Window Part Terminology Window Part Terminology Woodworkers try to bring order to the vocabulary universe and define "muntin," "mullion," "bar," "rail," and related window and door terminology. March 26, 2010 Question I had a pleasant discussion with a friend the other day about the real meaning of the terms muntins, mullions, bars and rails. I have a good deal of respect for this individual's intellectual knowledge of woodworking, but am curious how others define these items. When I told him I thought I'd write this post he thought it was a great idea. He wanted to know if others agreed with his definitions. I've been one of those that will describe the divider bars in windows as "muntins or mullions or whatever!" For years I've also referred to the vertical dividers that separate side by side panels as "vertical stiles." I've always known that I was probably wrong in making these references but never put out any effort to become more accurate. So, here are my friend's definitions, in my words. Do you agree? Mullion: a vertical space separating two architectural units such as a stud pocket between an entry door and a sidelight.

Not the divider bars between window panes. Rail: a horizontal component separating glass panes that goes between a pair of stiles just like the top, bottom and/or intermediate rails on a door. To be a rail, the part must cross the entire width of the opening in one unbroken piece. Bar: a component separating glass panes that goes either horizontally between a pair of stiles (another name for "rail") or vertically between a pair of rails in a door or window frame. In effect, if the part goes horizontally all the way across the opening it can be called a "rail" or a "bar," but if these primary unbroken components do the same thing vertically, then they are a "bar." Bar rail: totally unrelated to the above but clearly preferred by many at the end of a long hard day. Muntin: The shorter pane divider components that do not go all the way across the opening in one piece, but rather go only between the bars, rails or frame in short segments. Forum Responses I agree with your friend. From contributor T: If there's a bet riding on it, then you need an arbiter.

In my opinion, that arbiter should be the AWI manual, since they set the standards for all specified jobs. Their definition of mullion: an upright *or vertical* member between panels. Similar to a cross rail in the way it is fit and machined. Bar: A rabbeted moulding which extends the total height *or* width of the glass opening in a door. Muntin: A short bar, either horizontal *or* vertical, extending from a full bar to a stile, rail, or another bar. From contributor J: From Steven Mouzon's "Traditional Construction Patterns": Muntin: 1) A door muntin is any framing member that does not extend entirely from top to bottom of the door or from stile to stile. Muntins are most commonly used to divide vertical panels. 2) A window muntin is any framing member that divides panes of glass. He defines several specific types of rails, all of them horizontal members that cross an entire door from stile to stile, and all of them surrounding panels (not glass). Mullion: A member that joins wall openings such as doors, windows or cased openings (i.e.

the vertical casing that bridges the jambs of two windows set close together is a "casing mullion"). From contributor F: I don't know if I'm correct, but my understanding is: Stile - outside vertical frame member. Rail - outside horizontal frame member. Mullion - inside vertical member. Muntin - inside horizontal member. Bars - another description of muntins and mullions as a whole, i.e. barred (divided) glass as opposed to a single pane. From contributor D: I agree that while there are geographical differences in the terminology and applications, the diversity of definition arises mostly from the lack of continuity and formal education in our chosen profession. The shops I trained in were more than lax in linguistic accuracy, and "that thing" or "the stick" or "them sticks" sufficed for communication and de facto training. To ask for spelling or definitions would have caused such distrust as to seriously compromise one's ability to advance in such an environment. Our shop today relies more on drawings with dimensions than names, and mostly discriminates between verticals and horizontals.

We use the verb "mulled" more for joining sidelight frames to door frames than we use the noun "mull" to describe same. And "rail" is always horizontal, and more massive than a muntin, and can divide glass panels, glass from wood panels, or wood from wood panels. I carry a short piece of coped and stuck muntin bar to all the machinery shows - have for years. When a salesman approaches, I show the part, and ask how we can make the cope cut after the sides are profiled. He usually tapers off quickly and moves on to more likely prospects, but not after I try to get him to name the part. The regional names abound, and indeed, most people don't even know what they are looking at. From contributor U: Good question. I�ve always followed Cecil Hewett�s definitions, although if you learn one thing in this trade it�s that nothing should be considered definitive! �Astragel� is another term that can mean different things to different people. But on this specific issue, Hewett defines: Mullion � Vertical components of windows, placed in the void.

Muntin � Vertical members of paneled areas; the term may derive from mountants. The generally accepted use of "mullion" describes the vertical section that separates the two voids (the space before the windows are fitted) where two casements are placed side by side, or say, the vertical section(s) that separate the three parts of a combination sash (sometimes called a Venetian sash, although that can itself differ in detail) which will comprise part of the single window. Originally, of course, a mullion was the vertical post in what was originally just an unglazed opening in the wall to let in light, so the term pre-dates glass and windows as we think of them. Although I�ve heard "muntin" used in the way you describe (and I�m talking about the UK here), to me it�s always been the vertical bit between panels in, say, a cross-passage screen (referred to as panel and muntin), or wall paneling around a room (wainscoting). Jackson & Day in the glossary of their �Period Homes� book say: Muntin - A vertical member between panels (e.g.

of a door or wall paneling). Or another term for glazing bar (US). Mullion � A vertical member separating two windows. As for �bar� and �rail�, take your pick. I always have to ask the person I�m talking to if we�re referring to the same thing, just to make sure. My understanding of it is that a rail runs horizontally, a bar vertically, as in railway tracks and prison bars, which is how it was first described to me. Then in half-timbered houses you have posts and beams, which were explained to me as fence posts are fixed vertically and a torch beam shines horizontally. From contributor J: On a less erudite level, I once worked for a guy who called the dividers between panes of glass "mutton bars," which made me think he was describing a fence to restrain sheep, or perhaps a drying rack for lamb jerky...

From contributor U: Oh, and that reference to "astragels" should really also have included the fact that not only does the term mean different things to different people, it can also be spelled differently - either with a soft G as "astragel" or with a hard G as "astragal." And just to confuse it further, some UPVC guys use the term "astrical" bars to describe the stuck on duplex bars on double-glazed units. From contributor P: As defined in "Modern Carpentry", by Willis H. Wagner, first published in 1969: Mullion: "A slender bar or pier forming a division between units of windows, screens, or similar frames - generally nonstructural." Rail: "Cross or horizontal members of the framework of a sash, door, blind or other assembly." Stile: "The upright or vertical outside pieces of a sash, door, blind or screen." Bar: Not defined in the glossary of terms. But "sashbars" are mentioned in the muntin definition below. Bar rail: Something to lean on when having a beer. Muntin: 1. "Vertical member between two panels of the same piece of panel work." 2.

