Reverse Smoker Build

  • Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.


Meat Mopper
Original poster
May 8, 2012
Breaux Bridge, LA
Hey guys,

I have a small revers smoker that I built years ago. I also have a lager bar-b-q pit that I have had for 15 years. I will be converting this pit to a reverse flow smoker. I have a few questions, how do I insulate the fire box. I saw fire brick can be used but how do I get them to stay on the top and not fall over from the sides. Also how do I apply Dave's calculations to an existing pit?
  • Like
Reactions: JLeonard


Meat Mopper
Jan 31, 2022
New Mexico
When I've seen folks use fire brick, they place it only asking the bottom and up the sides of a round firebox. So the fire is sitting on the firebrick, but the top half is still exposed steel.
No personal experience, but I am interested in buying some and giving it a shot on my offset because I find my coals burn down too effectively. The wood goes straight from burning log to ash. I'm thinking the bricks will maintain some heat and block some airflow.


Meat Mopper
SMF Premier Member
Sep 30, 2020
I was planning to sleeve in another pipe into the firebox and let the dead air gap be the insulation. In my case, I have a 24” round FB and I found a 22” diameter pipe to sleeve. I can make a few spacers to center the pipe and try it. If it doesn’t behave correctly, it’s easy to remove.
As far as the calculator, you should be able to use the dimensions of your existing offset and base those on the exhaust plan (which I assume is what you want to use the calculator for?)
Aug 28, 2022
Kirkland, Washington
I went to a lot of trouble once to make a 2-layer insulated firebox. It was fun to figure out how to do it, but it added a lot of complexity. My goal was to make it more comfortable to stand near the firebox during a summer cook. The firebox worked exceptionally well but it still got quite warm near it. My conclusion was that insulating the firebox isn't worth the trouble.

If your goal is to make individual logs last longer, the only real way to do that is to use higher BTU wood. For example, you could go from hickory to walnut. If what you want is a big bed of hot coals, maybe you should start with a big fire damped down somewhat and let it go until it's all coals, then adjust air flow and temperature to normal and start cooking. Or use a secondary fire like the whole hog roasters and shovel in heaps of hot wood coals.

Thermodynamics tells us that heat will move from a hot place to a cold place. The question is how fast. If you perfectly insulated the firebox it seems to me you'd keep all the heat inside and thus burn up your logs even faster.


Latest posts

Hot Threads