A clear span is an open area without any structural supports that allows the user of a space to stack items in a variety of configurations without having to worry about obstacles. The more clear span available, the more useful the space will be. Some important design considerations are involved in clear span construction, as the building needs structural support, and this can be challenging when easy support methods like placing pillars in the middle of a room are not available.
This is typically a concern with industrial buildings like barns and warehouses. A large clear span means more room with which to work, and can make a building more efficient. If the building must be organized around supporting pillars and trusses, the user finds it less usable. In a barn, for example, it is not possible to pack in as much hay when the piles must make way for pillars, or when the beams in the roof are too low.
Builders can measure clear span between pillars, walls and columns. The structural supports of the building are located in the walls and may be larger than usual to accommodate the strain of the roof. The network of trusses and supports in the roof is carefully assembled to distribute weight evenly to the walls without sagging in the middle. Lightweight building materials can reduce the load, and metal may be a material of choice because of its strength and durability.
A client contracting for a new building can put in clear span requirements and solicit bids from multiple companies. Architects bidding on large projects may need to work with construction engineers to design a safe building, and the building inspector will evaluate the plans for signs of weakness or causes for concern. Once the project is approved, construction can commence. Temporary supports may need to be positioned under the roof during building, until the walls and trusses are wholly stable and the temporary pillars can be removed.
Clearance is especially important in facilities where large items are stored. Inadequate room can make it harder to store supplies and may also make it difficult to move vehicles like forklifts and delivery trucks. Personnel may also have difficulty stacking cartons and other containers if the clear span is not sufficient. Companies with an interest in buying a warehouse usually want precise internal measurements to determine if it will meet their needs.