Glossary of Terms

A list of industry related terms used by Window & Door professionals.

Air Chambers - Small honeycomb spaces within the sash and frame extrusions which help to insulate and strengthen the window.

Argon - A gas that is heavier than air used to fill the dead airspace of an insulated glass unit. Argon is a safe,colorless, odorless, tasteless, non-toxic gas which is six times more dense than air. Argon provides a significant increase in the insulating value of a glass unit as well as sound insulation.

Awning Window - A window that is hinged at the top, and cranks from the bottom, to open out on a horizontal (outward and upward) 45 degree swing.

Balance (spiral type, coil type) - Used to tension the sash in the desired position. A balance allows the sash to operate up and down.

Balance Coil Case - Housing for coil balance of constant force type.

Balance Cover - A cover to improve site lines by covering operating balance.

Balance Shoe - Attached to the bottom of balance as a receptacle for the tilt pin to hold the sash and frame together which allows tilting.

Balance Tube/or Sleeve - A tube attached to each jamb of a window that gives the moving sash stability when moving up and down.

Balance Winding Tool - Used to adjust the tension of the spiral balance.

Bay Window - Three windows in a single frame. The center lite is always twice as wide as the sidelites, which are generally a combination of a fixed and (2) operable flankers, (casement or double hung windows). The window bay projects out from the wall of the house 30 or 45 degrees.

Beveled Exterior - An extension of the vinyl frame that adds an aesthetically pleasing dimension to the exterior of the window.

Bow Window - 3, 4, or 5 windows in a single frame. All of the window widths are equal size, which are generally a combination of fixed centers and (2) operable flankers, (casement or double hung windows). The window bow projects out from the wall of the house 15 degrees. A bow is similar to a bay but the combination has a more circular arch appearance.

Buck Frame - Wood head, seat, and jambs designed to form a case to contain the window to fit in the rough opening,used on bay and bow windows.

Buck size - This is the exact window size not including the fin.

Butterfly Clip - This is a "w" shaped clip with jamb adjustment screw located at the middle of both jambs of some replacement models. The screws in a clockwise direction will cause the jamb middles to pull toward the center of window.

Butyl - A material used to seal glass to the spacer and acts as a sealant to form a dead air space water and air tight unit.

Cam Lock and Keeper - The mechanism which pulls sashes together when placed in the locked position on single hung, double hung, and slider windows.

Casement Window Fixed - A picture window made out of casement window extrusions and does not ventilate.

Casement Window Operable - A window that is hinged on the left or right jamb. The window cranks outward on a vertical plane to a full 90 degree swing. The unit may be hinged left or right (View the unit inside looking out).

Caulking - A compound for filing joints to prevent leakage of water and air. Weather-proof caulking is made of a silicone base. Caulking is used where leakage and/or movement may occur.

Colonial Arch - Special shapes window unit that has a half round radius head.

Condensation Resistance Factor - A measure of the effectiveness of a window or glazing system to reduce the potential for condensation. The higher the condensation resistance factor, the more efficient the window or glazing system.

Condensation - The formation of water vapor from the air on any cold surface whose temperature is below the dew point.

Conduction - Energy transfer from one material to another by direct contact.

Convection - Heat transfer by currants that flow from a warm surface to a colder one.

Cottage Window - A double hung or single hung window with a larger proportioned bottom sash. Standard Configuration is 3/5 of the window operates from the bottom. 2/5 operates on the top.

Dead Lite - A fixed lite inoperable unit insert only (no master frame).

Desiccated Matrix - A material used in insulating glass to absorb water vapor which causes fogging.

Dew Point - The temperature above 32 degree F at which visible water vapor begins to deposit on the glass surface.

Double Hung Window - A window with an upper and lower moving sash utilizing a tension balance to hold sashes in the desired position.

Drip Cap - A molding to divert water from the top casing so that water drips beyond the outside of the frame.

Dual Durometer - Two hardnesses of vinyl in one extrusion. Usually combines rigid and flexible vinyl. Mainly used for glazing beads and sashes.

Egress - The path or opening by means of which one goes out: emergency exit. All egress or rescue windows from sleeping rooms must have a net clear opening.

Elliptical - Special shape where height is at least 1/3 of base.

Equilateral Triangle - Special shapes window unit having all three sides equal.

Eyebrow Window - Special shape that has straight legs coming up from the base and attaching to the radius.

Fixed Lite - A window which is non-operable (Does not open).

Flanker - A window unit placed along side of another unit. A picture window may be flanked by a double hung on each side.

Fusion Welded - Refers to frames and sash fused together with intense heat.

Glazing Bead - A removable trim that holds the glass in place.

Glazing - The process of sealing the glass to the sash.

Grid/Muntin - A brass/aluminum or vinyl strip in the dead airspace of the glass unit. Available in either colonial or diamond patterns.

Guts - A slang term used for the internal workings of bay/bow units. ( i.e. window dimensions, projection, overall depth, etc.)

Head Expander - A vinyl cap that fits over the top of the head of a window. Used to fill in the gap.

Infiltration - Air is able to flow through cracks and other spaces around the window and at the meeting rail.

Isosceles Triangle - Special shapes window unit having two of three sides equal.

Jamb - The sides of the window frame.

J-Channel - "J" Configuration designed into window frame exterior for the primary purpose of receiving siding.

