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  • 3. DICTIONARY OFARCHITECTURE &CONSTRUCTION2300 illustrationsFourth EditionEdited byCyril M. HarrisProfessor Emeritus of ArchitectureGraduate School of Architecture, Planning, and PreservationColumbia UniversityMcGraw-HillNew York Chicago San Francisco Lisbon LondonMadrid Mexico City Milan New Delhi San JuanSeoul Singapore Sydney Toronto
  • 4. Copyright © 2006, 2000, 1993, 1975 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States ofAmerica. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distrib-uted in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher.0-07-158901-5The material in this eBook also appears in the print version of this title: 0-07-145237-0.All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of atrademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringe-ment of the trademark. Where such designations appear in this book, they have been printed with initial caps.McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use incorporate train-ing programs. For more information, please contact George Hoare, Special Sales, at george_hoare@mcgraw-hill.com or (212) 904-4069.TERMS OF USEThis is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw-Hill”) and its licensors reserve all rights in and to thework. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieveone copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon,transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s priorconsent.You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited.Your rightto use the work may be terminated if you fail to comply with these terms.THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES ASTO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK,INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE,AND EXPRESSLY DISCLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIEDWARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do notwarrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted orerror free. Neither McGraw-Hill nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardlessof cause, in the work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any informationaccessed through the work. Under no circumstances shall McGraw-Hill and/or its licensors be liable for any indirect, incidental, spe-cial, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has beenadvised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claimor cause arises in contract, tort or otherwise.DOI: 10.1036/0071452370
  • 5. We hope you enjoy thisMcGraw-Hill eBook! Ifyou’d like more information about this book,its author, or related books and websites,please click here.ProfessionalWant to learn more?
  • 6. This book is dedicated to the memory of Adolph K. Placzek,Avery Librarian at Columbia University, whose leadershipmade Avery Library one of the world’s greatest collectionson architecture. I am grateful to him for long and fruitfuldiscussions, for his exemplary scholarship, and for thegenerosity of spirit with which he shared his experience, hiswisdom, and the gift of his friendship.
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  • 8. PREFACEThis Fourth Edition of the Dictionary of Architecture & Construction defines more terms inarchitecture and building construction than any other dictionary in the English language.Because there have been significant changes, advances, and new developments in buildingmaterials and services, construction techniques, engineering practices, specifications writing,environmental concerns, community regulations, legal requirements, and other areas overthe last decade, a total of 2500 new terms, as well as 100 new illustrations, have beenadded to this edition. This coverage provides an up-to-date working tool for practicingprofessionals in the many fields and numerous trades related to architecture and construction,as well as an invaluable resource for conservationists, planners, architectural historians,and students.The Dictionary is designed to be comprehensive in scope. Its range spans terms encounteredin the practice of architecture from Classical to green, from traditional materials to thelatest products, from precise definitions of architectural styles to the particulars ofspecifications writing. Many of the new terms are associated with major expansions in thefield of building services, including air-conditioning systems, electrical supply systems, gassupply services, illumination engineering, noise control engineering, vertical transportationsystems, security services, and waste disposal, water supply, and fire protection systems.Other definitions pertain to environmental concerns, conservation, building preservation,community regulations, and recent applications of the Americans with Disabilities Act.Equivalent values in Standard International units are given for U.S. Customary units.Cyril M. HarrisviiCopyright © 2006, 2000, 1993, 1975 by The McGraw-Hill Companies, Inc. Click here for terms of use.
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  • 10. ixACKNOWLEDGMENTSThe editor owes a special debt to the core group of 54 contributors who helpedestablish the high standard of quality of the Dictionary; coming from widely diversebackgrounds, including practicing architects, professional engineers, specification writers,craftsmen, contractors, and art historians, they provided the necessary expertise requiredfor a comprehensive, authoritative work. I thank Walter F. Aikman; William H. Bauer;Bronson Binger, AIA; Donald Edward Brotherson, AIA; Robert Burns, AIA; A. E. Bye,F.A.S.L.A.; Richard K. Cook, Ph.D.; William C. Crager, C.S.P.; Frank L. Ehasz, Ph.D., PE;Francis Ferguson, AIA, AIP; Frederick G. Frost, FAIA; Alfred Greenberg, PE; JohnHagman; Michael M. Harris, FAIA; R. Bruce Hoadley, D.For.; Jerome S. B. Iffland, PE;George C. Izenour, AIEEE; Curtis A. Johnson, M.Sc., PE; Edgar Kaufmann, Jr., HAIA;Thomas C. Kavanaugh, Sc.D.; Robert L. Keeler; George Lacancellera, CSI; Paul Lampl,M.A., AIA; Valentine A. Lehr, M.S.C.E., PE; Robert E. Levin, Ph.D., PE; George W.McLellan; Emily Malino, AID; Roy J. Mascolino, R.A.; Donald E. Orner, PE; John BarrattPatton, Ph.D.; Adolf K. Placzek, Ph.D.; Albert J. Rosenthal, L.L.B.; Henry H. Rothman,F.F.C.S.; James V. Ryan, M.S.; John E. Ryan, PE, S.F.P.E.; Reuben Samuels, PE, F.A.S.C.E.;Joseph Shein, AIA; Joseph M. Shelley, B.S.Arch.; Kenneth Alexander Smith, AIA, PE;Perry M. Smith, PE; Fred G. Snook, M.S.; Carl A. Swanson, B.C.E., CSI; KennethThomas, M.Sc., C.Eng.; Charles W. Thurston, Ph.D., PE; Marvin Trachtenberg, Ph.D.;Everard M. Upjohn, M.Arch.; Oliver B. Volk; and Byron G. Wels.I would like to express my appreciation to the following organizations for permission toreproduce selected definitions and/or illustrations from certain copyrighted publications:the American Institute of Architects for selected definitions from the AIA Glossary ofConstruction Industry Terms; the American National Standards Institute (ANSI) and theAmerican Society for Testing and Materials (ASTM) for material from the ASTM Bookof Standards; and the British Standards Institution for extracts from publications BS 56,BS 3921, and CP 121. Further reproduction is not permitted without the explicit per-mission of these copyrighted sources.Permission has also been granted to reproduce material from the following publications:The Asphalt Handbook of the Asphalt Institute; Facts and Figures of the Pioneer Division,Portec Inc.; CPM in Construction: A Manual for General Contractors of the Association ofGeneral Contractors of America; Brick and Tile Engineering by H. C. Plummer, StructuralClay Products Institute; Ceramic Glossary of the American Ceramic Society; Plastics Glossaryof Modern Plastics magazine, published by McGraw-Hill; Timber Construction Manual of theAmerican Institute of Timber Construction, published by John Wiley & Sons; Wood-working Technology by J. J. Hammond et al., published by McKnight & McKnight; Funda-mentals of Business Law, published by Callaghan & Co.; Product Line Dictionary, published bythe Canadian Construction Information Corp.; Glossary of Architectural Metal Terms of theNational Association of Architectural Metal Manufacturers; ASCE Manual of EngineeringPractice; and Guide and Data Books, published by ASHRAE.I thank the following organizations for their permission to reproduce definitions and/orillustrations from their publications: Aluminum Association; American Institute of SteelConstruction; American Iron and Steel Institute; Architectural Aluminum ManufacturersAssociation; Copper Development Association; Revere Copper and Brass Co.; The SteelCompany of Canada; Steel Joist Institute; Zinc Institute, Inc.; National Fire ProtectionCopyright © 2006, 2000, 1993, 1975 by The McGraw-Hill Companies, Inc. Click here for terms of use.
