Glossary of Terms

ACCESSORY –A supplementary building product supplied with a SCG Building such as a door, window, ventilator, skylight, etc.

ALUMINIZED STEEL – Aluminum coated steel, usually utilized for roof and wall sheets.

ANCHOR BOLTS – Bolts used to anchor structural members to a concrete floor, foundation or other masonry support. Term generally refers to bolts that secure columns and jambs to the concrete slabs. (SCG does not furnish anchor bolts.)

ANCHOR BOLT PLAN –A plan of the foundation showing all dimensions and sections required to properly locate and set all anchor bolts, including projection above concrete, recesses, etc. – supplied with all SCG Buildings.

APPROVAL DRAWING –A drawing showing view and/or elevations of the finished building for the purpose of showing the general exterior and interior appearance and floor plan of the proposed building. (An architect usually prepares these drawings.)

ASTRAGAL – A closure between the leaves of a double slide or swing door used to close the junction.

AUTOMATIC WELDING – An automated welding operation producing a continuous, unbroken weld.

AUXILARY LOADS – Specified dynamic live loads that the building must safely withstand, such as cranes, impact loads, material handling systems, etc.

BAR JOIST – Open-web load-carrying members fabricated from steel bars and angles, used as horizontal structural members suitable for the support of room decks or floors. When utilized by SCG as purlins, screw down panels may not be used.

BASE ANGLE – A continuous angle secured to the foundation perimeter to support wall panels.

BASE CHANNEL – A “C” section secured at the foundation to support wall panels as an alternate to base angle.

BASE GIRT – A “C” or “Z” girt mounted 6” above the finished floor to support the wall panels; may be used as an alternate to a base angle.

Base Plate – A shop-welded, pre-punched plate on that portion of a structural column that rests on the concrete foundation and is secured by anchor bolts.

BASE TRIM – Light gauge painted steel or aluminum trim used to close off the base of the wall panels.

BAY (END) – The distance between the centerline of the first interior frame and the outside of the endwall structure.

BAY (INTERIOR) – The space between frame centerlines in the lengthwise direction of the building.

BEAM – A structural member subject to bending loads. Usually a horizontal member carrying vertical loads.

BEAM AND COLUMN – A SCG main frame system consisting of rafter beams supported by sidewall columns and one or more interior columns.

BEARING FRAME ENDWALL – Frame composed of corner columns, end columns, flush or by-pass girts and rafter beams, designed to carry one-half of the end bay loads. Also referred to as “light endwall” or “post and beam” endwall.

BENDING MOMENT – The tendency of an applied load or series of loads, acting at right angles to a structural member, to cause the member to bend and the ability of that member to resist bending.

BILL OF MATERIAL – A list of building components used for fabrication, shipping, receiving, and accounting purposes. Sometimes referred to as the “shipper.”

BIRD SCREEN – Wire mesh placed in ventilators to prevent birds from entering the building.

BLIND RIVET – A small headed pin with expandable shank for joining light gauge metal such as flashing, gutter, etc.; NOTE: POP RIVET is a registered trade name.

BONDED ROOF – A roof which carries a written warranty of weather tight integrity for a specified number of years (usually a built-up roof).

BRACE CABLES – Cables used as the primary bracing method for the roof and sidewalls of SCG Buildings; these cables transfer wind and seismic forces to the foundation.

BRACE RODS – Rods used on roof and sidewalls of some SCG Buildings to transfer wind, seismic, and lateral crane forces to the foundation.

BRACKET – A structural support projecting from a column or rafter for support of another structural member or accessory such as a crane runway beam.

BRIDGE CRANE – A material handling system within a building consisting of a hoist which moves laterally on a beam or bridge which, in turn, moves longitudinally on a runway made of beams and rails. Loads can be moved to any point within the area bounded by the bridge span and runway beams.

BRIDGING – Bracing used between structural members to provide weak axis stability. Usually used with bar joists.

BTU – British Thermal Unit – The amount of heat required to raise the temperature of one pound of water 1 ° F at sea level.

BUILDING CODE – Regulations established by a recognized agency describing design loads, construction details, and procedures for structures. Codes apply to a specific geographical area such as a city, county or state.

BUILT-UP ROOFING – A roof composed of multiple layers of tarpaper or felt, each layer set by a mopping of hot tar or asphalt.

BUILT-UP SECTION – A structural member, usually an “I” shape, made from individual web and flange flat plates by welding them together.

BUTT PLATE – The pre-punched end plate of a structural member that usually rests against a matching plate of another member forming a bolted connection.

BY-FRAMED GIRTS – Girts that overlap at outside column flange to form a continuous member.

“C” SECTION – A member cold formed from steel coil in the shape of a “C”, used primarily in bearing frame endwalls and framed openings.

C” VALUE – Thermal conductance. Similar to thermal conductivity “K” value, except that it expresses the heat that will pass through a material of any thickness under the same conditions of time and temperature. The lower the “C” value, the better the insulation value.

CALCULATED “U” VALUES – Theoretical thermal transmittance “U” values are obtained by taking the reciprocal of the sum of the “R” values. This method does not take into account the compression of the insulation at the framing members or the thermal “short circuits” caused by the fasteners. Calculated “U” values are rapidly being replaced by Certified “U” values, derived by using a guarded hot box to measure the rate of heat transfer through various assemblies of materials in accordance with ASTM C-236. The lower the “U” value, the better the insulation value.

