Air Infiltration – The amount of air that passes between a window sash and frame. In windows it is measured in terms of cubic feet or air per minute, per square foot of area. The lower the number, the less air the window lets pass through.

Argon Gas – An odorless, colorless, tasteless, non-toxic gas which is six times more dense than air. It is used to replace air between the glass panes to reduce temperature transfer.

Balance covers – A snap in covering that conceals the EvenForce’s block and tackle balance system within the window frame, helping to keep dirt and dust out of the chamber.

Block and Tackle Balance System – The block and tackle system utilizes a high-density nylon cord pulley action which is attached to a moveable block that travels up and down within a metal chamber. Tension from a heavy duty coil spring at the top of the block creates the proper resistance necessary for smooth operation of the window sash.

Brickmould – A molding, used to trim the outside edge of a door frame. Brickmould is most often applied to prehung units.

Cam Lock and Keeper – The mechanisms which pull the sash together when placed in the locked position.

Closed-Cell Foam: Sponge-like material, usually used in gaskets and weatherstripping, which compresses into joints, but absorbs little water.

Condensation – The deposit of water vapor from the air on any cold surface whose temperature is below the dew point, such as a cold window glass or frame that is exposed to humid indoor air.

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

Constant Coil Spring Balance System – Device for holding vertically sliding sash in any desired position through the use of a spring or weight to counterbalance the weight of the sash.

Convection – Heat transfer by currents that flow from a warm surface to a colder one.

Dead-air Space – The space between the panes of glass of an I.G. unit.

Double-strength Glass – Glass with a thickness of approximately 1/8″.

Extruded Screen Frame – Different from a Rollformed frame, this frame is pressed through a form or die.

Fascia Board – A board attached to the ends of the rafters between the roofing material and the soffit overhang. Fascia cap is the covering around that board.

Flashing – A thin, flat material, usually aluminum, positioned under or behind J-channels, corner posts, windows, etc., to keep draining water from penetrating the home.

Fusion-welded – The process of joining materials by melting them together with extreme heat (over 500ºF), resulting in the materials uniting into a one-piece unit.

Gas Fill – The space inside an insulating glass unit – between the glass panes – may be filled with Argon gas, an odorless, non-toxic gas that is six times denser than air. This acts as an added barrier for a higher level of efficiency.

Glass – An inorganic transparent material composed of sand (silica), soda (sodium bicarbonate), and lime (calcium carbonate) with small quantities of alumina, boric or magnesia oxides. Available Styles: clear, bronze tinted and grey tinted.

Glass Coatings – Many windows and doors are available with Low E glass. A transparent metallic oxide coating applied to the glass surface allows short-wave energy to pass through but reflects long-wave infrared energy for greater thermal efficiency.

Glazing Bead – A molding or stop around the inside of a window frame to hold the glass in place.

Grids – Decorative horizontal or vertical bars installed between the glass panes to create the appearance of the sash being dividing into smaller lites of glass.

I.G. UnitInsulating Glass Unit – Two or more lites of glass separated by a spacer and hermetically sealed at the glass edges.

Laminated Glass – Specially designed glass where two panes of glass are bonded to a durable interlayer, providing increased safety, UV protection and noise reduction. If the window or door gets broken the glass will adhere to the to the plastic interlayer-preventing glass fallout in the home.

Low E (Emissivity) Glass – Glass with a transparent metallic oxide coating applied onto or into a glass surface. The coating allows short-wave energy to pass through but reflects long-wave infrared energy which improves the U-value.

Meeting Rail – The horizontal sections of a pair of sash that meet when the sash are closed.

Mullion – A vertical or horizontal connecting unit between two or more windows.

Nailing Fin – An extrusion attached to the main frame of a window used to secure the unit to the rough opening.

Obscure Glass – Glass that has been made translucent instead of transparent.

Oriel – A window with the meeting rail located off center of the frame. Most oriels have a 60/40 configuration.

Profile – Describes the design of the panel (Clapboard, Dutch lap, Triple 3, etc.)

R-value – Resistance a material has to heat flow. The higher the R-value, the greater the resistance.

Relative Humidity Condensation Point – The relative humidity level at which visible water vapor or other liquid vapor begins to form on the surface of the sash or frame, based on an inside temperature of 70°F and an outside temperature of 0°F. The higher the percentage, the more moisture the air can hold before condensation will occur.

Rollformed Screen Frame – A method of fabrication in which a flat (usually metal) material is placed on a machine where the material is formed into shape using differently shaped rollers and pressure.

Sash – The part of the window which contains the glass.

Sash limit locks – A feature that allows a window to be safely raised to a certain height.

Sloped sill – The sill of the window that has a downward slope to the outside. This sill has sufficient degree of slope to aid in water runoff.

Soffit – 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 Coefficient – The percentage of heat gained from both direct sunlight and absorbed heat. The smaller the number, the greater the ability to reduce solar heat gain.

Spacer – Material placed between two or more pieces of glass in order to maintain a uniform width between the glass, and prevent sealant distortion.

Square – A measurement of siding. One square equals 100 square feet (10 x 10 wall).

Stepped Sill – An exclusive triple-stepped, sloped sill design.

Tempered Glass – Glass with a surface compression of not less than 10,000 psi, or an edge compression of not less than 9,700 psi. When broken, the glass breaks into pebbles instead of shards.

Tilt Latch – Mechanism that unlocks the sash and allows it to tilt in from the main frame.

Tilt-in/lift-out Sash – A sash that can be tilted to the interior and removed for cleaning and is manufactured by welding.

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.

UV reflection – The percentage of ultraviolet rays being blocked rather than being transmitted through the window’s glass unit. The higher the number, the lower the percentage of ultraviolet rays being transmitted through the window.

U-value (U-factor) – A measure of the rate of non-solar heat loss or gain through a material or assembly. It is expressed in units of Btu/hr-sq ft-°F (W/sq m-°C). Values are normally given for NFRC/ASHRAE winter conditions of 0°F (18° C) outdoor temperature, 70° F (21° C) indoor temperature, 15 mph wind and no solar load. The U-factor may be expressed for the glass alone or the entire window, which includes the effect of the frame and the spacer materials. The lower the U-factor, the greater a window’s resistance to heat flow and the better its insulating value.

UV Block – The percent of ultraviolet rays blocked from being transmitted through the glass. The higher the number the lower the percentage of ultraviolet rays transmitted through the window.

Warm-edge technology – The use of low-conductance spacers to reduce heat transfer near the edge of insulated glazing.

Weep Slots – Slots or holes in the sill (bottom) member of the sash frame that allows water to escape. Weep flaps add a vinyl flap to keep insects out.