  • 11. xAssociation; Illuminating Engineering Society; National Builder’s Hardware Association;and American Concrete Institute (ACI) and ACI Committees. Further reproductionrequires permission from the above organizations. Certain other organizations andpublications have authorized reproduction of definitions or illustrations without formalacknowledgment. I thank William A. Pierson for permission to reproduce his photographof Round Arch style.I acknowledge the help of and thank Cary Sullivan, senior editor for architecture, design,and construction books, McGraw-Hill Professional. At International Typesetting and Com-position, whose task it was to work with the publisher to move the Dictionary from manuscriptto printed book, I thank Mona Tiwary for her exemplary diligence.
  • 12. ABOUT THE EDITORCyril M. Harris, Ph.D., is Professor Emeritus of Architecture in the Graduate School ofArchitecture, Planning, and Preservation at Columbia University, where he was chairmanof the Division of Architectural Technology for 10 years. He is also the Charles BatchelorProfessor Emeritus of Electrical Engineering at Columbia. He became fascinated by thechallenge of writing succinct, lucid definitions many years ago, when he was working onCommittee C-20 of the American Society for Testing and Materials (ASTM), as well ason terminology committees of the American Standards Association (now called theNational Institute of Standards and Technology [NIST]).Dr. Harris has received the AIA Medal from the American Institute of Architects andthe Pupin Medal for Distinguished Service to the Nation from Columbia University. He isa member of both the National Academy of Sciences and the National Academy of Engi-neering. He has received international recognition for his work in the acoustical design ofmany auditoriums, including the Metropolitan Opera House and the John F. KennedyCenter for the Performing Arts. He has a Ph.D. in physics from the Massachusetts Insti-tute of Technology and has received honorary doctorates from Northwestern Universityand the New Jersey Institute of Technology.Other books on architecture written or edited by Dr. Harris include American Archi-tecture: An Illustrated Encyclopedia (W. W. Norton & Company), Illustrated Dictionaryof Historic Architecture (Dover Publications), and Acoustical Designing in Architecture(Acoustical Society of America). Seven of his books are currently in print.xiCopyright © 2006, 2000, 1993, 1975 by The McGraw-Hill Companies, Inc. Click here for terms of use.
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  • 14. Å Abbr. for angstrom.A 1. Abbr. for ampere, a unit of electric current.2. Abbr. for area.AA Abbr. for the “Architectural Association,”the largest school of architecture in England;address 34–36 Bedford Square, London, WC1B3ES.AAA Abbr. for “Architectural Aluminum Asso-ciation.”AAI Abbr. for “Architectural Association ofIreland.”AAMA Abbr. for “Architectural AluminumManufacturers Association.”A&E See architect-engineer.Aaron’s rod An ornament or molding consist-ing of a straight rod from which pointed leavesor scroll work emerge on either side, at regularintervals.ABA Abbr. for Architectural Barriers Act.abaciscus 1. A tessera, as used in mosaic work.Also called abaculus. 2. A small abacus.abaculus See abaciscus, 1.abacus The uppermost member of the capital ofa column; often a plain square slab, but some-times molded or otherwise enriched.abated Said of a surface that has been cut awayor beaten down so as to show a pattern or figurein low relief; also see relief.abatement The wastage of wood when lumberis sawed or planed to size.abat-jour 1. In a wall, an aperture whose sideshave been cut back and/or whose underside hasbeen sloped downward so as to admit a greateramount of light to the interior of the room. 2. Askylight.A1abacus Aabamurus A buttress, or a second wall added tostrengthen another.abate 1. To remove material, as in stone carv-ing. 2. In metalwork, to cut away or beat downso as to show a pattern or figure in low relief.abaton A sanctuary not to be entered by thepublic; a holy of holies.abat-sons Descriptive of a surface said to reflectsound downward.abat-vent 1. Louvers that are placed in an exte-rior wall opening to permit light and air to enter,but break the wind. 2. A sloping roof. 3. In theFrench Vernacular architecture of New Orleans,an extension of a roof over a sidewalk.abat-jour, 1Copyright © 2006, 2000, 1993, 1975 by The McGraw-Hill Companies, Inc. Click here for terms of use.
  • 15. abat-voix In a church, a sound reflector behindand over a pulpit.a web between, so that two cells are formedwhen the block is laid in a wall.Abney level A hand level used for measuringvertical angles; comprised of a small telescope,bubble tube, and graduated vertical arc.above-grade building volume The volumeof a building (in cubic feet or in cubic meters)measured from the average adjoining grade levelto the average roof level, and from outside tooutside of exterior walls, but not includingbreezeways, porches, or terraces.abrade To wear away or scrape off a surface,especially by friction.Abrams’ law A statement applying to givenconcrete materials and conditions of test: For amixture of workable consistency, the strength ofconcrete provided by the mixture is determinedby the ratio of the amount of water to theamount of cement.abrasion A surface discontinuity caused byroughening or scratching.abrasion resistance The ability of a surfaceto resist being worn away or to maintain its orig-inal appearance when rubbed with anotherobject.abrasion resistance index A measure of theabrasion resistance of a vulcanized material orsynthetic rubber compound relative to that ofa standard rubber compound under specifiedconditions.abrasive A hard substance for removing mate-rial by grinding, lapping, honing, and polish-ing. Common abrasives include silicon carbide,boron carbide, diamond, emery, garnet, quartz,tripoli, pumice, diatomite, metal shot, grit, andvarious sands; usually adhered to paper orcloth.abraum A red ocher used to stain mahogany.abreuvoir In masonry, a joint or intersticebetween stones, to be filled with mortar orcement.ABS Abbr. for acrylonitrile-butadiene-styrene.abscissa In the plane Cartesian coordinate sys-tem, the horizontal coordinate of a point on aplane; the x-coordinate, obtained by measuringthe distance from the point to the y-axis along aline parallel to the x-axis.abat-voix2abat-voixabbey A monastery or convent; particularly thechurch thereof.abbey: Plan of abbey of St. Germain-des-Prés, Paris, 13thcent. A, church; B, cloister; C, city gate; E, chapter house;F, chapel; G, refectory; H, cellars and presses; I, abbot’s lodg-ing; K, ditches; L, gardensabbreuvoir Same as abreuvoir.ABC 1. Abbr. for “aggregate base course.”2. Abbr. for “Associated Builders and Con-tractors.”A-block A hollow, concrete masonry unit withone end closed and the opposite end open, having