CAMBER – Predetermined curvature fabricated into a structural member to offset the anticipated deflection when load is applied.

CANOPY - Any overhanging or projecting structure with its extreme end unsupported.

CANTILEVER – A projecting beam that is supported and restrained at one end only.

CAPILLARY ACTION – That action which causes movement of liquid when in contact with two adjacent surfaces such as roof panel sidelaps.

CAULK – To seal and make weather tight joints, seams, or voids by filling with a waterproofing compound or material.

CHANNEL – An open-ended “C” shape with no return lips; may be either cold-formed or hot-rolled.


CLEAR SPAN – The distance or clear and unobstructed opening between two supports of a beam; when used with a rigid frame, this is generally less than the nominal building width.

CLIP – A plate or angle used to fasten two or more members together.

CLIP ANGLE – An angle used for fastening various members together.

CLOSER – A mechanical device which closes a door yet prevents it from closing with excessive force.

CLOSURE STRIP – Resilient material formed to match either inside or outside wall or roof panel configuration, used at base, eave, rake or accessory locations to provide closure against the elements. (Also called “filler strip”.)

COLD-FORMED – Various shapes such as angles, channels, girts, and purlins formed by press brakes or rolling mills from strip or sheet at normal room temperature.

COLLATERAL LOADS – A load in addition to normal dead loads. All specified additional dead loads other than the metal building framing; examples are mechanical, electrical or sprinkler systems, ceilings, partitions, etc.

COLUMN – A primary structural member used in a vertical position to transfer loads from roof beams, trusses or rafters to the foundation.

COMBINATION BASE TRIM – An option to the standard base angle that combines the base angle and base trim into one piece.

COMPOSITE SECTION – Structural members made up of dissimilar materials acting in unison. Usually consists of steel beams and concrete deck.

Compression – Forces acting on a member which tend to shorten it. A pressure or force that tends to decrease the size of the member being compressed, such as the downward force on a column.

COMPRESSIVE STRENGTH – Relative ability of the substance (such as steel) to withstand the forces of compressive loads, generally expressed in pounds per square inch (psi).

CONCENTRATED LOAD – A load applied to a structural element at one point rather than uniformly across a span, such as a heater unit hung from a rafter.

CONTINUOUS GIRT OR PURLIN – A girt or purlin that overlaps at columns or frames to form a continuous member.

CONTINUOUS RIDGE VENT – A series of 10’ roof ventilators located along the roof ridge.

CORNER COLUMN – A “C” channel or “I” section located at the corner of a bearing frame endwall, or a primary frame column at a main end frame.

CORNER TRIM – Preformed color sheet metal trim used to close the junction of side and endwall sheets.

CRANE RAIL – Track upon which a top running crane moves (usually hot-rolled A.S.C.E. rails).

CRANE RUNWAY BEAM – The member that supports a crane rail. On an underhung crane the runway beam also acts as crane rail. This usually consists of a hot rolled beam with a cap channel.

CURB – The raised edge on a concrete floor slab. See also ROOF CURB .

CURTAIN WALL – A non-load bearing wall that sustains only its own weight and does not support the roof of a building.

DAMPER – A baffle used to open or close the throat of ventilators.

DEAD LOAD – The weight of all permanent construction, such as roof, framing and covering members plus any collateral loads.

DEFLECTION – The displacement of a structural member under load, measured from its no-load position.

Design-Build Construction – The involvement of the contractor and building supplier in the early planning stage of the construction project.

DESIGN CODE (DESIGN STANDARD) – The building code used in a particular area to govern building design.

DESIGN LOADS – Loads specified by SCG to be used in the design of a building, to accommodate the building weight and other forces for which the building is to be designed.

DIAPHRAGM ACTION – The resistance to raking, caused by longitudinal forces, which is provided by roof and wall panels.

DOWNSPOUT – A hollow, rectangular, square or round tubular section used to carry water from the gutter of a building to the ground or sewer.

DRAFT CURTAIN – A transverse or longitudinal partition suspended below the roof to restrict free airflow.

DRIFT PIN – A tapered pin used during erection to align holes in steel members to be connected. See SPUD WRENCH .

EAVE – The line along the top of the sidewall, formed by the intersection of roof and wall panels.

EAVE CANOPY – A roof extension beyond the sidewall of a building.

EAVE FASCIA – Trim used to close off the top of sidewall panels in lieu of eave gutter or eave trim.

EAVE HEIGHT – The vertical dimension from finished floor to top of eave strut.

EAVE STRUT – A cold formed structural member at the eave to support roof and wall panels; also transmits forces due to wind on endwall from roof bracing to wall bracing.

EAVE STRUT GUSSET – A small gusset, shop-welded to main frame on RF and BC buildings, to support eave struts and afford alignment with by-framed girts.

ENDLAP – A term used to describe the lap condition occurring at the end of panels or sheeting.

ENDWALL – A term used to describe the entire composition of a building end.

ENGINEER / ARCHITECT OF RECORD –The engineer or architect who is responsible for the overall design of the building project.

