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Glossary of Architectural Terms


Abacus - the top slab of a capital

Acanthus - the plant whose leaf is used as decoration on column capitals of the Corinthian and Composite orders

Adaptive Use (Reuse) - the reuse of a building or structure usually for purposes different from the original use such as a residence converted into offices

Addition - new construction added to an existing building or structure

A.I.A. - the American Institute of Architects; the organization that licenses architects in the United States

Alteration - any act or process that changes any portion of the exterior architectural appearance or exceptionally significant interiors of a building, structure, or object, including, but not limited to the erection, construction, reconstruction, or removal of any exterior architectural features or interior architectural design of a structure; treatments such as sand blasting, water blasting, chemical cleaning, chemical stopping, or removal of any architectural feature, but not including changes to the color of exterior paint

Apron - a decorative, horizontal trim piece on the lower portion of an architectural element

Arabesque - a complex and ornate design that employs flowers, foliage, and sometimes animal and geometric figures to produce an intricate pattern of interlaced lines

Arcade - a number of arches carried on piers or columns

Arch - a curved or pointed structural element that is supported at its sides; a construction which spans an opening and supports the weight above it

Architrave - the lower part of an entablature running along the tope of the row of columns; the molding surrounding a door or window

Atrium - originally a central room or court found in Classical houses; in modern architecture the term is applied to a tall, multi-story open central area within a building that receives light from above

Balcony - a platform that projects from the wall of a building, and which is enclosed on its outer 3 sides by a balustrade, railing, or parapet

Baluster - a vertical supporting element similar to a small column

Balustrade - a railing consisting of a row of balusters supporting a rail; an entire rail system with top rail and balusters

Base - the lowermost portion of a wall, column, pier, or other structure, usually distinctively treated and considered as an architectural unit

Baseboard - horizontal board, usually trimmed with molding, placed at the bottom of a wall to cover the juncture between wall and floor

Bay - a section of a building distinguished by vertical elements such as columns or pillars often protruding from the surface of the wall in which it is situated thus creating a small, nook-like interior space, often of a rectangular or semi-hexagonal outline

Bay Window - a projecting bay that is lit on all of its projecting sides by windows

Beam - horizontal, load-bearing members of a building

Belvedere - square-shaped cupola

Bevel - a piece of wood, stone, or glass that has had the edge cut at an angle

Board-and-Batten - a wooden siding treatment in which wide, vertically oriented boards are separated by narrower strips of wood called battens which form the joints between the boards, technique common to American folk architecture

Boss - ornamental projection at the intersection of ribs or beams

Bow Window - a curved bay window

Bracket - a projection from a vertical surface that provides structural and/or visual support for overhanging elements such as cornices, balconies, and eaves

Buttress - masonry or brickwork which is built against, or projects from, a load-bearing wall to add strength

Canopy - a roofed structure constructed of fabric or other material placed so as to extend outward from a building providing a protective shield for doors, windows and other openings, supported by the building and supports extended to the ground directly under the canopy or cantilevered from the building

Cantilever - a horizontal projection from a wall, often balcony or stair, supported at one end only

Capital - the head of a column or pilaster; top section or crowning feature of a column, often elaborate

Casement Window - a window frame that is hinged on one vertical side and which swings open to either the inside or the outside of the buildings, often occurs in pairs

Casing - the framework around a door or window

Central Hallway - a passageway that cuts through the center of a building from front to back and off of which rooms open to the sides

Chamfered - beveled edge of stone or wood

Cladding - non-load-bearing external envelope or covering to a building

Clapboards - long slats of wood that are nailed to an exterior surface in a horizontal fashion overlapping one another from top to bottom; a traditional weather-proofing device

Classical Architecture - architecture originating in ancient Greece or Rome, the rules and forms of which were revived to establish the classical renaissance in Europe in the 15th and 16th centuries; noting or pertaining to architectural details or motifs adapted from ancient Greek or Roman models; architecture based on that of ancient Greece and Rome especially from the 5th century BCE in Greece to the 3rd century CE in Rome that emphasized the column and pediment