"The vertical and horizontal sashbars separating the different panes of glass in a window." Click here for higher quality, full size image From contributor U: That's got us in a bit deeper! The drawings make things simpler to refer to - many thanks. Your sash bars are (almost) universally referred to over here as "glazing bars" and defined further as either vertical or horizontal, which makes for an easier life. The "lock rail" is, again almost universally, referred to as the "meeting rail." As for door terminology, one term that is long gone is the "harr durn," or just "harr," which is the door stile to which the hinge is attached. Bringing it all together, Hewett, talking about Tolleshunt D'Arcy church in Essex (p205), "where flat planks were contrasted with the moulded v-sectioned muntins and edge framing. The highly contoured plank surfaces from Fobbing church were designed to produce an interesting surface that did not require the addition of any further items, such as muntins; and it was from this type that the more restrained 'creased' doors of the Elizabethan period were evolved." ...

"The iron hinges on the Fobbing door are of an earlier date and were designed for a flat surface, and the vertically moulded type of door gave rise to a change in hinging, the ironwork being redesigned so as to fasten to the rear face of the harr durn." Incidentally, one of the best books for UK (and I guess, to a great extent, the US) architectural woodworking field is "Care & Repair of Period Houses" by Albert Jackson & David Day, published by Collins. It's a hardback and probably one of the best books for anyone working on older buildings. Well worth the minor investment. From Gary Katz, forum technical advisor: What a great conversation. I've always agreed with the mullion as back-to-back jambs or trim on those jambs; and muntins just as they've been described - separating TDL glass (now they just install muntin grids). But I've never seen "field" stiles in wainscoting referred to as muntins. That would mean any stile on a cabinet face frame, which doesn't run from top to bottom on the frame, would also be a muntin? That's a little strange for me.

From Gary Katz, forum technical advisor: But I like it! How else do you describe those short stiles? From contributor P: Well, I mislabeled the "meeting rail/check rail" on the double hung sash. It is not called a lock rail here. So I've corrected the drawing. Thank you for your insights into the history of some of the other things. From Gary Katz, forum technical advisor: What program did you do that drawing in? Is that Sketchup? What's that font? It's great. From contributor P: The program is indeed Sketchup, and the font is "Handsf Single" a truetype font. From contributor I: We produce a moulding that would most likely be described as a "mullion"; it is typically 1 1/4" wide X 3/8" thick with a 1/4" rad on both edges. This piece is used to trim between a front entrance door and a sidelight. Many in our area refer to this moulding as a "burlap"; have you heard of this term? From contributor U: Another fascinating insight into the vagaries of terminology. To me "burlap" has always meant a coarse woven cloth.

I wonder what the roots of the word are as used in your area? The only other cloth-related term I can think of is "linenfold," which is virtually self-explanatory when you look at it. But burlap? There's bur-walnut and bur-elm, describing the wavy-knotted cross-section of such woods, which when highly polished, gives that beautifully textured surface on cabinets... From the original questioner: "Burlap" is a new one on me. I always called that a "mull strip." From Gary Katz, forum technical advisor: Mull casing. Mull cover. From contributor E: One little refinement to the Sketchup. I was taught to call the bottom rail of double hung sash a sill rail.

From contributor Y: I have always known the top and bottom rails of a door as the "head rail" and "kick rail." From contributor W: Hardware Glossary | Caldwell Hardware Ltd A pulley with a high performance ball or roller bearing for a sliding sash window Kogellager Pulley Mechanism to balance a sash using springs, pulleys & cord Block & Tackle Bolt weight connector A metal connector to connect the sash chain to the sash weight on a sliding sash window Bolt gewicht connector The bottom rail of the lower sash often deeper than that of the upper sash.

Bottom Rail Traditional timber vertical sliding window with weights and rope mechanism Schuifraam met koorden, katrollen en gewichten Caldwell balance A window balance supplied by Caldwell Hardware UK Ltd Caldwellveren A folding opener type mechanism Raamuitzetter, Raamboom A weight made from cast iron used to counterbalance the weight of a sliding sash window Gietijzer raamgreep gewicht The lower horizontal member of a window outer frame Onderdorpel The removal of dirt or contaminants from windows Ramenwassen A type of property used for business or public access Utiliteitsbouw A structure, predominantly glazed attached to a building Serre A type of sash balance which is produced from coiled flat spring steel strip Clockspring Patentveer met lint A large glazed area of a building Glasvliesgevel A means of access to a building Deur A window type with two sashes sliding vertically Schuifraam met twee schuivende vleugels Double Sprung A type of balance incorporating two springs Torso balansveer AVRI patent veer Duplex cam stays A type of over centre opening & closing mechanism for casement windows Raamboom, Raamsluiting A means of exit in

 an emergency Nooduitgang Eyebolt A metal bolt threaded at one end and formed into a ring at the other end to enable sash cord and sash weights to be connected Oog draad A company or person who assembles windows or doors Raam- of deurfabrikant A means of opening and closing casement windows hinged at the lower edge Raamknip A traditional lock mechanism for vertical sliding windows Schuifraamslot A type of over centre opening & closing mechanism for casement windows Raamuitzetter, Uitzetijzer, Bovenlichtopener, Bovenraamsluiting The peripheral structure of a window or door Kozijn A mechanism with in built friction functioning as a hinge for casement windows Remschaar A means of increasing or decreasing the friction in a door or window mechanism Glass The material predominantly used to glaze windows Glas, Isolatieglas, Thermopane The mechanism to enable windows and doors to open & close Scharnier A window hinged on the bottom edge which opens inwards Valraam Horn A short decorative extension of the sash styles extending beyond the meeting rail.

