Building a BBQ Smoker: Part 4. One issue that is not frequently discussed when building a fire box is the grate height from the floor of the smoker, where your coals rest. Personally, I like to have grate at least 3-4 inches or ¼ of the total height of the firebox off the floor of the fire box so ash can fall down , and air can move easily through. The material that comprises the grate has to be heavy enough to hold the weight of the wood and coals while red hot. Regular expanded metal won’t do it. If expanded metal is to be used, it needs to be out of the actual raised, grating rather than the flat metal. I personally like to use catwalk material. A lot of this catwalk material is galvanized, so you have to be sure to get some uncoated, unpainted material. Another option that I like to use is to use heavy ½” plate steel, and use a plasma cutter to cut slats into the plate. I have also built them out of round bar. If you are fortunate, you may even be able to find cast grating that fits your fire box dimensions. If nothing else, a grate for a fire place can be adapted to fit. Make sure whatever style is used, that the grating is easily replaceable. Additionally in terms of longevity, a floor liner can be used to prevent bottom burn out. If you have enough room, split fire brick is a good idea as it holds the heat, and offers decent bottom burnout protection if the smoker is cleaned and serviced after use. One of the first smokers I built needs a new firebox welded right now because of bottom burnout. Another cause of bottom burnout, is using too thin of material for the fire box. Ideally the fire box should be made out of material that is considerably thicker than the main smoke chamber. Usually for non commercial duty, 11 gauges are sufficient care is taken after every cook to wash and re-season the inside with protective vegetable oil while it is still warm.
Posted on: Tue, 13 Aug 2013 03:30:00 +0000