Keeper Rail - The bottom of the top sash on which the keeper is mounted. On sliders, the keeper rail is vertical.

Lift Rail/Handle - Handle (Applied or Integrated) for raising the sash in a window.

Lite - A unit of glass.

Lock Rail - An extrusion used on top of the bottom sash on which locks are mounted. On sliders, the lock rail is vertical.

Low-E (Emisivity) Glass - Glass treated with a thin transparent coating of metal oxide and silver. Allows natural light and short-wave heat energy to freely penetrate glass during the winter while reflecting long-wave heat energy back outside during the summer months. Keeping your house cool in the summer and warm in the winter. It reduces the penetration of ultraviolet rays to minimize fading of carpet and draperies.

Mainframe - The head, sill, and jambs make up the mainframe. It holds the sashes.

Mechanical Frame - Refers to frames fastened with screws.

Meeting Rail - The point at which the horizontal sections of the top and bottom sash meet. On sliders, the meeting rail is vertical.

Mesh - Fabric, made of either fiberglass or aluminum, used in the making of screens.

Mull - The joining of two or more windows at the jamb, or by the mainframe.

Mullion - The extrusion piece used to join two or more windows at the jamb, or by the mainframe.

Nailing Fin - Used to secure the window into a rough opening.

Obscure/Translucent Glass - A frosted glass that you cannot see through. Mainly used in the bathroom.

Octagon Window - An eight sided special shape window.

Operating - A window with a sash that opens or operates for ventilation.

Oriel Window - A single and/or double hung window with a larger proportioned top sash. Standard configuration is 3/5 of the window operates from the top. 2/5 operates on the bottom.

Overall Depth - In a bay or bow unit-This measurement is the width of head/seat board which is projection plus wall thickness.

Palladian - Of or designating a renaissance architectural style usually a mulled combination of special shapes window units.

Pentagon - Special shapes window unit having five sides usually in a doghouse style (i.e. horizontal base with both sides perpendicular and top two sides with pitch).

Picture Window - A window that has no moveable sash.

Pitch - Roof pitch is the ratio of rise to span. Special shapes trapezoid configurations especially will follow roof pitch. Plated/polished Brass Hardware- Hardware that is not solid brass but finished as plated.

Prairie Grid - Horizontal and vertical grid 4" from edge of glass to centerline of grid in windows (6" in Patio Doors).

Projection - In a bay or bow unit-This measurement is the distance a unit will project past the outside wall.

Quad - Quadruplet is a group of windows mulled in combination of fours.

Radiation - Wave energy transmitted directly from one object to another through the atmosphere or through transparent or translucent materials. The energy radiated is either transmitted, absorbed or reflected, or a combination of all three.

Rail - Horizontal member of a sash.

Replacement Window - A window designed to fit into an existing window opening.

Right Triangle - Special shapes window unit having one of three interior angles of 90 degrees.

R-Value - A measure of resistance to heat flow of material or construction. A higher value indicates a better heat insulating property.

Safety Tempered Glass - Glass that has been treated with high heat for strength. If safety glass is broken, it will shatter into very small pieces.

Sash Stop - An extrusion molding generally about 2" long that covers the joint between window sash and the jamb which stops the operable sash at its maximum opening.

Sash - The part of the window or door which contains the glass.

Screw Jack - This is a button shaped Jamb Adjustment Screw located at the middle of both jambs of some replacement models. Turning the screw in a clockwise direction will cause the jamb middles to pull towardcenter of window.

Sealant - A compound for filling joints to prevent leakage of water and air. Weatherproof sealant is made of a silicone base. Sealant is used where leakage and/or movement is expected.

Shrink or Stretch Wrap - A plastic coating wrapped around a finished product for protection during shipping and while in storage.

Sill - The bottom piece of the mainframe.

Sill Angle - An extrusion that is placed on the exterior sill of a replacement window to fill in any gap between the rough opening to the exterior window sill.

Single Hung Window - Window with a fixed top sash and an operating bottom sash.

Slider Window - Window that slides to the left or right.

Spiral Balance - A balance using a spirally wound spring.

Spring Line - The vertical point at which a radius starts for special shapes I.e. eyebrows, colonial arch. Stile - Vertical member of a sash.

Tape Glazing - A piece of two sided tape that holds the glass in place within the frame.

Thumb Latch - When compressed the tilt latch moves enabling the sash to tilt. (Same as tilt latch or sash release).

Tilt Latch - Mechanisms that locks sash in place (Sash release).

Tilt Pin - Pins in the lift rail of the sash that goes into the balance shoe and joins the sash to the jamb.

Transom - A horizontal window usually above a door.

Trapezoid - A four sided window in which one side is taller than the other.

Triple - A group of windows mulled in combination of threes.

Twinning - Joining two windows together with mullion.

U-Value - A value indicating the rate of heat flow transferred through a material. The lower the U Value, the slowerthe rate of heat flow. It is also referred to as the overall coefficient of heat transfer.

United Inch - The width in inches plus the height in inches.

Universal Slide - XO from the outside looking in, the moving lock sash will operate from left to right.

Weather-Strip - Material used to seal the opening between the sash and the mainframe.

Weephole - Small holes along the bottom edge of a window or door unit that allows any trapped water to escape outdoors.

Wet Glazing - Silicone based substance that holds the sash in place within the frame.

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