Originally to strengthen the joint but now usually purely decorative. Jamb liner A profile of plastic or metal used in timber windows to enable hardware to be fitted easily Raamstijlgeleiders, Schuifraamprofiel Lead sash weight A weight made from cast or extruded lead used to counterbalance the weight of a sliding sash window Lood raamgreep gewicht A method of removing sashes from vertical sliding windows Uitneembare vleugels, Verhuisraam A mechanism that permits sash lift off from vertical sliding windows Eenvoudig te verwijderen verhuisraam A vertical rail dividing sections of a window Kierstandhouder, begrenzer A metal loop used to connect sash chain to a sash weight Loop gewicht connector Make Weight A small iron or lead weight used to achieve the exact counterbalance effect on a box sash window. Meeting Rails lower horizontal rail of the upper sash and the upper horizontal rail of the lower sash. Normally rebated to accommodate weather seals and sometimes a security interlock rail.

Mullion A mechanism that enables more than one locking point to engage when a single handle is operated Tussendorpel A mechanism that restricts linear or rotational travel in doors & windows Meerpuntssluiting Nylon cord to support the sash weight on a sliding sash window Raamgreep nylondraad Mechanisms for operating window & door hardware Hang- en sluitwerk, Raambeslag See folding opener Parting Bead A vertical bead that separates and controls the path of the two sliding sashes and enables weather seals to be used. Patio rollers Rollers designed for use on horizontal sliding doors Patiodeurrollers A product that enables sashes on vertical sliding windows to be tilted inwards Scharnierstaaf A hinge mechanism for windows designed to rotate about a vertical or horizontal axis Draairaam, Speun A mechanism to enable sashes on vertical sliding windows to tilt whilst balances are fitted Remblokje Pocket An access to the weights box in a box sash window. Usually cut into the pulley stile.

Pole operator An extended pole to enable the operation of window hardware when located in a high location Raambedieningsstok, Pikhaak, Bootshaak, Raamstok A balance with the correct tension for a specific sash weight supplied ready to install OP bestelling gemaakte balansveer Pulley Stile side panel in the box of a box sash window. It supports the weight of the sash and the sash weights via the pulley. Over Centre Cam stay Carbon wire steel springs wound from flat or round wire Verenstaal, Veren Staff Bead Staff bead – A moulded bead on the inside of the window which retains the lower sash and may be used with a weather seal. Stiles The side rails of the sliding sashes. Storm catch A device for opening and closing window sashes that are hinged.

Often used in difficult to access places Stromvanger, Kierstandhouder Take Out System A mechanism that enables sliding sash balance mechanisms to remain in place whilst a sash is removed Tandem bar A rigid bar linking two remote folding opener mechanisms Raambedieningsstang Two rollers operating one behind the other Patiodeurrollers Tension tool A hand held tool used to apply turns to a spiral balance to create the required tension to support the sash mass Opwindingsslingertje Waxed cotton cord to support the sash weight on a sliding sash window Gewaxt katoen koord Waxed cotton cord to support the sash weight on a sliding sash window Gewaxt katoen koord A purpose made frame glazed and for fitment to a building or structure Raam Window balance A device to counter weight the mass of a sliding sash on a vertical sliding window Uitbalanceren A device to lock the opening sash of a window Kierstandhouder The plural of window catch Kierstandhouders Components and assemblies which enable windows to be assembled and operated correctly Raambeslag, Raamgarnituur Window hardware from the UK Eungels raambeslag Devices that permit windows

 and sashes to be opened Raampen Mechanisms that permit an operable window to be opened Raamopener Window pole opener An extended rod with a suitable end attachment which permits a user to open or close windows Raamstok Window pole operator An extended rod with a suitable end attachment which permits a user to open or close windows Raamoog Architectural Terminology A semicircular or polygonal passageway around the apse of a church.

Image courtesy of Gretchen Ranger Apse A semicircular, polygonal, or rectangular extension at the end of a Roman basilica or a Christian church. Image courtesy of Heather Russell Anta In Classical temples, the pilaster like projecting end of a portico wall often framing columns, which are then said to be in antis Image courtesy of Gayle Goudy Kochanski Arcade A series of arches supported on piers or columns. A "blind" arcade is a row of arches applied to the wall as an ornamental feature. Image courtesy of Gayle Goudy Kochanski Arch A structural devise, curved in shape, to span an opening by means of wedge-shaped bricks or stones (voussoirs) that support each other by exerting mutual pressure and that are buttressed at the sides. Image courtesy of Gayle Goudy Kochanski Architrave A square beam that is the lowest of the three horizontal components of a Classical entablature. Image courtesy of Heather Russell Archivolt A molded band carried around an arch. Image courtesy of Gayle Goudy Kochanski Arcuated Any form of construction using arches.

Image courtesy of Gayle Goudy Kochanski Ashlar Building stone that has been squared and finished, and the masonry constructed of such blocks. Courtesy of Heather Russell Barrel Vault A half-cylindrical vault, semicircular or pointed in cross section; also called tunnel vault. Image courtesy of Heather Russell Bay A vertical compartment of a building in which several such compartments are repeated; each bay mignt be defined by columns, piers, windows, or vaulting units. Michelangelo Museo Capitolino is divided into 7 bays by pilasters. Image courtesy of Phil Gruen Basilica In ancient Roman architecture, a large rectangular building used as a tribunal or for other public purposes and generally arranged with nave, aisles, and one or more apses. In Christian architecture, a longitudinal church of related form. Image courtesy of Gayle Goudy Kochanski Boss Sculpted ornament of joints, found primarily in vaults. Image courtesy of Gretchen Ranger Buttress A projecting mass of masonry serving to provide additional strength for the wall as it resists the lateral thrust exerted by an arch or vault.

Plying Buttress: in a church, a buttress in the form of an arch, or set of arches, that carries the thrust of a nave vault over the side aisle roofs down to a massive external pier. Image courtesy of Gretchen Ranger Capital The uppermost part of a column, usually shaped to articulate the joint with the lintel or arch supported; in Classical types, comprising an abacus, echinus, and other carved detail. Image courtesy of Heather Russell Caryatid A sculpted female figure used as a support in place of a column or pier. Image courtesy of Heather Russell Cella The body and main sanctuary of a Classical temple, as distinct from its portico and other external parts; sometimes used synonymously with naos, the principal room of a temple where the cult statue is housed. Image courtesy of Gayle Goudy Kochanski Centering Temporary wooden framework used to hold construction material in place until a vault or arch is self-sustaining. Image courtesy of Gail Gould Chancel The eastern portion of a church set apart for the clergy, and often separated from the main body of the church by a screen, rail, or steps. The term is also used to describe the entire east end of a church beyond the crossing.

