A closeup of the firebrick and cooking chamber floor. Gap in bricks was filled with refractory cement.
The floor of the cooking chamber is 1/4" steel plate. Heat and smoke enters the brick-lined lower plenum from the firebox and rises into the cooking chamber through the 8" round hole in the floor plate. The round cap diffuses the heat and smoke toward all corners of the smoker. The 1" ring welded around the opening is to prevent grease from dripping down into the lower plenum. The grease drain (1-1/4" pipe) is visible in the back left corner of the chamber.
