ACTUAL DIMENSION
The outside horizontal and vertical measurements of a window or door excluding the nailing fins. Also referred to as overall dimension.

AIR LEAKAGE (AL)
Heat loss and gain occur by infiltration through cracks in the window assembly. Air leakage is expressed in cubic feet of air passing through a square foot of window area. The lower the AL, the less air will pass through cracks in the assembly. While many think that air leakage is extremely important, it is not as important as U-factor and the Solar Heat Gain Coefficient.

AIRSPACE
The measured distance between the inner surfaces of the two pieces of glass in an insulated unit. Also used in reference to the thickness of the spacer bar.

ANGLE TOP
Any window with a horizontal sill, vertical jambs, and a straight sloping head (See TRAPEZOID)

ANNEALED GLASS
Non-tempered glass. The most common glass used in window products.

ANODIZE
An electrochemical process that increases the natural oxide coating of aluminum. Clear anodizing gives aluminum a smooth consistent surface that reduces corrosion, especially in salt air. Color anodizing can be effected by the use of dyes or special alloys. Anodizing is not normally used in residential applications, except in some coastal areas.

APPLIED MUNTIN
A muntin in a glazed window that does not actually separate individual lights of glass. This muntin may be of a material different than the main frame- work of the window. The applied muntin may be attached to the glass with an adhesive or placed over the glass and held in place by the glazing bead.

ARCH TOP
Any window with a horizontal sill, vertical jambs, and a head that is curved upward. (See CIRCLE TOP and EYEBROW)

ARCHITECTURAL MODULAR
An early method of sizing Awning windows for frame construction.

ASSEMBLED
A condition of a sliding glass door when all of the parts are in place, as opposed to Knocked Down (KD).

ASTRAGAL
A channel on a sliding glass door panel, which allows another panel to slide into it. May also be used on screen doors.

AWNING WINDOW
A window with the sash hinged at the top that can be opened outward. Awning windows can have more than one sash and allows for a maximum venting area. Though once common in Florida and more tropical areas, it is less popular today.

BACK BEDDING
The same as Glazing Compound.

BACKER
A strip of aluminum glued to the interior side of a raised grid unit. When applied with a raised grid, the look simulates a true divided light.

BALANCE
A device in a hung window that allows the sash to be adjusted to any position between fully open and fully closed. Originally, balances were weights attached to the top corners of the sash and draped over a pulley on either jamb. The weights and the friction of the pulleys "balanced" the weight of the sash. Balances normally are placed in pairs for each sash, one at each jamb. A heavier window may use two balances on each jamb. (See BLOCK AND FRICTION BALANCE, SPIRAL BALANCE, or TACKLE BALANCE)

BALANCE ROD
Same as Spiral Balance.

BALANCE TOOL
A hook-like tool used for adjusting spiral balances.

BAY
A combination of three window units mulled together with the end units offset at a 45 degree angle. The center unit, which is parallel to the wall, can be a mulled window of two or more units.

BLOCK AND TACKLE BALANCE
A type of balance that employs a block and tackle apparatus and coiled spring. This type balance allows the sash to be easily removed from the window frame. A block and tackle balance can normally carry a heavier load than a spiral or friction balance. (See BALANCE)

BLOCK MODULAR
A method of sizing Awning windows for concrete block construction. Dimensions are based on full or half block sizes.

BOW
A combination of two or more windows mulled together with each window offset at a small angle (usually between 10 and 20 degrees). A horizontal cross section would resemble an archer's bow. Bow window units normally consist of four to six individual hung windows or picture windows or a combination of both types.

BUCK DIMENSION
The height or width a window will finish to on the inside of the structure.

BUMPER
A soft vinyl or rubber cushion that prevents the moving panel of a sliding glass door from striking the jamb on the fixed panel side of the door.

BYPASS DOOR
A sliding glass door style whereby the door panels pass around each other on separate tracks.

CALL OUT SIZE (C.O.S.)
The nominal size of a window or door. In other words the "name" of the size. For instance, a window that is 3 feet wide and 4 feet high would have a call out size of 3040.

CAM LOCK
A pivoting type latch usually attached by a screw or rivet to the top rail of a single hung sash or the centermost side rail of a sliding window sash. The latch locks to the meeting rail, some type of keeper, or strike plate attached to the meeting rail.

CAULKING
A soft semi liquid material used to seal cracks around a window and doorframe adjacent to the wall opening. Normally, this is applied from a tube in a caulking gun.

CENTER JAMB
The same as Lockstile.

CERTIFICATION
A document that certifies a window or door has been tested and has met certain requirements of strength, safety, air and water infiltration, and resistance to forced entry. Qualified testing labs issue certifications after testing or witnessing the test of a manufacturers product.