Image courtesy of Gretchen Ranger Chevet A French term used to describe the developed east end of a church, usually a French Gothic cathedral, with its apse, ambulatory, and radiating chapels. Image courtesy of Gretchen Ranger Choir The part of a church, generally located toward or in the apse, reserved for clergy and singers. (This photograph was taken looking down the nave toward the apse. The choir screen is highlighted, which is just beyond the transept.) Image courtesy of Gretchen Ranger Clerestory A part of a building that rises above adjoining roof-tops and is pierced by window openings to admit light to the interior. Image courtesy of Gretchen Ranger Cloister An open square court surrounded by a covered ambulatory, often archaded. It is generally attached to a church or monastery and is distinguished from a secular courtyard by its function as a lace of seclusion and repose. Image courtesy of Gretchen Ranger Coffering Recessed panels, square or polygonal, that ornament a vault, ceiling, or the underside (soffit) of an arch. Image courtesy of Gretchen Ranger Colonnette A small or greately attenuated, slender column.

Image courtesy of Gayle Goudy Kochanski Colossal/Giant Order Columns or pilasters that rise through several stories; also called a Giant Order. Image courtesy of Phil Gruen Column A vertical, usually cylindrical, support, commonly consisting of a base, shaft, and capital; in Classical archtecture, its parts are governed by proportional rules. Image courtesy of Heather Russell Composite Order One of the five Classical orders; favored in late Roman architecture. On the capital, large conjoined Ionic volutes are combined with the acanthus leaves of the Corinthian order. Image courtesy of Gail Gould Compound Pier A pier with columns, shafts, and pilaters attached, sometimes in clusters, to its faces. Image courtesy of Gayle Goudy Kochanski Corbel A masonry block projecting from a wall to support a superincumbent element. Image courtesy of Gretchen Ranger Corbeled Arch Masonry constructed over a wall opening by a series of courses projecting from each side and stepped progressively further forward until they meet at midpoint; not a true arch.

Corinthian Order The most richly embellished of the thre orders (Doric, Ionic, and Corinthian) developed by the Greeks, with a tall capital composed of a bell-shaped core (kalathoss) envelped by layers of acanthus leaves terminating in the corner volutes, surmounted by concave-sided abacus. Image courtesy of Gail Gould Cornice The uppermost, projecting portion of an entablature; also the crowing horizontal molding of a building or wall. Image courtesy of Heather Russell Crossing The area where the nave and transept intersect in a cruciform church, frequently surmounted by a tower or dome. (This tower is over the crossing). Image courtesy of Gail Gould Crypt A vaulted space beneath the pavement of a church, often housing relics or tombs. Diaphragm Arch A transverse arch across the nave of a church partitioning the roof into sections. Image courtesy of Gretchen Ranger Dipteral Referring to a temple surrounded by a double range of columns. Image courtesy of Gayle Goudy Kochanski Distyle in Antis In a Classical temple referring to a portico with two columns between piers (antae) projecting from the cella walls.

Image courtesy of Gayle Goudy Kochanski Dome A curved vault that is erected on a circular base and that is semicircular, pointed, or bulbous in section. If raised over a square or polygonal base transitional squinches or pendentives must be inserted at the corners of the base to transform it into a near circle. Image courtesy of Gayle Goudy Kochanski Doric Order The column and entablature developed on mainland Greece; the fluted columnar shaft is without a base; its capital is an abacus above a simple cushionlike molding (echinus). The entablature has a plain architrave, a frieze composd of metopes and triglyphs, and a cornice with projecting blocks (mutules). In Roman Doric, the colun is slimmer than the Greek prototype, is unfluted, and stands on a low base; the capital is smaller. Image courtesy of Heather Russell Drum 1. The cylindrical or polygonal wall supporting a dome. Image courtesy of Gayle Goudy Kochanski 2. One of the cylindrical sections comprsing the shaft of a column. Image courtesy of Heather Russell Dry Masonry Masonry laid without mortar.

Image courtesy of Heather Russell Echinus A convex, cushion like molding between the shaft and the abacus in the Doric or Tuscan order; in an Ionic capital, found beneath the volutes, generally in decorated form. Image courtesy of Heather Russel Engaged Column A column attached to or appearing to be partly embedded wthin a wall. Images courtesy of Heather Russell (left) and Gayle Goudy Kochanski (right) Entablature The upper part of a Classical order comprising architrave, frieze, and cornice. Image courtesy of Heather Russell Entasis The slight swelling of the vertical profile of a Classical column as it tapers toward the top to counteract the illusion of concavity that accompanies straight-sided columns. (orange lines exaggerated) Image courtesy of Heather Russell Exedra A semicircular recess or niche; a large apse. Image courtesy of Gretchen Ranger Extrados The upper surface of an arch or vault. Image courtesy of Gayle Goudy Kochanski Facade The principal exterior face of a building, usually the front. Image courtesy of Phil Gruen Fluting The shallow concave channels cut vertically into the shaft of a column or pilaster.

In Doric columns, they meet in a sharp edge (arris); in Ionic, Corinthian, and Composite columns, they are separated by a narrow strip. Image courtesy of Heather Russell Frieze A horizontal band, sometimes painted or decorated with sulpture or moldings. It may run along the upper portion of a wall just beneath a cornice or it may be that part of a classical entablature that lies between the architrave and cornice. A Doric frieze often has continuous relief sculpture. Image courstesy of Heather Russel Gable A triangular element. It may be the end of a pitched roof framed by the sloping sides. It also refers to the top of a Gothic panel, or to the triangular area above the portals of a Gothic building. Image courtesy of Gretchen Ranger Gallery An upper story projecting from the interior wall of a building, or placed above the aisles of a church. It may function as a corridor or as an area for assembly or seating. Image courtesy of Gail Gould Groin Vault A vault formed when two barrel vaults of identical size intersect at right angles (also called a cross vault).

