What is Ballast in Construction?

Definition: What Does the Term Ballast Mean?
Normally the reference to any weight that is designed to hold down a structure or roof. The construction reference, in many cases, is the layer of stone that is installed above a roof deck, whether it is a built up roofing system or a single ply system. Roof ballast can be an architectural material such as white washed stone, or can simply be clean gravel. The depth of the ballast is normally based upon the exposure of the roof material / or whatever is being held down, to the environment and the local weather conditions. Shoreline areas will receive a heavier concentration of material, due to the constant prevailing winds off the ocean. Ballast can also be used to hold down liners of all sorts, or tarps and sheathing that the completed hold down systems have not been completed for. Ballast is extremely important when burying an underground tank or vessel. The buoyancy of an underground container of any type, if surrounded by water, is tremendous, and the tendency to blow out of the ground if the proper amount of ballast is not maintained is extremely likely. The simple filling of an underground tank or vessel is also considered ballast to hold down the tank. Ballast is a universal term for anything that is holding down another system.