Principal rafters are sometimes simply called "principals". Common rafter (minor rafter): being smaller than a principal rafter. A "principal/common rafter roof" or "double roof" has both principals and commons. (Also called major/minor, primary/secondary). Auxiliary (cushon, compound, secondary, sub-) rafter: A secondary rafter below and supporting a principal rafter. A rare type of rafter. Compass rafter: A rafter curved or bowed on the top (the top surface of a rafter is called its "back") or both the top and bottom surfaces. Curb rafter: The upper rafters in a curb (kerb, gambrel, Mansard roof) roof. Hip rafter (angle rafter): The rafter in the corners of a hip roof. The foot of a hip rafter lands on a dragon beam. King rafter: the longest rafter on the side of a hip roof in line with the ridge. Valley rafter (historically also called a sleeper): A rafter forming a valley (look for illustration showing a valley). Intermediate rafter: "one between principal or common rafters to strengthen a given place" (rare). Jack rafter, cripple rafter, cripple-jack rafter: A shortened rafter such as landing on a hip rafter or interrupted by a dormer. Arched rafter: Of segmental form in an arched roof. Knee (crook, kneeling, cranked) rafter: A rafter with a bend typically a few feet from the foot used to gain attic space like adding a kneewall. Rare in America. Barge rafter: The outermost rafter on a gable end, sometimes forming a roof overhang. Butt rafter: A smaller rafter interrupted by and joined to a butt purlin. Common rafters pass over and are supported by a principal purlin, if present. A "binding rafter" is not a rafter but an obsolete name for a purlin or support. Part of a cruck frame may function as a rafter but they are called a cruck blade. Rafters are usually made of pine or cedar. For longer span rafters, building materials manufacturers have created LVL (Laminated veneer lumber) rafters that can be 2–5 times longer than typical wood rafter. In US, most wood rafters have maximum length of 20 feet. If a longer rafter is needed, LVL is the ideal combination alternative. See also Birdsmouth joint Chantlate Fascia (architecture) Joist knee wall Lookout (architecture) Purlin Rafter angle square Soffit Truss Timber framing Timber roof truss Wind brace References Roofs Building engineering Structural system Carpentry