ERECTION – The assembling of pre-engineered components to form a complete structure.

ERECTION DRAWING – Drawings showing the roof framing plan, wall framing plan, endwall framing, cross section, and other parts of the building.

EXPANSION JOINT – A break of space in construction to allow for thermal expansion and contraction.

FAÇADE – An accessory whose function is to enhance the appearance of a building and cover the eave and/or gable of the building.

FASCIA – Decorative trim or panel projection from the face of a wall.

FIBERGLASS – A flexible, non-flammable, moisture and rot-proof material made of glass spun into filaments; widely used in blanket form faced with a vapor retardant material for building insulation. Fiberglass in sheet form is also used in other products such as translucent panels.

FIELD WORK – A term used to indicate required on-site modification of building components by field personnel.



FINISHED FLOOR – Top of the concrete slab or the finished concrete surface.

FIXED BASE – A vertical structural member, bolted to and positioned at 90 ° to a sidewall column to provide additional base fastening and to prevent column base rotation or racking due to longitudinal wind force. Usually installed as a substitute for “X” bracing.

FLANGE – The projecting edge of a structural member.

FLANGE BRACE – A brace from flange of column or rafter to girt or purlin to provide lateral support and stability.

FLASHING – A sheet metal closure to insure weathertightness.

FLOATING CLIP – A concealed clip used with SCG’s SCGlok2000 standing seam roof system. This clip allows for thermal expansion of the panel and provides adjustment for the roof purlins being up to 7 ° out of plane.

FLOATING ROOF – Refers to a standing seam roof system which is attached to the purlins with a clip designed so the entire roof can expand and contract independently of the structural system.

FLOOR LIVE LOAD – Loads imposed upon a floor system, the magnitude of which is determined by the use and occupancy of the space.

FLUSH MOUNTED GIRT – A girt system where the outside flanges of the girts and columns are flush. The girts are supported by the use of a clip bolted to the column web.

FOOTING – A pad or mat, usually concrete, located under a column, wall or other structural member, used to distribute loads from the member into the supporting soil.

FORCE – The action of one body on another body which changes or tends to change its state of rest or motion. A force may be expressed in pounds, kips, or other similar units and may act in any one of the following ways:

Compression – Shear

Tension – Torsion

FORMWORK – The total system of framing in which concrete is to be poured.

FOUNDATION – The substructure on which a building rests.

FRAME – Primary structural members, made up of columns and rafters, which support the secondary framing of girts and purlins.

Frame Drift – Horizontal displacement at the top of the columns due to lateral loads.

FRAMED OPENINGS – Framing (header and jambs) which surround an opening in a building for field installed accessories such as overhead doors, roof curbs, etc.

GABLE – The triangular portion of the endwall of a building, directly under the sloping roof and above the eave line.



GABLED ROOF – A ridged roof that terminates in gables.

GAGE OR GAUGE – The numerical designation for the thickness of sheet metal. Also refers to the distance between holes.

GALVALUME – Trade name of BIEC (formerly Bethlehem Steel) for zinc-aluminum alloy coated steel.

GALVANIZED – Steel coated with zinc for corrosion resistance.

GALVANIC ACTION – An electrochemical reaction between dissimilar metals (such as steel and aluminum) in the presence of moisture.

GIRDER – A main horizontal or near horizontal structural member that supports vertical loads.

GIRT – A secondary horizontal structural member attached to sidewall or end-wall columns to which wall covering is attached and supported horizontally; usually a cold-formed ”Z” shape.

GLAZING – The process of installing glass in window or door openings.

GRADE – The terms used to refer to the ground elevation around a building.

GRADE BEAM – A concrete beam around the perimeter of a building carrying an exterior wall.

GROUND SNOW LOAD – The weight of snow on the ground. The 50-year mean recurrence of ground snow is used to determine the design roof snow load.

GROUT – A mixture of cement, sand, and water used to fill cracks and cavities. Sometimes used under base plates or leveling plates to obtain uniform bearing surfaces.

GUSSET PLATE – Usually a triangular steel stiffener plate used to help distribute load at a connection.

GUTTER – A light gauge channel member installed at the eave, valley or parapet for the purpose of carrying water from the roof to the drains or downspouts.

GUY WIRE – A wire rope used to hold a structure in a desired position.

“H” SECTION – A steel member with an “H” profile.

HARPIN – Reinforcing steel used to transfer anchor bolt shear (due to column thrust) to concrete floor mass.

HAT SECTION – A cold-formed section used for fastening sheeting to some type of substructure.

HAUNCH – The deepened portion of a column or rafter designed to accommodate the high stress where column and rafter intersect and connect.

HEADER – A horizontal structural member over a door opening, window or other framed opening.

HEADER TRIM – Trim used above a wall opening.

HEX HEAD – Refers to a screw or bolt which has six-sides.

HIGH STRENGTH BOLTS – Any bolt made from steel having a tensile strength in excess of 100,000 pounds per square inch (psi). Some examples are ASTM A-325 and A-490.

HIGH TENSILE STEEL – Structural steel having a yield in excess of 36,000 pounds per square inch (psi).

HILLSIDE WASHERS – A washer having non-parallel faces, normally used to secure brace rods or cables to the structure.