Image courtesy of Gail Gould Hall Church A church in which the nave and aisles are the same height, giving the building the appearace of a great hall. Impost In a pier, the projecting molding at the springing of an arch. A rectangular impost block transmits the weight of an arch to a supporting member; it may appear between the capital of a column and the springing of an arch. Image courtesy of Gayle Goudy Kochanski In Antis The term used to describe columns placed between the ends of two walls, commonly projecting from the ends of the cella of a small Greek Temple. Image courtesy of Gayle Goudy Kochanski Intrados The undersurface (as opposed to extrados) of an arch (or vault); also called a soffit. Image courtesy of Gayle Goudy Kochanski Intercolumnation The space between adjacent colunms in a colonnade, frequently determined by some multiple of the diameter of the column itself. Image courtesy of Heather Russell Ionic Order One of the five Classical Orders, the Ionic is characterized by a scroll-shaped (voluted) capital element, the presence of dentils in the cornice, and a frieze that mighta contain continuous relief ornament.

Image courtesy of Gretchen Ranger Keystone The central voussoir at the top of a completed arch. Image courtesy of Gayle Goudy Kochanski Lancet Window A tall, slender window with a sharply pointed arch (like a lance), common in early Gothic architecture. Image courtesy of Gretchen Ranger Lantern A cylindrical or polygonal structure that crowns a dome, its base usually open to allow light to enter the area below. Image courtesy of Gretchen Ranger Loggia An arcade supported by piers or coluns, open on one side at least; either part of a building (as a porch) or a separate structure. Image courtesy of Gayle Goudy Kochanski Lunette A semicircular wall area, or opening, above a door or window; when above the portal of a church, often called a tympanum. Image courtesy of Gretchen Ranger Martyrium A struction, oftenof central plan, erectred on a site sacred to Christianity, symbolizing an act of martydom or marking the grave of a martyr who died for the faith. Megaron The principal hall of an Aegean dwelling, oblong in shape and formed with sloping sides and a flat top, with a passage leading to an underground burial chamber.

Melon Dome/Umbrella Dome A dome subdivided into individual concave webs; sometimes called an umbrella dome. Image courtesy of Gretchen Ranger Metope In the frieze of a Doric order, the rectangular area between tryglyphs; often left plain but sometimes decorated with relief ornament. Image courtesy of Heather Russell Molding A sculpted, ornamental band, carved with a distinctive profile or pattern; highly developed in Classical architecture. Image courtesy of Heather Russell Mullion A slender upright dividing an opening, usually a window, into two or more sections. Image courtesy of Gayle Goudy Kochanski Naos The principal enclosed area of a Greek temple, containing the cult statue of god or goddess. Image courtesy of Gayle Goudy Kochanski Narthex A colonnaded porch in front of the facade of a church, in early Chrisian architectue often serving as the fourth side of an atrium; also a transverse vestibule preceding the church nave and aisles. Image courtesy of Gayle Goudy Kochanski Nave The central, longitudinal space of a basilican church, separated from the aisles or from side chaples, and extending from the main entrance to the transept or to the apse.

Image courtesy of Gretchen Ranger Niche A concave recess in a wall, often used to house statuary. Image courtesy of Heather Russell Oculus A round window. Image courtesy of Gretchen Ranger Opisthodomos The room at the rear of a Greek temple, behind the naos. Image courtesy of Gayle Goudy Kochanski Order A system for the forms and relationship of elements in the column and entablature of Classical architecture according to one of five modes: Doric, Ionic, Corinthian (developed by the Greeks), and Tuscan and Composite (developed by the Romans). Palladian Motif/Serliana A triple opening formed by a central semicircular arch springing from the entablature of narrower flanking square-headed bays, used by architect Andrea Palladio. Also known as a Serliana because it was first illustrated in the architecture treatise of 1537 by Sebastiano Serlio. Image courtesy of Gail Gould Parapet A low wall for protection at the edge of a balcony, terrace, roof, bridge, etc. Image courtesy of Gayle Goudy Kochanski Pedestal A supporting substructure for a column or statue.

Image courtesy of Heather Russell Pediment A triangular space formed by the raking cornices (sloping sides) and horizontal cornice of a gabled temple; also used above a door or window. If the apex or base is split, the pediment is described as broken. Image courtesy of Heather Russell Pendentive An inverted, concave, triangular piece of masonry serving as the transition from a square support system to the circular base of a dome. Image courtesy of Gretchen Ranger Peripteral Pertaining to a building surrounded by a row of columns on all sides. Image courtesy of Heather Russell Piano Nobile The principal reception and living area in an Italian palace, the first floor above the ground. Image courtesy of Gretchen Ranger Piazza The Italian term for a city square. Image courtesy of Phil Gruen Pier A massive vertical support often rectangular in plan and therefore differing from a column, sometimes having its own capital and base. When combined with pilasters, columns, or shafts, it is called a compound pier. Its proportions are far more variable than a Classical column. Pier is also the term used for the solid mass between windows, doors, and arches.

Image courtesy of Heather Russell Pilaster A column is flattened, rectangular shape, projecting slightly form the face of the wall. Image courtesy of Gayle Goudy Kochanski Plinth A generally square block forming the bottommost element of a column base; or the projecting lowest portion of a wall. Image courtesy of Gayle Goudy Kochanski Podium A massive platform on which an Etruscan, Roman, or other ancient building was sometimes placed. Image courtesy of Gail Gould Portico An open, colonnaded, roofed space serving as a porch before the entrance to a building. Image courtesy of Gail Gould Post and Lintel A system of construction in which two or more uprights support a horizontal beam; also called trabeated. Image courtesy of Heather Russell Pronaos The porch in font of the cella of a Greek or Roman temple formed by the projection of the side walls and a range of columns between the projections. Image courtesy of Gayle Goudy Kochanski Pylon In ancient Egyptian architecture, the sloping, tower-like walls flanking the entrance to a temple.