CHANNEL GLAZING
A method of glazing that entails a soft vinyl or rubber gasket-like material folded over the edges of the glass and then fitted inside a channel opening in the sash frame members. It is most commonly used in sliding glass doors. Also known as marine or wrap around glazing.

CIRCLE
A fixed lite window in the shape of a whole circle.

CIRCLE TOP
A fixed lite window whereby the head of the window is formed into a full radius half circle. This curved head is either attached to the jambs of a window or to a sill section that can then be attached to a horizontal head of a standard window. Circle top units are occasionally used alone.

CLERESTORY
A window in the upper part of a lofty room, usually out of reach from the floor. These windows can be fixed or operating and an extension device is used for operating clerestory windows.

CLOSED POCKET DOOR
A sliding glass door style whereby the door panels stack up inside a wall.

COLONIAL LITE
Windows with small rectangular panes or divided lites and designated as a 12-lite, 16-lite, and so on.

COMMERCIAL WINDOW
A window used in commercial buildings, which are normally heavier than residential windows and often anodized.

COMMODITY
A Florida window industry method of determining standard window opening sizes.

CONDENSATION
A condition caused by warm moist air coming into contact with a colder object with moisture appearing on the colder surface. A large difference in the temperature of either side of a window and humid air present on the warmer side will cause condensation to appear.

CORNER KEY
A metal or plastic device used to secure the corners of a sash, frame, spacer bar, or screen section. The device is generally an "L" shaped part that fits inside mitered ends of the perimeter parts. The corner key can be crimped (staked) in place or screws can be inserted. The corner key makes a rigid joint possible. (See CORNER LOCK)

CORNER LOCK
The same as Corner Key.

C.O.S.
Same as Call Out Size and Nominal Size.

CRF (Condensation Resistance Factor)
A number assigned to a tested window that determines how much moisture might condense on its inner surfaces. The testing is done in a chamber with controllable different temperatures on each side of the window.

CYLINDER LOCK
A type of adjustable pin lock, cylindrical in shape, used in sliding glass doors and storm doors for security.

DIVIDED LIGHT
A pattern of muntin bars using horizontal and vertical members to form a "tic tac toe" design on a light of glass. Originally, these crossed muntins divided a single glazed light into smaller pieces (called true colonial). Insulated glass can have the muntin bars placed between the panes of glass (called internal muntins) or attached as a grid on the inner side of the structure, but not outside the insulated glass light itself (called external muntins). Divided light windows are sometimes referred to Colonial Lite, "Cut Up" windows or True Colonial.

DOGHOUSE WINDOW
A fixed-lite window with a horizontal sill, vertical jambs and a peaked head that resembles the front view of a common doghouse. Also known as a pentagon or a double rake head.

DOOR
A movable device used to close off the entrance to a structure, room, or covered enclosure, typically consisting of a panel of glass, wood or metal. It slides horizontally or swings on hinges.

DOUBLE
Two windows mulled side by side to form one unit. Also known as a twin window.

DOUBLE HUNG
A type of window with two vertically moving sashes, with each sash employing balances. (See BALANCE and HUNG)

DOUBLE STRENGTH GLASS
Glass that is approximately 1/8” (3mm) thick. (See DSB, SINGLE STRENGTH GLASS, SSB)

DROP IN GLAZING
A type of glazing that attaches directly to the glazing leg in the sash and frame members using glazing compounds or tape and glazing bead.

DSB
This symbol represents Double Strength sheet glass, which is 1/8" (3mm) in thickness. The B specifies “B quality” glass that at one time was a lesser grade than “A quality”. Improvements in glass manufacturing are now such that B quality is of very good strength and clarity. The term “A quality” is not used today.
 

EGRESS
The act of leaving an enclosed space. In the window industry, the term refers to the dimensions of the net clear opening of a window or door (the horizontal clear distance, vertical clear distance and the net clear opening are established by local building codes). The reason for establishing minimum egress dimensions is to insure that a person attempting to leave a building in an emergency situation will have room to maneuver. Also, proper egress will allow a firefighter to enter a home while wearing emergency equipment. In 2001, the minimum egress dimensions required by most codes are 20" horizontally, 24" vertically, 5.0 square feet net clear opening for first floor applications and 5.7 square feet net clear opening for second floor applications. Some areas of the country use different dimensions.

ELEVATION
The front view or views from the street as shown in the blueprint plans of a home.

ELONGATED OCTAGON
A fixed lite window shaped in the form of an extended octagon.

ENTRY DOOR
A door, usually swinging or hung, that leads to the outside of a structure.