HOLES IN PLATES – Pitch = distance between holes along longitudinal axis of plate. Gauge = distance between holes along transverse axis of plate. Edge distance = distance from center of hole to edge of plate.

HOIST – A mechanical lifting devise attached to a trolley that travels along a bridge, monorail or jib crane. May be chain or electric operated.

HOOD FLASH – The metal flashing used over exterior slide door track along the full length of the door header for weather protection and aesthetics.

HORIZONTAL THRUST – A lateral load in the horizontal plane. Always present at the base of a loaded rigid frame or arch. The tendency of a rigid frame column to “kick outward” at its base.

HOT-ROLLED SHAPES – Steel sections (angles, channels, I-beams, etc.). Formed by rolling mills while the steel is in a semi-molten state.

IMPACT LOAD – The assumed load resulting from the motion of machinery, elevators, crane ways, vehicles and other similar dynamic forces such as the starting and stopping of an overhead crane or hoist.

IMPORTANCE FACTOR – A factor that accounts for the degree of hazard to human life and damage to property. Used in Building Codes to modify wind, snow and seismic loads. The value is based on the building’s Building Use Classification.

INERTIA – The property of matter, by virtue of which any physical body persists in its state of rest or uniform motion until acted upon by some external force.


INSIDE CORNER TRIM – Trim used to finish out inside corners.

INSULATION – Any material used in building construction for the reduction of thermal transfer, or in some cases for reduction of fire hazard.

INTERMEDIATE BAY – The distance between two interior main frames within a building, other than end frames.

INTERNATIONAL BUILDING CODE (IBC) – A new code developed through the joint efforts of the groups that publish the Standard Building Code, the BOCA Building Code, and the Uniform Building Code. The IBC was first published in 2000. The three model code organizations are now going through a process to merge into a single group called the International Code Council (ICC) The ICC will push for the adoption of the IBC nationwide without amendments.

JACK BEAM – A beam or truss used to support another beam or rafter used to eliminate a column support.


JAMB – A side column of a doorway or other framed opening.

JIB CRANE – A cantilevered boom or horizontal beam with hoist and trolley. This lifting machine may pick up loads in all or part of a circle around the column to which it is attached.

JIG – A devise used to hold pieces of material in a certain position for punching, cutting, welding assembly or other type of fabrication.

JOIST – Light beam for supporting the floor or roof. See BAR JOIST .

“K” VALUE – Thermal conductivity. The amount of heat in BTU’s that will pass through one square foot of a homogeneous material, one inch in thickness, in one hour, when the difference in temperature between the two sides of material is 1 ° F. The “K” value varies at different temperatures, however, for comparison, most insulations are measured in 75 ° F. The lower the “K” value, the better the insulation value.

KIP - One thousand pounds.

SCGWALL PANEL – Standard panel used on exterior walls and facades.

KNEE – The joint between the column and rafter of a structural frame such as a rigid frame.

KNEE BRACE – A diagonal brace designed to resist horizontal loads, usually from wind or moving material handling equipment. This brace member normally has the lower end connected to a column and the upper end connected to a rafter or eave strut.

KNOCKED DOWN – Unassembled building components shipped to the jobsite ready for erection assembly.

KRII – SCGRibII, SCG’s standard roof and wall panels with purlin bearing leg.

KTM – An abbreviation for the SCG Trapezoid Mechanically Seamed Standing Seam Roof. This offers a full 180 ° sidelap seam, utilizing an electric seaming tool.

KTS – An abbreviation for the SCG Trapezoid Snap Seam Standing Seam Roof. Sidelaps are snapped together using a manual hand seamer.

LATERAL STABILITY – Quality of a structural member that prevents it from twisting or rotating under load. Usually accomplished by bracing the member with secondary framing ties or struts.

LATERAL SUPPORT – The means whereby walls are braced either vertically or horizontally by columns, pilasters, cross walls, or by floor or roof constructions.

LEAN-TO – A structure having only one slope or pitch and depending on another structure for partial support.

LEVELING PLATE – A square or rectangular steel plate fabricated with pre-punched holes that match the anchor bolt plan. This plate is used to establish a column base elevation prior to setting columns where a grouted column base is required.

LINER PANEL – Sheeting (usually SCGRib) applied to the interior face of the girts as an interior building finish; may be either full or partial height. May also be used on the interior face of the purlins as a roof liner.

LIP – A flange extension, which adds strength by acting as a stiffener.

LIVE LOAD –The non-permanent load to which a structure is subjected to in addition to its own weight. Live load includes loads induced by the use and occupancy of the building, the weight of persons occupying the building, and freestanding materials, but does not include snow loads, wind loads, seismic loads or dead loads. See ROOF or FLOOR LIVE LOAD.

LOADS – Anything that causes an external force to be exerted on a structural member. Examples are dead loads, impact load, crane load, roof live load, seismic load, and wind load.

LOAD BEARING WALLS – Any wall bearing its own weight as well as other weight (such as a roof) and wind load.

LOAD COMBINATIONS – The various loads such as wind, live, crane etc. that are to be applied in structural design as occurring on the structure at any one time.

