Glossary of Terms

GLOSSARY OF WINDOW AND DOOR TERMS

When replacing the windows and doors in your home, you may hear a number of terms and phrases that are unfamiliar. Nobody should make you feel uncomfortable by using language that leaves you wondering what they mean. Here are some terms that you should be familiar with…

• Bay Window
  A composite of three windows, usually made up of a large center fixed unit and two flanking units at 30°,45° or 90° degree angles to the wall.
  
  
• Beveled Exterior
  An angled extension from the frame that adds an aesthetically-pleasing dimension to the exterior of the window.
  
  
• Block Frame Window
  Used when replacing the wood sash of an old double hung wood window.
  
  
• Bow Window
  A composite of four or more window units in a radial or bow formation.
  
  
• Cam Lock and Keeper
  The mechanisms which pull the sash together when placed in the locked position.
  
  
• Casement Window
  A window unit in which the single sash cranks outward, to the right or left.
  
  
• Casing
  Molding of various widths, thickness and shapes applied to the framework of window and door units.
  
  
• Caulk
  A mastic compound for filling joints and sealing cracks to prevent leakage of water and air, commonly made of silicone, bituminous, acrylic, or rubber-based material.
  
  
• Conduction
  Energy transfer from one material to another by direct contact.
  
  
• Convection
  Heat transfer by currents that flow from a warm surface to a colder one.
  
  
• Dormer
  A space which protrudes from the roof of a house, usually including one or more windows.
  
  
• Double-hung Window
  A window unit that has two operable sashes which move vertically in the frame.
  
  
• Drip Cap
  A molding placed on the top of the head brickmold or casing of a window frame.
  
  
• Double or Dual Glazing
  Use of two panes of glass in a window to increase energy efficiency and provide other performance benefits.
  
  
• Emissivity
  The relative ability of a surface to radiate heat.
  
  
• Fenestration
  An architectural term referring to the arrangement of windows in a wall. From the Latin word, "fenestra," meaning window.
  
  
• Frame
  The enclosure in which window sash or door panels are mounted.Frieze
  The horizontal member connecting the top of the siding with the soffit.
  
  
• Glazing
  Glass in a window or door; the act or process of fitting with glass.
  
  
• Glazing Bead
  A plastic or wood strip applied to the window sash around the perimeter of the glass.
  
  
• Glazing Stop
  The part of the sash or door panel that holds the glass in place.
  
  
• Head
  The main horizontal member forming the top of the window or door frame.
  
  
• Header
  A horizontal framing member placed over the rough opening of a window to prevent the weight of wall or roof from resting on the window frame.
  
  
• Inert Gas
  Safe, odorless, colorless, non-toxic, non-flammable gas that is commonly used in place of air between the glass panes of an insulated Low-E glass unit to reduce temperature transfer. Usually either argon or krypton gas.
  
  
• Insulating Glass
  A combination of two or more panes of glass with a hermetically sealed air space between the panes of glass. This space may or may not be filled with an inert gas, such as argon.
  
  
• Jamb
  The main vertical members forming the sides of a window or door frame.
  
  
• Lineal
  Molding of various widths used to trim door and window openings at the jambs. Also referred to as box post, window and door surround.
  
  
• Lift
  A handle or grip installed on the bottom rail of the lower sash of a double-hung window to make it easier to raise or lower the sash.
  
  
• Light (or Lite)
  Glazing framed by lattice and/or sash in a window or door.
  
  
• Lintel
  A horizontal member above a window or door opening that supports the structure above.
  
  
• Low-E Glass
  A common term used to refer to glass that has low emissivity due to a film or metallic coating on the glass or suspended between the two lights of glass to restrict the passage of radiant heat.
  
  
• Mullion
  A wood or metal part used to structurally join two window or door units.
  
  
• Rail
  The top and bottom horizontal members of the framework of a window sash.
  
  
• Rough Opening
  The framed opening in a wall into which a window or door unit is to be installed
  
  
• R-Value
  Resistance to thermal transfer or heat flow. Higher R-value numbers indicate greater insulating value.
  
  
• Pane
  A framed sheet of glass within a window.
  
  
• Sash
  A single assembly of stiles and rails made into a frame for holding glass.
  
  
• Sash balance
  A system of weight, cords and/or coiled springs which assist in raising double-hung sash and tend to keep the sash in any placed position by counterbalancing the weight of the sash.
  
  
• Sash cord
  In double-hung windows, the rope or chain that attaches  the sash to the counter balance.
  
  
• Sash Lift
  A protruding handle screwed to the inside bottom rail of the lower sash on a double-hung window.
  
  
• Sash lock
  Generally, a cam-action type lock applied to the rails of a sliding window or at the open edges of a projecting window to pull the check rails tightly together or to seal the sash tightly to the frame, both for security and weathertightness.
  
  
• Sash weights
  In older double-hung windows, the concealed cast-iron weights that are used to counterbalance the sash.
  
  
• Seat Board
  A flat board cut to fit the contour of a bow or bay window and installed between the sills and the flat wall surface, providing a seat or shelf space.
  
  
• Shims
  Wood wedges (often wood shingles) used to secure the window or door unit in the rough or masonry opening in a square, level and plumb position during and after installation.
  
  
• Sidelites
  Narrow fixed units mulled or joined to door units to give a more open appearance.
  
  
• Sill
  The main horizontal member forming the bottom of the frame of a window or door.
  
  
• Single Glazing
  Use of single panes of glass in a window. Not as energy-efficient as double glazing.
  
  
• Single-hung Window
  A double-hung type of window in which the top sash is fixed or inoperable.
  
  
• Slider Window
  Both sashes slide horizontally in a double-sliding window. Only one sash slides in a single-sliding window. Ventilation area can vary from a small crack to an opening of one-half the total glass area. Screens can be placed on the exterior or interior of the window unit.
  
  
• Stile
  The main vertical members of the framework of a sash.Strikeplate
  Protects the jamb from the hardware latch on a door. Covers the latch and deadbolt.
  
  
• Stool
  An interior trim piece on a window which extends the sill and acts as a narrow shelf.
  
  
• Stop Molding
  A molding used to hold, position or separate window parts.
  
  
• Tempered Glass
  Glass manufactured to withstand greater than normal forces on its surface. When it breaks, it shatters into small pieces to reduce hazard. Standard on all doors and large fixed windows.
  
  
• Threshold
  The bottom part of the door frame, the area you step on when entering or exiting through the doorway.
  
  
• Transom
  A small window that fits over the top of a door or window, primarily for additional light and aesthetic value.
  
  
• True Divided Lite
  A term which refers to windows in which multiple individual panes of glass or lites are assembled in the sash.
  
  
• U-Factor
  A measure of heat transmission through a wall or window. The lower the U-Factor, the better the insulating value.
  
  
• Vinyl
  A plastic material used for cladding or entire window units.
  
  
• Weatherstripping
  A material or device used to seal the openings, gaps or cracks of venting window and door units to prevent water and air infiltration.
  
  
• Windowpane divider
  A short bar used to separate glass in a sash into multiple lights. Also called muntin or a grille.
  

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