Stud is an ancient word related to similar words in Old English, Old Norse, Middle High German, and Old Teutonic generally meaning prop or support. Other historical words with similar meaning are quarter and scantling. Stick is a colloquial term for both framing lumber and a "timber tree". Thus the names "stick and platform", "stick and frame", "stick and box", or simply stick framing. The stud height usually determines the ceiling height thus sayings like: "...These rooms were usually high in stud..."
Purpose
Studs form walls and may carry vertical structural loads or be non load-bearing such as in partition walls which only separate spaces. They hold in place the windows, doors, interior finish, exterior sheathing or siding, insulation and utilities and help give shape to a building. Studs run from sill plate to wall plate. In modern construction studs are fastened to the plates in a way, such as using ties, to prevent the building from being lifted off the foundation by severe wind or earthquake.
Properties
Studs are usually slender, so more studs are needed than in post and beam framing. Sometimes studs are long, as in balloon framing, where the studs extend two stories and carry a ledger which carries joists. Balloon framing has been made illegal in new construction in many jurisdictions for fire safety reasons because the open wall cavities allow fire to quickly spread such as from a basement to an attic; the plates and platforms in platform framing providing an automatic fire stop inside the walls, and so are deemed much safer by fire safety officials. Being thinner and lighter, stick construction techniques are easier to cut and carry and is speedier than the timber framing. In the United States and Canada, studs are traditionally made of wood, usually 2×4 or 2×6 by name; however, these historical dimensions have been reduced but still carry the name of "two by four" and "two by six". Typical dimensions of today's "two by four" is dimensional lumber and typically placed from each other's center, but sometimes also at or. The wood needs to be dry when used, or problems may occur as the studs shrink and twist as they dry out. Steel studs are gaining popularity, especially for non load-bearing walls, and are required in some firewalls.
Other terms
Studs used to frame around window and door openings are given different names, including
king stud − stud to left or right of a window or door that is continuous from the bottom plate to the top plate
trimmer or jack − stud to the left or right of a window or door that runs from the bottom plate to the underside of a lintel or header
cripple stud – a stud located either above or below a framed opening, that does not run the full height of the wall
post or column − a doubled or other integral multiple of a group of studs nailed side by side. Posts in walls are used at point loads such as long spans near a wide window or sliding door, etc.
A building technique mostly associated with Lincolnshire, England, and parts of Scotland gets part of its name from the studs: mud and stud. This building method uses studs in a framework which is then totally covered with mud which resembles the building material cob. Another traditional building method is called stud and plaster where the plaster walls are held by lath on the studs. Studs are also the namesake of a type of timber framing called close studding.
Grades
Based on the American West Coast Lumber Inspection Bureau grading rules, there is only one grade of stud: STUD. A stud is graded for vertical application and its stress requirements and allowable visual defects reflect that application. A stud is most similar to a #2 grade, which is held to a higher standard during grading. The biggest difference between the two is the frequency, placement and size of knots and overall allowable wane.