LONGITUDINAL – Pertaining to longitude or length, running lengthwise. The longitudinal strength of a structural system is its resistance to forces coming from the end in a lengthwise direction (i.e. wind force). The bracing system, including diaphragm action, provides most of the longitudinal strength of a building.

LOUVER – An opening provided with fixed or adjustable blades to allow airflow.



MANSARD – A tilted facade system mounted to the roof outside of the steel line, and above the roof line to form a decorative appearance and hide the roof line.

MAIN OR PRIMARY FRAMING – Steel frames which support secondary framing members such as girts, purlins or eave struts.

MASTIC – Caulking or sealant furnished in rolls; used in sealing roof panel end and sidelaps, and other roof metal to metal joints, which may be exposed to the weather.

MESH – Welded wire mesh generally used to reinforce concrete floors.

MEZZANINE – A second floor above the ground floor. An intermediate level between floor and ceiling, occupying a portion of the floor space.

MILD STEEL – A grade of steel having a low percentage of carbon content and general lower strength.


MOMENT – A tendency of a force to cause rotation about a point or axis.

MOMENT CONNECTION – A connection between two members which transfer the moment from one side of the connection to the other side and maintains under application of load the same angle between the connected members that existed prior to the loading. Also, a connection that maintains continuity.

MOMENT OF INERTIA – A geometric property of a structural member which helps define strength and deflection characteristics.

MONOLITHIC CONSTRUCTION – A method of pouring concrete grade beam and floor slab together to form the building foundation rather than forming and pouring each separately.

MONORAIL – A single rail supported material handling system. Normally utilizes a hot-rolled “I” beam and a simple hoist.

MULLION – A vertical member connecting two windows located side by side.

MS (MULTI-SPAN) – More than one building tied together, multiple gable buildings. Also, buildings consisting of more that one span across the width of the building, as with SCG beam and column structures.

NIBBLER – An electric hand tool used to cut steel roof or wall sheeting openings.

OUTRIGGER – A projecting beam or member used to support roof overhangs.

OUT-TO-OUT – Overall dimensions.

OVERHAND – A roof extension beyond the endwall or sidewall.

PANEL – Ribbed configuration metal sheets used for roof and wall covering.

PANEL LINE – The extreme outer edge of panels attached to a building.

PARAPET – That portion of the wall extending vertically above the roofline to hide roof slopes.

PARTITION – A non-load bearing interior wall that sustains its own weight but does not support roof or ceiling and does not withstand wind loads.

PEAK – The highest point on the roof of the building where the two roof slopes meet.

PEAK BOX – A trim piece that flashes and encloses rake fascia connections at the apex of the building gable, and bears a metal plate that displays SCG’s logo.

PEAK PANEL – SCGRib panel installed at building ridge; conforms to roof slope and configuration.

PEAK SIGN – A sign affixed to the peak box that names the manufacturer.

PERIMETER – The total length of the distance around the outside edge of a building.

PIECE MARK – A number given to each separate part of the building for erection identification. Also called part number or mark number.

PIER – A concrete structure designed to transfer vertical load from the base of a column to a footing.

PIG SPOUT – A sheet metal section designed to direct the flow of water out through the face of the gutter rather than through a downspout.

PILASTER – A reinforced or enlarged portion of a masonry wall to provide support for roof loads or lateral loads on the wall.

PINNED BASE – A column base that is designed to resist horizontal and vertical movement, but not rotation.

PIN CONNECTION – A member connected to a foundation, structure or other member in such a way that free rotation is permitted.

PIPE COLUMN – A vertical structure support member made of pipe. Normally used as an interior support column in beam and column buildings.

PITCH – To incline or slope. The inclination of a roof, usually stated in terms of vertical rise compared to horizontal width (i.e. 1:12 refers to one foot of vertical rise for every twelve feet of horizontal building width).

PLASTIC DESIGN – A design concept based on multiplying the actual loads by a suitable load factor and using the yield stress as the maximum stress in any member.


PLUMB BOB – A weight used at the end of a plumb line, used to check vertical perpendicularity or depth.


PONDING – The gathering of water at low or irregular areas on a roof.


PORTAL BRACE – Light gauge member used to brace bays where diagonal rod or cable bracing cannot be used.

PORTAL FRAME – A rigid frame structure designed to offer rigidity and stability in its plane. It is used to resist longitudinal loads where diagonal rod or cable bracing is not permitted.

PREPAINTED COIL – Coil steel that receives a paint coating prior to the forming operation.

PRE-STRESSED CONCRETE – Concrete in which the reinforcing cables, wires or rods in the concrete are tensioned before there is load on the member, holding the concrete in compression for greater strength.

PRESS BRAKE – A machine used in cold forming metal sheet or strip into desired shapes.

PRIMARY FRAMING – The main load carrying member of a structural system, generally the columns and rafters or other main support members.

PRIMER PAINT – Initial coat of paint applied at factory to structural framing for protection against elements during shipping and erection only.

PURLIN – A secondary, cold-formed horizontal structural member located in the roof to support sheeting, that is itself supported by the rafters. Purlins in SCG Buildings overlap at frames to form a continuous design.


PURLIN EXTENSION CANOPY – A cantilevered continuation of the roof at rake line.

PURLIN LINE – The extreme outer, or exterior edge of the purlins.