Coffering - recessed panels usually found in ceilings, vaults or domes

Colonnade - a range of columns that supports a string of continuous arches or a horizontal entablature

Column - a supporting pillar consisting of a base, a cylindrical shaft, and a capital on top of the shaft, plain or ornamental columns

Composite Order - a combination of the Ionic and Corinthian orders, the volute scrolls of the Ionic order are grafted onto the capitals of the Corinthian order

Conical Roof - a roof that is circular and terminates to a point at its peak, forming the shape of a cone

Corbel - in masonry, a projection or one of a series of projections, each stepped progressively farther forward with height and articulating a cornice or supporting an overhanging member

Corinthian Order - a variation of the Ionic and the youngest (dating from the 4th century B.C.E.) of the three basic orders of classical Greek architecture (the others being the Doric and the Ionic orders); the showiest of the three basic columns with a tall acanthus leaf capital, a molded base, and a slender fluted shaft

Cornice - a crowning projection at a roof line often with molding or other classical detail

Course - horizontal layer of bricks or stone forming part of a wall

Courtyard - an open space, usually open to the sky, enclosed by a building, often with an arcade or colonnade

Cove - large concave molding used like a cornice to join walls to ceilings

Crenelation - a sequence of alternating raised and lowered wall sections at the top of a high exterior wall or parapet, originally used for defensive purposes but later used for decoration

Cresting - an ornamental decoration at the ridge of a roof or top of a wall or screen

Crown Molding - the very top molding above the fascia in a Classical cornice; generic term for the cornice between the ceiling and the wall

Cupola - a small dome, or hexagonal or octagonal tower, located at the top of a building, sometimes topped with a lantern

Dado - the major part of a pedestal between the base and the cornice or cap; lower portion of an interior wall when faced or treated differently from the upper section as with paneling or wallpaper

Decorative Motif - a repeated pattern, image, idea, or theme

Dentils - small rectangular blocks that, when placed together in a row abutting a molding suggest a row of teeth

Design Guidelines - the "Standards for Rehabilitation and Guidelines for Rehabilitating Historic Buildings" as adopted by the Secretary of the United States Department of the Interior, and other guidelines which may be adopted from time to time

Diamond-Paned Windows - windows that are made up of many small, diamond-shaped panes of glass, common in Colonial and Colonial Revival buildings

Doric Order - the oldest (dating to the 6th century B.C.E.) and plainest of the three basic orders of classical Greek architecture (the others being the Ionic and the Corinthian orders; a stout column with a fluted shaft (ideally with 20 flutes), a plain capital, and no base

Dormer Window - a perpendicular window located in a sloping roof, triangular walls join the window to the roof, sometimes crowned with pediments, used to light attic rooms, derives from "dormir," French for "to sleep"

Double-Hung Windows - a window with two sashes that move independently of each other

Eaves - the projecting edges of a roof that overhangs an exterior wall to protect it from the rain

Elevation - any one of the external vertical planes of a building or structure

Entablature - a part of a building of classical order resting on the column capital, consists of an architrave, frieze, and cornice

Fabric - original or old building materials (masonry, wood, stone, metals, marble) or construction; the physical material of a building, structure, site, or community conveying an interweaving of component parts

Facade - an exterior wall or face of a building, the front facade of a building contains the building’s main entrance

Fan Light - a semi-circular or semi-elliptical window with wedge-shaped panes of glass separated by mullions arranged like the spokes of a wagon wheel, usually found over entrance doors and windows particularly in Federal and Greek Revival homes

Fascia - a projecting flat horizontal member or molding; forms the trim of a flat roof or a pitched roof; also a part of a classical entablature

