The most commonly used primary framing systems are shown below. All are shown symmetrical about the ridge line. Framing systems which are unsymmetrical about the ridge line, multi-span and multi-gable framing systems with unequal modules are possible but may require more engineering time.

Building Width: No matter what the primary framing systems used, the building width is defined as the distance from outside of eave strut of one sidewall to the outside of eave strut of the opposite sidewall.

Building length: The distance between the outside flanges of the end-wall is considered the building length. Building length is a combination of several bay lengths.