RAKING ACTION – The tendency of a building to lean and/or fall because of wind loads imposed on the endwall.

RAFTER – A fabricated roof-framing member that supports the roof secondary framing members.

RAKE – The intersection of the roof and endwall planes.

RAKE ANGLE, RAKE CHANNEL – Angle or channel attached to purlins at rake for attachment of endwall sheets.

RAKE BEAM – Cold-formed endwall rafter “C” section.

RAKE FASCIA – A flashing designed to close the opening between the roof and endwall panels. Also referred to as rake trim.

REACTIONS – Forces required to resist the loads from a structure.

REINFORCING STEEL – The steel placed in concrete to help carry the tension, compression, and shear stresses.

REVISION – A significant change in building design or accessories worthy of notification in writing.

RIDGE – Highest point on the roof of a building that causes a horizontal line running the length of the building.

RIDGE CAP – Metal panels used at the ridge to transition between the roof slopes. Also know as ridge roll or ridge flashing. See PEAK PANEL .

RIDGE VENT – Circular or continuous vent placed at the ridge to produce air movement through the building. See CONTINUOUS VENT .

RIGID CONNECTION – A joint capable of transmitting moment to another member of the system. See MOMENT CONNECTION .

RIGID FRAME – A structural frame consisting of tapered rafters and columns joined together with rigid connections which render the frame stable with respect to the design loads, without need for bracing in its plane. (Usually a clear span frame with no interior support columns.)

ROLLFORMING MACHINE – A machine used in the fabricating process to produce cold formed parts. Usually used to produce “C” and “Z” sections, etc. from coil steel stock.

ROLLING DOORS – Doors that are supported on wheels and run on a track.

ROOF COVERING – The exposed exterior roof skin consisting of panels or sheets.

ROOF CURB – An accessory used to mount and level units (such as air conditioning and exhaust fans) on the sloped portion of the building roof.

ROOF JACK – An accessory used to flash around and cover pipes or stacks (such as sewer or furnace ventilation pipes) that penetrate the roof.

ROOF LIVE LOAD – Those loads induced 1) during maintenance by workers, equipment, and materials, and 2) during the life of the structure by movable objects, not including wind load, snow load, seismic load, or dead load.

ROOF-LOK – The SCG 16” architectural, vertical seam roof panel. Sidelaps are mechanically seamed. This panel is typically used on facades, canopys or HIP type roof structures.

ROOF OVERHANG – A roof extension beyond the endwall or sidewall of a building.

ROOF SLOPE (PITCH) – Slope of a roof plane expressed as a ratio of vertical rise per unit of horizontal run.

ROOF SNOW LOAD – Load induced by the weight of snow on the roof of the structure.

SAG ROD OR ANGLE – Tie rods or angles located between the webs of girts or purlins to provide lateral web stability and to limit the deflection of the girt or purlin in the direction of the weak axis. Also known as a purlin brace.

SAG STRAP – A metal strap used to hold purlins or girts in alignment.

SANDWICH PANEL – A panel assembly used as a covering consisting of an insulating core material with inner and outer skins.

SCAB PLACE – A steel plate factory or field welded to the flange and/or web of a column or rafter to increase load-carrying ability.

SCREEDING – The process of striking off the excess concrete to bring the top surface of a concrete slab to proper finish and elevation.

SEALANT – Any material used to close up cracks or joints to protect against leaks.

SECONDARY FRAMING – Framing members that transmit loads to the main framing. Secondary framing members are purlins, girts, eave struts, etc.

SECTION MODULUS – A physical property of a structural member. It is used to design and basically describe the bending strength of a member.

SEISMIC LOAD – The assumed lateral load acting in any horizontal direction on a structural system due to the action of an earthquake.

SELF-DRILLING SCREW – A fastener that drills and taps its own hole. Used as a fastener for attaching panels to purlins and girts.

SELF-TAPPING SCREW – A fastener that taps its own threads in a predrilled hole. Used for attaching panels to purlins and girts, for stitching panel sidelaps, and for trim and flashing.

SHEAR – The force tending to make two contacting parts slide upon each other in opposite directions parallel to their place of contact.

SHEAR DIAPHRAGM – Membranes capable of resisting deformation when loaded by in-plane shear forces.

SHEAR STRENGTH – The ability of a structural element to withstand loads or forces perpendicular to its principal axis.

SHEET GROOVE OR NOTCH – A notch or block-out formed along the outside edge of the foundation to provide support for the wall panels and serve as a closer along their bottom edge.

SHEETING ANGLE – An angle used for securing sheeting.

SHIM – A piece of steel, used as a spacer to level or square beams and base plates. Also used to align or as a spacer in beam and column connections.


SHOP DETAILS OR DRAWINGS – Details prepared for and used by manufacturing in the fabrication of parts and assemblies.

SIDELAP – The overlap portion of two parallel panels.

SIDEWALL – A term used to describe the entire composition of a building side. The exterior wall parallel to the ridgeline of the building.

SILL – The bottom horizontal framing member of a door or window opening.


SIMPLE BEAM – A beam without restraint or continuity at its support.

SIMPLE SPAN – A term used in structural analysis to describe a support condition for a beam, girt, purlin, etc., which offers no resistance to rotation at the supports.