  • 16. abside Same as apse.absidiole Same as apsidiole.absolute humidity The mass of water vaporper unit volume of air.absolute pressure The sum of the gauge pres-sure plus atmospheric pressure.absolute volume 1.Of a granular material, thetotal volume of the particles, including the perme-able and impermeable voids, but excluding thespaces between the particles. 2.Of fluid, the vol-ume which the fluid occupies. 3.The displacementvolume of an ingredient of concrete or mortar.absorbed moisture Moisture that has entereda solid material by absorption and has physicalproperties not substantially different from ordi-nary water at the same temperature and pressure.Also see absorption.absorbency The property of a material thatmeasures its capacity to soak up liquids.absorbent A material which, owing to an affin-ity for certain substances, extracts one or moresuch substances from a liquid or gas with whichit is in contact, and which changes physically orchemically, or both, during the process.absorber 1.A device containing liquid for absorb-ing refrigerant vapor or other vapors. 2.In anabsorption system, that part of the low-pressureside of the system which is used for absorbing refrig-erant vapor. 3.That part of a solar collector whoseprimary function is to absorb radiant solar energy.absorber plate Same as solar collector.absorbing well, dry well, waste well Awell used for draining off surface water and con-ducting it underground, where it is absorbed.absorptance In illumination engineering, theratio of the absorbed flux to the incident flux.absorption 1.The process by which a liquid, or amixture of gases and liquid, is drawn into and tendsto fill permeable pores in a porous solid material;usually accompanied by a physical change, chemi-cal change, or both, of the material. 2.Theincrease in weight of a porous solid body resultingfrom the penetration of liquid into its permeablepores. 3.The increase in weight of a brick or tileunit when immersed in either cold or boiling waterfor a stated length of time; expressed as a percent-age of the weight of the dry unit. 4.The process bywhich radiant energy, which is incident on asurface, is converted to other forms of energy.5. See sound absorption. 6. See light absorption.absorption bed A pit of relatively largedimensions which is filled with coarse aggregateand contains a distribution pipe system; used toabsorb the effluent of a septic tank.absorption coefficient See sound absorptioncoefficient.absorption field, disposal field A system oftrenches containing coarse aggregate and distri-bution pipes through which septic-tank effluentmay seep into the surrounding soil.absorption field3absorption field composed of absorption trenchesExtent of coarse aggregate indicated by shaded areaabscissa: P, any point; NP, abscissa
  • 17. absorption rate, initial rate of absorptionThe weight of water absorbed when a brick is par-tially immersed for one minute; usually expressedin grams per minute or ounces per minute.absorption system A refrigeration system inwhich the refrigerant gas evolved in the evapo-rator is taken up in an absorber and (upon theapplication of heat) released in a generator.absorption trench A trench containing coarseaggregate and a distribution tile pipe throughwhich septic-tank effluent may flow, coveredwith earth.abutment piece See solepiece.abuttals Those boundaries of one piece of landthat abut on adjacent pieces.abutting joint A joint between two pieces ofwood, in which the direction of the grain in onepiece is at an angle (usually 90°) to the grain inthe other.abutting tenon One of two tenons which areinserted in a common mortise from oppositesides, so as to touch each other.ac, a-c, a.c. Abbr. for “alternating current.”AC 1.On drawings, abbr. for “alternating current.”2.On drawings, abbr. for armored cable. 3.Abbr.for air conditioning. 4.Abbr. for “asbestos cement.”acacia Same as gum arabic.Acadian cottage Same as Cajun cottage.acanthus A common plant of the Mediter-ranean, whose leaves, stylized, form the charac-teristic decoration of capitals of Corinthian andComposite orders. In scroll form it appears onfriezes, panels, etc.absorption rate4absorption-type liquid chiller Equipmentutilizing a generator, condenser, absorber, evapo-rator, pumps, controls, and accessories to coolwater, or other secondary liquid, using absorp-tion techniques.ABS plastic A plastic of acrylonitrile-butadiene-styrene; has good resistance to impact, heat, andchemicals; esp. used for piping.abstract of title An outline history of the own-ership of a parcel of land, from the originalgrant, with changes in title, and with a state-ment of all mortgages, liens, encumbrances, etc.,affecting the property.abut To adjoin at an end; to be contiguous.abutment A masonry mass (or the like) whichreceives the thrust of an arch, vault, or strut.absorption trenchacanthusabutment AACB 1. Abbr. for asbestos-cement board. 2.Abbr. for “air circuit breaker.”accelerated aging The speeding-up of theaging process in a material; obtaining, in ashort time, the results that would occur in agingunder normal conditions. The most commonfactors that increase aging include exposure ofthe material to water, ozone, oxygen, or sun-light.accelerated life test A test in which one ormore parameters (e.g., temperature) is increasedor decreased beyond its normal or rated value todetermine the resulting deterioration within areasonable time period.accelerated weathering A laboratory testingtechnique to determine, in a relatively shorttime, the weather resistance of a paint film orother exposed surface.
  • 18. accelerating admixture An admixture thatspeeds the setting and/or the early strengthdevelopment of hydraulic concrete.acceleration 1. The rate of change of thevelocity of a moving body. 2. The rate of change,esp. the quickening of the natural progress of aprocess, such as hardening, setting, or strengthdevelopment of concrete.acceleration of gravity (g) The accelerationproduced by the force of gravity at the surface ofthe earth. (By international agreement the valueof g is 386.089 inches per second square =32.1740 feet per second square = 9.80665 metersper second square.)acceleration stress In a wire rope (or thelike), the additional stress imposed as a result ofthe acceleration of the load.accelerator 1.A substance which, when addedto concrete, mortar, or grout, increases the rate ofhydration of a hydraulic cement, shortens thetime of set, or increases the rate of hardening orstrength development. 2.A substance, added witha curing agent, to speed a vulcanization processand enhance the physical properties of a vulcan-ized material. 3.Same as accelerating admixture.accent lighting Any directional lighting whichemphasizes a particular object or draws attentionto a particular area.acceptable air quality Inside a building, airthat is free of harmful concentrations of contam-inants and that is judged acceptable to at least80% of the building’s occupants.acceptable water pressure See maximumacceptable pressure and minimum acceptablepressure.acceptance See final acceptance.acceptance test A test conducted by a pur-chaser (or an agent thereof) (a) to determine ifthe material, devices, or equipment deliveredconforms to the purchase contract specificationsand/or (b) to determine the degree of uniformityof the product supplied by the vendor.access A means of approach, e.g., a road, street,or walk.access door A door, usually small, which isprovided through a finished construction, asinto a duct, through a ceiling, behind a wall, in alarge piece of mechanical equipment, etc.; usedto provide a means of inspection of equipmentor services housed within.accessory use5access dooraccess eye See cleanout, 1.access floor Same as raised floor.access flooring system See raised flooringsystem.accessibility standards See Americans withDisabilities Act and Uniform Federal AccessibilityStandards.accessible 1. Allowing physical contact, as bymeans of an easily removable cover or door or apart of the building structure or finish materials.2. Providing access to a fixture, appliance, orpiece of equipment; removal of a cover, panel,plate, or similar obstruction may be required.3. Said of a building, facility, or site that can beapproached, entered, and used by a physicallydisabled person. 4. According to the Americanswith Disabilities Act (ADA), a term used for a spacethat complies with the standards of the Act forthose having disabilities or impairments (includingvisual, hearing, mental, or mobility), and does notrequire the assistance of others to enter the space.accessible means of egress A path of travel,usable by a mobility-impaired person, that leadsto a public way.accessible route According to the ADA, acontinuous, unobstructed path between allaccessible elements and areas of a building,including corridors, ramps, and elevators; theroute must provide adequate clearance arounddesks, furniture, and the like.accessible space A space that complies with allprovisions of the Americans with Disabilities Act.accessory building A secondary building,whose use is incidental to that of the main build-ing located on the same plot.accessory use The use or occupancy incidentalto the principal use or occupancy of a building.