EXFILTRATION
The escape of air from a structure. The opposite of infiltration.

EXPOSED POCKET DOOR
A sliding glass door style whereby the door panels stack up onto the exterior of a wall.

EXTERIOR TRACK SLIDING GLASS DOOR
A sliding glass track style that is used for exterior applications and is available in various riser heights to protect against water infiltration.

EXTRUSION
The act of forcing a material through a die to form a part that has a cross section similar to the opening in the die. In the window industry, the resulting part obtained from the extrusion process makes up the structural members of a window or door. This part is usually aluminum or a vinyl. Vinyl parts are sometimes called "Profiles" and aluminum parts are sometimes called "Shapes" or "Extruded Shapes". As an example, when toothpaste is squeezed from a tube, the portion of paste squeezed out is an extrusion that has a cross section similar to the opening of the tube. If the tube has a round opening then the paste is cylindrical, but if the tube were to have a square opening, the paste would have a cross section with four straight sides.

EYEBROW
A fixed lite window with a gently arched head similar in appearance to one's eyebrow and has jambs of equal height.

EYELID
A fixed lite window with a gently arched head similar in appearance to one's eyelid. Similar to an eyebrow but the eyelid has no jambs.

FER (Forced Entry Resistant)
A requirement of some codes that a locked window or door meet certified tests that determine if the product is resistant to entry from the outside using normal hand tools. Also, that any attempt to enter the locked door or window will show definite signs of the attempt. FER does not mean "burglar proof". Any structure can be entered with enough time, privacy and effort.

FIELD GLAZE
The glazing of a window after the frame has been installed in the structure. (See OPEN)

FIN SEAL
A trade name for a type of wool pile weather strip employing a strip of rigid plastic material running lengthwise, greatly reducing air infiltration.

FINISH
The preparation of the surface of an aluminum window that adds color or protection to the aluminum. Mill finish is the unfinished surface of aluminum just as it comes from the mill. Painted finishes are factory applied to the aluminum extrusions before the assembly of the final product. Painted finishes come in many colors most commonly bronze (or brown), white, or beige. In rare instances and by special order, gray, blue, red or any color can been used. Anodized finishes are sometimes used, but mainly in architectural applications because of the expense. Clear lacquer finishes are called for on mill finish surfaces for protection during construction. (See ANODIZE)

FIXED FRAME
A type of window with no operating parts, just simply, a frame and glass. Also, referred to as a Picture Window.

FIXED LITE
A light of glass in a window or door that does not operate. It is usually the upper light of a single hung window. Sometimes the same as a picture window or fixed frame window.

FIXED PANEL
The non-operating panel of a sliding glass door.

FIXED VENT
The non-operating sash, lite, or panel of a sliding window or door.

FLANGE
A term used for masonry construction, it is a window frame with a head, jamb, and sill exterior perimeter leg _” longer than the interior perimeter leg.

FLAT GRID
A rectangular shaped grid applied to the exterior side of a light.

FLOATING MUNTIN
A type of muntin that actually separates lights of glass in a window but is not attached to the frame itself. (See MUNTIN and DIVIDED LIGHT)

FRAME
The outer members of a window or door. The frame includes the head, sill or threshold, the two jambs and the meeting rail of a window.

FRICTION BALANCE
A type of balance that holds a sash in position by friction. The friction balance usually has an adjustment device. This is a low cost substitute for other types of balances and is often not accepted by many building codes.

GASKET
A type of channel glazing that uses vinyl glazing material formed into a rectangular piece that fits around a particular size of glass. The gasket has welded corners to form a continuous cushion. This type of glazing is usually found in sliding glass door units or commerical applications. (See CHANNEL GLAZING)

GLASS
Any of a large class of materials with highly variable mechanical and optical properties that solidify from the molten state without crystallization. They are typically based on silicon dioxide (sand), boric oxide, aluminum oxide, or phosphorus pentoxide, generally transparent or translucent, and are regarded physically as supercooled liquids rather than true solids. (From The American Heritage Dictionary)

GLAZE
The act of installing glass or other glazing materials, such as plastic, into a window or door. (See REGLAZE)

GLAZING BEAD
A part used to trim around the edge of the glass after it has been installed in a window. Glazing bead can be made from vinyl, aluminum extrusion, or aluminum formed sheet. The glazing bead either is screwed in place or snapped into grooves in the sash member.

GLAZING COMPOUND
A pliable material placed between the glazing leg of a window or door and the glass around its edges to seal the unit against air and water infiltration and to help hold the glass in place.

GLAZING LEG
A flat surface in frame members parallel with the glass, to which the glass is affixed using a glazing compound and glazing bead.