SINGLE SLOPE – A sloping roof in one plane. The slope is from one sidewall to the opposite sidewall.

SINGLE SPAN – A building or structural member without intermediate support.

SIPHON BREAK – A small groove to arrest the capillary action of two adjacent surfaces (anti-capillary groove).

SKYLIGHT – A roof accessory to admit light, normally mounted on a curbed framed opening. See TRANSLUCENT PANELS .

SLAB – A flat molded layer of reinforced or plain concrete, usually of uniform thickness. Generally used as a floor in most buildings.

SLEEVE NUT – A long, slender nut normally used to join two brace rods of the same diameter together.

SLIDE DOOR – A single or double leaf door that opens horizontally by means of overhead trolleys or bottom rollers.

SLIDING CLIP – A clip used to attach a raised or standing seam roof to purlins, designed to allow the roof to expand and contract independently of the structural system.

SNAP SEAM – Method of joining adjacent standing seam panels by forming an interlocking seam that “snaps” into place with simple foot pressure.


SOFFIT – A metal panel (usually SCG Rib) that covers the underside of a canopy or purlin extension.

SOLDIER COLUMN – An independent column added in a sidewall to support girts in a long bay building, façade or canopy that terminated at a frame column line.

SOIL PRESSURE – The load per unit area a structure will exert through its foundation on the soil.

SPACESAVER – SCG’s straight sidewall, slope beam rafter building. Girts are flush-framed.

SPALL – A chip or fragment of concrete which has chipped, weathered, or otherwise broken from the slab; usually occurs at edge.

SPAN – Width of building inside to inside of wall panels (sidewall to sidewall).


SPECIFICATIONS – A statement of particulars of a given job as to size of buildings, quality and performance of men and materials to be used, and terms of the contract, etc.

SPLICE – A connection in a structural member.


SPUD WRENCH – A tool used by erectors to line up holes and make up bolted connections; a wrench with a tapered handle.

SQUARE – The term used for an area of 100 square feet.


STAINLESS STEEL – An alloy of steel that contains a high percentage of chromium. Also contains copper, nickel and other substances. Has excellent resistance to corrosion.

STANDING SEAM ROOF – An exposed metal roof system designed in such a way that panel sidelaps are joined in a waterproof fashion above the flat of the panel without the use of through fasteners.

STEEL LINE – The extreme outer limits of a building’s structural framing system to which sheets are attached.

STIFFENER – A member used to strengthen a plate against lateral or local buckling. Usually a bar welded perpendicular to the longitudinal axis of the member. Large concentrated loads such as crane loads usually require stiffeners at the point of connection.

STIFFENER LIP – A short extension of material at an angle to the flange of cold-formed structural members that adds strength to the member.

STILES – The vertical side members of framed and paneled doors.

STITCH SCREW – A self-tapping screw used to connect panels together at the side cap.

STRAIN – Change in length per unit length. The deformation of a body which is acted upon by external force.

STRESS – A measure of the load on a structural member in terms of force per unit area (kips per square inch). That internal force required to hold a body in equilibrium when acted upon by external forces.

STRUTT – A support piece; an inside brace fitted into a framework that resists axial forces.

STUD – A vertical wall member to which external or interior covering or collateral material may be attached. May be either load bearing or non-load bearing.


SUCTION – Partial vacuum resulting from wind loads on a building causing a load in the outward direction.


TAPERED MEMBER – A built-up plate member consisting of flanges welded to a variable depth web.

TEMPERATURE REINFORCING – Lightweight deformed steel rods or wire mesh placed in concrete to resist possible cracks from thermal expansion or contraction.

TEMPLATE – A pattern made from wood or metal; used as a guide in shaping something or checking the accuracy of work (e.g., a template is used to set and align anchor bolts).

TENSILE STRENGTH – The longitudinal pulling stress a material can bear without tearing apart, usually expressed in pounds per square inch (psi).

TENSION – Stress in a structural member created by forces tending to draw it apart longitudinally.

THERMAL BLOCK – A spacer of low thermal conductance material.

THERMAL CONDUCTIVITY (“K”) – The rate of heat flow, in BTU’s per hour, though a square foot of material exactly one inch thick whose surfaces have a temperature differential of 1 ° F.

THERMAL CONDUCTANCE (“C”) – The rate of heat flow, in BTU’s per hour through a square foot of material or combination of materials whose surfaces have a temperature differential of 1 ° F.

THERMAL FACTOR – A factor required for the calculation of roof snow loads. The value of this factor is given below.

  • All structures except as indicated below.
  • Structures kept just above freezing and others with cold, ventilated roofs in which the R-value between the ventilated space and the heated space exceeds 25 ° F · h · ft 2/Btu.
  • Unheated structures and structures intentionally kept below freezing.

THERMAL RESISTANCE (“R”) – Resistance to heat flow. The reciprocal of conductance (“C”).

THERMAL TRANSMITTANCE (“U”) – The rate of heat flow per square foot under steady conditions from the air on the warm side of a barrier to the air on the cold side, for 1 ° F of temperature difference between the two.

THRESHOLD – An aluminum extrusion kick plate that spans from jamb to jamb beneath a personnel walk door leaf.

THRUST – A horizontal force tending to push a structural member outward or sideways.