Federal Historic Rehabilitation Tax Credit - 20% Federal tax credit to support the rehabilitation of historic and older buildings administered by the National Park Service with the Internal Revenue Service in partnership with State Historic Preservation Offices

Fenestration - the arrangement of windows on a building

Finial - a projecting decorative element at the top of a roof turret or gable

Fireplace Surround - a molding about a fireplace often highly decorated

Flashing - thin metal sheets used to prevent moisture infiltration at joints of roof planes and between the roof and vertical surfaces

Floor Plan - a scale diagram of the arrangement of rooms in a single floor of building presented in a one-dimensional drawing

Fluting - shallow vertical grooves in the shaft of a column or pilaster

Foundation - the lowest exposed portion of the building wall which supports the structure above

French Doors - two adjacent doors that share the same door frame and between which there is no separating vertical member

Fresco - method of painting directly on wall or ceiling before plaster dries

Frieze - a band of richly sculpted ornamentation on a building

Gable - the triangular section of a wall to carry a pitched roof

Gable Roof - a roof with two slopes, front and rear, joining at a single

ridge line parallel to the entrance facade; when the ridge line of gable-roofed house is perpendicular to the street, the roof is said to be a "gable-end roof"

Gambrel Roof - a ridged roof with two slopes at each side, the lower slopes being steeper than the upper slopes

Gesso - made from gypsum powder or chalk, it is mixed with size or a binding glue to form a dense white absorbent base for the decoration of paneling or for gilded moldings

Gingerbread - wooden architectural ornament popular with American folk houses in the late-19th and early 20th centuries particularly in the Stick Style; often took the form of scalloped or zig-zag-edged clapboards which were often painted in contrasting colors; used widely in the mid-19th century

Half-Timbered - a timber framework of Medieval European derivative whose timbers are in-filled with masonry or plaster

Hardware - the metal fittings of a building such as locks, latches, hinges, handles, and knobs

Heritage Tourism - travel for the purpose of experiencing the places, artifacts, and activities that authentically represent the stories and people of the past and present; includes cultural, historic, and natural resources

Hipped Roof - a roof with uniform slopes on all sides

Historic Context - patterns or trends in history by which a specific occurrence, property, or site is understood and its meaning and significance within history or prehistory is made clear; historical patterns that can be identified through consideration of the history of the property and the history of the surrounding area; may relate to an event or series of events, pattern of development, building form, architectural style, engineering technique, landscape, artistic value, use of materials of methods of construction, or be associated with the life of an important person; also the setting in which a historic element, site, structure, street, or district exists

Historic District - an area designated as a "historic district" by ordinance of the city council and which may contain within definable geographic boundaries one or more landmarks and which may have within its boundaries other proportions or structures that, while not of such historic or architectural significant to be designated as landmarks, nevertheless contribute to the overall historic or architectural characteristics of the historic district

Historic Integrity - the ability of a property to convey its significance; the retention of sufficient aspects of location, design, setting, workmanship, materials, feeling, or association for a property to convey its historic significance

Historic Landmark - a building, district, object, site, or structure that is officially recognized by the United States government for its outstanding historical significance

Historic Preservation - see Preservation; according to the National Historic Preservation Act, includes identification, evaluation, recordation, documentation, curation, acquisition, protection, management, rehabilitation, restoration, stabilization, maintenance, research, interpretation, conservation, and education and training regarding the foregoing activities or a combination of the foregoing activities

Historic Property - a district, site, building, structure or object significant in American history, architecture, engineering, archeology or culture at the national, State, or local level

Historic Significance - determines why, were, and when a property is important; the importance of a property with regard to history, architecture, engineering, or the culture of a state, community, or nation; the characteristics or associations must be considered within its historic context - properties can be significant for their association or linkage to events or persons important in the past, as representatives of manmade expression of culture (design/construction) or technology, or for their ability to yield important information about history or prehistory

Intarsia - a form of mosaic made up of different colored woods that was popular in 15th and 16th century Italy especially for floors