Image courtesy of Phil Gruen Quoin Large stone or block laid at the corner of a building (or at an opening) used either for reinforcement of the angle or for ornament. Image courtesy of Gail Gould Revetment The facing of a surface, usually a wall, with stone for ornamentation or protection. (Notice how the ornamental revetment is only on the facade and does not continue on the side surfaces.) Image courtesy of Gretchen Ranger Rib A slender, projecting arched member of a vault, used to facilitate its construction, reinforce its structure, or articulate its form in varying ways in Roman, Byzantine, and Islamic, Gothic, and Baroque architecture. Image courtesy of Gretchen Ranger Rib Vault An arched ceiling or roof supported or reinforced by ribs. Image courtesy of Gretchen Ranger Rustication Masonry with massive, strongly textured or rough-hew blocks and sharply sunk joints, distinguished form smooth ashlar. Image courtesy of Phil Gruen Scotia A concave molding used as the intermediate part of a base. Image courtesy of Heather Russell Shaft The cylindrical body of a column between capital and base. Image courtesy of Heather Russell Spandrel The triangular area between adjoining arches, or the triangualr area next to a single arch.

Image courtesy of Gayle Goudy Kochanski Spire A tall pointed termination of a tower or roof. Image courtesy of Gretchen Ranger Splay The widening of windows, doorways, and other openings by slanting the sides. Springing The point from which an arch or vault springs or rises from its supports. Image courtesy of Gayle Goudy Kochanski Squinch A small arch, or sometimes a lintel, thrown across the angle of a square or polygon to make them more nearly round and thus able to recieve the circular base of a dome. Image courtesy of Gail Gould Stringcourse A continuous, projecting horizontal course of masonry, ususally molded, running along, the surface of a wall, to mark an architectural subdivision. Image courtesy of Gayle Goudy Kochanski Stylobate The continuous platform of masonry on which a colonnade rests; the uppermost level of the stepped base (crepidoma) of a Greek temple. Image courtesy of Heather Russell Thrust The outward force exerted by an arch or vault. Image courtesy of Gayle Goudy Kochanski Torus A large convex molding found principally at the base of a column.

Image courtesy of Heather Russell Trabeated An architectural system using a horizontal beam over supports, as opposed to an arched or arcuated system; synonymous with post and lintel. Image courtesy of Heather Russell Tracery Ornamental intersecting stonework in Gothic windows, panels, and screen of Gothic buildings; also used on the surface of late Gothic vaults. Varied techniques and patterns are given names such as plate tracery (built up in corsed layers like the framing walls), bar tracery (constructed of complex fragments of the total pattern), flowing tracery (seemingly freehand, curvilinear design, though compass drawn), etc. Image courtesy of Gail Gould Transept In a basilican church, the arm that crosses the nave at right angles, usually separating it from the apse; twin transept arms may also project from the nave without interrupting it. Triforium An arcaded wall passage in a Gothic nave wall, between the clerestory and the main arcade in a three-story elevation; in a four-story elevation, it appears between the gallery and the clerstory.

Image courtesy of Gail Gould Triglyph In a Doric frieze, the projecting block marked by vertical grooves (glyphs) between the rectangular areas known as metopes Image courtesy of Heather Russell Vault An arched ceiling or roof made of stone, brick, or concrete (cf. barrel vault, fan vault). Image courtesy of Heather Russell Volute Ornament in the form of a spiral scroll, and the principal feature of the Ionic capital. Image courtesy of Gayle Goudy Kochanski Voussoir A wedge-shaped stone used in the construction of an arch or vault. Image courtesy of Gayle Goudy Kochanski Westwork In a Carolingian or Romanesque church, the towerlike west end, often containing an entrance vestibule surmounted by a large room open to the nave. Image courtesy of Gail Gould Glossary Helpful glossary for any window replacement or door replacement project for your home. Apron A piece of window trim attached to the wall underneath the interior stool (interior sill). Argon Gas An inert, nontoxic gas (denser than air) used between window panes to insulate by reducing heat transfer.

Astragal A component fastened to one sash/panel of a gliding window or patio door that becomes the closing shoulder of the operating sash/panel. Its function is similar to a mull post. Awning Window Hinged at the top, opens outward from the bottom with a crank, push bar, or manually operated using pressure hinges. Balance Also called balancer. Mechanical device used on double-hung windows to counterbalance the weight of each sash during opening and closing. There are four balances in a double-hung window . Bay Window Three or more window units attached together to project outward from a building wall. Bay angles vary; most common are 30°, 45° and 90°. Units can be the same or a combination of stationary and operating windows. Bottom Rail The bottom horizontal component of a window sash that supports the weight of the glass. Bow window A composite of four or more window units in a radial or bow formation. Brickmould A milled wood trim piece that covers the gap between the window frame and the exterior of the building. On traditional wood windows, the brick mould is nailed through to attach the window to the wall.

Capstock Various materials used to coat wood, vinyl, metal, composite or other building materials. Provides a durable layer that protects against environmental exposure such as ultraviolet light. Casement Window Hinged top and/or bottom, may pivot inward or outward, and opens with a bar or manual crank. Casing Brickmould Trim, usually milled wood, attached to the interior wall around a window to cover the space between the window frame and the wall. Check Rail The horizontal middle rails that meet where the sash come together and lock on a double-hung window . Upper check rail refers to the bottom rail of the upper sash and lower check rail refers to the top rail of the lower sash. Also called meeting rail. Coil Stock A sheet (usually prefinished aluminum), commonly packaged 12 to 30 inches wide on a 50-foot roll. Used for external covering and trim, shaped and cut using a brake. Composite A solid material composed of two or more substances. Condensation Water vapor from the air deposited on any surface having a temperature below the dew point, e.g., humid indoor air on cold window glass.

Conduction The transfer of heat through a solid material, where heat flows to a lower-temperature area from a higher-temperature area. Convection The transfer of heat through a fluid material such as air due to differences in fluid density and the effects of gravity. Divided Light A window having several small glass panes held in place by muntins within the window sash. Double Glazing Two panes (or lites) of glass separated by an insulating space in a window or patio door. They may be individual panels or a sealed unit. The dry, airtight space between the panes minimizes condensation and provides excellent insulation properties. Double-Hung Two movable sash that slide up and down independently. Drip Cap A Type of flashing, often made from sheet metals, installed at the head of a window or door and extending to the exterior claddings. Used to divert water to the exterior or block the flow of water into the gap between the head jamb of a window or door and the wall. (See Flashing.) Egress A window opening providing a secondary means of escape or rescue in an emergency.

