On Center (OC)

What is On Center (OC)?

Definition of On Center ( OC ) in Construction
This references an on-center spacing of components.

This means the distance from the middle of one element to the middle of the next. For example, on center dimensions in a wall framing system, is normally from the middle of a stud to the middle of the next stud. If the elements are common in dimension, then the edge to edge spacing is also the same. The on center designation is also commonly used in the placement of reinforcing steel within a concrete structure, or the designation of repetitive elements within a structure. Roof joists, floor joist, purlins, beams, etc., are all designated on the structural documents with an on center spacing. When attaching something on a interior wall or exterior wall, knowledge of the on center spacing of the supportive structure is important, to ensure that the support for the product hung on the wall, is directly attached to the structural members framing the wall. Most wood framing systems ( residential ) are constructed at a 16″ on center spacing, so starting from a corner, the normal placement of a supporting member would be 16″ from the corner to the edge of the next framing member. On center designation, is a common phrase in construction and can be applied to consistently located windows, doors, architectural elements, etc.n.