  • 19. access panel A removable panel (usually securedwith screws) in a frame which is usually mounted ina ceiling or wall; provides access to a concealed itemthat does not require frequent attention.access plate A removable plate (usually boltedin place) that provides access to an area that sel-dom requires attention; permits inspection of anotherwise inaccessible area.access platform Same as cherry picker.access stair A stair, from one floor level toanother, which does not serve as a required exitstair. Also see exterior stair.access street A low-traffic-volume street, usu-ally comprised of individual dwelling units,which conveys vehicular traffic to or from astreet carrying heavier traffic.access way A roadway, usually paved, intendedto provide ingress and egress of vehicular trafficfrom a public right-of-way to an off-street parkingarea.accident A sudden, unexpected event identifi-able as to time and place. Also see occurrence.accidental air See entrapped air.acclivity The upward slope of a hillside.accolade An ornamental treatment, used overan arch, a door, or a window, composed of twoogee curves meeting in the middle; often a richlydecorated molding.door consisting of a system of panels which arehung from an overhead track. When the door isopen, the faces of the panels close flat againsteach other; when the door is closed, the edges ofadjacent panels butt against (or interlock with)each other to form a solid barrier.accordion partition A fabric-faced partitionwhich is hung from an overhead track and foldsback like the bellows of an accordion.accouplement The placement of columns orpilasters close together, in pairs.access panel6accrued depreciation 1. The reduction inactual value of property over a period of time, asa result of wear and tear, obsolescence, etc. 2.The accumulated reductions in the stated valueof property over a period of time, entered on bal-ance sheets for accounting or tax purposes.accumulator 1. In a refrigeration system, astorage chamber for low-side liquid refrigerant;also called a surge drum or surge header. 2. In arefrigerant circuit, a vessel whose volume is usedto reduce pulsation.ACD Abbr. for automatic closing device.ACE Abbr. for “Architects Council of Europe.”acetone A highly flammable solvent whichevaporates rapidly; used in lacquers, paintremovers, thinners, etc.accoladeaccompaniment A decoration added to abuilding with the intention of enhancing itsappearance.accordion door 1. Any fabric-faced doorwhich is hung from an overhead track and foldsback like the bellows of an accordion. 2.A hingedaccouplement
  • 20. acetylene A colorless gas, when mixed withoxygen, burns at a temperature of about 3500°C;used in welding.acetylene torch A torch, used in welding andin metal cutting, which is operated by com-pressed acetylene gas and oxygen.AC generator A generator which producesalternating current when driven by a primemover.Achaemenid architecture An architecturedeveloped under the Achaemenid rulers ofPersia (6th to 4th cent. B.C.) by a synthesis andeclectic adaptation of architectural elementswhich included those of surrounding countries.In the hypostyle hall it achieved a highly origi-nal new building type.achromatic Said of architecture that is with-out color, for example, the white buildings ofGreek Revival.achromatic color White light; a color thatdoes not elicit hue.ACI Abbr. for “American Concrete Institute.”acid-etched Said of a metallic surface (e.g., anail) that has been treated in an acid bath toprovide a rough surface.acidic Said of igneous rocks containing morethan 65% silica.aciding The light etching of a cast-stonesurface.acid lead Fully refined lead to which a smallamount of copper has been added; 99.9% pure.acid neutralizer A device installed in adrainage system into which the discharge ofacid is probable; neutralizes the discharge suffi-ciently to permit it to enter the drainage systemsafely.acid polishing The polishing of a glass surfaceby acid treatment.acid resistance The degree to which a surface,such as porcelain enamel, will resist attack byacids.acid-resistant brick Brick suitable for use incontact with chemicals; usually laid with acid-resistant mortars.acid-resistant cast-iron pipe A cast-ironpipe containing between 14.25 and 15% siliconand small amounts of manganese, sulfur, and car-bon; manufactured in the same dimensions ascast-iron pipe.acid soil Soil having an acid reaction; usually asoil having a pH value of less than 6.6.acisculis A mason’s small pick, with a flat faceand pointed peen.acorn A small ornament in the shape of a nut ofthe oak tree; sometimes used as a finial, pendant,or decorative element within a broken pedi-ment, or as a decoration on a carved panel.acoustic7acornacid neutralizeracous 1. Abbr. for acoustical. 2. Abbr. foracoustics.acoustic, acoustical The qualifying adjec-tives acoustic and acoustical have the followingmeanings: arising from, actuated by, containing,producing, or related to sound. In general,acoustic is used when the term being qualifieddesignates something that has the properties,dimensions, or physical characteristics associated
  • 21. with sound waves; acoustical is used when theterm being qualified does not explicitly desig-nate something that has the properties, dimen-sions, or physical characteristics of sound (e.g.,acoustical engineering). However, sometimesthese two terms are used interchangeably.acoustical barrier See sound barrier.acoustical board See acoustical ceiling board.acoustical ceiling A ceiling covered by, orformed of, an acoustical material.acoustical ceiling board An acoustical mate-rial in board form, designed primarily for sus-pended ceiling application.acoustical ceiling system A structural sys-tem for supporting an acoustical ceiling; mayincorporate lighting fixtures and air diffusers.acoustical panel Same as acoustical lay-inpanel.acoustical plaster A special low-density sound-absorptive plaster, applied in the form of a finish-coat, to provide a continuous finished surface.acoustical power See sound power.acoustical sprayed-on material An acous-tical material applied by a spray process to forma continuous finished surface.acoustical tile An acoustical material in boardform, often having unit dimensions of 24 in. by24 in. (approx. 61 cm by 61 cm) or less. Usuallyused on ceilings but also may be applied to side-walls.acoustics 1. The science of sound, includingthe generation, transmission, and effects ofsound waves. 2. The totality of those physicalcharacteristics of an auditorium or room (such asthe size and shape of elements on the walls orceiling which scatter sound, the amount ofsound absorption, and noise level within theroom) which affect an individual’s perception,and judgment, of the quality of speech and musicproduced in the room.acph Abbr. for “air changes per hour.”acquiescence 1. An act of concurrence byadjoining property owners which resolves aboundary dispute or establishes a commonboundary, where the definite or more accurateposition of same has not or cannot be defined bysurvey. 2. The tacit consent of one owner, by notinterposing a formal objection, to what mightbe an encroachment by an adjoining propertyowner over a questionable boundary.acre A unit of land measurement equal to43,560 sq ft or 4046.85 sq m; 1 sq mile (2.59 sqkm) equals 640 acres.acre-foot The amount of water required tocover an area of 1 acre to a depth of 1 foot;equivalent to 43,560 cubic feet (4046.9 m3);sometimes used as a measure of materials inplace (e.g., gravel).acrolith A statue or sculptured figure in whichonly the head, hands, and feet are of stone, therest being usually of wood.acropodium 1. An elevated pedestal bearing astatue, particularly if raised from the substruc-ture on supports. 2. The plinth of a statue if rest-ing on supports.acoustical barrier8acoustical ceiling systemacoustical door A solid, heavy door which isgasketed along the top and sides; usually has anautomatic door bottom; especially constructedto reduce noise transmission through it; usuallycarries a sound transmission class (STC) rating,which is a measure of its sound insulation value.acoustical duct lining See duct lining.acoustical insulation board A porous mate-rial in board form, designed or used as an acousti-cal material or as an element in a sound-insulationconstruction.acoustical lay-in panel An acoustical ceilingboard designed to be laid into an exposed gridsuspension system.acoustical material Any material especiallydesigned to absorb sound.acoustical model A model of an auditoriumor room used to study certain acoustical proper-ties of the full-sized enclosure, such as the distri-bution of sound pressure, the paths of sound rays,and focusing effects.
