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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).
By supporting the rafters they allow longer spans than the rafters alone could span, thus allowing a wider building. Purlin plates are very commonly found in large old barns in North America. A crown plate has similarities to a purlin plate but supports collar beams in the middle of a timber-framed building.
Key: 1: queen posts, 2: tie beam, 3: straining beam, 4: principal rafters. A queen post truss has two principal rafters and two vertical queen posts. [5] The queen post truss extends the span, and combined with spliced joints in the longer members extends the useful span for trusses of these types.
A hammer-beam is a form of timber roof truss, allowing a hammerbeam roof to span greater than the length of any individual piece of timber.In place of a normal tie beam spanning the entire width of the roof, short beams – the hammer beams – are supported by curved braces from the wall, and hammer posts or arch-braces are built on top to support the rafters and typically a collar beam.
Portal frame is a construction technique where vertical supports are connected to horizontal beams or trusses via fixed joints with designed-in moment-resisting capacity. [1] The result is wide spans and open floors. Portal frame structures can be constructed using a variety of materials and methods.
Greek: the ridge height is 1 ⁄ 9 to 1 ⁄ 7 the span (an angle of 12.5° to 16°); Roman: the ridge height is 2 ⁄ 9 to 1 ⁄ 3 the span (an angle of 24° to 34°); Common: the rafter length is 3 ⁄ 4 the span (about 48°); Gothic: the rafters equal the span (60°); and; Elizabethan: the rafters are longer than the span (more than 60°). [7]
In engineering, span is the distance between two adjacent structural supports (e.g., two piers) of a structural member (e.g., a beam). Span is measured in the horizontal direction either between the faces of the supports (clear span) or between the centers of the bearing surfaces (effective span): [1] A span can be closed by a solid beam or by ...
The top ends of the rafters often meet at a ridge beam, but may butt directly to another rafter to form a pair of rafters called a couple. Depending on the roof covering material, either horizontal laths , battens , or purlins are fixed to the rafters; or boards, plywood , or oriented strand board form the roof deck (also called the sheeting or ...