Various state or local codes have restrictions affecting the clear opening height and width a window must possess if it is a designated egress window. Energy Rating Energy performance as affected by the energy efficiency of the framing, weatherstrip, and window glazing. Set by the National Fenestration Rating Council. ENERGY STAR® Certification Program An Environmental Agency (EPA) and Department of Energy (DOE) certification program for NFRC windows that are 30% or more energy efficient above Model Energy Code standards. Renewal by Andersen® windows are rated ENERGY STAR qualified. Extension Jamb A wood trim accessory that fills the space between the innermost edge of the window and the interior wall face. Extrusion The process of forcing heated materials such as aluminum or vinyl through a die to produce specified shapes. Fenestration Term used to refer to window and door products and accessories. Fibrex® Material An Andersen patented structural composite of wood fiber and specially formulated thermoplastic polymer. Polymer surrounds and coats each fiber, providing moisture resistance and superior strength and rigidity. Fixed Light A glass pane installed in a non-operational frame. Fixed Panel A non-operational panel in a gliding window or a href="">sliding glass door.

Fixed Window A window having no operational sash. (i.e. a picture window ) Flanker A window set on either or both sides of a center unit (usually a picture unit). Flashing Material such as sheet metal installed to shed water away from joints. Full-Frame Replacement Replacement method where the entire old window is removed and replaced with a Renewal by Andersen® window. Fusion Weld A manufacturing process for fusing sash or frame components together. The lineal ends are thermally softened with a hot plate, then welded to form a structural bond. Used in vinyl window manufacture and the manufacture of Renewal by Andersen products. Gas Fill Gas, typically argon or krypton, is placed between glazing panels to suppress conduction and convection (reduce the U-Factor). Glass An inorganic material composed of sand (silica), soda (sodium bicarbonate), and lime (calcium carbonate). Also includes small quantities of alumina, boric, or magnesium oxides. Glass Stop Removable trim piece holding the glass in place on traditional windows. Also referred to as a glazing bead.

(Renewal by Andersen uses this only on picture windows.) Glazing Usually refers to the glass system used by a window, including the glass, glass coating, insulating spacer, and glass sealants. Glazing Bead A molding or stop around the stiles and rails of the sash which holds the glass in place. Gliding Window Window style with two or more independent sash. One or more of the sash travel horizontally for ventilation. Also called glider. Grilles Decorative element that visually divides the glass into a desired pattern. Also called muntins. (Renewal by Andersen offers aluminum grilles between-the-glass (GBG) or wood snap-on grilles (removable) for interior glass surface.) Head Jamb The topmost component of the window or door frame. The window sash seats against it. Head Track The head member and track along the top of a sliding glass door or gliding window . Header The horizontal structural framing component forming the top of the rough opening in the wall or door. Heat Gain Heat transfer from the outside to the inside of a structure by conduction, convection, and radiation through all surfaces.

Heat Loss Heat transfer from the inside of a house to the outside due to conduction, convection, and radiation through all surfaces. High-Performance™ Low-E4® Glass Andersen Corporation's brand name for their Low E (low emissivity) insulated glazing system. High-Performance™ Low-E4® Sun Glass Andersen Corporation's brand name for a slightly gray-tinted low emissivity glazing system designed for southern climates or windows in rooms where heat buildup (solar heat gain) is a factor. Infiltration The term used to describe the tendency of a window to allow air or water to move into or out of the building through or around the product's weather stripping or joints. Organizations such as WDMA, AAMA, and NFRC have adopted test standards for measuring acceptable levels of air and water infiltration for specific grades of product performance. Insect Screen Woven metal or plastic mesh stretched over a screen frame. Allows window ventilation while keeping insects out. Insert Replacement Window replacement method where a complete frame/sash unit is inserted inside the jamb area (pocket) of the original window frame.

Inside Stop On an older wood window, a piece of wood trim attached to each side jamb that defines the inner edge for the lower sash channel. Installation Flange A fin of vinyl or metal that extends outward perpendicular from the frame of a window, which allows the window to be suspended within a rough opening. Insulating Glass Two or more pieces of glass with a space between them that are hermetically sealed to provide insulating characteristics. Insulation Any type of material used to prevent the passage of heat, cold, fire, or noise. Interlock The place where a mechanism of one panel/sash connects tightly with the corresponding mechanism of an adjacent panel/sash, as in patio doors , gliding and double-hung windows . Jamb The members that make up the sides and head of a window frame. Jamb Cover (Liner) Material used to trim off visible surfaces on windows and doors. Often used to create travel channels and weatherstrip shoulders; can hide and protect functional hardware such as double-hung balancers. Keeper The hardware piece where the lock engages on the sash.

Jamb Cover Laminated Glass A type of safety glass; two or more sheets of glass with an inner layer of plastic which holds the glass pieces if the glass is broken. Lift The handle attached to the rail on a double-hung or gliding window . Light (Lite) A window; an individual pane of glass installed in a window. Also one section of the glass pane when visually divided by grille bars. Lineal Long length of extruded window material; includes wood, aluminum, vinyl, or Fibrex composite extrusions. Low-E Abbreviation for low emissivity, a glass coating process that allows most of the sun's visible spectrum to pass through to the interior and reflects most heat energy back to its source (in cold weather, a low-E coating reflects radiant energy back into the house; in hot weather, it reflects the sun's heat energy back to the outside). A variety of low-E coatings are offered by glass manufacturers, with varying degrees of efficiency. Meeting Rails The two horizontal members of a double-hung sash that meet and are locked together when the window is closed. Also called check rail.

Meeting Stile Either vertical-edge member in a pair of gliding window sash or door panel that meet and lock when the sash/panel are closed. Comparable to the meeting rail on a double-hung window . Miter A method of cutting and joining two pieces of trim. The edge of a material beveled to make a miter joint; usually at a 45° angle. Mortise and Tenon A slot (mortise) made in a piece of wood to receive an extension (tenon) of another piece of wood. Renewal by Andersen® gliding and double-hung windows provide the interior appearance of a traditional hand-crafted mortise and tenon joint via a patented sash welding method. Mullion/Mull A member between two separate windows being attached together. May be vertical or horizontal, structural or integral. Mull Post/Muntin A strip of wood or metal separating and holding panes of glass in a window. NFRC National Fenestration Rating Council. An independent agency established in 1992 to test and rate window and door products. Also see Energy Rating. WDMA Organization established by window and door manufacturers to create industry standards and advocate self-monitoring.

