Offset Smoker Fire Management

The key to great tasting barbecue

Managing Fire

The firebox is the heart and soul of an offset smoker. Mastering the craft of fire management for great barbecue requires many hours spent in front of a firebox, so it should not come as a surprise that every pitmaster eventually develops their own unique methods and style. There are books, videos, forums, and in-person courses entirely dedicated to teaching the art of offset smoker fire management. Based on our experience, we’ve summarized how we like to tackle a few of key aspects of fire management below.

Wood Selection

The flavor that can be achieved when cooking with a wood fire is paramount in the barbecue world. When cooking on an offset smoker, burning wood is not only responsible for the flavor of the final product, it also acts as the fuel to provide the heat which cooks the food. With this in mind, it should be no surprise that choosing the right wood is absolutely critical to the success of the cook. Different species of wood will impart different types, depths, and strengths of smoke flavor and while this can be a matter of personal preference, it is generally recommended to use only wood from a fruit or nut bearing tree.

It is important that the wood has an appropriate moisture content, with around 15 - 20% being ideal in most cases. If the wood is too wet, it will not burn cleanly and can make fire management challenging; if the wood is too dry, it will burn quickly and may not impart enough flavor to the food. The time needed to season wood to an appropriate moisture content depends on the type of wood, the size of the log/split, and the environment in which it is seasoned. A moisture meter is a good investment and will provide peace of mind that the wood you’re using will be right for your cook.

Splits of wood should be sized appropriately to the dimensions of the firebox; backyard offset smokers often use splits that are 8 - 12 in. long and 2 - 4 in. diameter, while 250 - 1000 gallon commercial offsets may use splits that are 14 - 18 in. long and 4 - 6 in. diameter.

No two splits are exactly the same, and so it is important to learn and understand how any given piece of wood will impact the cook once it is added to the firebox. Dense pieces of wood will feel heavier than they look when picked up from the pile, and will provide many BTUs for long periods of time; this is perfect to add to the fire if you need to the offset to run at or near temperature for longer periods of time without any active fire management. Lighter pieces of wood will burn more quickly and are great for providing finer adjustment to the temperature of the cooker or to add a quick puff of smoke when it is needed to develop flavor. The best, cleanest looking splits should only be used during the portion of the cook where the meat is on the smoker and not wrapped - this is when all of the smoke flavor is developed. Gnarly, knotted pieces of wood are great for creating an initial coal bed when the cooking grates are empty, or after the meat has been wrapped and will no longer be exposed to the smoke from the fire.

Choosing a Split

"The best, cleanest looking splits should only be used during the portion of the cook where the meat is on the smoker and not wrapped - this is when all of the smoke flavor is developed."

Building a Coal Bed

There are many ways to build a fire within the firebox of an offset smoker, with our favorite being the ‘log cabin’ method. First, two large splits of wood are added to the firebox lengthwise to create a strong base; you will find that the shape of most wood splits will contour nicely to a round firebox. The horizontal separation between these first two splits will set the gap underneath the fire where the burning wood will eventually fall and create a bed of hot coals; this gap is usually around 3 - 4 in. high. Next, a second layer of wood is added horizontally across the first two pieces from end to end with gaps in between to allow for good air flow and heat rise; depending on the size of your firebox, this will usually be 2, 3, or 4 splits. At this point, tinder - something that can be easily lit using a lighter/torch and will burn hot and long enough to light the splits of wood - can be added to the space underneath and between the first two layers of splits; butcher paper left over from a brisket cook or or covered in grapeseed oil works really well for this, or you can simply make some kindling from your cookwood pile. Finally, a third and sometimes fourth layer of wood is stacked on top of the second layer in an alternating 90 degree pattern to finish the cabin. When building the initial log cabin, it is helpful to use relatively large pieces of wood in order to generate a substantial coal bed.

Lighting the fire can be done with a match or lighter, but a gas torch (please follow all manufacturer operating/safety guidelines) can speed up the process and can also be used to quickly add heat into the cook chamber to start creating some draft up through the smokestack; this early draft will help pull fresh air into the firebox and aid in quickly establishing a hot coal bed. With the firebox door (or damper) and smokestack wide open, allow the fire to burn until a hot coal bed is established and the cooker has heated up and reached a stable temperature - it is common to overshoot the desired cooking temperature when building the coal bed and this is ok; the temperature will eventually start to fall and new splits can be added as it starts to reach your target.

