Everything you wanted to know about residential glass, but were afraid to ask.
At Speedy Glass, we want you to make an informed choice. Below you’ll find an alphabetical list which we hope will help answer some of your questions about the terms and technology of residential glass repair and replacement.
A type of thermoplastic, sometimes used for glazing. Good weather resistance, shatter resistance and visual clarity.
The amount of air leaking in and out of a building through cracks in walls, windows and doors.
Bubbles of air that form within a compound used to adhere/affix glass.
Standard float glass (see below).
Similar to a casement (see below) except the sash in most cases (see below) is hinged at the top and always projects out.
Small bead of glazing material between the glass and the sash, on the opposite side of the glass from the face glazing (see below).
An arrangement of three or more individual window units, attached in such a way as to project from the building at various angles.
Sealant or compound in a joint, a molding, or a stop (see below) used to hold glass or panels in position.
Bed or Bedding
The bead of a compound applied between a lite (plate) of glass or a panel and the sash or frame. Usually the first bead of compound to be applied when setting glass or panes.
Amount of overlap between the top of a stop (see below) and the inserted edge of a panel or lite of glass.
A piece of lead, neoprene or other suitable material used to position the glass in the frame.
To shim (see below), level and plumb windows/doors in required position.
A window with three or more units of equal width, which can be fixed, operable or mixed in any combination.
British Thermal Unit
Applying a compound or sealant to the flat surface of glass before placing it into position.
A synthetic rubber used as a sealant and architectural glazing tape.
A unit of glass, generally longer vertically than horizontally. It can either be opened to the outside (most common) or inside.
The blocking of exterior air or moisture leaks by filling cracks around doors, windows, or anywhere else with a putty-like compound.
When an outer wall is fastened to an inner wall separated by an air space.
A unit for air flow referring to cubic feet per minute.
Wire spring devices to hold glass in a rabbetted (see below) sash without stops.
The ability of two or more materials to exist in close and permanent association for an indefinite period with no adverse effect of one on the other.
Process of heat transfer through a material from a warm surface to a cool surface.
Heat transfer by the movement of fluid or air.
Bead of compound with convex exposed surface.
Condensation Resistance Factor.
An exterior building wall which carries no roof or floor loads, made entirely or mostly of metal, or a combination of metal, glass and other surfacing materials supported by a metal framework.
A porous transparent substance that absorbs moisture from within sealed air space or an insulating glass unit.
Two sheets of glass, separated by an air space. Double glazing improves insulation against heat transfer and/or sound transmission.
A window consisting of two sashes of glass operating in the same rectangular frame. Both the upper and lower halves can be slid up and down. There is usually use a counter balance mechanism to hold the sash in place.
A method of securing glass in a frame without the use of a compound.
Ability to take up a certain degree of expansion and contraction.
A weather-protection compound with good resistance to ultra-violet radiation.
A thermoplastic resin.
Glass set from the exterior of the building.
The removable molding that holds the panel in place on the exterior side.
Exterior perimeter of the roof just below the roof-line, perpendicular to the overhang.
A window which is stationary, also known as a picture window.
High optical quality glass with parallel surfaces that retain the fire-finished brilliance of the finest sheet glass without polishing and grinding. Float is replacing plate glass.
A warp on the inside surface of a sealed insulating glass unit. Caused by extremes of temperatures.
A pre-formed shape of rubber or rubber-like composition used to fill and seal joints or openings.
The work of installing glass in a frame.
A molding or stop around the inside of a frame to hold the glass in place.
A soft dough-like material used for filling and sealing the space between a pane of glass and its surrounding frame.
Head or Header
Upper horizontal component of the master frame of a window, patio door or entrance way.
The transfer of heat from outside to inside.
The transfer of heat from inside to outside.
Glass which is reheated to just below melting point and then cooled. A compressed surface is formed which increases its strength.