Integrity - the authenticity of a property’s historic identity evidence by the survival of physical characteristics that existed during the property’s historic or prehistoric period

Inventory - a list of historic properties determined to meet specified criteria of significance

Ionic Order - the second oldest (mid 6th-5th century B.C.E.) of the three basic orders of classical Greek architecture (the others being Doric and Corinthian; tall and slender with a fluted shaft of 24 flutes, a capital with prominent volute scrolls, and an elegantly molded base

Jambs - the sides of a door opening or just an opening, whether made of stone, brick or wood

Joist - one of the horizontal wood beams that support the floors or ceilings of a house

Keystone - the wedge-shaped top or center member of an arch

Lancet Window - a narrow, vertical window that ends in a point

Lantern - small glazed turret on the top of a roof or dome

Lattice Window - a window with diamond shaped panes of glass

Lintel - the horizontal top member of a window, door, or other opening

Local Historic District - a structure, site, individual building, or group of buildings that has been recognized for its historic importance based on the application of at certain criteria

Main Street America - a program sponsored by the National Trust for Historic Preservation that helps communities revitalize their downtowns and commercial districts

Mansard Roof - a four-sided hipped roof featuring two slopes on each side, the lower slopes being very steep, almost vertical, and the upper slopes sometimes being so horizontal that they are not visible from the ground; named after the French 17th century architect Francois Mansart (1598-1666) who popularized the form

Masonry - stone, brick, or concrete

Molding - a decorative strip of wood

Mullions - the structural units that divide adjacent windows; vertical members between the lights of a window or the panels in wainscoting

Muntins - dividing bars between panes of glass

Mural - a large picture painted on or applied directly to a wall or ceiling surface

Newel - the supportive central post or column around which the steps of a circular staircase wind

Newel Post - a tall ornamental post at the top or bottom of a stair that supports the handrail; supportive posts at any change of direction in the staircase

Niche - an ornamental recess in a wall, often semicircular in plan and surmounted by a half dome as for a statue or other decorative object

Nomination - official recommendation for listing a property in the National Register of Historic Places

Order - a classical style of architecture; see Doric Order, Ionic Order, Corinthian Order, Tuscan Order, and Composite Order

Palladian Window - an arched window immediately flanked by two smaller, non-arched windows, popularized by Andrea Palladio in northern Italy in the 16th century; frequently used in American Georgian and American Palladian architecture in the 17th and 18th centuries

Panel - a smooth surface usually rectangular in shape and framed by molding

Parapet - a low wall located at the top of any sudden drop such as at the top of a building’s façade

Parquet Floor - wood floor made from thin hardwood blocks (about a quarter-inch thick) often arranged in herringbone or squared patterns on a wood subfloor then highly polished

Patio - similar to a terrace, an outdoor extension of a building situated above the ground level and open to the sky

Pavilion - a small but prominent portion of a building that juts out from a main building either above its roof line or to the side and which is identified by a unique (usually diminutive) height and individual roof type; may also stand alone separate from a larger building or connected to a main building by a terrace or path

Pedestal - a construction upon which a column, statue, memorial shaft, or the like is elevated, usually consisting of a base, a dado, and a cornice or cap

Pediment - a decorative triangular piece situated over a portico, door, window, fireplace, etc; the space inside the triangular piece is called the "tympanum" and is often decorated

Pergola - a garden structure built up over a path or narrow terrace, lined with evenly spaced columns or posts hat support a wooden-framed roof without sheathing; vines are often trained around the wooden framework and it may lead from one building to another

Period of Significance - the span of time when a property was associated with important events, activities, or persons, or attained the characteristics which qualify it for National Register listing; usually begins with the date when historically significant activities or events began, often a date of construction; continues for the duration of time that the property is associated with significant activities or events

Pier - a vertical structural element, square or rectangular in cross-section

Pilaster - a shallow non-structural rectangular column attached to and projecting only slightly from a wall surface

