The Ultimate Guide: Build Your Own Offset Smoker

Updated: 03/27/21 •  6 min read

Last Updated on November 24, 2022

Jim Bob – A long-time contributor to GrillBabyGrill. Jim has had a lifelong relationship with the art of grilling, passed on from his father and grandfather to him.

The Ultimate Guide: Build Your Own Offset Smoker

Offset smokers use indirect heat to cook meat and vegetables low and slow, giving you juicy, tender dishes every time. There is a wealth of outstanding offset grill models available, but with all the different features and brands, it can be overwhelming to find the right one for you.

When you build your own offset smoker, you can choose all the features you want, from fuel type to how your insulation and airflow are constructed. This is the ultimate guide for those who want to rise to the challenge.

1. What is an Offset Smoker?

An offset smoker is a basic cooking apparatus, and its main job is to generate enough warm smoke for a sustained amount of time.

An offset smoker requires two important components: a firebox and the main chamber. The firebox is where the heat comes from. The main chamber is where all the food will be cooked.

These two sections need to be connected for the smoker to work. Vents must be installed to regulate airflow, which will manage the heat and ensure the smoke doesn’t overpower the food.

2. Building Safety

You can create a high-quality smoker from a few simple materials, including metal barrels or an old gas tank. 

If you have sourced used barrels, it’s imperative that you find out whether any chemicals have been previously stored in them. This is a major health and safety hazard as barrels may have previously stored flammable or toxic substances.

Ideally, use two 33 gallon barrels. Don’t worry if they are slightly smaller or bigger. However, the bigger the barrel, the longer the smoker will take to heat the main chamber, meaning you may find it harder to control the temperature. 

To secure the main chamber to the firebox and raise the structure off the ground, you’ll need to secure it to a sturdy frame. The ideal frame should be constructed from metal which means you may need to perform some welding

A MIG welder is not only much faster, but it’s also a more affordable technique.

3. Build Your Frame

To eliminate fire risks, build your frame from steel. Because a DIY build means you can customize the frame to suit your needs, build the frame so that the main chamber will be at waist height. This ergonomic design ensures you won’t need to bend over to check the progress of your smoking meat continuously. 

Source 1” square steel, and use an angle grinder or chop saw to cut the frame to your specifications. The rectangular box frame should be ½-1” smaller than the width and length of the barrel for the main chamber. You don’t need any fasteners on the frame as the barrel should sit neatly in the frame—weld the steel together.

4. Cut Your Barrels

If your barrels are similar in size, cut out a section of the one you’re using for your firebox and scale it down. This is because it doesn’t need to be as big as the chamber barrel.

Cut a door in the chamber barrel, but make sure the hole is large with rounded corners to prevent injuring yourself. Cut as smoothly as you can to eliminate smoke leaking when you cook. Cut a matching smaller door in your firebox barrel.

5. Welding Time

If you removed a part of the small barrel, weld it back together. Arrange the two barrels, so they are configured in an offset design with the top section of the firebox barrel to the bottom of the chamber. 

Mark and cut two small holes where the two barrels connect. Weld together the small and large barrel using the cuts as a guide. There needs to be a passage between the two to ensure a steady flow of smoke.

6. Cutting the Vents

You need to make holes on each end of your offset smoker to build the vents mentioned earlier. Specifically, these are the intake and exhaust vents. Be generous with sizing, as a good amount of air will need to flow in and out of the smoker.

For the firebox intake, make a circular incision. Make another round hole for the exhaust on the side of the cooking chamber.

7. Extras and Attachments

Offset smokers require attachments in the same way DIY pellet smokers do. A crucial attachment is an exhaust pipe for the exhaust damper. All you need is a heat ductor elbow, which is readily available at your local hardware store. Ideally, purchase one around 3’ long.

You’ll also need a damper to control how much air flows into your intake hole.

To give your smoker an extra flair, install handles to keep it stable. You may also want to add casters to your offset smoker to make it portable. If you want to protect it from cold winter weather, you can also purchase a welding blanket for insulation.

8. How to Mount the Grates?

Now you’ve built the structure; you’re going to need something to cook on. Invest in some sturdy grill grates and hangers. You can weld these into your chamber to keep everything together. Or add small metal mounts to the inside of the chamber so you can rest the grates on top and remove them easily for cleaning.

9. The Importance of Controlling Air Flow

This is probably the most important aspect in the whole build; the smoking process mechanics rely on the fact that air needs to flow through the smoker. 

The air needs to pass into the smoker box and bring the heat to the main chamber before it can leave through the exhaust vent you built.

The airflow is responsible for maintaining a healthy oxygen supply and ensuring the fire burns efficiently. It also helps smoke escape so that there is not an excessive build-up, tainting your food with a bitter creosote flavor. 

Its in the tips on using offset smoker that one should have a well-maintained flow of air and level of smoke will ensure that all the food cooked on the smoker will be infused with that infamous smoky BBQ flavor.

Jim B.

Jim has had a lifelong relationship with the art of grilling, passed on from his father and grandfather to him. To him, grilling is more than just a way to cookit’s a way of life, and his travels have taken him far and wide, around the country and beyond to find the best there is in grilling and techniques. Every product he reviews is painstakingly looked over and tested using his extensive knowledge of the craft and personal experience. He currently lives in Tennessee, though never stays in one place for long.