TIE – A structural member binding two bodies together which have a tendency to separate or diverge from each other.

TOLERANCE – A fractional allowance for variations from the specified standards of construction or fabrication.

TONGUE AND GROOVE – A projected edge of a panel inserted into a corresponding groove of another panel, thus forming a tongue and groove joint.

TOP RUNNING CRANE – A crane that runs on top of a crane mounted to a crane runway beam.

TORQUE – The twisting force exerted by or on a shaft without reference to the speed of the shaft.

TORQUE WRENCH – A wrench containing an adjustable mechanism for measuring and controlling the amount of torque or turning force to be exerted – often used to tighten nuts on high strength bolts.

TORSION – Force acting on a body which tends to rotate or twist the body.

TRACT – A metal way for wheeled vehicles; specifically one or more lines of rails for a crane, monorail or slide door.

TRANSIT – An instrument used to survey land and establish ground elevations.

TRANSLATION – Motion in which all points of a moving body have, at any instant, the same velocity and direction of motion.

TRANSLUCENT PANELS – Panels used to admit light. Usually formed in the shape of a roof or wall panel, and made from a fiberglass reinforced plastic.

TRANSVERSE – The direction perpendicular to the ridge of a building.

TRANSVERSE EXPANSION JOINT – A joint across the width of a building to allow small relative movements, such as those caused by temperature change in the building length.

TRIBUTARY AREA – The area that contributes load to a specific structural component.

Tributary Reduction – A reduction in the roof live loads based on the slope of the roof and the area supported by a particular member.

TRIM – Light gauge metal used in the finish of a building, especially around openings and at intersection of surfaces. Often referred to as flashing.

TRUSS – A structure made up of three or more members with each member designed to carry a tension or compression force. The entire structure, in turn, acts as a beam.

TURNBUCKLE – A form of coupling threaded so that when connected lengthwise between two metal rods, it may be turned to regulate the distance between them.

TURN OF THE NUT METHOD – A method of tightening bolts in a connection. A rotation of the nut through ½ to ¾ turn beyond the snug-tight position will produce the desired minimum tension on the bolt. (“Snug-tight” is defined as the point at which the plate between the bolt head and the nut is in firm contact.)

TURN KEY CONSTRUCTION SERVICE – Construction service that includes all phases of construction in a single contract.

TURNOUT – An extension attached to the bottom of a downspout to direct water away from a wall.

UL 90 – A roof assembly rating by Underwriters Laboratory. The assembly is investigated for susceptibility to damage from both internal and external pressures on the panel. These pressures are those associated with high velocity winds. The UL 90 Class Rating is the highest rating available.

UNDERHUNG CRANE – A crane that runs on a track suspended from the rafter of a structure. The crane end tracks are mounted underneath the crane runway beam.

UNIT STRESS – Stress per unit area.

UNIFORM LOAD – Loads that cover all or part of a beam, and throughout the portion covered, the amount of load per unit is the same.

UNSUPPORTED COLUMN – The condition that exists when a column has no lateral support. A column is unsupported when there are no braces, girts, masonry, etc. attached to the flanges.

UPLIFT – Wind load on a building that causes a load in the upward direction.

VALLEY GUTTER – A channel used to carry off water from the valley area which is created behind a sidewall facade, or when two buildings are joined side by side or when a reverse angle eave canopy is attached to the building.

VAPOR BARRIER – Material used to retard the flow of vapor or moisture into walls or roof, thus preventing condensation.

VENTILATOR – An accessory usually installed in the roof that allows air to pass through. Ventilators can be round, square or rectangular.

WAINSCOT – Wall material used in the lower portion of a wall that is different from the material in the rest of the wall.

WALK DOOR – An accessory that provides an entrance to the building interior. Walk doors are normally man size and swing on hinges.

WALL BEARING – Wall capable of supporting a structural system.

WALL COVERING – The exterior wall skin consisting of panels (or sheets) and their attachments, trim and weather sealants.

WEB – The part of a channel, purlin, girt, column, or rafter between the flanges.

WEB MEMBERS – Secondary structural members interposed between the top and bottom cords of a truss.

WEEP HOLES – Openings in flashing, etc., to permit drainage and reduce pressures (usually field drilled).

WIND BRACING – Cables, rods or other structural members used in roof and walls to transfer wind loads, seismic loads, etc., to the foundation.


WIND COLUMN – A vertical column supporting a wall system designed to withstand horizontal wind loads.

WIND LOAD – A load representing the pressure exerted on a structure by a given wind velocity. A load caused by the wind blowing from any horizontal direction.

WORK POINT – An intersection of planes from which dimensions are located.


YIELD STRESS – The stress at which the strain ceases to be directly proportional to the stress; also refers to the stress by which steel is identified, e.g., 36 ksi steel indicates steel with a yield strength of 36,000 psi.

YIELD POINT – The amount of stress, measured in a unit area, under which a given material will exhibit permanent deformation; the point at which a stress or strain just exceeds the elastic strength of the material.

“Z” SECTION – A girt or purlin; a member cold-formed from steel coil in the shape of a block “Z” with stiffener lips.

ZINC-ALUMINUM COATED – Steel coated with an alloy of zinc and aluminum to provide corrosion resistance.