Hermetically Sealed Unit
An insulated glass unit made up of two lites (panes) of glass which are separated by an aluminum spacer tube. The unit is completely sealed, creating a moisture-free, clean, dead-air space.
Similar to casement window except the sash is hinged at the bottom.
A window in which the moveable panel slides horizontally.
Insulating glass refers to two pieces of glass spaced apart and hermetically sealed to form a single-glazed unit with an air space between.
Glass set from the interior of the building.
A window of horizontally mounted, louvered glass panels that abut tightly when closed and extend outward when cranked open.
The two vertical members of the perimeter of the sash (see below).
A device into which a latch hooks for security.
A cut, notch, or groove in a material.
Two or more sheets with an inner layer of transparent plastic to which the glass adheres if broken. Used for overhead, safety glazing, and sound reduction.
Another term for a pane of window glass.
A window in which slats are so placed to block rain, sunlight or vision.
A connector bridging two or more windows or patio doors together.
Wooden exterior framing of the window.
The picture window is stationary and framed so that it is usually, but not always, longer horizontally than vertically to provide a panoramic view.
Polished plate glass is a rolled, ground and polished product that offers excellent vision. It has less surface polish than sheet glass and is available in thickness varying from 1/4″ to 1-1/4″. Now replaced by float glass (see above).
A window installed during initial construction, serving as an integral part of the structure.
Pounds per square foot.
A two-sided L-shaped recess in sash or frame to accommodate lites or panels.
The portion of a window which includes the glass and the framing sections directly attached to it.
Strain put on a compound between two surfaces when there is slippage.
A transparent, flat glass whose surface has a characteristic waviness being replaced by float glass (see above).
Small blocks of composition, neoprene, etc., placed under bottom edge of lite or panel to prevent it from settling down onto the bottom of frame and distorting the sealant.
The use of single thickness of glass in a window or door (as opposed to sealed insulated glass which offers far superior insulating characteristics).
Similar in appearance to the double-hung window, the single-hung window features a stationary top and a movable bottom half.
A slider window may have one or two movable panes of glass. Whatever the type, the windows slide horizontally in the frame.
Small blocks of composition, wood, rubber, etc., placed on each side of glass panels to center them in the channel of the frame.
Heat-strengthened float glass (see above) with a colored ceramic coating on the surface. It has double the strength of annealed glass. It is available in a wide array of colors.
The upright vertical edges of a door, window or screen.
Either the stationary lip at the back of a rabbet (see above), or the removable molding at the front of the rabbet, which helps hold the glass panel in place.
A second set of windows installed on the outside or inside of the prime windows to provide additional insulation.
When shattered it breaks into small, rounded pieces of glass, rather than sharp, irregular pieces. It is approximately 4 times stronger than standard annealed glass, and is used as safety glazing in patio doors, entrance doors, side lites (see above), and other hazardous locations.
A single or double hung window whose operable sash (see above) can be tilted into the room, for easier washing.
A colored mineral admixture is incorporated in the glass. Tinting offers sun protection and better temperature control.
Glass covered concrete wall that collects and stores heat passively. Heat radiates back into the outdoors or into internal air or heating.
An abbreviation for Uniform Building Code
Term normally used to refer to one single lite (see above) of insulating glass.
The measurement used in determining the ability of different structural components (such as windows) to conduct heat. U-values can tell you how well your windows will hold in your heated or cooled air. The lower the number, the better.
Glass is held in place in vinyl channels.
A small opening in a wall or window member through which water may drain to the building exterior.
A method of sealing glass in a frame by using a knife or gun-applied glazing compound or sealant.
A metal curtain wall (see above) in which windows are the most prominent element. Also refers to the smallest fixed lites (see above) used with wall systems.
Wire mesh is embedded within the glass so it won’t shatter when broken and remains in the opening longer in the case of a fire. Frequently used in locations where a fire-rated glass is required.
Speedy Glass, The National Glass Association, The Glass Encyclopedia, The British Glass Manufacturers’ Confederation, Glassonline.com, Glass.com