A firebrandís effectiveness in contributing to spot fires is driven by its size, which determines the distance it will travel. The firebrand must continue to burn as it is transported, still be a viable heat source when it lands, and land on a receptive fuelbed. Natural fuel, such as cone scales, grass clumps, bark flakes, parts of branchwood, and moss, constitute potential firebrand material (Andrews 1996).
While firebrands can be lofted from surface fires, they are much more common from torching trees, active crown fires, or accumulations of fuel. Firebrands and the spot fires they cause can be a major contributor to fire growth (Andrews 1996).