Building Systems
General Considerations:
  1. Buildings have various systems which perform specific functions. Some systems are primarily structural in nature. The primary purpose of structural systems is to carry the various loads which act on the building such as gravity and wind. Other systems are used primarily as enclosures. Enclosure systems transfer the weight of live loads to the structural system. They also separate the internal environment from the outside environment. Often enclosure systems add aesthetic value to the appearance and functioning of the building.

  2. Typically structural and enclosure parts of a building which are underground are referred to as substructure parts. Structural parts and enclosure parts which are above ground are superstructure parts.

  3. Footings and other foundation parts provide basic structural support for the building. They "attach" the building to the site. They carry the weight of the building to the bedrock of the earth, or earth (soil) which will support the gravity load. In addition, footings and foundations help the building to support wind loads which act upon it.

    Most residential buildings are supported on spread footings. A spread footing for most houses is made from concrete and reinforcement rod. The depth of these footings is usually equal to or greater than the thickness of the walls which they support. The width of the footings is usually at least twice as wide as the width of the wall. The spread footing spreads the load over a larger area, making the force per square inch on the soil below it less.

    Some buildings are built as a slab-on-grade meaning that the bottom floor is a reinforced concrete floor built at ground level. The load of the building is carried to the floor, and the floor "floats" on the surface of the ground to some extent.

    Larger buildings or structures often have caissons or pilings to carry building loads to the earth or bedrock. Caissons are produced by drilling a large diameter hole into the earth, sometimes 30 or more feet deep. Reinforcement rod is lowered into the caisson hole, and the hole is filled with concrete. Pilings are made of wood (perhaps the size of very long power line poles) concrete, or steel (often large H-beams) which are driven into the earth with a pile driver.

  4. Floor systems are horizontal enclosures which carry loads to walls and footings or foundation systems. In residential homes these systems are often framed with wide planks such as 2 x 10s or 2 x 12s called joists. Many floors in modern homes are supported by engineered beams or trusses. The rough floor or subfloor is usually made of plywood which is glued and/or nailed to the hoists. Often the joints of the plywood are fitted together using a tongue-and-groove joint. The plywood subfloor encloses the space and also adds considerable structural strength to the floor system.
UNDER CONSTRUCTION . . . NOT COMPLETE
Footings & FoundationsFloors, Walls, CeiliingsRoof Systems
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April 10, 2006