Glossary: I


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TermDefinition
I JoistA wood joist made of an assembly of laminated veneer wood top and bottom flanges and a web of plywood or oriented strandboard.
ICBOInternational Conference of Building Officials, a nonprofit organization that publishes the Uniform Building Code.
Igneous RockRock formed by the solidification of molten material to a solid state.
IlluminanceThe density of luminous power in lumens per a specified area.
Impact Insulation ClassAn index of the extent to which a floor assembly transmits impact noise from a room above to the room below.
Impact Insulation Class (IIC)Single-number rating used to compare and evaluate the performance of floor-ceiling constructions in isolating impact noise. The advantages of this rating system are positive values and the correlation with Sound Transmission Class (STC) values — both providing approximately equal isolation at a particular value. The IIC rating is used by building agencies for specifying minimum sound-control performance of assemblies in residential construction.
Impact NoiseSound generated by impact on the floor or other parts of a building that is carried through the building.
Impact Noise Rating (INR)Obsolete rating system for floor-ceiling construction in isolating impact noise. INR ratings can be converted to approximate IIC ratings by adding 51 points; however, a variation of 1 or 2 points may occur.
Impact StrengthThe energy required to fracture a specimen when struck with a rapidly applied load.
Impact TestA test for determining the resistance of a specimen fracture from a high-velocity blow.
In SituUndisturbed soil.
IncandescenceThe emission of visible light produced by heating.
IncombustibleSee Noncombustible.
Independent FootingsFootings supporting a single structural element, such as a column.
InfiltrationThe process by which water soaks into the ground. Also called Percolation.
IngotA mass of molten metal cast in a mold and solidified to be stored until used for forging or rolling into a finished product.
InsolationThe amount of solar radiation on a given plane or surface.
Insulatig GlassA glazing unit used to reduce the transfer of heat through a glazed opening by leaving an air space between layers of glass.
Insulation (Thermal)Any material that measurably retards heat transfer. There is wide variation in the insulating value of different materials. A material having a low density (weight/volume) will usually be a good thermal insulator.
Insulation, ElectricA material that is a poor conductor of electricty.
InterceptorA trapping device designed to collect materials that will not be able to be handled by a sewage treatment plant, such as grease, glass or metal chips, and hair.
InterpolateTo estimate untested values that fall between tested values.
IntumescenceThe swelling of a fire-retardant coating when heated, which forms a low-density film that provides some resistance to the spread of flame on the surface.
Invert ElevationThe elevation of the bottom (flow line) of a pipe.
IronA metallic element existing in the crust of the earth from which ferrous alloys, such as cast iron, are made.
ISOInternational Standards Organization, an organization similar in nature.