Pillar - a structural support similar to a column but larger and more massive and often without ornamentation; can be round or square in section and are often made of masonry though substantial wooden timbers can be formed into pillars

Pitch - the degree of the slope of a roof

Plan - the layout of a building drawn in a horizontal plane

Plate Glass - very strong glass used for large picture windows made out of a mixture of soda, lime, and silica which is then rolled into large sheets, then ground and polished

Plinth - the square base upon which a column sits

Pocket Door - a standard-sized door (or double doors) that is designed to slide away sideways into an opening fashioned out of the supporting wall

Pointing - the mortar filling between bricks of stones in a wall

Porch - a covered veranda

Porte-Cochere - an entrance large enough for wheeled vehicles to pass through

Portico - an entrance porch with columns or pilasters and a roof and often crowned by a triangular pediment

Post - a stiff vertical support, especially a wooden column in timber framing

Preservation - the act or process of applying measures necessary to sustain the existing form, integrity, and materials of an historic property; work, including preliminary measures to protect and stabilize the property, generally focuses upon the ongoing maintenance and repair of historic materials and features rather than extensive replacement and new construction; does not include new exterior additions, however, the limited and sensitive upgrading of mechanical, electrical, and plumbing systems and other code-required work to make properties functional is appropriate with a preservation project

Projection - a side wing, tower, or window bay that protrudes from a building

Pyramidal Roof - a roof with four identical sides rising to a central peak

Quoins - large prominent masonry units outlining windows, doorways, segments, and corners of buildings

Rafters - the inclined sloping framing members of a roof, and to which the roof covering is affixed

Reconstruction - the act or process of depicting, by means of new construction, the form, features, and detailing of a non-surviving site, landscape, building, structure, or object for the purpose of replicating its appearance at a specific period of time and in its historic location

Refurbish - to renovate, or make clean, fresh, or functional again through a process of major maintenance or minor repair

Rehabilitation - the act or process of making possible a compatible use for a property through repair, alterations, and additions while preserving those portions or features which convey its historical, cultural, or architectural values; also referred to as adaptive reuse

Remodel - to change a building without regard to its distinctive features or style; often involves changing the appearance of a structure by removing or covering original details and substituting new materials and forms

Renovate - to repair a structure and make it usable again, without attempting to restore its historic appearance or duplicate original construction methods or material

Repair - acts of ordinary maintenance that do not include a change in the design, material, form, or outer appearance of resource such as repainting; includes methods of stabilizing and preventing further decay and may incorporate replacement in kind or refurbishment of materials on a building or structure

Research Design - a statement of proposed identification, documentation, investigation, or other treatment of a historic property that identifies the project’s goals, methods and techniques, expected results, and the relationship of the expected results to other proposed activities or treatments

Restoration - an act or process of accurately depicting the form, features, and character of a property as it appeared at a particular period of time by means of the removal of features from other periods in its history and reconstruction of missing features from the restoration period; includes limited and sensitive upgrading of mechanical, electrical, and plumbing systems and other code-required work to make properties functional

Reveal - the visible exterior parts of a window jamb or door between the frame and main wall surface

Ridge - the horizontal intersection of two roof slopes at the top of a roof

Riser - the vertical face of a step or stair

Rondel (roundel) - a small circular panel or window

Rotunda - a circular or polygonal building which is usually capped with a dome

Saltbox Roof - a gable roof whose rear slope is longer than its front slope; the rear slope often nearly meets the ground; common to New England architecture

Sash - the movable frames in a window in which window panes are set

Section - a drawing showing a vertical "cut" through a building

Shingles - small, rectangular-shaped slats of wood that are nailed to an exterior surface overlapping one another from top to bottom; a traditional weather-proofing method for building

Shutters - pairs of solid or slatted window coverings traditionally hinged to the exterior of a building to either side of a window; used to block light or wind from a building’s interior

Side Light - a fixed window positioned to the side of a doorway or window

Sill - the bottom crosspiece of a window frame

Site - the location of a significant event, a prehistoric or historic occupation or activity, or a building or structure, whether standing or ruined, or vanished, where the location itself possesses historic, cultural, or archeological value regardless of the value of any existing structure; examples include battlefield, campsite, designed landscape, shipwreck, ruins of a building or structure, natural feature, trail, rock carvings, ceremonial site

Soffit - the underside of a structural part, as of a beam, arch, etc.

