Framed opening with removable cover providing access to the attic.
BEARING
A structural support, usually a beam or wall that is designed by the building designer
to carry truss reaction loads to the foundation.
BENDING MOMENT
Term used in the analysis of the internal stresses across the cross section of a member
(chord or web) when it is subjected to forces which cause it to bend.
BOB-TAIL
A term used to describe a gable shaped truss that is clipped at the end.
BOTTOM CHORD UPSET
Same as BUTT CUT
BOTTOM CHORD
An inclined or horizontal member that establishes the bottom of a truss. An example of
an inclined bottom chord member is the bottom chord of a scissors truss or a truss
positioned between supports at different elevations.
BOTTOM CHORD BEARING
Term usually used to describe the bearing condition of a parallel chord truss that bears
on its bottom chord.
BRIDGING
Wood or metal members that are placed between trusses and joists in an angled
position intended to spread the loads.
BIRDSMOUTH CUT
A long notch at the ends of a member to allow for an overhang "over the wall
height" less than the width of the member.
BUILDING DESIGNER
Registered architect or registered engineer who is responsible for the design of the
building.
BUILDING OFFICIALS AND CODE ADMINISTRATORS INTERNATIONAL (BOCA)
A model building code located in Country Club Hills, IL, serving primarily the North
Central and Northeast United States.
BUILT-UP ROOF
Roofing composed of three to five layers of asphalt.
BUTT CUT
Slight vertical cut at outside edge of truss bottom chord to ensure uniform nominal span
and tight joints.
BUTT JOINT
The interface at which the ends of two members or other members meet in a
square cut joint.
CAD
Computer aided design and drafting (software).
CAMBER
An upward curvature built into a truss bottom chord to compensate for
deflection due to loading conditions.
CANTILEVER
The part of a truss that extends beyond its support, exclusive of overhang.
CENTER LINE SPAN
Theoretical span sometimes used to design trusses.
CLEAR SPAN
(Clear Opening) GeneralIy indicates the inside or interior frame to frame dimensions.
Not to be confused with SPAN
CLINCHED NAIL
A nail selected to be longer than the member it is driven through and which is
bent back the dimension of its excess length.
CLIPPED (CLIPPED END)
Same as stubbed or stub truss.
COLLAR BEAM
Wooden member connecting opposite roof rafters.
COLLAR TIE
A horizontal member placed between two rafters a specific vertical distance
above the very top plate line for the purpose of limiting outward thrust of the rafters.
COMPOSITE LUMBER
(Structural, wood composites) A family of materials that contain wood in whole or
fiber form bound together with an adhesive of natural or synthetic form.
COMPOUND CUT
A double cut made across the member width.
CONTRACT DOCUMENTS
Architectural drawings (plans), specifications, etc., used to produce a structure.
CONVENTIONAL FRAMING.
(Common Framing) Framing with conventional joists, rafters and wall studs.
CREEP
Time-dependent deformation of a structural member under constant load.
CRICKET
A ridge or drainage diverting roof framing. Generally found on the high sloped end
of a chimney.
CUTTING SHEETS
A diagram of lumber lengths and angles of cut for truss web members and chords.
CUTTING BILL
See CUTTING SHEETS
DIRECT NAIL
To nail perpendicular to the member being nailed.
DRYWALL
Interior finish material sheet manufactured with gypsum (gypsum board).
FASCIA.
The flat surface located at the outer end of a roof overhang or cantilever end
FEATHER CUT
A heel cut which has been made with a zero butt cut (a sawn member with a feathered
edge).
FlREPLACE TRUSS .
A truss which has a modified shape to allow for penetration of a roof chimney whose
loads are supported by a fireplace master (girder) truss. This truss requires special
engineering.
GABLE END FRAME
A component manufactured to the profile of the mating common truss. It has
vertical "in-plane" members fastened to the chords instead of diagonal web
members. It is not a structural truss and requires continuous support by a bearing wall or
other load bearing element such as a beam along the bottom chord.
GABLE
The portion of the roof above the eave line of a double sloped roof.
GAMBREL
A roof having two slopes on each side, the lower slope usually steeper than the
upper one.
GIRDER TRUSS
A truss designed to carry heavy loads from other structural members framing
into it. Usually a multiple ply truss.
HARDWARE
A computer and its peripherals (printer, plotter, etc.)
HEADER
A conventionally framed wood girder located between stud, joist, rafter, or
truss openings.
HEEL JOINT
The point on the truss where the top and bottom chords intersect.
HIP MASTER
Hip girder truss designed to carry prefabricated roof jacks or common framing and hip
corners.
