Common Terminology

When we discuss glazing systems we must first learn the common terms and phrasing used within the industry. Below are common terms and their meanings:

• Annealed glass: standard float glass.
• Air infiltration: the amount of air leaking in and out of windows, walls, doors, etc.
• Air space: the space in the cavity between the two panes of glass in an I.G.U.
• Bite: amount of glass recessed into the framing.
• Butyl: synthetic rubber used as a sealant and architectural glazing tape.
• Curtain wall: exterior cladding system made mostly of metal and glass, can be used in high rise applications
• CRF: condensation resistance factor.
• EPDM: Ethylene Propylene Diene Monomer – many setting blocks are made from this
• Extrusion: the process of producing an aluminum shape by forcing heated material through an orifice in a die. Gaskets, PVC, etc. can also be extruded in similar fashion.
• Gasket: pre-formed shape of rubber or rubber-like material used to fill and seal openings. Typically installed between the glass and metal components of glazing systems.
• Heat gain: transfer of heat from the outside to inside of the building.
• Heat loss: transfer of heat from the inside to outside of the building.
• I.G.U. (insulated glass unit): two or more glass panes separated by a spacer and sealed at the edges.
• Jamb: the vertical member of a framing system adjacent to the rough opening.
• Laminated glass: glass composed of two sheets of glass which are fused together with an inter-layer commonly made of clear PVB.
• Lite: another term for pane or piece of glass.
• Low-E (emissivity) coating: transparent coating applied to an inside face of an I.G.U. to improve the units energy efficiency.
• Mullion: the vertical member of a framing system.
• PSF: pounds per square foot.
• Setting block: block which the glass sits on within the glazing system.
• Shim: small pieces of material used to hold the glazing system away from the surrounding conditions.
• Solar heat gain coefficient: refers to the solar gain through the glass relative to the current solar radiation.
• Spacer: material placed between two or more pieces of glass to create an I.G.U. This can consist of aluminum or a different material, such as available “warm edge spacers.”
• Spandrel glass: glass which has a coating on the inside which keeps the inside of the building hidden from the outside.
• Storefront: exterior cladding system made mostly of metal and glass, used for mainly low rise and first floor applications.
• Tempered glass: glass which has been through a tempering oven creating specific surface tension to strengthen the glass and cause it to break into small pieces instead of shards when broken.
• Tinted glass: glass that has had a mixture incorporated into it to provide color and protection from the sun.
• U-value: measurement used to determine the ability of the glazing systems (and other components) to conduct heat. Typically, the lower the number the more efficient your window is.