Dead loads are due to the weight of all materials that constitute a structural member. This also includes the weight of fixed equipments that are built into the structure, such as piping, ducts, air conditioning, and heating equipment. In buildings where partitions are likely to be erected, a uniform partition live load is provided in addition to the basic design loads, whether or not partitions are shown on plans. Partition live loads are not subjected to reduction for large effective areas. Roof live loads occur for a short time during the roofing or reroofing process. In load combinations, either the roof live load, or the snow load, is included because both are not likely to occur simultaneously. The estimation of dead load of a member requires knowledge about what items and materials constitute that member. A reasonable dead load for a structural member may be assumed, only to be revised when it is found to be grossly out of order.