GLAZING TAPE
A tape with adhesive on both sides used to glaze glass to the glazing leg of a sash member.

GREEN HOUSE WINDOW (Garden Vu)
A five-sided window unit that protrudes out from the exterior wall of a structure. The unit acts as, and somewhat resembles, a greenhouse. The unit contains shelves and has ventilating apparatus.

GRID
A removable muntin pattern applied to a single light of glass. Whereas a true divided light actually separates the pieces of glass, a grid only appears to divide the glass into smaller lights. A grid is applied to the exterior side of glass.

GULFSTREAM SCREEN
A sliding glass door screen framed with panel extrusion material.

HANDING
A term describing the way a sliding glass door opens or on which side of a hung (swinging) door the hinges and locks are located. (See OX, OXO, XO)

HEAD
The top or uppermost horizontal member or of the frame of a window or door. Sometimes called a header.

HEADER
The structural member in a building that spans the upper portion of a window or door opening. (See HEAD)

HEAT-STRENGTHENED GLASS
This glass is produced in much the same way as tempered glass, but with lower levels of surface compression, 3500-7500 psi.  The final product is two times stronger than annealed glass.  The break pattern varies with level of surface compression with lower levels having a break pattern similar to annealed glass.  And higher levels resulting in patterns similar to tempered glass.

HEAT ABSORBING GLASS
Types of glass containing minute particles of metal that absorbs solar heat and is primarily used in commerical applications.

HEAT LOSS
Heat escaping from a structure.

HEAT GAIN
Heat entering a structure.

HEXAGON
A six-sided fixed lite window with opposite sides parallel but not necessarily with all sides of equal length.

HINGED WINDOW
A operable window that is hinged on one side and is primarily used to meet egress requirements.

HOLLOW SHAPE
A class of extrusion with a cross section enclosing an open area. A tube is a hollow shape. It is a stronger and more rigid part than a solid shape. In other words, a channel extrusion of the same height, width and wall thickness will not be as strong as a square tube. Hollow shapes are generally more expensive than solid shapes and are used mostly in meeting rails, sash heads, and sash sill or bottom rails.

HORIZONTAL ROLLER (Horizontal Slider)
A common type of window with a horizontal rolling or sliding sash. (See PICTURE SLIDER, PICTURE WINDOW SLIDER, and SLIDER)

HUNG
A type of window with one or more vertically moving sashes that employs balances. (See BALANCE, DOUBLE HUNG, SINGLE HUNG, and TRIPLE HUNG) Also refers to a type of door with hinges on one jamb. A hung door is a swinging door as opposed to a sliding door.
 

IMPACT RESISTANT GLASS
A dual lamination of glass and plastic that is designed to resist penetration from flying debris.

INFILTRATION
The air or moisture that leaks through the cracks of a window or door from outside of a structure. A tight window (low infiltration rate) will prevent the loss of energy more than any other single factor. (See EXFILTRATION)

INSULATED GLASS
A light of glass made up of two sheets of glass, a spacer bar filled with a desiccant material placed between the two sheets at the perimeter, and a sealant applied around the entire perimeter of the assembly. This assembly creates an envelope of dead air which when used in a window or door, greatly reduces the passage of heat through the glass, thereby producing a savings at an increased material cost. 
INTEGRAL FIN WINDOW
A window with a nailing fin, it is primarily used in wood frame construction. (See NAILING FIN)

INTERIOR TRACK SLIDING GLASS DOOR
Also known as a flush track, it has no riser to protect against water infiltration.

INTERLOCK
A design feature of a window or door that provides a hooking action between the sash rail and the mid-rail, sill or jamb. This action reduces air infiltration and increases security to the unit.

INTERMEDIATE JAMB
A vertical member in a window or door, with three or more panels, that is located in the central area of the unit, and acts as a jamb in receiving the moving panel.

INTERNAL MUNTINS
Muntin bars located between the sheets of glass in an insulated glass unit. These muntins are purely decorative and only give the appearance of a divided light window. (See MUNTINS)

JAMB
The sides or outermost vertical side members of a window or door frame. (See INTERMEDIATE JAMB)

KD
Abbreviation for Knocked Down or not assembled. All of the parts of a window or door are ready for assembly.

KEEPER
A part of a locking device attached to the frame or mid-rail of a window or door that accepts the mating part of the lock.

LAMINATED GLASS
A type of safety glass composed of a plastic film with adhesive sandwiched between two sheets of glass. This type of glass is used in windows, doors, skylights and automobile windshields.

LATCH
The locking device on a door or window.

LIGHT
A piece of glass in a window or door. (See LITE)

LIGHT AREA
The area of a window or door, expressed in square feet, that allows exterior light to enter a structure.

