Put the fire pit downhill of the smokehouse and join them with a buried channel 8-15 feet long, so that smoke rises up the slope and cools on the way to the chamber. The parent article’s channel is a trench 12-18 inches deep and 12 inches wide, lined with stone, brick or clay tile and covered with flat stones or metal and then earth, rising 2-3 feet over its length from a stone-lined fire pit about 2 feet in each dimension.
Part of Large-Scale Smoking & Curing
A smoke channel is a covered, non-combustible duct that carries smoke from a fire pit to a smokehouse and gives it distance in which to cool.
The Slope Does The Work Of A Chimney
Smoke is warm gas, so it rises. Putting the fire at the low end of a sloping channel makes the smoke climb toward the smokehouse without a fan. The parent article calls the slope critical and gives a 2-3 foot elevation difference over 10-15 feet. As a gradient that is
- shallowest: 2 ft ÷ 15 ft = 0.13, about 13%
- steepest: 3 ft ÷ 10 ft = 0.30, 30%
so roughly 8 to 17 degrees from horizontal. The distance also matters: the longer the buried channel, the more heat the smoke gives up to the surrounding earth, which is the reason the parent specifies 8-15 feet for cold smoking. For hot smoking the channel is shortened or omitted, and the same fire heats the chamber (Hot Smoke vs Cold Smoke Design).
What You Need
- A site with enough fall from the smokehouse floor level down to the fire pit
- Stone, brick or clay tile for the lining
- Flat stones or metal sheet for the cover, and earth to bury it
- A stone-lined fire pit about 2 by 2 by 2 feet, with a cover or door to shut off the fire
- A thermometer for the chamber inlet
Method: Laying The Channel
Step 1: Dig a trench 12-18 inches deep and 12 inches wide, rising from the fire pit to the smokehouse.
Step 2: Line it with stone, brick or clay tile.
Step 3: Cover with flat stones or metal sheet, then earth. Leave the top of the earth cover firm, not loose, so that the roof does not shift.
Step 4: Build the fire pit at the low end, stone-lined and about 2 by 2 by 2 feet.
Step 5: Let the smoke enter the smokehouse at floor level through a vent, as the parent article specifies.
Step 6: Test with a small fire and a thermometer at the chamber inlet. The goal is smoke arriving below 85°F, as in Below-85°F smoke generation. Adjust the channel length or the fire size until it does.
Common Mistakes
- A channel that dips. A low point collects condensate and tar, and smoke will not flow through a blockage.
- A combustible lining or cover. Embers travelling up the channel can ignite wood.
- A channel with no way to clean it. Soot and tar accumulate. Leave an access point.
- A fire pit too large. A big fire makes hot smoke that the channel cannot cool.
Safety
Carbon monoxide and creeping fire
A smouldering fire in a pit and long channel makes carbon monoxide, which flows with the smoke into the chamber. Do not enter the smokehouse while the fire is burning. Embers can travel up a channel and ignite fat or wood in the chamber, so keep the lining non-combustible, close the pit when you leave and keep wood stacks well clear of it. Check the channel for tar before each season; it burns.
What’s Next
- Learn next: Ventilation control and draft management — keeping smoke moving once it arrives
- Combine with: Fire Box & Smoke Channel — a second design for the same arrangement