  • 22. acropolis 1. The elevated stronghold of a Greekcity, usually with the temple of the patron divinity.2. (cap.) The Acropolis of Athens. 3. Any ele-vated group of buildings serving as a civic symbol.acrylic carpet A carpet having a combinationof acrylic and modacrylic fibers; known for itsstain-resistant qualities, high durability, andwool-like appearance.acrylic fiber A synthetic fiber manufacturedby polymerizing acrylonitrile.acrylic paint A type of latex paint made fromacrylic resins; also called acrylic latex paint.acrylic resin, acrylate resin One of a groupof thermoplastic resins made from esters ofacrylic acid; exceptionally tough, stable, resis-tant to chemicals, and transparent; used as abinder, in sheet form, as an air-curing adhesive,and as the main ingredient in some caulks andsealants.acrylonitrile-butadiene-styrene (ABS) Aplastic used for piping in drainage systems, stormsewers, and underground electrical conduit.ACS Abbr. for “American Ceramic Society.”ACT. On drawings, abbreviation for “actual.”act curtain, act drop, front curtain, housecurtain A curtain, behind the asbestos cur-tain in a theater, which closes the prosceniumand serves as an indication of the beginning orend of an act or scene.act drop See act curtain.acting area That part of a theater stage floor onwhich the actors perform.acting area light A spotlight used to illumi-nate a selected acting area.acting level A platform above the theater stagefloor which is used for acting.acting level9acropolis: Acropolis at Athens. A, Propylaea; B, Temple ofNiké Apteros; C, Parthenon; D, Erechtheum; E, foundationsof old Temple of Athena 6th cent. B.C.acroterion, acroter, acroterium 1. Strictly,a pedestal at the corners or peak of a roof to sup-port an ornament. 2. More usually, the ornamentitself.acroterion,1acroterion,2
  • 23. actinic glass A glass having a yellow tintwhich reduces the transmission of infrared andultraviolet rays; sometimes used in factory win-dows or skylights.action hinge Same as double-acting hinge.activated alumina A form of aluminum oxidewhich adsorbs moisture readily and is used as adrying agent.activated carbon See activated charcoal.activated charcoal, activated carbon Char-coal obtained by carbonizing organic material,usually in the absence of air; usually in gran-ular or powdered form; highly effective in adsor-bing odors in air or in removing colors insolution.activated rosin flux A flux having a resin orrosin base and containing an additive to increasewetting by the solder.activated sludge Sewage sediment that hasbeen subjected to vigorous aeration and theaction of microorganisms.activator Same as catalyst.active door In a pair of doors, the leaf, 1 that isthe first to open and is the leaf to which a lock isapplied.active earth pressure The component ofpressure in a horizontal direction which a massof earth exerts on a wall.active lateral pressure The horizontal soilpressure which is exerted by soil on a retainingstructure.active leaf, active door In a door having apair of leaves, that leaf to which the latching orlocking mechanism is attached; usually the leafthat is permitted to open first; sometimes bothleaves are active.active sludge A sludge, 3 which is rich indestructive bacteria; useful in breaking downfresh sewage.active solar energy system A building sub-system in which solar energy is collected and istransferred predominantly by mechanical equip-ment (fans, pumps) powered by energy notderived from solar radiation. Compare with pas-sive solar energy system.active sound attenuator A special type ofsound attenuator that incorporates a soundsource which generates sound waves intended tocancel some of the noise generated by the fans inan HVAC system.activity In CPM terminology, a task or item ofwork that must be performed in order to com-plete a project.activity duration In CPM terminology, theamount of time estimated as required to accom-plish an activity.actual start of construction The first place-ment of permanent construction of a building ona site, such as pile driving, or the pouring of slabsor footings.acuminated Finished in a point, as a loftyGothic roof.acute angle An angle of less than 90°.acute arch, lancet arch A sharply pointedarch whose centers are farther apart than thewidth of the arch.actinic glass10acute archa.d. Abbr. for “air-dried.”AD 1. Abbr. for “air-dried.” 2. Abbr. for accessdoor. 3. Abbr. for area drain. 4. Abbr. for “asdrawn.”ADA Abbr. for Americans with Disabilities Act.Adamesque style An inexact term implying aderivation from the Adam style, but having pos-sible differences depending on the time andlocation of application.Adam Revival See Colonial Revival.
  • 24. addendum11Adam style An architectural style based on thework of Robert Adam (1728–1792) and hisbrothers, predominant in England in the late18th century and strongly influential in the US,Russia, and elsewhere. It is characterized by clar-ity of form, use of color, subtle detailing, and uni-fied schemes of interior design. BasicallyNeoclassical, it also adapted Neo-Gothic, Egypt-ian, and Etruscan motifs.adapt To make suitable for a particular purposeor new requirements or conditions, by means ofmodifications or changes.adaptability The capacity of building spaces andelements for being altered or being added to forspecific needs, as, for example, to accommodatethe needs of persons with and without disabilities.adaptable According to the ADA, a restroomor bathroom to which grab bars can be added orwhich can be otherwise altered to accommodatethe needs of individuals with disabilities.adaptable dwelling unit One of a number ofdwelling units that is on an accessible route andequipped so it may be converted to be used, witha minimum of structural change, by all cate-gories of physically disabled persons.adaptation The process by which the eyechanges sensitivity and becomes accustomed tomore or less light than it was exposed to duringan immediately preceding period.adapter 1. A device for matching and properlyconnecting items, tubing, or devices (especiallyelectric) which are of different size, operatingcharacteristics, or design. 2. A device thatenables different sizes or types of plugs, pipes,etc., to be joined.Adam style fireplaceadapteradaptive use, adaptive re-use The extensivealteration, restoration, and/or renovation of anexisting building so that it will serve a new ormodified purpose. Also see building rehabilitation.ADC Abbr. for “Air Diffusion Council.”ADD. 1. On drawings, abbr. for addendum.2. On drawings, abbr. for addition.added lean-to Same as integral lean-to.addendum A written or graphic instrumentissued prior to the execution of the contractwhich modifies or interprets the bidding docu-ments, including drawings, and specifications,by additions, deletions, clarifications or cor-rections; becomes part of the contract docu-ments when the construction contract isexecuted.