LIGHT (LITE) PATTERN
The arrangement of muntin bars in a window.
• A single or double hung window with one horizontal muntin in each the upper and lower sash would have a light pattern designated as 2/2, which is called "two over two". A similar window with two horizontal muntins and three vertical muntins in the upper sash, and one horizontal muntin and three vertical muntins in the lower sash would be designated 12/8 which is called "twelve over eight". A similar window with no muntins in either sash is a 1/1 called "one over one".
• A horizontal sliding window or door with no muntins would be designated 1 x 1, which is called "one by one". Windows or doors with muntins are designated by the number of individual lights in each sash or panel. For instance a window with one vertical muntin and two horizontal muntins in each sash would be designated as 6 x 6 or called "six by six".
• A non-operating window (Picture Window) with no muntins is designated as 1 light. A Picture Window with no two vertical and three horizontal muntins would be either a 12 light unit or sometimes a 3 x 4 unit. Windows with diagonal muntins are referred to as "Diamond Light" units. (See DIVIDED LIGHT or COLONIAL LITE)

LINTEL
A structural member, usually a steel angle or channel, designed to support the wall or siding above a window or door.

LITE
Another term for a pane of glass used in a window. Frequently spelled "lite" in the industry literature to avoid confusion with light as in "visible light".

LOCK
The device on a window or door that secures it in a closed position. This can either be a keyed lock, a sliding bolt, a spring-loaded catch or a pivoting part that engages a keeper or strike.

LOCKSTILE
The vertical rail in a sliding glass door panel containing the lock.

LOW-E GLASS
Stands for low emissivity glass, it is a glass type with a transparent coating applied to its’ surface that helps keeps your house cooler in the summer and warmer in the winter.

MARINE GLAZING
The term comes about because this type of glazing is often used in boats and other marine applications. (Same as CHANNEL GLAZING or WRAP AROUND GLAZING)

MASONRY OPENING
The opening size in a concrete block wall where a window will be installed. It is measured block to block.

MEETING RAIL
A cross member of a window or sliding glass door where the sash comes together with an interlocking action. (Same as MID-RAIL)

MID-RAIL
Same as Meeting Rail.

MILL FINISH
Uncoated aluminum as it comes from the mill. (See FINISH)

MODULAR
The national industry standard method of determining standard window opening sizes.

MOVING VENT
The operating sash of a window or the operating panel of a sliding glass door.

MULL
A shorten version for Mullion. Also used as a verb, as in "to mull” two windows together.

MULLION
A horizontal or vertical member that holds together two adjacent lights of glass or windows or sections of curtain wall.

MUNTIN
A part of a window that divides a light of glass into smaller sections. A true muntin (the first "n" in "muntin" is silent) actually separates the pieces of glass. Insulated glass usually uses internal muntins, which only appear to divide the glass into smaller lights. Muntins are normally either vertical or horizontal although diagonal and curved are also used. (See DIVIDED LIGHT)

NAILING FIN
A protruding portion of the frame of a window or door that allows the unit to be secured in a structure by driving nails (or screws) through it and into the framing of the structure. (See INTEGRAL FIN WINDOW)

NOMINAL SIZE
The name of the size of a door. (See CALL OUT SIZE)

NUVIEW
A window style where the fixed lite is larger than the operable lite.

O

The designation for a door panel or window vent that is fixed in place.

OBSCURE GLASS
A type of glass with one surface roughened in such a way as to reduce visibility but yet allow light to enter a structure. This type of glass is often used in bathroom windows. Also referred to as translucent glass.

OCTAGON
A type of fixed window with eight sides whereby opposite sides are parallel but not necessarily equal in length.

OFFSET
A measurement in a bow or bay window specifying the distance from the outer edge of the floor plate to the nailing fin line of the window unit furthermost from the floor plate.

ONE OVER ONE (1/1)
A hung window with no muntins in either sash. (See LIGHT PATTERN)

OPEN
A window frame with no glass installed. Sometimes an open frame is installed in a structure and glazed later. This is done to prevent construction damage to special glass that is very expensive or difficult to replace. (See FIELD GLAZING)

OPERABLE WINDOW
A window that can be opened for ventilation.

OVAL
A fixed lite window in the shape of an oval.

OX
The designation for a two-panel sliding window or door with the right hand panel, as viewed from the exterior of the structure, the movable panel.

OXO
The designation for a three-panel sliding window or door with the center panel operable and the two end units fixed (non-moving).

OXXO
The designation of a four-panel sliding glass door with the two center panels operable. One sliding panel must lock against the other. This type door gives a larger opening.

