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Roofs:  roofs can be steep, gently sloped, or flat (which still have a slight slope to facilitate drainage) and take many forms, gable, gambrel, hipped, stepped gable, shed, pent or Mansard.  The roof type is an important key to identifying the style of a building.

Parapet:  a wall-like barrier at the edge of a roof that extends above the roof.

  • Where extending above a roof, it may simply be the portion of an exterior wall that continues above the line of the roof surface, or may be a continuation of a vertical feature beneath the roof such as a fire wall.
  • Parapets were originally used to defend buildings from military attack, but in contemporary architecture they are primarily used to terminate flat roofs into walls and/or prevent the spread of fires.

Soffit: the underside of a part or member of a building.

  • On a roof a soffit is the underside of the horizontal overhanging edge of the roof.  In most cases on buildings with sloping roofs the wall terminates into the soffit.  This overhang can be different widths depending on the design and preference. This will provide protection from the weather as well as add to the aesthetics of the building.
  • As opposed to the fascia that is the vertical face at the edge of a sloping roof.
  • the underside of an architectural feature, as a beam, arch, ceiling, vault, or cornice.
  • the underside of a part of a building or a structural component, such as an arch, beam, stair, etc.

Eaves: the overhanging edge of a roof that projects beyond the wall at the bottom of sloping roof.

  • Typically consists of a soffit and fascia.
  • Gutters are typically placed at the eaves to collect and channel water away from the building walls and foundations.
  • As opposed to a rake which is the overhang on the side of a sloping roof as seen on a typical gable end for example.

Shed:    A sloping roof that consists of only one sloping plane.

Gable:  The generally triangular section of wall at the end of a pitched roof, occupying the space between the two slopes of the roof

  • A triangular, usually ornamental architectural section, as one above an arched door or window.

Hipped Roof: A hip roof, or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus it is a building with no gables or other vertical sides to the roof.

  • A square hip roof is shaped like a pyramid. Hip roofs on the houses could have two triangular sides and two trapezoidal one. A hip roof on a rectangular plan has four faces. They are almost always at the same pitch or slope, which makes them symmetrical about the centerline.
  • Hip roofs have a consistent level fascia, meaning that a gutter can be fitted all around. Hip roofs often have dormer slanted sides.

Gambrel: A gambrel is a usually symmetrical two-sided roof with two slopes on each side. The upper slope is positioned at a shallow angle, while the lower slope is steep. This design provides the advantages of a sloped roof while maximizing headroom on the building’s upper level.  This efficient use of space is one reason gambrel roof are found on many barns.  The name comes from the Medieval Latin word gamba, meaning horse’s hock or leg.

  • The cross-section of a gambrel roof is similar to that of a mansard roof, but a gambrel has vertical gable ends instead of being hipped at the four corners of the building. A gambrel roof overhangs the façade, whereas a mansard normally does not.

Mansard Roof:  named after the French architect Francois Mansart (1598-1666); a double sloped roof with the lower slope being longer and steeper, with a concave curve.  Can be sloped on all four sides or just two sides (front and back).

  • A mansard or mansard roof (also called a French roof) is a four-sided gambrel-style hip roof characterized by two slopes on each of its sides with the lower slope, punctured by dormer windows, at a steeper angle than the upper. The roof creates an additional floor of habitable space, such as a garret. The upper slope of the roof may not be visible from street level when viewed from close proximity to the building.

Pediment:  a triangular space created by a front facing gable roof, often seen in Classical Revival style buildings.

  • A pediment is a classical architectural element consisting of the triangular section found above the horizontal structure (entablature), typically supported by columns. The gable end of the pediment is surrounded by the cornice molding.  The tympanum, or triangular area within the pediment, was often decorated with sculptures and reliefs demonstrating scenes of Greek and Roman mythology or allegorical figures.
  • (In classical architecture) a low gable, typically triangular with a horizontal cornice and raking cornices, surmounting a colonnade, an end wall, or a major division of a façade.
  • Any imitation of this, often fancifully treated, used to crown an opening, a monument, etc., or to form part of a decorative scheme.