  • 25. addition 1.A floor or floors, a room, wing, orother expansion to an existing building. 2.Inbuilding code usage: Any new construction whichincreases the height or floor area of an existingbuilding or adds to it (as a porch or attachedgarage). 3.An amount added to the contract sumby a charge order; also see extra.additional service authorization An AIAform that authorizes additional work, 1 to be per-formed, for an additional fee, for services notcovered in the originally specified scope of thearchitect’s work.additional services The professional serviceswhich may, upon the owner’s request or approval,be rendered by the architect in addition to thebasic services or the designated services.additive A material, used in very small quan-tity, to modify a specific property of anothermaterial or otherwise improve its characteristics;used in paints, plasters, mortars, etc.additive alternate An alternate bid resultingin an addition to the same bidder’s base bid. Alsosee alternate bid.additus maximus In an ancient Romanamphitheater, a main entrance.addorsed, adorsed Said of animals or figuresplaced back to back in decorative sculpture.sticking together of two surfaces by means ofphysical and chemical forces such as thosewhich bind a paint film to a surface.adhesion bond The adhesion of mortar orgrout to masonry units.adhesion-type ceramic veneer Thin sec-tions of ceramic veneer held in place by theadhesion of mortar to unit and backing, requiringno metal anchors; not more than 11⁄4 in. (3.2 cm)in overall thickness. Also see anchored-typeceramic veneer.adhesion-type filter A type of air filter inwhich dirt particles are removed from air byadhering to the filter as the air flows through it.adhesive A substance capable of holding mate-rials together by bonding the surfaces that are incontact.adhesive failure The separation of two sur-faces joined by an adhesive, either by a force lessthan that specified by the manufacturer or byservice conditions.adiabatic Occurring without the gain or loss ofheat.adiabatic curing The curing of concrete ormortar in which adiabatic conditions are main-tained during the curing period.Adirondack Rustic style See Rustic style.adit An entrance or passage.adjoining grade elevation The average ele-vation of the final grade adjoining all exteriorwalls of a building, calculated from grade eleva-tions taken at intervals (usually 10 ft or 3 m)around the perimeter of the building.adjustable base anchor A device used tohold a doorframe above the finished floor.addition12addressable system A fire alarm systemwhose integrity can be monitored and whichprovides easy identification of the location of analarm condition; also provides for remote testingand monitoring of the sensitivity of the detec-tors from a control panel.ADF In the lumber industry, abbr. for “afterdeducting freight.”ADH On drawings, abbr. for adhesive.adherend A body which is held to another byan adhesive.adhesion 1. The joining of two surfaces aspieces of wood, metal, plastic, or other construc-tion materials, by means of a viscous, stickycomposition such as cement or glue. 2. Theaddorsed dolphinsadjustable base anchoradjustable doorframe A doorframe whichhas an adjustable jamb so that it can be installedin walls of different thicknesses.
  • 26. adjustable hanger A hanger having a provi-sion for adjusting its length.adobe13adjustable wrench Any one of several typesof wrenches having one jaw fixed and the otheradjustable; set to the desired size by means of aknurled screw.adjustable multiple-point suspension scaf-fold 1. See mason’s adjustable multiple-pointsuspension scaffold. 2.See stone-setter’s adjustablemultiple-point suspension scaffold.adjustable proscenium On a theater stage,an inner proscenium which is variable in height,width, or position; may be hung from riggingoverhead or floor-mounted.adjustable shelving Shelving supported bymetal clips or other movable supports, making itpossible to adjust the height of individual shelves.adjustable shore, adjustable steel prop Avertical shore used to support reinforced con-crete beams and slab forms; usually all metal or acombination of wood and metal; can be raised orlowered within certain limits.adjustable-speed motor An electric motorin which the speed can be varied gradually overa considerable range, but which, once adjusted,remains virtually unaffected by the load, 3.adjustable square, double square A trysquare the arm of which is at right angles to thehandle; the position of the arm may be moved soas to form an L or a T.administration of the construction con-tract See construction phase—administrationof the construction contract.administrative authority The individual,official, board, department, or agency estab-lished and authorized by a city, county, state, orpolitical subdivision created by law to adminis-ter and enforce the provisions of a code.admixture A material other than water,aggregates, lime, or cement, used as an ingredi-ent of concrete or mortar, and added to thebatch immediately before or during its mixing;used as a water repellent, as a coloring agent, asa retarder or accelerator (to modify its settingrate), etc.adobe A heavy soil, composed largely of clayand silt in sufficient quantities to form a matrixin which sand particles are firmly imbedded;water is added, and straw, manure, and fragmentsof tile are sometimes combined with this mix-ture to provide increased mechanical strengthand cohesion when it dries. It can be used as aplaster or be formed into bricks, often shaped byhand in a wooden form, then sun-dried; widelyused in Spanish Colonial architecture and itsderivatives. Adobe brick walls are often lime-plastered to improve resistance to weather; aadjustable hangeradjustable squareadjustable wrenches
  • 27. coating such as slaked lime acts as a stabilizingagent.adobe blasting Same as mud-capping.adobe brick Large, roughly molded, sundriedclay brick, usually of varying sizes.adobe quemado An adobe brick that hasbeen kiln-dried at a temperature lower than thatrequired to produce a hard-burnt brick; usuallydeep red in color, relatively soft, and rough intexture.adobero A box for mixing adobe and shaping itinto bricks.adopted street In Britain, a dedicated street.ADS Abbr. for “automatic door seal.”adsorbed water 1. Water which is held on thesurfaces of a material by electrochemical forces;its physical properties are substantially differentfrom those of absorbed water or chemically com-bined water at the same temperature and pres-sure. 2. Water which is bound to soil particles asa result of the attraction between electricalcharges on their surfaces and water molecules.adsorbent A material (such as activated char-coal) which has the ability to extract certain sub-stances from gases, liquids, or solids by causing thesubstances to adhere to its internal surface withoutchanging the adsorbent physically or chemically.adsorption The action of a material in extract-ing a substance from the atmosphere (or a mix-ture of gases and liquids) and gathering it on thesurface in a condensed layer; the process is notaccompanied by physical or chemical change.adulterine In the Middle Ages in Britain, saidof a castle that was crenelated without a licenseto erect battlements. Such licenses were grantedby the reigning monarch in exchange for a cashpayment from the castle’s owner.advance slope grouting Grouting by a tech-nique in which the front of the mass of grout isforced to move horizontally through preplacedaggregate.advance slope method A method of con-crete placement in which the face of the freshconcrete moves forward as the concrete is placed;the face of the fresh concrete is not vertical.advanced nursery stock A deciduous tree,of specified size, which has been transplantedseveral times and has had its roots pruned inpreparation for its final transplantation.adverse possession Occupation of propertyby one not the true owner, openly, notoriously,and continuously. See statute of limitations;squatter’s right; proscription.advertisement curtain On the stage of a the-ater, a curtain which bears advertisements; usu-ally behind the asbestos curtain, but sometimes(rarely) the asbestos itself.advertisement for bids The published publicnotice soliciting bids for a construction project.Most frequently used to conform to legal re-quirements pertaining to projects to be con-structed under public authority, and usuallypublished in newspapers of general circulationin those districts from which the public funds arederived.adytum, adyton 1. The inner shrine of a tem-ple reserved for the priests. 2. The most sacredpart of a place of worship.adobe blasting14adzadytum: plan of a Roman temple, showing the adytum at Aadz A cutting tool whose thin arching blade isperpendicular to the handle; used for the rough-shaping of wood.adze British term for adz.A/E Abbr. for architect-engineer.AEA Abbr. for “Aluminum Extruders Associ-ation.”
