Defintions I - L

"I" Beam: See "S" shape.
Ice Dam: A buildup or ice which forms a dam on the roof covering along the eave of the building.
ICBO: International Conference of Building Officials.
Impact Load: A dynamic load resulting from the motion of machinery, elevators, crane ways, vehicles, and other similar moving forces. See auxiliary forces.
Impact Wrench: A power tool used to tighten nuts or bolts.
Importance Factor: A factor that accounts for the degree of hazard to human life and damage to property.
Insulation: Any material used in building construction to reduce heat transfer.
Internal Pressure: Pressure inside a building which is a function of wind velocity, and number and location of openings.
Jack Beam: A beam used to support another beam, rafter or truss and eliminate a column support.
Jack Truss: A truss used to support another beam, rafter or truss and eliminate a column support.
Jamb: The vertical framing members located at the sides of an opening.
Jib Crane: A cantilevered or suspended beam with hoist and trolley. This lifting device may pick up loads in all or part of a circle around a column to which it is attached.
Jig: A device used to hold pieces of material in a certain position during fabrication.
Joist: Light beam for supporting a floor or roof.
Kick-out (elbow) (turn-out): An extension attached to the bottom of a downspout to direct water away from the wall.
Kip: A unit of measure equal to 1,000 pounds (4.4 KN)
Knee: The connecting area of a column and a rafter of a structural frame such as a rigid frame.
Knee Brace: A diagonal member at a column and rafter intersection designed to resist horizontal loads.
Lean-to: a structure such as a shed, having only one slope or pitch and depending upon another structure for partial support.
Length: The dimension of the building measured perpendicular to the main framing from outside to outside of endwall girts.
Leveling Plate: A steel plate used on top of a foundation or other support on which a structural column can rest.
Lift (crane): Maximum safe vertical distance through which the hook, magnet, or bucket can move.
Lifting Devices (cranes): Buckets, magnets, grabs and other supplemental devices, the weight of which is to be considered part of the rated load, used for ease in handling certain types of loads.
Light Transmitting Panels: Panels used to admit light. Refers to either transmitting panel or wall light.
Liner Panel: A metal panel attached to the inside flange of the girts or inside of a wall panel.
Live Load: Loads that are produced (1) during maintenance by workers, equipment, and materials, and (2) during the life of the structure by movable objects and do not include wind, snow, seismic, or dead loads. Also see "Roof or Floor Live Load".
Loads: Anything that causes a force to be exerted on a structural member. Examples of different types are
Dead Load, Impact Load, Roof Live Load, Seismic Load, Wind Load, Crane Load, Collateral Load, Auxiliary Load
Loading Indicating Washers: A washer with dimples which flatten when the high strength bolt is tightened. The bolt tension can be then determined by the use of feeler gages to determine the gap between the washer and the bolt head.
Longitudinal: The direction parallel to the ridge of the sidewall.
Longitudinal (crane): direction parallel to the crane runway beams.
Louver: An opening provided with fixed or movable, slanted fins to allow flow of air.
Low Rise Building: A description of a class of buildings usually less than 60' eave height. Commonly, they are single story, but do not exceed 4 stories.
LRFD: Load and Resistance Factor Design