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Glossary of Terms used in Trussed Rafter Construction
Hip End
An alternative to a GABLE END where the end wall finishes at the same height as the adjacent walls. The roof inclines from the end wall, usually (but not always) at the same PITCH as the main trusses.
 
Hip Set
The trusses, girders and loose timbers required to form a hip end.
 
Horn/nib
An extension of the ceiling tie of a truss (usually monos or bobtailed trusses) which is built into masonry as a bearing.
 
Imposed Load
The load produced by occupancy and use including storage, inhabitants, moveable partitions and snow but not wind. Can be long, medium or short term.
 
Internal Member
See Webs.
 
Intersection
The area where roofs meet.
 
Jack Rafter
An infill rafter completing the roof surface in areas such as corners of HIP ENDS or around chimneys.
 
Live Load
Term sometimes used for IMPOSED LOADS. 
 
Longitudinal Bracing
Component of STABILITY BRACING.
 
Loose Timber
Timbers not part of a truss but added to form the roof in areas where trusses cannot be used.
 
Mono-Pitch Truss
A truss in the form of a right-angled triangle with a single rafter.
 
Nailplate
Metal PLATE having integral teeth punched from the plate material. It is used for joining timber in one plane with no overlap. It will have an accreditation certificate and will be manufactured, usually, from galvanised steel. It is also available in stainless steel.
 
Nib
See HORN
 
Node
Point on a truss where the members intersect.
 
Noggings
Timber pieces fitted at right angles between the trussed rafters to form fixing points.
 
Overhang
The extension of a rafter or ceiling tie of a truss beyond its support or bearing.
Part Profile
See BOBTAIL.
 
Peak
See APEX.
 
Permissible Stresses
Design stresses for grades of timber published in BS5268: Part2:
 
Pitch
The angle of the chords to the horizontal, measured in degrees.
 
Plate
See NAILPLATE.
 
Purlins
Timber members spanning over trusses to support cladding or between trusses to support loose timbers.
 
Quarter Point
The point on a rafter where the web intersects in a FINK TRUSS.
 
Queen
Internal member (WEB) which connects the APEX to a third point on a FINK TRUSS.
 
Rafter
The uppermost member of a truss which normally carries the roof covering.
 
Rafter Diagonal Bracing
Component of STABILITY BRACING.
 
Raised Tie Truss
A truss which is supported at a point on the rafter which is beyond the point where the rafter meets the ceiling tie.
 
Reducing Trusses
See VALLEY FRAMES.
 
Remedial Detail
A modification produced by the TRUSSED RAFTER DESIGNER to overcome a problem with the truss after its manufacture.
 
Return Span
The span of a truss being supported by a girder.
 
Ridge
The line formed by the truss apexes.
 
Ridgeboard
Timber running along a ridge and sandwiched between loose rafters.
 
Roof Designer
The person responsible for the roof structure as a whole and who takes into account its stability and capability of transmitting wind forces on the roof to
suitable load-bearing walls.