APEX/PEAK
The uppermost point of a TRUSS.

ASYMMETRIC TRUSS
A duo type truss that has a different pitch on both sides.

ATTIC TRUSS/ROOM-IN-THE-ROOF
A truss which forms a habitable space within the roof, the lack of internal webs is be compensated by larger timber sizes elsewhere.

B Top

BARGEBOARD
Board fitted to conceal roof timbers at the end Gable of a roof.

BATTENS
Small timber members which span over trusses to provide fixings for the roof covering e.g. tiles etc.

BEARER
A timber member designed to distribute loads over a number of trusses.

BEARING
The point or points at which the truss receives structural support. This is usually a wall plate but can be an internal wall etc.

BINDER
Timber member which can be a multiple installed at ceiling level to supporting other timbers or trusses, normally supported by multiply trusses on either side.

BIRDSMOUTH
A notch/seat cut in the underside of a RAFTER at the point of support (usually used with RAISED TIE TRUSSES).

BLOCKING
Short timbers fixed between chords to laterally brace them.

BOBTAIL
A truss type formed by truncating a normal triangular truss Also known as a STUB or STUB END TRUSS.

BOTTOM CHORD
See CEILING TIE.

BRACING
This can be Temporary, Stability or Wind Bracing which are described under these headings.

BUILDING DESIGNER
The person responsible for the structural stability and integrity of the building as a whole.

C

CANTILEVER
Occurs when part of a TRUSS extends beyond its normal bearing position.

CEILING TIE
The lowest member of a truss, usually horizontal which carries the ceiling construction,
Storage loads and water tank in an attic truss this is the floor joist.

CHEVRON BRACING
Diagonal bracing nailed to the truss in the plane of the specified webs to add stability

CONCENTRATED LOAD
A load applied at a point.

CONNECTOR PLATE
See NAILPLATE.

D

DEAD LOAD
The load produced by the fabric of the building, always long term e.g. Tiles, felt and Battens, (see DESIGN LOADS).

DEFLECTION
The deformation caused by the loads.

DESIGN LOADS
The loads for which the unit is designed. These can be either long term, medium term, short term or very short term Depending on their duration.

DUO PITCH TRUSS
A truss with two rafters meeting at the APEX having the same pitch on both sides.


E

EAVES
The line where the rafter meets the wall.


F

FASCIA
Board fitted along the length of the building to the edge of the truss overhangs.


FINK TRUSS
The most common type of truss used for Buildings. It is duo-pitch with the webs forming the letter W

FIRRING PIECE
A tapered timber member used to give a fall to flat roof areas.

FRENCH HEEL
An EAVES joint where the rafter sits on the ceiling tie often used in Girder Trusses.

G

GABLE END
The end wall which extends upwards vertically to the rafters parallel to the trusses.

GABLE LADDER
Components used to form an overhang at the gable end.

GIRDER TRUSS
A truss made up of two or more trusses Bolted and/or Nailed together and designed to the loads imposed by other trusses/timber members which are fixed to it.

H

HEEL
The point at which the Rafter and Ceiling tie intersect on a truss.

HIP BOARD
A timber member which forms the sloping ridge which runs normally from Apex to the corner intersection of overhangs on the end of a Hipped Roof.

HIP END
An alternative to a GABLE END where the end wall finishes at the same height as the adjacent walls. The pitch on this end can be different from the main pitch of the roof.

HORN/NIB
An extension of the ceiling/bottom chord of a truss which is built into masonry as a bearing.

I

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 WEB.

INTERSECTION
The position at which two or more roofs meet

J

JACK RAFTER
An infill rafter completing the roof surface in areas such as the hip corner of a roof.

L

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.

M

MONO TRUSS
A truss in the form of a right-angled triangle.

N

NAILPLATE
Metal PLATE having integral teeth punched from the plate material. Used to fix timber members together in truss production

NIB
See HORN.

NODE
Point on a truss where the members intersect.

NOGGINGS
Timber fixed between trusses at ceiling level to form fixing points.

O

OVERHANG
The Projection of a rafter or ceiling tie of a truss beyond its support.

P

PEAK
See APEX.

PITCH
The angle of the rafter to the horizontal, measured in degrees.

POLE PLATE
Timber used in for example in cantilevered hips to support loose Rafters.

PURLINS
Timber members spanning between trusses to support loose timbers. Often in the infill around velux windows and chimneys

Q

QUEEN POST Truss
Duo Pitch with three internal webs in the form of an inverted arrow head.

R

RAFTER
The sloping 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 below where the rafter meets the ceiling tie normally requiring
Heavier rafter timbers and closer centres depending on the distance and pitch.

REDUCING TRUSSES
See VALLEY SETS.

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 which provides support to loose rafters and can be itself supported between girder trusses

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.

ROOM IN THE ROOF
See ATTIC TRUSS.

S

SCAB
Additional timber fitted to the side of a truss to effect a local reinforcement, particularly in Raised tie Trusses and large attic trusses.

SETTING-OUT-POINT
The point on a truss where the undersides of the rafter and ceiling tie meet.

SKEW NAILING
A method of fixing trusses to the wall plate. (See TRUSS CLIP.)

SOFFIT
Board fixed underneath EAVES overhang along the length of the building to conceal timbers.

SPAN
Span over wall plate is the distance between the outside edges of the two supporting wall plates.
This is usually the overall length of the ceiling tie when the Truss span between setting out points is equal to the span over wall plates.

SPANDREL PANEL
A timber frame/panel forming gable wall above ceiling line.

SPLICE
A joint between two members in line using a NAILPLATE

STABILITY BRACING
An arrangement of additional timbers fixed in the roof space to provide lateral support to the trusses.

STRAP
Metal component designed to fix trusses or wall plates to walls.

STUB END/STUB TRUSS
See BOBTAIL.

T

TEMPORARY BRACING
An arrangement of diagonal loose timbers installed for safety during erection.

TIMBER STRESS GRADING
The classification of timber into different structural qualities based on strength (Truss Timber TR26).

TRIMMER
A piece of timber used to frame around openings.

TRUSS/TRUSSED RAFTER
A lightweight framework, generally but not always triangulated, Space at a maximum of 600mm to form the roofscape.

TRUSSED RAFTER DESIGNER
The person responsible for the design of the TRUSSED RAFTER as a component, and for specifying the points where design/compression bracing is required.

TRUSS CLIP
A metal component designed to provide a safe structural connection of trusses to wall plates.

TRUSS SHOE
A metal component designed to provide a structural connection and support for a truss to a girder or beam.

U Top

UNIFORMLY DISTRIBUTED LOAD (UDL)
A load which uniformly spread over a specified length.

V Top

VALLEY BOARD
A member used to support e.g. infill rafters in valley Construction

VALLEY FRAMES/SET
Frames used infill at the intersection of roofs.

VERGE
The line where the trussed rafters meet the gable wall.

W Top

WALLPLATE
A timber member laid along the length of the load-bearing walls to support the trusses. Normal 50mm deep by 100mm wide

WEBS
Timber members that form triangular patterns connecting the ceiling and rafters in a truss transmitting the loads between them.

WIND BRACING
An arrangement of additional timbers, or other structural elements in the roof space, specially designed to transmit wind forces to suitable load-bearing walls.