PAINTED FINISH
After aluminum extruded shapes have been anodized (See ANODIZE), a coating of paint is applied, usually electrostatically and then oven dried. This coating is available in many colors (most commonly dark brown, white or tan) and helps protect the metal, as well as, add beauty to a window or door.

PANE
A lite of glass.

PANEL
A part of a door, or sometimes a window, composed of a light of glass and surrounded by a frame. Panels can be fixed in place or movable. It is similar to a sash or vent.

PASS-THRU WINDOW
A single-hung window without a sill that is used for counter-top applications.

PATIO DOOR
A sliding glass door used in a patio area.

PATIO DOOR SCREEN
A rolling screen for a patio sliding glass door.

PICTURE SLIDER
A horizontal sliding window with two moving sash, one each located on either side of a fixed panel to make up a three-panel window. (See PICTURE WINDOW SLIDER)

PICTURE WINDOW
A non-operating window consisting only of frame and glass.

PICTURE WINDOW SLIDER
The same as a PICTURE SLIDER.

POCKET DOOR
A sliding door that has the moving panels slide into (interior) or onto (exterior) a wall when opened.

PRIMARY WINDOW
A window installed into the wall of a structure. Storm windows, which attach to or over a prime window, are called secondary windows.

PROFILE
The term used to designate a vinyl extrusion (See EXTRUSION or EXTRUDED SHAPE)

PVC (Polyvinyl Chloride)
A material used to make vinyl window parts, weather strip and glazing bead.

QUARTER CIRCLE
A fixed special non-operating window shaped of one quarter of a full circle.

R-FACTOR
A number indicating a body's resistance to transferring heat. (See U-FACTOR)

RAIL
The outer members of a sash. (See STILE)

RAISED GRID
A dimensional grid applied to the exterior side of a light simulating the same look of a true divided light when used with a backer. The shape resembles a modified triangle.

RECTANGULAR SHAPED WINDOW
A fixed lite window that can be used as a sidelite or transom. (See SIDELITE or TRANSOM)

REFLECTANCE
A coefficient that indicates the capability of glass to reflect sunlight.

REFLECTIVE GLASS
A type of glass with a mirror-like surface that reduces the transmittance of sunlight through a window.

REGLAZE
To glaze a window or door again or to replace broken or defective glass or other glazing material in a window or door. (See GLAZE)

REMOVABLE SASH
Any sash in a window that can be easily removed without tools or by a major disassembly of the window or door.

RETURN
A channel formed in the outer frame of a window or door that accepts sheet rock or some other wall covering. This channel allows for a neat and inexpensive way of finishing. Also the distance from the inside edge of a window or door to the inside surface of the wall into which the window or door is installed measured perpendicular to the wall.

REVEAL
A protrusion on the head and jambs of a window frame, parallel to the wall of the structure allowing room for final trim within the opening in the wall.

RIGID VINYL
A type of polyvinyl chloride (PVC) used as glazing bead or weather strip in a window or door. This vinyl is firmer than soft vinyl, which is also used as weather strip.

RISE
In a window with a curved head, the vertical distance from the uppermost point of the curve to the top of the shorter jamb, if the jambs are different heights. (See EYEBROW)

ROLLERS
Wheels attached to the bottom of the sash or panel of a window or door that allows it to slide easily.

ROUGH OPENING
The space in the wall of a structure into which a window or door is to be installed. This space is slightly larger than the actual buck size of the window.

SAFETY GLASS
A type of glass designed to prevent injury if it is broken. (See LAMINATED GLASS and TEMPERED GLASS)

SASH
Normally the moving segment of a window, although sash is sometimes referred to as fixed sash. (See PANEL and VENT)

SASH GUIDE
A part of the sash of a window usually made from some type of plastic, which allows the window to move freely within the frame.

SASH HEAD
The uppermost horizontal member of the sash.

SASH JAMB
The outermost vertical members of a sash. (See SIDE RAIL)

SASH SILL
The bottom member or rail of a sash. Also known as a lift rail.

SASH STOP
A device placed near the top of the jambs of a hung window to prevent the sash from striking the head of the window.

SCREEN
A product used with a window or door, consisting of a four-sided frame surrounding a mesh of wire or plastic material used to keep out insects. The screen can be fixed in place or it can be rolled side to side as on a sliding glass door.

SCREEN CLOTH
The mesh of wire or plastic used in a screen. (See SCREEN)

SCREEN SPLINE
A thin strip of plastic used to hold screen cloth into a screen frame.

SCREW BOSS (Also SCREW SLOT)
A "C" shaped groove in an extrusion that will accept a screw parallel to the extrusion when forming a joint of two parts perpendicular to each other.

