Barbecues, smokers and stoves

This is the thing most often ordered from a welder, and the most underestimated. From outside a barbecue is a box on legs, and it looks as though dearer and cheaper differ in prettiness. They differ in wall thickness, in whether there are grate bars, and in where the smoke goes.

How a firebox is built

A firebox has four layers up its height and each answers for its own thing: the cooking grate on top, the coals, the grate bars under them and the ash pan at the bottom. A barbecue built without the bars technically works, but the charcoal sits in its own ash and dies, and the floor burns through first, because all the heat rests straight on it.

Barbecue set in oblique projection: firebox in section with coals, grate bars and ash pan, cooking grate on top, lid folded back, flue with a cap, work top with a lower shelf, with sizes and seven callouts — The proportions are schematic: a real firebox is lower and flatter. Four layers up the height would otherwise merge into one band.

Wall thickness settles everything else. Two millimetres burns through in two seasons: steel does not burn, it oxidises and thins with every firing, and the floor goes first. Three to four millimetres lasts years and holds the heat more evenly — a thick wall works as a store and does not pull out of shape.

What kinds there are

Six panels: a knock-down barbecue, a fixed one with a lid, a barbecue complex with a flue, a smoker, a stove for a cauldron and a barrel grill — Six variants. The lid is not decoration: it holds the heat and blocks the wind that otherwise carries it off in ten minutes.

A knock-down one is a season and a car boot: light, thin, and it lasts exactly as long as you do not mind. A fixed one with a lid is already something that stays put and outlives its owner. A drum grill and a cauldron stove are not barbecues at all but different appliances: in the first the heat comes from below and the side, in the second it is the base of the pot that is heated.

The barbecue set

A set differs from a barbecue not in size but in what stands around the fire: a top to cut on, a shelf for wood, a sink, sometimes a cauldron and a smoker. The point of it is one thing — not walking across the yard with plates.

Six layouts of a barbecue set: firebox on legs, firebox with a work top, a set with a cauldron, a set with a smoker, a set under a shelter and an island set with a sink — Six layouts. A smoker is not combined with a barbecue in one body: it has different smoke and a different temperature.

A smoker cannot be merged with the firebox into one body, though people ask for it often. Smoking runs at 30–90 °C on smoke from smouldering chips, while over charcoal the temperature is three times that and the smoke is different. So the smoker is a separate cabinet with its own smoke generator, and all that joins them is a shared work top.

Flue and draught

Draught comes from the difference in height, not from the diameter of the pipe. A metre and a half above the coals is the minimum at which smoke goes up on a still day too. If there is a roof nearby, the pipe has to come out above the ridge, or the wind will kill it with a downdraught and the smoke will come back in your face.

Six ways a flue can end: plain pipe, with a rain cap, with a mesh spark arrester, with a damper, an extraction hood over the fire, and a pipe passing through a wall in a sleeve — Six ways a pipe can end. A rain cap, a spark arrester and a damper do different jobs and do not replace one another.

Three pipe ends get confused constantly. A cap keeps out rain and snow. A spark arrester is a mesh that stops burning particles getting out, and it is required wherever there is roofing, dry grass or a tarpaulin nearby. A damper sits not at the top but in the pipe itself and controls the draught: close it down and the charcoal burns slower and the heat lasts longer.

Where to go next

A barbecue under cover and a gazebo with a grill bay are in yard and garden. Stainless for kitchens, tanks and pipework are in shop products. What it costs and how long it takes is in how ordering works.

Frequently asked questions

How thick does the steel need to be?

From 3 mm, better 4. A two-millimetre wall burns through in two seasons: the metal does not so much burn as oxidise and thin out with every firing. Four millimetres lasts years and holds the heat more evenly — a thick wall works as a heat store and does not distort from overheating.

Does a barbecue need grate bars in the bottom?

It does if you cook long and often. The bars lift the coals off the floor and let air in from below — the charcoal burns evenly and does not smother in its own ash. Without them the ash settles on the coals and chokes them, and the floor of the firebox burns through first, because all the heat sits straight on it.

How tall does the flue have to be?

At least a metre and a half above the coals, and above the ridge if there is a roof nearby. Draught comes from the difference in height: a short pipe only pulls in wind, and on a still day the smoke goes in your face. A rain cap does not stop downdraught — it only keeps the wind from beating straight down the pipe.

Can a barbecue stand under a shelter?

It can, if there is a flue or an extraction hood and the roofing is not combustible. Polycarbonate over a fire melts from the rising heat even without flames, and a tarpaulin catches from a single spark. Under a shelter the barbecue gets a pipe taken above the roofing, with a spark arrester on it.

Author: welder Updated: 21 August 2026