Windura / Glossary

Glossary of Window & Door Terms


Air infiltration
The amount of air leaking in and out of a building through cracks in walls, windows and doors.

A metallic element that has good electrical and thermal conductivity, high reflectivity, and resistance to oxidation.

Aluminum-Clad Windows
Windows with an aluminum material applied to the exterior surfaces of the window to provide a durable, low-maintenance exterior surface.

Argon gas
An inert (motionless), nontoxic gas used in insulating glass units to reduce heat transfer.

Awning window
A window that is hinged at the top and swings outward for ventilation.

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Bay window
An angled combination of three windows that project out from the wall of the home. Typically, the center unit is a picture window and the two flanking windows are operable casements or double-hungs.

Bow window
A gently curved combination of windows that are joined to each other and form an arch shape that projects from the wall of the home.

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Casement window
A window that opens from the side like a door. Historically, casements were the first working windows. They were strategically placed throughout a house to capture breezes and direct them through the rooms. Screens are hung internally to prevent dirt and insects from entering the house. Well designed casement windows today are exceptionally efficient.

The interior trim around door and window openings. Casings are shaped and decorative pieces of moulding cover the inside edges of the jambs and the rough opening between the window unit and the wall. Casing, like all interior trim, can be painted or stained.

A blend of thermoplastic alloys that is heated, pressurized and melted through a main extruder creating a solid core extrusion.

Condensation occurs when excess humidity in warmer air is released in the form of water droplets onto a colder surface such as a pane of glass.

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Direct-set window
A stationary window in which the glass is set directly into the structural frame, without the added protection a sash provides. These windows are often used in homes 30 years and newer. One benefit is increased glass space.

Double Glazing
Two panes of glass separated by an air-space to form insulating glass.

Double-hung window
A window with two sashes, upper and lower, that slide vertically past each other. Double-hung windows are the most common style of residential window.

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ENERGY STAR is an independent U.S. government program establishing a standard set of guidelines to recognize the energy efficiency of various products. ENERGY STAR guidelines are used in conjunction with a variety of building materials, including windows and patio doors. Over the past 10 years, ENERGY STAR guidelines have helped double the efficiency of windows they endorse.

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The placement (or arrangement) and design of the windows and exterior doors in a building.

The assembly of structural members (head, sill, jambs) used to fasten a window sash or a door panel to a structure.

The process of joining materials by melting them together with extreme heat which results in the material combining into one piece. This is a common design practice in the assembly of fine quality vinyl windows and patio doors, and is performed by highly sophisticated, automated equipment.

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Garden window
Designed much like a bay or bow window, a garden window also extends from the wall to the exterior of the home. It is built in a square or rectangular shape at right angles. The two side panels often operate for added ventilation.

Gas Fill
A gas other than air, usually argon or krypton, placed between window or skylight glazing panes to reduce the U-factor by suppressing conduction and convection. Being heavier than air, these gases produce an improved level of insulation.

The process of mounting glass into windows and doors. Glazing also refers to the lowest quality of plate glass. The purpose of glazing is to retain the glass adequately under the design load, provide an effective weather seal, prevent loads or pressure points on the glass resulting from building movement, prevent glass-to-metal contact, and minimize glass breakage from mechanical or thermal stress. An insulating glass (IG) unit is two glass panes separated by a spacer and sealed. IG glass is offered in clear (no special coating) and high performance, which has a tinted, low-emissivity coating for exceptional energy efficiency.

Optional horizontal or vertical lines installed between the glass panes help to create the appearance of a divided window design.

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Hinged patio doors
A two panel glass door where one panel is stationary or fixed, while the other operates and swings either inward or outward.

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The K-value of any material describes the amount of heat that moves through a material over time. The higher the K-value the more heat is transferred. Therefore a material with a lower K-value is a better insulator.

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Low-Emmisivity (Low-E) Glass
Low-E glass is manufactured by depositing a microscopically thin, transparent metal or metallic oxide layer on the glass. Low-E coatings reduce radiant heat loss, and can reduce the passage of UV rays.

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The individual pieces of a decorative grid that help divide a window opening into smaller sections.

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National Fenestration Rating Council (NFRC)
The NFRC is an independent, third-party certification organization with industry-accepted standards for evaluating and certifying energy performance. The NFRC Certificate contains U-factor, SHGC (Solar Heat Gain Coefficient) and VT (Visible Transmittance) values. These values form the basis for the ENERGY STAR® Door and Window Program.

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A single section of glass.

A major component of a sliding glass door, consisting of a lite of glass in a frame installed within the main (or outer) frame of the door. A panel may be sliding or fixed.

Picture window
A fixed (inoperable) window – typically of a large size in relation to adjacent windows.

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Refers to a window’s resistance to thermal transfer or heat flow. The higher the R-value, the better the insulation.

The transfer of heat in the form of electromagnetic waves from one separate surface to another. Energy from the sun reaches the earth by radiation and a person’s body can lose heat to a cold window or skylight surface in a similar way.

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Separate from the masterframe, the portion of the window that contains the glass. Some sashes are operable, as in double-hungs and casements, and some sashes are stationary, as in picture windows.

Sash limit locks
A feature that allows a window to be safely raised to a certain height. This feature comes on many replacement window double-hung designs.

Running a utility knife blade, a sharpened awl, scoring tool, or other sharp implement across a soffit or siding panel face without cutting all the way through the panel. This weakens the vinyl surface in a specific area and allows the panel to be bent and broken off cleanly.

The horizontal, bottom section of the masterframe of a door or window. Sills are generally sloped to the exterior to promote drainage away from the home.

Single-hung window
A window with a fixed upper sash and movable lower sash that slides vertically.

Sliding window
A window with a sash or sashes that move horizontally. Sliding windows come in two and three-section configurations.

Sliding patio doors
A combination of fixed and sliding glass door panels that operate solid brass roller trucks. Available in up to three lite configurations with the operable panel available in any position.

Material used to enclose the horizontal underside of an eave, cornice, or overhang. Some soffit panels may also be used as vertical siding.

Solar Heat Gain
Solar Heat Gain Coefficient (SHGC) measures how well a product blocks heat caused by sunlight. The SHGC is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed, then subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window’s SHGC, the less solar heat it transmits.

A structural object placed between two or more pieces of glass which helps to maintain a uniform width between the glass, and prevent sealant distortion. Spacers vary in efficiency, and play an important role in the overall performance of the glass unit.

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Tempered glass
Also called safety glass, tempered glass is treated with heat during the manufacturing process. Safety glass can withstand abnormal force or pressure on its surface and doesn’t break into sharp pieces. Code requires tempered glass in all doors (including patio doors) and in windows that are located near doors, bathtubs or showers, and other applications. For specific requirements, refer to the International Residential Building Code.

Tilt window
A double-hung window designed in such a way that the sashes tilt inward for easy cleaning of both sides.

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U-factor or U-value is a number that represents the rate of heat loss through a window or door. The lower the number, the greater a window resists the transfer of heat. A U-factor of 0.4 or lower represents good insulating value.

UV (Ultraviolet light)
The invisible rays of the spectrum that are outside of the visible spectrum at its short-wavelength violet end. Ultraviolet rays are found in everyday sunlight and can cause fading of paint finishes, carpets and fabrics.

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Any of a various number of tough, flexible, shiny plastics.

Visible Transmittance
Visible Transmittance (VT) measures how much light comes through a product. The visible transmittance is an optical property that indicates the amount of visible light transmitted. VT is expressed as a number between 0 and 1. The higher the VT, the more light is transmitted.

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Material used to form a weather-resistant seal around an operable sash or door panel.

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