Obscure Glass One of several types of specialty glazings that are textured for privacy, light diffusion, or decoration (frosted, etched, etc.). Operable Window Window that can be opened and closed. Operator A device for opening and closing windows. Usually refers to a crank-operated mechanism found on casement and awning windows . Outside Stop On an older wood window, a piece of external wood trim attached to each side jamb that defines the outer edge for the upper sash channel. Also called blind stop. Pane A sheet of glass; a compartment in a door or window containing a sheet of glass. Panel A sliding or fixed unit consisting of a frame containing a light of glass. Panning A type of metal flashing system used under the door or window sill to channel water away from the framing and siding. Parting Stop A narrow strip that separates and secures two sash in the window frame. It provides a channel in which the sash can move. Passive A sash that can be operated if necessary but usually is not, e.g., the left-hand sash of a gliding window.

Perma-Shield® Andersen Corporation's trademark name for a system of products that provides next-to-no maintenance through vinyl wrapping of wood, high durability paint finishes, and other techniques. It originally referred to Andersen's use of the process for extruding a vinyl sheath completely around a wood component. Picture Window Fixed window with no opening sash. Plumb Vertically straight up/down. As an installation term, it refers to the importance of making sure that the window sides are perfectly perpendicular to the earth. Profile The end view shape of a lineal piece of the extruded or milled material. R-Value A measure of resistance to heat flow; a higher value indicates better heat-insulating property. Rail Horizontal member of a window sash or door panel. There are four rails on a double-hung window : the bottom rail, two meeting rails or check rails, and the top rail. Rough Opening The opening in a wall where a window or door will be installed. Safety Glass Also called tempered or wire-mesh glass, it meets a variety of industry and government safety standards. See Laminated Glass. Sash Lock The lock that connects with the keeper. Used on double-hung , casement, awning , and gliding windows.

Sash Pack A window replacement system using a sash and jamb liner components applied to an existing window frame. Sealant Various materials used to seal openings or the junctions between parts. May be liquid or solid, depending upon the application. Shim A thin slip of material for straightening jambs and leveling window and door frames. Shims are also used to adjust hardware positioning. Term is also used to describe the action of bringing to a level by inserting a shim. Side Jamb The left and right sides of the window frame. See Jamb. Sill Angle Slope of the outside window sill. Simulated Divided Lights A single unit of insulating glass with a simulated grille installed on the glass surface or between the glass panes that gives the appearance of small panes separated by muntins. Simulated True Divided Light A single unit of insulating glass with three sets of grilles: on the exterior and interior surfaces, and between the glass panes. Single-Hung A variation of the double-hung window style where the upper sash does not operate. Typically less expensive than a true double-hung window. Sliding Glass Door A door fitted with two or more panels that move horizontally on a track or in grooves.

Solar Heat Gain Coefficient (SHGC) The fraction of solar radiation admitted through a window (directly transmitted and absorbed) and then released inward. The lower the SHGC, the less solar heat it transmits and the greater the shading ability. Stationary A glazed sash or panel that cannot be operated. Stile The vertical-edge framing components of a window sash. Stool The interior window trim applied horizontally at 90 degrees to the wall at the base of a window (normally double-hung ), commonly called the window sill. Stop See Inside Stop, Outside Stop, Parting Stop. Storm Door A seasonal second door installed in front of an exterior access door to provide additional insulation or protection from bad weather and allow ventilation. Storm Window A seasonal second window installed on the outside or inside of a window to provide additional insulation or protection from bad weather and allow ventilation. Tempered Glass Treated glass strengthened by reheating and then sudden cooling; upt to 4 times stronger than normal glass. (See Safety Glass.) Thermal Break An element (space or other material) placed between other elements to reduce conduction.

(Andersen uses a vinyl thermal break on patio door sills.) Thermal Conductivity Refers to a physical property that affects the extent to which heat or cold is transferred by a material. For example: aluminum has 1,000 times the thermal conductivity of Fibrex™ material , making it a far more efficient insulating window material. Thermal Expansion A term that describes the expansion a material exhibits when exposed to high temperature, or the shrinkage (contraction) that results when exposed to low temperatures. Threshold The piece (wood, stone or other material) placed beneath a door to trim off the inside of the door sill. Tilt-Wash Double-hung window design that pivots or tilts for ease of cleaning. Tinted Glass Glass that is colored using a mineral admixture; sometimes a silver coating applied to the glass surface. Used to reduce radiation transmission. Transom A crosspiece separating a door from a window above it. Transom Window Also called a transom light, the window located above a door or other window. Triple Glazing Three panes with two air spaces between.

TruScene® Insect Screen A nearly invisible micro-fine stainless steel mesh insect screen that is one-third the diameter of a standard screen wire and allows over 50% more clarity than an Andersen conventional insect screen. U-Factor Sometimes called U-Value. A measure of the thermal efficiency of a window or a window component. Measures the amount of heat transferred through windows. The mathematical reciprocal of the same component or window R-Value. Ultraviolet Light (UV) Invisible rays of the spectrum at its short-wavelength violet end; the invisible solar radiation that can cause heat buildup and fading of wood, fabrics and other surfaces. (Low-E coatings are added to window glazing to moderate or eliminate harmful undesired UV wavelengths of light.) United Inch Term used to describe a method of calculating the size of a window, by adding the height to the width and expressing the sum in inches. Used for price estimating. Unit Dimension (UD) The UD is the precise size of the window (unit) when measured in width and height from the outermost edge of the window frame, not including any installation flange or brick mould. Vinyl-Clad Window A window with exterior wood parts covered with extruded vinyl.

Weatherstripping A narrow strip of material placed between window sash or door panels and frame to keep out rain, air, etc. May take many different forms, depending on product design and usage. Welding The fusing or melting together of two or more individual components to form a solid bond. For example, Renewal by Andersen window sash stile and rails, and many frame components are welded together. Window Hardware Mechanical devices and attaching hardware such as locks, hinges, pivots, catches, lifts and pulls, and stays. Request an Estimate

Question: What name is given to the vertical bar that divides the sections in a window?
Answer: A MULLION.