Kickstart your Fire

"Lighting the fire can be done with a match or lighter, but a gas torch can speed up the process and can also be used to quickly add heat into the cook chamber to start creating some draft up through the smokestack; this early draft will help pull fresh air into the firebox and aid in quickly establishing a hot coal bed."

Preheating Wood Splits

When a new split is added to the firebox, it needs to be heated to combustion temperatures before it will ignite; before this happens, the wood will pass through a wide temperature range in which it will smolder and produce much dirtier smoke. One way to minimize or eliminate the time that the wood spends within this temperature zone inside the firebox is to preheat each split before it is added. The most common way to preheat splits is to rest them on top of the hot firebox until they are needed; this will bring the splits closer to combustion temperatures but they will not get hot enough to ignite. Wood splits can also be preheated directly inside the firebox by locating them in a spot that doesn’t see hot coals or flame, though there is a risk that they may ignite and cause the cooker temperature to spike; a deep firebox will have much more space to make this work than will a shallow one.

Controlling Temperature

Maintaining a consistent temperature throughout the cook has a significant impact on the quality of the final product. While there are some who manage to keep their pits within a few degrees of their target, a good goal is to aim for no more than ± 5 - 10 degrees of variation for the majority of the cook. The temperature of the cook chamber will depend primarily on the size of the fire and coal bed in the firebox; however, the location of the fire within the firebox can also be important. A fire that is located directly at the throat between the firebox and the cook chamber will contribute more radiative heat to the cook chamber; radiative heat is not uniform and can create hot zones where food can dry out or burn. Locating the fire closer to the firebox door minimizes radiative heating and allows for more uniform, convection style heating across the cooking grates.

Each pit is unique, and understanding how the cook chamber temperature will respond to a new split being added/burned is something that requires time and experience; however, there are some guidelines that will always remain true. First, the temperature of a small backyard pit will tend to respond more quickly than a 250 or 500 gallon offset. This means that temperatures will rise more quickly and drastically when a new split is added, and temperatures will fall more quickly as that split is burned and consumed; this is why many find small offsets much harder to control than their larger counterparts. Second, there is always some ‘lag’ time between a new split being added to the fire and when the cook chamber temperature starts to rise again. This means that you should anticipate when a split is needed by monitoring the fire rather than waiting until the temperature gauge starts to fall below your target; if you wait, the temperature may continue to fall much lower than you would like before the heat from the new split can start to create balance. Finally, a heavy, dense piece of wood will have more BTUs to contribute to a fire than a light piece of wood. Adding a dense piece of wood to the fire will provide long lasting heat but there is a risk that the temperature may initially overshoot; light pieces of wood provide finer control of the pit temperature but need to be added more frequently. With experience, you will understand where, how, and when to add different types of splits to the fire to keep the temperature on target.

Holding Temperature

"...there is always some ‘lag’ time between a new split being added to the fire and when the cook chamber temperature starts to rise again. This means that you should anticipate when a split is needed by monitoring the fire rather than waiting until the temperature gauge starts to fall below your target."

Use the Smokestack damper

As you continue to refine your fire management skills, you will quickly learn that the ability to control the amount of smoke inside the pit throughout different phases of the cook will have a significant impact on the final product. During the early hours of a cook, it is often best to run a slightly smokier fire while the meat is cool and able to take on the maximum amount of flavor. Later in the cook when the meat is much hotter (or wrapped), a cleaner fire can be used to increase temperatures and cook more efficiently while avoiding adding too much 'bitter' taste. Many offset smokers have an adjustable damper on the smokestack that can act as a throttle for how much air is moving into the firebox and through the pit. By throttling the damper by as little as 25% (75% open), the airflow will slow down leading to a smokier fire and more trapped heat inside the pit. While smokiness can also be managed at the fire itself by changing the arrangement of the burning splits, the stack damper is the easiest - and most often underutilized - tool for the job.

After the Cook

Once the food has been pulled from the smoker, the fire can be left to burn itself out. While it may seem enticing to close every door and damper to remove all air from the firebox and speed up the process, most pits are not 100% air tight and this will only cause the fire to smolder for a long time and cause much dirtier smoke to collect inside the pit. Our preferred method is to allow the fire to burn out naturally with the dampers and doors open. Once the fire is out, the pit can be closed up and allowed to cool down before cleaning the following day.