Build the fire in a small masonry fire chamber or fire pit that is separate from the smoking chamber, and join them with a pipe, trench or tunnel 3-5 m long made of non-combustible material so the smoke cools to below 30 °C before it reaches the meat. The fire is smoldering hardwood, which makes carbon monoxide, so tend it in the open air and keep the channel clean of tar.
Part of Smoke Houses
The fire box and smoke channel are the parts of a cold smoke house that make the smoke and carry it, cooled, to the food chamber.
The Channel’s Length Is The Cooling System
A cold smoke house works because the fire is far enough from the food that the smoke arrives cool. The channel does the cooling by giving the smoke a long path in contact with cooler walls: 3-5 m is enough to bring it from fire temperature to below 30 °C. A short channel puts hot smoke on the meat. A channel of wood or other fuel is a fuse leading from the fire to the chamber, so the channel is built of earth, stone, clay, metal or masonry, never timber.
Hot fire is the wrong fire: a smoke house wants a controlled, smoldering fire that makes plenty of smoke and not much flame. Control comes from the air supply. Restrict the air and the fire smoulders; open it and it flames, heating the channel and the meat.
What You Need
- A fire box: a small masonry chamber or fire pit with a controllable air intake
- A channel, 3-5 m, of earth trench with stone or clay lining, clay pipe or sheet metal
- A smoking chamber, 2-3 m tall, with a vent at the top
- Seasoned hardwood: hickory, oak, apple, cherry or maple. Resinous softwoods (pine, spruce, cedar) give toxic smoke and a bad taste
- A slope: the fire box at the low end and the chamber higher, so the smoke rises; the simplest build is in Smokehouse Build
Method: Build And Run
Step 1: Site the fire box downhill of the chamber and downwind of living areas. Smoke odor is persistent.
Step 2: Build the fire box of masonry with an adjustable air inlet. A small door or a stone you can slide gives control.
Step 3: Build the channel of non-combustible material. Line a trench with stone or clay, or use clay pipe. Keep it accessible so it can be cleaned.
Step 4: Join to the chamber. Make the join tight so smoke does not leak, and give the chamber a top vent so the smoke is drawn through.
Step 5: Burn seasoned hardwood only. Never burn pressure-treated, painted or glued wood, or resinous softwood.
Step 6: Check the chamber temperature. Measure it. If it is above 30 °C in cold smoking, damp the fire and lengthen the channel.
Step 7: Clean the channel. Smoke deposits tar, which burns; scrape it out between runs.
Common Mistakes
- A wooden channel — it catches fire.
- A fierce, flaming fire — heats the meat and the channel.
- Burning treated or painted wood — toxic smoke.
- Letting tar build up — a channel fire.
Safety
Carbon monoxide, creosote fire and burns
Carbon monoxide. Smoldering wood makes carbon monoxide, which has no smell or color and can kill in an enclosed or poorly ventilated space. Tend the fire in the open air; never sleep in or near a closed smoke house; see Carbon Monoxide Risk.
Fire. Tar and creosote deposits in the channel can ignite and flare through the chamber, burning the meat and the building. Build with non-combustible material, scrape the channel, keep the area around it clear, and keep water at hand. Fat dripping on hot coals can also flare.
Toxic fuel. Never burn pressure-treated, painted, varnished or glued wood.
What’s Next
- Learn next: Hanging & Rack Systems — what goes in the chamber
- Combine with: Smokehouse Build — the simplest complete build