Conventional and nonconventional codes regulate the strength needed in the walls, floors, roofs, and connections to resist the forces on buildings. The conventional code describes a prescriptive standard to resist the forces. The standard applies to simple buildings using common construction methods. The nonconventional code is a performance-rated system and provides non-prescriptive engineering
guidelines that can be applied to more unusual or more difficult buildings.
The prescriptive format has specific requirements, such as the size of studs needed or the type of wall bracing. If you build the structure following these requirements, then the building meets the minimum code standards for a safe building. The prescriptive codes are covered in more detail in Chapter 10.
Framers meet prescriptive code requirements on a regular basis, sometimes without even knowing it. As they brace their walls, block and nail their floor system, nail their walls to the floors, and bolt the building to the foundation, they are creating a load path that transfers the forces of nature to the ground-in ways that are prescribed by the code.
The performance, or non-prescriptive, code provides for free design, as long as it stays within certain code standards. Performance designing is different for each building, and the engineer or architect must specify and detail all aspects of the design.
A special design might be needed because a building is in a high-earthquake or a high-wind zone, because it requires large open spaces or window walls, or to resist other forces. The most common forces affecting buildings are shown in the illustration “Forces on Buildings."
A
Snow load Gravity