Facade:  A facade is generally one exterior side of a building, usually, but not always, the front. The word comes from the French language, literally meaning “frontage” or “face.”

  • In architecture, the facade of a building is often the most important from a design standpoint, as it sets the tone for the rest of the building.  Many facades are historic, and local zoning regulations or other laws greatly restrict or even forbid their alteration.
  • The front of a building, especially an imposing or decorative one.

Bay: a division of space that is repeated within a building, a three bay house would have three spaces repeated along one side as in two rooms and a hall.

  • A space that projects from the rest of the building as in a bay window.
  • Architecture:
    • any of a number of similar major vertical divisions of a large interior, wall, etc.: The nave is divided into six bays.
    • a division of a window between a mullion and an adjoining mullion or jamb.
    • bay window
    • an alcove or recess in a wall

Mullion: a vertical structural element which divides adjacent window units. When used to support glazing, they are teamed with horizontal supporting elements called “transoms“.

  • In the commercial door industry, the term is also applied to a piece of hardware that divides the opening of a pair of doors.
  • A mullion acts as a structural member.  It carries the dead load of the weight above the opening and/or the wind load acting on the window unit back to the building structure. The term is also properly applied to very large and deep structural members in many curtain wall systems.

Muntin or Muntin bar:  is sometimes similar in appearance to a mullion, but they are not structural.  A muntin is a strip of wood or metal separating and holding panes of glass in a window.  Muntins divide a single window into a grid system of smaller panes of glass, called “lights” or “lites”.

  • Muntins can be found in doors and windows.
  • Windows with “true divided lights” make use of thin muntins positioned between individual panes of glass.  True divided lights are not typically seen in modern windows as they decrease performance and are more expensive/difficult to implement.
  • In contemporary windows muntins frequently do not actually separate panes of glass, but are decorative elements attached to the inside and/or outside of panes of glass to give the appearance of multiple smaller panes.  This is commonly called a “simulated divided light.”
  • Muntins are frequently mistakenly referred to as mullions.

Jamb:  One of a pair of vertical posts or pieces that together form the sides of a door, window frame, or fireplace, for example.

  • Architecture, Building Trades:
    • either of the vertical sides of a doorway, arch, window, or other opening.
    • either of two stones, timbers, etc., forming the sidepieces for the frame of an opening.
    • A projecting mass or columnar part.

Transom: a bar of wood or stone across the top of a door or window

  • a crosspiece separating a door or the like from a window or fanlight above it.
  • Also called transom light, transom window.
  • a window above such a crosspiece.
  • a crossbar of wood or stone, dividing a window horizontally
  • Compare mullion.  Also called: traverse

Fanlight:  A fanlight is a window, semicircular or semi-elliptical in shape, with glazing bars or tracery sets radiating out like an open fan, It is placed over another window or a doorway and is sometimes hinged to a transom. The bars in the fixed glazed window spread out in the manner a sunburst. It is also called a “sunburst light”.

  • A chiefly British use of the word is to mean “transom“.

Traverse:  a transverse gallery or loft of communication in a church or other large building.

  • Something being or lying across, such as a transom
  • A gallery or loft inside a building that crosses it
  • construction: Crossbeam: something that is set across a gap or lies crosswise, e.g. a structural member of a building
  • buildings :  Gallery: a gallery or loft that crosses from side to side inside a building
  • buildings :  Barrier within building: a railing, curtain, screen, or partition forming a barrier within a building
  • civil engineering:  Survey using intersecting straight lines: a survey made using a series of intersecting straight lines of known length whose angles of intersection are measured for recording on a map or in a table of data

Tracery:  window ornamentation: decorative ribs in windows, especially medieval church windows, and screens

  • interlaced pattern: a decorative pattern of interlaced lines, especially one that resembles the form or patterns found in church windows
  • In architecture, Tracery is the stonework elements that support the glass in a Gothic window. The term probably derives from the ‘tracing floors’ on which the complex patterns of late Gothic windows were laid out

Casement: in a window refers to a vertical window hinged on its vertical side, meant to open either out or in.