HYDRAULIC PRESS
A press consisting of a "C" clamp hydraulic cylinder; or an l-beam
platen, or flat upper pressing platen, powered by hydrauIic cylinders which are used to
embed truss connector plates.
INTERIOR BEARING
Term used to describe supports which are interior to two exterior supports.
JIG
The fixture which holds the truss in position until rigidly fastened with
connectors.
JOINT
See PANEL POINT
JOIST
A horizontal roof or floor framing member.
KICKER
Alternate expression for a truss web member cantilever strut.
KNEE BRACE
A brace positioned between a column and truss panel points when trusses are
supported by columns lacking transverse bracing.
LADDER PANEL
Prefabricated wall panel fastened to the roof eave to create a sloped overhang.
LATERAL BRACING
Members placed and connected at right angles to a chord or web member of a truss.
LET TAILS RUN
When a piece of lumber making up the top chord is not cut off to a specified
overhang length, but retains the length of the lumber used for the purpose of meeting
specific overhang requirements in the field.
LEVEL RETURN
Lumber filler placed horizontally from the end of an overhang to the outside wall to
form a soffit.
LVL
Laminated Veneer Lumber.
MITER CUT
A single cut made at an angle to the member length.
MODEM
An electronic device used to transmit information from one computer to another
by means of telephone lines.
MOE
Modulus of Elasticity.
MOMENT
A force that produces rotation of a member and commensurate bending stresses.
MPCWT
Metal plate connected wood truss.
MSR
Machine stress rated lumber.
NAIL-ON PLATE
Light-gauge cold-formed steel truss connector plates with pre-punched holes or, if
cut to size, without holes having identifying marks through which nails are driven by hand
or pneumatic means into the lumber. They are usually located on the near face and far face
of the joint.
NAILER (Scab)
A member fastened to another member by nails for reinforcement.
NATIONAL DESIGN SPECIFICATION (NDS) FOR WOOD CONSTRUCTION
Publication of the American Forest & Paper Association (AFPA) providing an
appendix of lumber sizes, grades, species and allowable stresses.
NATIONAL DESIGN STANDARD FOR METAL PLATE CONNECTED WOOD TRUSS CONSTRUCTION
A publication of the Truss Plate Institute (TPI) being developed under the ANSI
consensus process, to be designated as an ANSI/TPI standard.
NATIONAL EVALUATION REPORT (NER)
Product acceptance research evaluation report prepared for construction products that
are not in the building code. This evaluation report is prepared by the model building
code group under the Council of American Building Officials (CABO).
NET FREE VENTILATED AREA
Area required by building codes to allow for proper ventilation in enclosed
building spaces.
NOMINAL SPAN
Horizontal distance between outside edges of supports.
NOTCH
A vertical and crosswise horizontal cut at the end of the chord, joist or rafter.
ON EDGE
Vertical placement of a member's wide edge.
ON THE FLAT
Horizontal placement of a member's wide edge.
OUT-TO-OUT SPAN
Same as OVERALL SPAN
OUTRIGGER
A wood member nailed to a truss to form an overhang beyond the wall line.
OVERALL SPAN
Outside of frame dimensions (not outside of veneer dimensions).
OVERHANG
The extension of the top chord of a truss beyond the outside of the bearing support.
PCT
Parallel chord trusses.
P.E.
Licensed registered professional engineer.
PANEL POINT
The location on a truss where the web members intersect the top and bottom
chord.
PANEL
The chord segment defined by two adjacent joints.
PANEL LENGTH
The distance between joints measured along the chord center line.
PEAK
Point on the truss where the sloped chords meet.
PENNY
Common nail length. Originally, nails were sold by "penny weight", or
price per hundred.
PIGGY BACK TRUSS
A truss made in two pieces usually consisting of a hip type truss with a triangular
cap fastened to it. Designed when shipping or manufacturing limitations are affected by
overall truss height.
PITCH
The incline angle of the roof described as the ratio of the total rise of the roof to
the total width of the structure. For example, a 10 foot rise and a 30 foot width gives a
roof pitch of one third. The roof pitch is also designated as the angle that the top chord
makes with the lower chord such as a 20 pitch or a 45 pitch.
PLACING DRAWING
Line drawing used to located assumed placement positions of roof and floor
trusses by truss fabricator.
PLUMB CUT
Top chord end cut to provide for vertical (plumb) installation of fascia.
PLY
One truss of a girder truss.
PPSA
Purdue Plane Structures Analyzer. A wood structures computer program developed at Purdue
University. The latest edition is Version 4.
PRESS
A term used to describe the device used to embed truss connector plates.
