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Glossary of Terms

Astragal:  A molding or strip used to cover or close the gap between double doors.

Awning Window:  A window unit in which the bottom of the  sash  swings outward.

Backset:  The offset or horizontal distance from the edge of a door to the centerline of the lockset knob, or cylinder.

Ball-Bearing Hinge:  A hinge equipped with a ball-bearing raceway between the hinge knuckles that slides easily to reduce friction.

Bay Window:  A composite of three windows, most often made up of a large central window with two flanking units placed at 30 to 45 degree angles to the wall.

Bevel of Door:  The angle of the lock edge in relation to the face of the lock stile.

Bow Window:  A fan-shaped composite of four or more windows installed in a radial or bow formation.

Brickmold:  A type of exterior casing around a window or door frame; often used in construction of a masonry or brick veneer walls.

Came:  A grooved rod made of cast lead and usually H-shaped [in profile]; used to install stained glass.

Casement Window:  A window sash that opens outward to the right or the left, using a cranking mechanism.

Casing:  Molding or trim of various thickness and design applied to the framework of window and door units.

Check Rail:  Found on a double-hung window at the upper and lower sash, where the lock is mounted.

Circlehead:  A generic term that refers to any of a variety of window units with a curved frame; often used over another window or door opening.

Closed-Cell Backer Rod:  A round non-absorbent foam seal used to fill the gaps around window and door frames.

Core:  The insulating material used in the center of hollow-core doors.

Cottage Double-Hung Window:  A double-hung window with a shorter upper sash than the sill below.

Cylinder Lock:  A lock type in which the keyhole and tumbler mechanism are contained in a cylinder separate from the lock case.

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D - E - F

Dado:  A rectangular groove recessed into a wood frame.

Dead Bolt:  A lock bolt that is operated by a key or turn-piece, and which lacks spring-action and beveling.

Dormer:  A space that protrudes out from the roof of a house, usually including one or more windows.

Double-Hung Window:  A unit with two operable sashes that both move vertically within the frame.

Drip Cap:  A molding placed on the top of the brickmold or casing of a window frame to redirect the flow of rainwater.

Dummy Cylinder:  A mock cylinder without any operating mechanism, for use where  the appearance of a lock is desired; such as on an inactive double door.

Electric Strike:  An electromechanical device that replaces an ordinary strike and enables remote electric locking/unlocking of the door.  When the control mechanism inside actuates the electric strike, the door becomes open and can be relocked once it is closed.

Escutcheon:  The ornamental shield or plate mounted behind the doorknob, which "surrounds" the lock base.

Extrusion:  A form produced by forcing material through a die. Quality window frames are clad with an extruded aluminum.

Fenestration:  An architectural term referring to the aesthetic and functional arrangement of windows in a wall [Latin 'fenestra'-window].

Finger Joint:  A joint consisting of a series of precision-machined fingers or points; two matching pieces are joined and meshed together using adhesives and pressure.

Fixed:  A non-venting or non-operable window unit.

Flashing:  A thin strip of metal or synthetic material that diverts water away from a window or skylight.

Flush Bolt:  A door bolt that is designed to sit flush with the face or edge of the door it sits in.

Frame:  [see jamb].

French Hinged Door:  Hinged door(s) that have wider panels situated around the glass panes.

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G - H - I

Glazing:  The glass in a window or door; the act of installing a pane of glass.

Glazing Stop:  The sash or door panel that holds the glass in place.

Glazing Cavity (or pocket):  The section of the window frame in which the sealed unit is located.

Grill:  A term referring to windowpane dividers [muntins] that allow the pane to be detached from the sash for cleaning.

Header:  A horizontal framing member placed over the rough opening of a window to prevent the weight of the roof or surrounding wall from resting on the window frame.

Head Jamb:  The cross or horizontal jamb member forming the top of a window frame.

Hinge:  A pair of jointed plates attached to a door and frame that enable the door to swing open and shut.

Hinge Stile:  A stile to which hinges are applied [as compared to a lock stile].

Inactive Door:  A door that does not contain a lock and has a flat strike plate where the doorknob goes; usually bolted shut when not in use.

Hopper:  A window unit in which the top of the sash swings inwards.

Insulating Glass:  Using two or more panes of glass in a window with a hermetically sealed air space in between the panes filled with an inert gas such as argon.

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J - K - L

Jamb:  The inside vertical face, or support, of the sides of a door or window frame.

Keeper:  The strike plate, or lock strike.

Kerf:  A cut made into a door frame to accommodate installation of a weatherstrip flange.

Lights [or Lites]:  Separately framed glass or clear panes applied to a door to admit more light.

Lock Block:  A block of wood measured to match the thickness of a door stile into which the lock is fitted.  The block is attached to the inside edge of the stile and over the mortise.

Lock Rail:  A broad rail situated on a door to receive the deadbolt.

Lock Stile:  The metal cover plate area of a door to which a knob/handle and lockset have been equipped [in comparison with a hinge stile].

Low-Emissivity [Low-E] Glass:  A special type of glass coated with a transparent material that is adhered to the surface using intense heat; the pane acts as a thermal mirror to regulate temperature and reduce energy loss.

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M - N - O

Masonry Opening:  The space in a masonry wall left open for windows or a door.

Miter:  A method of applying molding trim that is diagonally cut and fitted together to make a corner.