  • a window containing frames hinged at the side or at the top or bottom
  • a poetic word for window
  • hinged window: a window that opens on hinges located at one side, as distinct from one that slides up and down

Casing:  Casing is a type of trim moulding used to trim out windows and doors. This trim is called door casing or window casing depending on the application. Casing will come in different sizes and profiles. Two poplar casing are colonial and tear drop.

  • frame for door or window: a frame containing a door, window, or stairway

Clearstory (or Clerestory):  the upper level of a room that extends beyond the single-story height; often found in churches and penetrated by windows.

  • May also refer to the upper row of windows that is close to the ceiling
  • In modern usage, clerestory refers to any high windows above eye level; the purpose is to bring outside light, fresh air, or both into the space.
  • A clerestory is a high wall with a band of narrow windows along the very top. The clerestory wall usually rises above adjoining roofs.
  • Originally, the word clerestory referred to the upper level of a church or cathedral.
  • Pronunciation: Clerestory is pronounced clear story.

Fenestration:  The arrangement of windows across the facade of a building.

  • Fenestration, refers to the design and/or disposition of openings in a building or wall envelope.
  • Fenestration products typically include: windows, doors, louvers, vents, wall panels, skylights, storefronts, curtain walls, and slope glazed systems.
  • the arrangement, proportioning, and design of windows and doors in a building
  • an opening in a surface (as a wall or membrane)

Louver: A louver (American English) or louvre (British English), from the French l’ouvert; (“the open one”) is a window, blind or shutter with horizontal slats that are angled to admit light and air, but to keep out rain, direct sunshine, and noise. The angle of the slats may be adjustable, usually in blinds and windows, or fixed.

Glazing:  Glazing, which derives from the Middle English for ‘glass’, is a part of a wall or window, made of glass. Glazing also describes the work done by a professional “glazier“.

  • Common types of glazing that are used in architectural applications include clear and tinted float glass, tempered glass, and laminated glass as well as a variety of coated glasses, all of which can be glazed singly or as double, or even triple, glazing units. Ordinary clear glass has a slight green tinge but special clear glasses are offered by several manufacturers.
  • Glazing can be mounted into a window sash or door stile, usually made of wood, aluminium or PVC. The glass is fixed into a rabbet (rebate) in the frame in a number of ways including triangular glazing points, putty, etc.. Toughened and laminated glass can be glazed by bolting panes directly to a metal framework by bolts passing through drilled holes.
  • Glazing is commonly used in low temperature solar thermal collectors because it helps retain the collected heat.

So now the big question, is that “window” a window, storefront, or curtainwall?  Generally speaking all three are means to insert glazing, i.e. glass, in the exterior envelope of the building, but there are important technical and cost differences between the three.

Window:  A window is a complete manufactured unit that includes glass, frame, and componentry all in one.  Windows are delivered to the job site ready to install in a framed opening in the building.

  • Windows are most common in residential construction.
  • Big box home improvement stores carry windows, but not storefront or curtainwall.
  • Generally speaking windows are the least expensive of the three systems.

Storefront:  Storefront is different from windows in that it typically does not come to the job site assembled as a complete glazed unit.  The frames are either be pre-assembled and delivered to the site, or can be assembled in a framed opening on site.  The glazing is later installed in the frame on site.  This allows storefront to be more customizable and much larger than a window.

  • In most cases storefront will consist of multiple windows and/or doors in one framed opening in the building envelope.  While multiple windows and doors can be attached to one and other the effect is not as seamless or stable as can be achieved with storefront.
  • Storefront is generally more expensive and durable than windows.
  • Although large windows are available, typically storefront or curtainwall are used when larger individual glazed areas or a large combination of windows and doors is desired.  Ultimately the size of any individual area of glazing is limited by available glass sizes.
  • Storefront is typically used in openings up to two stories in height.  Larger openings require the use of curtainwall to resist wind loads.
  • The name here is telling.  Storefront is typically used at the front of retail stores to allow the store to feel open and welcoming to customers by maximizing visibility.  That being said storefront is also used in many other commercial building applications and even occasionally in custom residential work.