PRESS-ON PLATE
A truss connector manufactured with pre-formed teeth that are embedded into the
lumber usually by an air or hydraulic press.
PROFILE DRAWING
Sketches of truss profiles used by mechanical engineer to determine where
mechanical ducts, piping, etc., are located.
PSL
Parallel strand lumber.
PURLIN
A horizontal member attached perpendicular to the truss top chord for support of the
roofing (i .e., corrugated roofing or plywood and shingles).
RAFTER
A sloping roof framing member.
RAKE
Edge of a roof with the intersection of the gable.
RAKE OVERHANG PANEL
Prefabricated overhang panel that extends over the edge of the roof and is fastened
to the gable end truss.
REVIEW ENGINEER
Term used to define the truss engineer who checks and certifies computer generated
designs of the truss fabricator. The review engineer may be an employee experienced in the
design and testing of trusses, and assigned this responsibility by a truss plate
manufacturer. He may also be an independent consultant experienced in the design and
testing of metal plate connected trusses, and contracted by the truss fabricator to
perform such services. Computer generated designs are assumed to be reviewed and checked
on the review engineer's computer.
RIDGE
The horizontal line made by the top surfaces of the two sloping roof surfaces
RIDGE VENT
A prefabricated and formed metal strip placed along the apex of the roof to allow
exhaust ventilation in combination with intake soffit or gable end ventilation.
RISE
Vertical distance form the bottom of the bottom chord to bottom (inside) of the
top chord.
ROLLER PRESS
A press that embeds connector plates by forcing them through two opposing rollers.
ROOF SCUTTLE
Framed opening in commercial roofs surrounded by a hinged door used for access to a
commercial roof.
SCUPPER
Roof drain.
SET BACK
The distance from the outside edge of the wall exclusive of veneer to the face of a hip
master (girder) truss.
SHOP DRAWING
Drawings of roof trusses prepared by the truss fabricator from truss engineering
drawings used to fabricate trusses.
SHOULDER JOINT
Same as BREAK POINT JOINT.
SLIDER
Two inch dimension Lumber inserted between the top and bottom chords at the heel
joint in the plane of the truss to reinforce the top or bottom chord.
SLOPE
The incline angle of the roof described in inches of rise per foot of run (e.g.,
6/12).
SLOPED SOFFIT
Sloped overhang with no level return .
SOFFIT VENTS
Prefabricated soffit material with perforated openings created for the purpose of
providing intake ventilation.
SOFFIT
The underside of a roof overhang or truss cantilever end.
SOFTWARE
Computer programs used to create management and engineering information, etc.
SPAN
Term generally used to communicate out-to-out span or overall span of a truss
design. Sometimes also indicates center line to centerline of bearing.
SPIKED
Nailed.
SPLICE POINT
The point at which two chord members are joined together to form a single
member. It may occur at a panel point or between panel points.
SQUARE CUT
End of top chord perpendicular to the slope of the member. Cut made at 90 to the
length of the member.
STACKED CHORDS
Term used for agricultural trusses when two members are positioned on top of each other
to create a bottom chord.
STRINGER
Lumber industry terminology for lumber graded with respect to its strength in
bending when loaded on the narrow face. Used for cross members in floors or ceilings.
STRONGBACK
Two inch dimensional framing member attached perpendicular to floor trusses often
through the chase opening and placed vertically against the vertical web.
STUB TRUSS
Same as BOB TAILED TRUSS
STUDDED GABLE
Terminology for a gable end truss built as a wall and resembling a stud wall built in
the shape of a triangle. Chords are usually ON THE FLAT
SUBSTRATE
The surface upon which the roofing membrane is placed.
T-BRACE
A brace consisting of two inch dimension lumber nailed directly to the member
requiring a brace, and with the width of the member perpendicular to the width of the
brace.
THRUST
Term used to describe outward horizontal force.
TOENAIL
A nail driven at an angle to the member.
TOP CHORD BEARING
The bearing condition of a parallel chord truss that bears on its top chord
extension. Can also apply to a sloping chord truss bearing on a top chord extension.
TOP PLATE
Framing consisting of two members ON THE FLAT hat form the top of exterior stud bearing
walls of platform frame construction. A single member ON THE FLAT in non-bearing wall
construction.
TOP CHORD
An inclined or horizontal member that establishes the top member of a truss.
TRIMMER
A conventionally framed wall usually consisting of fastened multiple studs in a framed
wall opening, used to carry the header reactions.
TRUSS
An engineered structural component, assembled from wood members, metal
connector plates and other mechanical fasteners, designed to carry its own weight and
super imposed design loads. The truss members form a semi-rigid structural framework and
are assembled such that the members form triangles.
