Indirect Heat Explained: Grill Better Meat With 2-Zone Cooking

Indirect grilling is an essential BBQ skill that yields juicier, tastier, better quality food. This is how to get the most out of your charcoal grill with this fundamental cooking technique.

Indirect grilling is an invaluable cooking technique that gives you greater control over your grill’s temperatures, while also allowing you to grill more than one type of food at once on the same grill without the need for separate setups.

There are two main worries for most people when it comes to grilling – producing overcooked food or producing undercooked food. It can sometimes seem impossible to find that ‘Goldilocks zone’ of the grill being just right temperature-wise so that everything cooks evenly and still has a nice smokey taste. 

We’re going to let you into a secret: It’s not actually that hard at all. You just need to learn about indirect grilling and how to set up your own zone system on your backyard grill.

What is Indirect Grilling?

Indirect grilling is a fundamental barbecue cooking technique where you establish two distinct cooking zones: One is the direct zone, where your heat source (usually charcoal) sits. The other is the indirect zone, sat opposite where your heat is. The idea is that instead of being cooked at high temperatures by the coals or burners underneath it, it relies on the hot air and smoke circulating it to cook it more slowly and evenly, much like food is cooked in an oven.

The technique is particularly useful for cooking larger, tougher cuts of meat, like pork shoulders, ribs or even briskets, as it’s perfectly possible to achieve the more moderate 250-300°F temperature range that is associated with low and slow barbecue smoking.

Not only does the technique allow you a greater deal of flexibility with how you cook, but it also introduces opportunities for using wood, as well as added techniques like smoking and reverse searing.

How Does Indirect Grilling Work?

When broken down into scientific terms, cooking is essentially the process of exposing food to a specific type of energy. The exposure to this energy makes the molecules in food vibrate, and when they vibrate fast enough, they produce heat and start the cooking process.

When grilling, energy can transfer to our food in three different ways: conduction, convection, or thermal radiation.

Conduction is the transfer of energy when in direct contact with an energy source. For example, in the case of grilling, this can be seen when we get grill marks on food. This is because the flames transfer heat energy to the grates, and the grates transfer that energy directly to the food leaving scorch marks.

Convection is the transfer of energy when carried by a fluid. When cooking, water and oil are the main fluids you think of, but air is also a fluid (thanks to the water droplets it holds). Even if food is not touching the hot metal grates in a grill, it can still be cooked by the hot air that surrounds it. Using 2-zone cooking creates a natural convection airflow from the hot to the cold side, meaning that the hot air circulates the whole grill.

It’s important to note that convection doesn’t cook food on its own. The hot airflow only cooks the outside of foods – the inside cooks via conduction as the heat energy builds up on the surface layer of the meat and then travels through.

Thermal Radiation is the transfer of energy by exposure to a source of light energy; in the case of grilling, this is infrared (IR) energy. Grilling a hotdog or toasting a marshmallow on a stick over a campfire are both prime examples of thermal radiation. Infrared is the way that most charcoal grills cook and is the best way to get high heat to food on a grill. Infrared is an intense wavelength of light that we can’t see with the naked eye; it’s the energy emitted by flames or glowing coals on the grill. It is an excellent source of direct heat, and that’s why food browns (or burns!) so quickly when cooked over flames. 

Direct grilling works mainly via conduction and thermal radiation; it cooks food quicker but also has the potential to burn more easily. 

Indirect grilling works via convection by creating an oven-like environment and also by conduction once the temperature builds on the surface and travels through the rest of the food.

How to Use Indirect Grilling on a Charcoal Grill

Setting up your charcoal grill for indirect grilling achieves the optimum environment for cooking those bigger cuts of meat.

Start by visually dividing your grill grate into two halves. One of these will be your direct heat zone, while the other will be your indirect zone.

With those two zones established, ignite your coals. The best way to do this is to use a chimney starter, with a natural firelighter placed underneath with your coals piled on top. Ignite the firelighter and leave the chimney to do its work by lighting the coals.

Once the coals have turned to white-ish embers, carefully pour them onto one side of your charcoal grill to create your direct heat zone.

If you have a thermometer probe, use a BBQ clip (like these on Amazon) to stage the probe on the grill grates. You want to do this in your indirect zone, below the top vent, to get the best measure of cooking temperature.

Finally, set both your intake vents (otherwise known as dampers) and exhaust vents to fully open. Once your thermometer is reporting a good cooking temperature of anywhere between 225-300°F (107-150°C), try closing them slightly to about two-thirds open. In theory, this should help slow the rate of combustion by limiting the amount of oxygen flowing through your grill’s chamber but truthfully there’s no hard-and-fast rule for this as every grill reacts differently. It’ll just take a bit of practice for you to get a sense of what works on your grill!