Curtainwall:  Curtainwall is the most complex, durable, and expensive glazing system of the three. That being said it shares one important similarity with windows.  It is typically delivered to a site in fully assemble panels that are ready to hang from the structure.  Where it differs is that the assemblies are large enough to require a crane for installation.

  • Curtainwall also differs from windows and storefront in that instead of being installed in framed openings in the exterior envelope it typically is the building envelope.
  • Curtain Wall Systems are typically designed with extruded aluminum members, although the first curtain walls were made of steel. The aluminum frame is typically infilled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting
  • Curtain walls differ from store-front systems in that they are designed to span multiple floors, and take into consideration design requirements such as: thermal expansion and contraction; building sway and movement.
  • Although it is accurate to say that curtainwall is non-structural in the sense that it is not part of the structural frame of the building, it is the strongest of the three glazing systems in its resistance to wind loads.
  • Curtain wall is typically suspended from a buildings structural frame.
  • It is typically used on high rise buildings and other large commercial buildings.
  • On smaller projects that do not require the use of curtainwall to resist wind loads it is typically avoided due to its high cost.

Astragal: a symmetrical moulding used in creating panels and horizontal banking in cornice, wainscoting, and pilaster assemblies.

  • a small convex molding cut into the form of a string of beads. Compare bead and reel.
  • a molding attached to one or both meeting stiles of a pair of double doors in order to prevent drafts.
    • An astragal is a moulding profile composed of a half-round surface surrounded by two flat planes (fillets). An astragal is sometimes referred to as a miniature torus. It can be an architectural element used at the top or base of a column, but is also employed as a framing device on furniture and woodwork.

Moulding or molding:  (USA) a strip of material with various profiles used to cover transitions between surfaces or for decoration. It is traditionally made from solid milled wood or plaster but may be made from plastic or reformed wood.

  • A “sprung” moulding has beveled edges that allow mounting between two non-parallel planes (such as a wall and a ceiling). Other types of moulding are referred to as “plain”.

Cornice molding: a horizontal decorative molding that crowns any building or furniture element: the cornice over a door or window, for instance, or the cornice around the edge of a pedestal. A simple cornice may be formed just with a crown molding.

Wainscot:  to line the walls of (a room, hallway, etc.) with or as if with woodwork: a room wainscoted in oak.

  • wood, especially oak and usually in the form of paneling, for lining interior walls.  
  • the lining itself, especially as covering the lower portion of a wall.
  • a dado, especially of wood, lining an interior wall.  
  • British. oak of superior quality and cut, imported from the Baltic countries for fine woodwork.

Pilaster:  a shallow rectangular feature projecting from a wall, having a capital and base and usually imitating the form of a column.

  • a shallow rectangular column attached to the face of a wall.

Torus: Architecture. a large convex molding, more or less semicircular in profile, commonly forming the lowest molding of the base of a column, directly above the plinth, sometimes occurring as one of a pair separated by a scotia and fillets and column.

  • Not to be confused with the sign of the horoscope: Taurus the bull.

Scotia: a deep concave moulding, esp one used on the base of an Ionic column between the two torus mouldings.

Fillet: Architecture. A flat narrow molding: a raised or sunken ornamental surface set between larger surfaces. Not to be confused with:

  • Food. boneless portion of fish or meat: a boneless portion cut from a fish, a poultry breast, or the rib area of beef, lamb, or pork.
  • Dress. ribbon worn around the head: a ribbon worn across the forehead, as an ornament or to hold back the hair.
  • Printing. corative line on the cover of book: a thin decorative line impressed onto the cover of a book, or the tool used to make it.