster the inner part of firebrick chimney with refractory mortar to make it smooth to reduce air friction and reduce creosote buildup ?
3. Is 8"X8" width chimney size sufficient ?
4. In term of long term maintenance what should I look out for ?

I am also open to other alternatives. Masonry solutions are most cost efficient for in my area.

[david s]

Although you may have difficulty obtaining thin walled stainless pipe, if you have acces to a metal fabrication shop, which should be almost anywhere, they are all set up and experienced at fabricating pipes from thin sheet metal. Ask for 0.5mm thick stainless 304 grade, length up to you.

[eorl]

Thanks David. This is a great idea. I have already approached two fabricators and they will not be able to fabricate using 0.5mm but can do 1mm which is still way better.

Waiting on pricing but hopefully this works out as they can even fabricate the base and spark arrestor cap.

[Javier04]

Firebrick is a solid option and plenty of pizza ovens run masonry flues successfully, but a few things worth knowing before you commit to that build.

Smooth interior surface matters more than most people expect. Rough or uneven firebrick joints inside the flue create turbulence, and turbulence is what slows draft and encourages creosote to stick rather than get carried up and out. So yes, parging the inside with refractory mortar is worth doing, not just for looks but for draft performance and easier cleaning down the line.

On sizing, 8x8 works for a lot of masonry flue builds, but the ratio that actually matters is flue area relative to your throat opening, not a fixed number. If the flue is undersized relative to the opening, you'll get lazy draft and smoke spillage no matter how well built it is.

For long-term maintenance, masonry chimneys need more attention than stainless, not less. Mortar joints can crack from thermal cycling over time, and any hairline crack becomes a spot where creosote and moisture concentrate. An annual visual inspection of the joints, along with checking for creosote buildup at the base where flow slows down the most, will catch problems early before they become structural.