Solarium - a glass-enclosed porch, room, or gallery used for sunbathing or for therapeutic exposure to sunlight

Spandrel - the surface between two arches or ribs in a vault

Spire - a slender pointed construction atop a building, often a church

Stabilization - temporarily closing or stabilizing a building to protect it from the weather as well as to secure it from vandalism; the act or process of applying measures essential to the maintenance of a deteriorated building as it exists at present, establishing structural stability and a weather-resistant enclosure

Stained Glass Windows - windows fitted with pieces of colored glass often depicting a picture or scene

Stile - a vertical piece in a panel or frame, as of a door or window

Story - a complete horizontal division of a building, having a continuous or nearly continuous floor and comprising the space between two adjacent levels; the set of rooms on the same floor or level of a building

Stucco - a plaster used as a coating for walls and ceilings and often used for decoration; it is common to many parts of the world particularly the Mediterranean region and regions of the U.S. originally colonized by Spain

Style - a type of architecture distinguished by special characteristics of structure and ornament and often related in time; also a general quality with distinctive characteristics

Surround - an architectural element that surrounds a fireplace providing aesthetic and safety benefits

Symmetry - a characteristic (particularly of classical architecture) by which the two sides of a facade or architectural floor plan of a building present mirror images of one another

Terrace - an outdoor extension of a building situated above the ground level and open to the sky

Threshold - a place or point of entering or beginning

Tiffany Glass - the many types of glass developed and produced from 1878 to 1933 at the Tiffany Studios in New York by Louis Comfort Tiffany and a team of designers

Timber Frame - method of construction which is based around a frame of interlocking or connected timber beams

Tower - an exceptionally tall portion of a building

Transom - a narrow window, sometimes hinged at the top, positioned over a doorway or larger window

Tread - the top surface of a step or stair

Trim - literally the trimmings of a room including the baseboards, cornices, coves, paneling, wainscoting, dados, picture moldings, chair rails, architraves, and window and door surrounds

Trompe L’oeil - wall or ceiling painting which deceives the eye into believing objects portrayed are three-dimensional

Truss - a rigid framework of wooden beams or metal bars which supports a structure such as a roof

Tuscan Order - the Roman simplification of the Greek Doric order

Vault - an arched structure of stone, brick or reinforced concrete, forming a ceiling or roof over a hall, room, or other wholly or partially enclosed space; since it behaves as an arch extended in a third dimension, the longitudinal supporting walls must be buttressed to counteract the thrusts of the arching action

Venetian Window - a window with a rounded, arched head closely flanked by two smaller and narrower flat-headed windows; also known as a Palladian window

Veranda - an open, roofed porch usually enclosed on the outside by a railing or balustrade and often wrapping around two or more (or all of the) sides of a building

Vernacular - a regional form or adaptation of an architectural style

Villa - a country residence or estate

Wainscot - a facing of wood paneling, especially when covering the lower portion of an interior wall

Widow’s Walk - a railed rooftop walkway or balustraded platform, usually on early coastal houses; built to make it easier to look out to sea for approaching boats

Window Hood - the piece found above window openings, typically of an ornate design and only covering the top third of the opening; hoods are commonly placed above arched or curved openings and can be included on windows and doors

Wrought Iron - iron that has been wrought, bent, twisted, formed, and reformed; iron that has been drawn out and extended by heating


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