SEALANT
A compound used to fill and seal a joint or opening, as contrasted to a sealer, which is a liquid used to seal a porous surface. Also, the material used to seal the edges of insulated glass.

SECONDARY LOCK
A lock on a window or door in addition to the primary locking device. This lock is required by some building codes for additional security.

SETTING BLOCK
A small block of material, usually a rubber-like product but sometimes wood, placed between the edge of insulating glass and the glazing leg to cushion the glass. These blocks are placed at the sill but sometimes at the jambs and head.

SHADING COEFFICIENT
A number expressed as a percentage, indicating the amount of sunlight that passes through a piece of glass relative to another piece of glass used as a standard.

SHAPE
The same as an Extrusion.

SIDE RAIL
The same as a Sash Jamb.

SIDELITE
A fixed lite rectangular shaped window that is placed next to a door for ornamentation and/or to allow light to pass through.

SILICONE
A plastic type material used for sealing cracks in window frames, and is used sometimes as a glazing compound.

SILL
The threshold or lowest horizontal member of the frame of a window or door.

SINGLE GLAZED
A window or door that is glazed with a single sheet glass, as opposed to multiple glazing (insulated glass) which uses two or more sheets of glass.

SINGLE HUNG
A type of hung window with only the lower sash being operable. (See DOUBLE HUNG and TRIPLE HUNG)

SINGLE STRENGTH GLASS
Glass that is approximately 3/32” (2.5mm) thick. (SSB)

SKYLIGHT
A type of window installed in the roof of a structure to allow admittance of sunlight. These units can be fixed in placed or they can be of a type that opens for ventilation. The glazing, either plastic or tempered, can be a single sheet or multiple and can be clear or tinted.

SLIDER
A horizontal sliding or rolling window or sometimes a sliding glass door (See HORIZONTAL ROLLER)

SLIDING GLASS DOOR
A type of door with one or more horizontally sliding glass panels. This type of door acts as a window, as well as, a door. It is commonly used for access to patios and may be called a Patio Door.

SMALL VENT AWNING WINDOW
An Awning window style in which the vent(s) are thinner in height than in a standard vent. Therefore, a Standard Vent 25 Awning window has 4 vents and a Small Vent 25 Awning window has 5 vents.

SOFT VINYL
A type of PVC (Polyvinyl Chloride) material used for glazing bead or weather strip in a door or window that is more flexible than rigid vinyl.

SOLAR HEAT GAIN COEFFICIENT (SHGC)
The SHGC is the fraction of incident solar radiation admitted through a window and is expressed as a number between 0 and 1. The lower a window’s solar heat gain coefficient, the less solar heat it transmits.

SOLID SHAPE
An extrusion that has no enclosed voids, as opposed to a hollow shape. (See HOLLOW SHAPE and EXTRUSION)

SPACER BAR
A hollow tube with flat sides used around the perimeter of insulated glass to separate the sheets of glass and provide for a dead air space. The tube is vented to the interior of the piece of insulated glass and is normally filled with a desiccant to absorb any moisture that might have been present during the manufacture of the insulated glass. The tube is usually made of roll formed thin aluminum sheet, although other materials such as plastic are also used. The first insulated glass used wood strips. (See INSULATED GLASS)

SPECIAL WINDOW
A group of windows that are not listed in a manufacturers standard catalog. These windows can include shapes such as trapezoid, diamond, hexagon, triangle, circular or nonrectangular configurations. Special windows may also have nonstandard glass types, muntin bar arrangements, unusual finishes, or nonstandard locking devices.

SPIRAL BALANCE
See Balance.

SQUARE
A fixed lite window in the shape of a square.

SSB
This symbol represents Single Strength “B quality” sheet glass, which is approximately 3/32" (2.5mm)
thick. (See DOUBLE STRENGTH GLASS, DSB, SINGLE STRENGTH GLASS)

STACK
A condition where one or more windows are attached above another window or door that is to be installed in a structure. Also refers to the total thickness of an insulated glass unit.

STANDARD LIGHT (2/2, 3/2)
A designation for a window with horizontal but no vertical muntins, with a light pattern of either 2/2 or 3/2. (See LIGHT PATTERN)

STEP SILL
A condition in the sill of a door or window that employs a "step like" configuration to act as a dam against the infiltration of water.

STICK BUILT
A slang term for a prefab structure with a framework made of wood.

STILE
Another name for the vertical side rails of a sash or a sash jamb.

STOOL
The part of the framing around a window located at the bottom of the window opening and either under or next to the window's sill.

STRIKE
A part of a locking device into which the moving portion of the latch engages. The moving parts to the lock are usually located on the sash or panel of a window or door, while the strike is located on the jamb or meeting rail.