  • 28. aedes 1. In Roman antiquity, any edifice or aminor shrine, not formally consecrated. 2. Now,any chapel or temple.aedicula 1. A canopied niche flanked by colon-nettes intended as a shelter for a statue or as ashrine. 2. A door or window framed by columnsor pilasters and crowned with a pediment. 3.Diminutive of aedes. 4. A small chapel.aerarium In ancient Rome, the publictreasury.aerate To introduce air into soil or water by nat-ural or artificial means.aerated concrete See cellular concrete.aerated plastic Same as foamed plastic.aeration 1. Exposing a substance to circulat-ing air. 2. In landscape architecture, the addi-tion of air into the soil; may be implementedby a plow-like mechanism or by the addition ofan air-entrained material, such as vermiculiteor peat moss, during the soil-conditioningprocess.aerator fitting A device which introduces airinto an exiting stream of water.aerial cable An overhead electric cable (field-assembled at a construction site) which isattached to poles or other supporting structures.aerial photograph, aerophoto A photo-graph taken from a vehicle in flight.aerial photomap An aerial photograph orphotomosaic to which is added basic mappinginformation such as place names, boundaries,etc.aerial photomosaic A composite of aerialphotographs depicting a portion of the earth’ssurface.aerodynamic noise Noise resulting fromthe flow of air; often generated in an air-conditioning system when an airstream encoun-ters protuberances, rough surfaces, and/or bluntedges.aerofilter A bed of coarse material used for therapid filtering of sewage; recirculation of theeffluent may be employed.aerograph A spray gun for paint.aerophoto An aerial photograph.aerosol paints Paints which are packaged in apressurized container for spray application.Pressure is supplied by compressed liquefiedgas.aes In ancient Rome or Greece: copper, tin, orany alloy of these metals.aetoma, aetos A pediment, or the tympanumof a pediment.A/F In a portland cement mixture, the abbr. for“molar or weight ratio of aluminum oxide to ironoxide.”A/F15aedicula, 1aegicranes Sculptured representations of theheads or skulls of goats or of rams; used as deco-rations on ancient altars, friezes, etc.aegicranes
  • 29. affronted, affronté Said of animals or figuresfacing each other, as in pediments, overdoors, etc.after cooler A device that cools compressed airafter it is fully compressed.afterfilter, final filter In an air-conditioningsystem, a high-efficiency filter located near a ter-minal unit.afterflaming The continued flaming combus-tion of a material after the exposing flame hasbeen removed.after-flush The residue of water in a toilet flushtank after it has been flushed; after flushing, theresidue gradually drains from the flush tank toseal the trap.afterglow The glow in a material after theremoval of an external source of fire to which itis exposed, or after the cessation (natural orinduced) of flames.aftertack, residual tack The lingering tackor stickiness of a paint film which remains over along period of time.AG 1. Abbr. for “above grade.” 2. Abbr. for“against the grain.”AGA Abbr. for “American Gas Association.”agalma In ancient Greece, any work of art ded-icated to a god.agba A large central African tree with ratherlightweight wood of a creamy to pinkish browncolor. Used for plywood, interior millwork, andcarpentry.AGC Abbr. for “Associated General Contractors.”age hardening An aging process in certainmetals, at room temperature, which results inincreased strength and hardness.ageing British variant of aging.agency 1. A relationship by which one party,usually the agent, is empowered to enter intobinding transactions affecting the legal rights ofanother party, usually called the principal, as, forexample, entering into a contract or buying orselling property in his name or on his behalf.2. An administrative branch of government(federal, state, or local).agent One who is empowered to enter intobinding transactions on behalf of another (usu-ally called the principal).age softening The loss of strength and hard-ness at room temperature which takes place incertain alloys owing to spontaneous reduction ofresidual stresses in the strainhardened structure.affronted16AFNOR Abbr. for “Association Française deNormalisation.”A-frame A three-piece rigid structural frame inthe shape of the upright capital letter A.A-frame house A house, usually constructedof wood, with a roof that extends steeply down-ward from both sides of a central ridge, almost tothe building foundation; the roof is supported bya rigid structural framework in the shape of thecapital letter A. One or both end walls of thehouse are often almost completely glazed. Muchof the living area on the ground floor is open tothe underside of the roof; the bedrooms are fre-quently located on a balcony directly under theroof; often, there is an exterior deck at one endor both ends of the house. Also see rafter house.A-frame houseaffrontedAfrican cherry See makore.African ebony See ebony.African mahogany Same as khaya.African rosewood See bubinga.