Mortise:  A cavity made to receive a lock or other hardware parts.

Mortise-and-Tenon:  A strong wood joint made by fitting together a mortise in one board and a matching tenon [projection] on the other; used as a corner joint in sashes.

Mortise-Type Lock:  A lock installed in the prepared recess, or mortise, of a door.

Mullion:  A fixed or movable post made of wood or metal that structurally joins two window or door units.

Muntin:  A vertical or horizontal bar that separates the glass in a sash into separate lights, or panes.

Night Latch:  A door lock containing a spring bolt that is impossible to operate from the outside without a key.

Obscure Glass:  Glass that has been made translucent [rather than transparent] in order to diffuse natural light.

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P - Q - R - S

Palladian Window:  A large, arch-top window flanked by smaller windows on each side.

Panel:  Usually refers to the separate panel/panels in a door frame.

Parting Stop:  In a double-hung window, a strip of wood applied to the jamb to separate the sash.

Plants (Plant-on):  Decorative moldings applied to a door.

PVC (Polyvinyl chloride):  A plastic used in the threshold and screen track to seal and insulate.

Rabbet:  A flat cut in a door frame designed to allow space for a door stop.

Rabbeted Door:  A door whose front edge has a half-inch step, rather than a beveled surface.

Rail:  The top and bottom horizontal members of a window or door that join the two stiles together; they can be exposed, as in a paneled door, or concealed in a flush unit.

Rough Opening:  The framed opening in a wall into which a unit is to be installed.

R-Value:  Refers to resistance to thermal transfer or heat loss; higher R-values indicate a greater insulating value.

Sash:  An assembly of stiles and rails that make up a frame to hold a glass pane or panes.

Sash Cord:  In double-hung windows, a rope or chain attaching the sash to the counter balance.

Sash Lift:  A protruding handle screwed to the inside bottom rail of the lower sash on a vertical sliding window.

Sash Weight:  Used in older double-hung windows to counterbalance the sash.

Shading Coefficient:  The percentage of natural, or radiant, light that a glazed unit allows to pass through.

Shim:  A tapered spacer used to install a window or door frame; usually made of wood or plastic.

Sidelight:  Narrow, fixed, ventilating or non-ventilating windows mulled or joined to an operating door.

Sidelight Frame:  A wood framing that surrounds the sidelight sash.

Sidelight Sash:  A panel [ventilating/non-ventilating] that fits into and is surrounded by the sidelight frame.

Sill:  The main horizontal member forming the bottom of a frame for a window or door.

Simulated Divided Light:  A method of constructing windows in which the muntins are affixed to the inside and outside of a pane of insulating glass.

Single-Hung:  A double-hung window in which the upper sash is fixed, or inoperable.

Slab:  A door without lites or a sweep installed.

Spacers:  Small blocks wedged in around the frame of a window to center the unit and maintain a uniform width of sealant beads, preventing excessive sealant distortion.

Steel Skin:  Sheet metal on a door's surface.

Stile:  The main vertical members in the framework of a sash or door [see rail]. 

Stool:  An interior trim piece on a window extending from the sill to serve as a narrow shelf.

Stop:  A molding used to hold, position, or separate window parts; placed as a stationary lip at the back of a rabbet, or at the front of the rabbet to hold the light or panel in place within the sash or frame.

Strike:  A metal plate or box that has been pierced or recessed to receive a projected bolt or latch.

Stud:  An upright beam in the framework of a building.

Substrate:  Material that supports and reinforces.

Surface Hinge:  A hinge with leaves applied to the surface of a unit, as opposed to a mortised [recessed] hinge.

Swaging:  A slight offset of a hinge at the barrel that permits the leaves to lie closer to each other, improving the operation and appearance of the door.

Sweep:  The weatherstrip applied to the bottom of a door.

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T - U - V - W

Tempered Glass:  Glass panes subjected to a process of rapid reheating and cooling to increase their strength.

Tenon:  A rectangular projection cut out of a piece of wood for insertion into a mortise.

Thermal Break:  An element that does not conduct heat easily; used as a buffer between two conductive materials to maximize energy efficiency.

Thermal Resistance:  The amount of resistance that a given material has to heat transfer.

Thermal Glass:  A sealed window unit that contains air or an inert gas between two or more panes of glass.

Threshold [Vinyl Saddle]:  A strip fastened to the floor beneath a door, usually required to cover a joint where two types of floor meet.

TPE [Thermal Plastic Elastomer]:  A rubber-like sealant.

Transom:  A small window or panel over a door.

True Divided Light:  A term for the assembly of multiple individual panes of glass [lights] using muntins.

U-Value:  Indicates the rate of energy flow through the heat barrier, from room temperature to outside temp; a lower U-value means better insulated walls.

Vapour Barrier:  A plastic film placed on the walls of a building prior to the insulation in order to prevent the buildup of condensation.

Vent Unit:  A window or door unit that opens or operates.

Visible Light Transmission:  The shading coefficient.

Weatherstripping:  A strip of flexible material used to cover the gap between the bottom of a door and the sill, casing, or threshold to prevent water and air infiltration.

Windload:  The force exerted on a surface by moving air.

Wire Glass:  Glass with an embedded layer of thin wire mesh that holds the pane together when the glass is shattered.

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