SWIGGLE
The trade name for Tru-Seal, which is utilized in the manufacture of insulated glass.

TAB CORNER
A type of joinery in a window or door frame, that uses a tab on one part that fits into a slot on the part to be joined to, and then the tab is bent over to secure it, such as awning vents.

TAB LOCK
A type of joint, in the corner of a sash of a window or door, that employs a protrusion on one part that fits into a groove on the other part, and tends to keep the corner square. This corner usually is also screwed together.

TAPE BALANCE
A type of balance using a spring retractable strip of steel that resembles a retractable steel tape measure. (See BALANCE)

TEMPERED GLASS
A type of safety glass that has been heat treated so when it breaks it separates into very small pieces that reducing the possibility of injury. Tempered glass is used in doors, windows located near doors, and other locations where safety is critical. Glass tempering is achieved by heating annealed glass to near it's softening point, rapidly cooling the surface and allowing the inner core to cool naturally. The result is layers of high compression at the surfaces balanced by a high-tension layer through the center of the glass making it much stronger than annealed glass. Once tempered, the glass will fracture if cut.

THERMAL BREAK
A type of window that employs an insulating material in the sash and frame members to reduce the flow of heat either inward or outward. The outer portion of the frame and sash are separated from the inner portion. This type of frame is mostly used in colder climates because it saves energy and reduces condensation on the inner surfaces of the window.

TINTED GLASS
A special type glass with additives, usually metallic particles that reduce the passage of sunlight. Tinted glass can be bronze, gray, green or blue as well as other more exotic colors.

TRANSOM
A fixed lite rectangular window that is placed over a door.

TRAPEZOID
Another name for an Angle Top or Rake Head window.

TRIANGLE
A fixed lite window in the shape of a triangle. Can be a right, equilateral, or isosceles shape.

TRIPLE
Three windows mulled together horizontally in the same plane to form one unit.

TRIPLE HUNG
A hung window with three operable sash each in it's own track and with it's own balances.

TRUE COLONIAL
A pattern of muntin bars using horizontal and vertical members to form a "tic tac toe" design on a light of glass by dividing a single glazed light into smaller individual pieces.

TWIN
Two windows mulled together in the same plane to form one unit.

U-FACTOR
The number of BTU's that will pass through each square foot of area of a window or door per hour, per degree Fahrenheit difference from one side of unit to the other. For example, a 3050 window (15 sq. ft.) with a U-factor of 1.0 will allow 150 BTU's to escape every hour if the outside temperature is 55 degrees and the inside temperature 65 degrees (a difference of 10 degrees). The lower the U-factor the better the unit is at conserving energy. The U-factor of a window or door is an indication of how much heat will be lost while the R-factor indicates a body's resistance to losing heat. The R-factor is used when referring to a single construction material, while the U-factor is used when there are several materials involved such as aluminum, glass and plastic. The U-factor divided into 1.0 will equal the R-factor.

UNITED INCHES
Total of one width and one height of a window or lite of glass in inches.

VENT
Another word for a sash or panel of a window or door.

VENT AREA
In a fully opened door or window, the area of the opening that will allow passage of air in or out. Some building codes require a minimum vent area in a structure, which is usually a percentage of the floor area or the wall area.

VINYL
A shortened form for polyvinyl chloride or PVC. (See PVC)

VISIBLE LIGHT TRANSMITTANCE (VT)
Visible Light Transmittance indicates the amount of available visible light energy that is allowed to pass through a transparent or translucent material. This measurement is noted as a percentage figure and the higher the percentage, the more visible light is transmitted through the material.

WEATHER STRIP
A part of a window or door, used to seal the cracks around moving sash or panels against the passage of air or water, when the door or window is in the closed position. Weather strip can be made of metal, vinyl, wool pile or other materials.

WEEPHOLE
An opening at the sill of a window or door allowing moisture to drain free.

WINDOW
An opening constructed in a wall or roof and functioning to admit light or air to an enclosure, usually framed and spanned with glass mounted to permit opening and closing. (From the Old Norse word "vindauga", which is an eye for the wind" or "wind eye".)

WINDOW WORKS
NuAir’s component system for mulling windows together.

WOOL PILE
A type of weather strip material used to reduce the passage of air or water around sash members of a window or door.

WRAP AROUND GLAZING
The same as Channel Glazing or Marine Glazing.

XO
The designation for two-panel sliding window or door with the left hand panel, as viewed from the exterior of the structure, operable.

XX
The designation for two-panel window or door with both panels operable.

XXX
The designation for three-panel sliding window or door in which all three panels are operable.