What Does On-Center Stud Spacing Mean?
Stud spacing is normally described as "on center," or OC. This means the distance is measured from the center of one stud to the center of the next rather than from one edge of a stud to another.
Common spacing in wood-framed walls includes 16 inches and 24 inches on center, although the spacing required for a particular wall depends on its construction and structural requirements. Using consistent on-center spacing also helps sheet materials such as drywall and sheathing land on predictable framing locations.
Why a Wall Needs More Than Regularly Spaced Studs
Simply dividing the length of a wall by the stud spacing doesn't give a complete framing-material estimate. Walls normally require framing at their ends, and additional studs may be needed at corners, where walls intersect, and around doors and windows.
Framed openings can require king studs, jack or trimmer studs, and cripple studs in addition to the regular wall layout. The exact framing detail depends on the opening and how the wall is being constructed.
Stud Length and Wall Height Are Not the Same
The vertical studs in a framed wall are normally shorter than the finished wall height because the studs fit between the bottom and top plates.
For example, adding another top-plate layer changes the available vertical space between the plates. When cutting studs rather than purchasing precut lengths, use the actual thickness of the lumber and the planned number of plate layers to determine the required stud length.
Plan Openings Before Laying Out the Wall
Knowing where doors and windows will be located before laying out the studs can make framing easier. A regular stud position may fall inside a planned opening and need to be replaced by the framing arrangement used around that opening.
Marking the wall ends, openings, corners, intersections, and regular stud locations before cutting or assembling the wall can also make it easier to compare the planned layout with the calculated material quantities.