  • 30. agger 1. In ancient Rome, an earthwork; anartificial mound or rampart. 2. The fill for a roadover low ground.agglomerate stone See artificial stone.agglomeration The collecting together of tinysuspended particles into a mass of larger size, onewhich will settle more rapidly.AGGR On drawings, abbr. for aggregate.aggradation The addition of a material to theearth’s surface to promote the uniformity of agrade or slope.aggregate 1. An inert granular material such asnatural sand, manufactured sand, gravel, crushedgravel, crushed stone, vermiculite, perlite, andair-cooled blast-furnace slag, which when boundtogether into a conglomerate mass by a matrixforms concrete or mortar. 2. An inert granularmaterial that may be added to gypsum plaster.aggregate bin A structure designed for storingand dispensing dry granular construction materi-als such as sand, crushed stone, and gravel; usu-ally has a hopper-like bottom that funnels thematerial to a gate under the structure.aggregate blending The mixing of two ormore aggregates so as to obtain different aggre-gate properties.aggregate interlock The projection of aggre-gate particles or portions thereof from one side ofa joint or crack in concrete into recesses in theother side so as to effect load transfer in compres-sion and shear, and maintain mutual alignment.aggregate strength The strength of a wirerope determined by summing the individualbreaking strength of the strands of which it isfabricated.agiasterium In the early church, that part of abasilica in which the altar was set up.aging, Brit. ageing 1. The progressive changein a chemical and physical material withincreased age; in natural rubber and syntheticelastomers, usually marked by a deteriorationcaused by oxidation. Also see accelerated aging,age hardening, age softening. 2. The storing ofvarnish to improve clarity and gloss.agitating lorry British term for agitating truck.agitating speed The rate of rotation of thedrum or blades of a truck mixer or other deviceused for agitation of mixed concrete.agitating truck, Brit. agitating lorry Avehicle carrying a drum in which freshly mixedconcrete can be conveyed from the point of mix-ing to that of placing, the drum being rotatedcontinuously so as to agitate the contents.agitation 1. The process of providing gentlemotion in mixed concrete, just sufficient to pre-vent segregation or loss of plasticity. 2. The mix-ing and homogenization of slurries or finelyground powders by air or mechanical means.agitator 1. A mechanical device used to mix aliquid contained in a vessel. 2. A device formaintaining plasticity and preventing segrega-tion of mixed concrete by agitation.agitator body A truck-mounted drum for trans-porting freshly mixed concrete; rotating internalpaddles or rotation of the drum prevents the set-ting of the mixture prior to its delivery at the site.agnus dei17agitator bodyAGL Abbr. for “above ground level.”agnus dei Any image or representation of alamb as emblematic of Christ, esp. such aagnus dei
  • 31. representation with a halo and supporting thebanner of the cross.agora The chief meeting place or marketplacein an ancient Greek city.agreement form A document setting forth inprinted form the general provisions of an agree-ment with spaces provided for insertion of spe-cific data relating to a particular project.Agrément Board See British Board of Agré-ment.agricultural drain Same as agricultural pipedrain.agricultural lime A hydrated lime which isused to condition soil.agricultural pipe drain A system of porous orperforated pipes laid in a trench filled withgravel (or the like); used for draining subsoil.aguilla An obelisk, or the spire of a churchtower.Ah Abbr. for “ampere-hour.”aha Same as ha-ha.AHU Abbr. for air-handling unit.AIA Abbr. for “American Institute of Archi-tects.”AIA uniform system See contract documentsand uniform system.AIEE Abbr. for “American Institute of ElectricalEngineers.”aiguille A slender form of drill used for boringor drilling a blasthole in rock.aileron A half gable, such as that which closes theend of a penthouse roof or of the aisle of a church.AIMA Abbr. for “Acoustical and InsulatingMaterials Association.”aiming angle Same as angle of illumination;usually measured in degrees.air balancing A procedure used to adjust theflow of air in an HVAC system so as to meet thedesign goals for airflow throughout the system.air barrier A membrane that acts as a resis-tance to air leakage.air-blown mortar Same as shotcrete.air blowpipe A pipe which emits a jet of air;used to clean an area of debris.airborne sound Sound that reaches a pointin a building by propagation from the sourcethrough air.air-bound Said of a pipe or apparatus in whichthe presence of a pocket of air prevents orreduces the desired liquid flow in the pipe orapparatus. Also see air lock, 2.agora18agora: plan of the agora of Antiphellusagrafe, agraffe The voussoir or keystone of anarch, especially when carved as a cartouche.agrafeagreement 1. A meeting of minds. 2. A legallyenforceable promise or promises between two oramong several persons. 3. On a construction proj-ect, the document stating the essential terms ofthe construction contract which incorporates byreference the other contract documents. 4. Thedocument setting forth the terms of the contractbetween the architect and owner or between thearchitect and a consultant. 5. An arrangementindicating the intent of a contract but not neces-sarily fulfilling all the enforceable provisions of it.Also see agreement form, contract.
  • 32. air break In a drainage system, a pipingarrangement in which a drain from an appli-ance, device, or fixture discharges into the openair and then into another fixture, receptacle, orinterceptor; used to prevent back siphonage orbackflow.air brick A perforated brick or perforated metalunit of brick size which is built into a wall; usedfor ventilation.airbrush A small tool used for the fine-sprayapplication of paint, dye, watercolor pigment, orink by compressed air.air content19AIR COND On drawings, abbr. for “air con-dition.”air conditioner A device for providing airconditioning.air conditioning 1. The process of treating airso as to control simultaneously its temperature,humidity, cleanliness, and distribution within aninterior space such as a room or building. 2.Same as definition 1, but also controlling odorand noise.air-conditioning duct See air duct.air-conditioning grille Same as insertedgrille.air-conditioning lock A type of window lockrequiring a special key or wrench to open it; usedwhere the window is to be opened only for spe-cial purposes, such as cleaning.air compressorairbrushair chamber In a water piping system near avalve or faucet, a vertical pipe stub which issealed at the top and contains air; the entrappedair provides a cushion when the valve is closedsuddenly, thereby eliminating the noise of waterhammer.air changes A measure of the volume of airsupplied to or exhausted from a building (orroom); usually expressed in terms of the numberof complete changes of air per hour in the roomor space under consideration.air circuit breaker A type of circuit breakerutilized in commercial buildings at mediumvoltage; the word “air” refers to the insulatingmedium between contacts in the circuit breaker.air circulation Natural or imparted motion ofair.air cleaner A device (such as an air washer, airfilter, electrostatic precipitator, or charcoal fil-ter) which removes airborne impurities such asdust, smoke, or fumes.air cock Same as pet cock.air compressor A machine which draws in airat atmospheric pressure, then compresses it topressures higher than atmospheric and deliversit at a rate sufficient to operate pneumatic toolsor equipment.air-conditioning lockair-conditioning system An assembly ofcomponents for the treatment of air, controllingits temperature, humidity, cleanliness, and dis-tribution within an air-conditioned space. Typesof systems differ, but the basic components mayinclude: outside-air intake, preheater, return-air intake, filters, dehumidifier, heating coil,humidifier, fans, ductwork, air outlets, air termi-nals, refrigeration machine, piping, pumps, andwater or brine. See heating, ventilating, and air-conditioning system.air-conditioning unit Same as room airconditioner.air content The volume of air voids in cementpaste, mortar, or concrete, exclusive of pore
  • 33. space in aggregate particles, usually expressed asa percentage of total volume of the mixture.air control valve Same as air maintenancedevice.air-cooled blast-furnace slag The materialresulting from solidification of molten blast-furnace slag under atmospheric conditions. Alsosee blast-furnace slag.air-cure To vulcanize at ordinary room temper-atures, or without the aid of heat.air cushion tank Same as expansion tank.air curtain A stream of high-velocity tempera-ture-controlled air which is directed downward,across an opening; excludes insects, exteriordrafts, etc.; prevents the transfer of heat acrossit, and makes it possible to air-condition a spacehaving an open entrance; used in exterior doors,on loading platforms, etc.mixing of the air which is supplied to the roomwith the air already in the room.air-distributing acoustical ceiling A sus-pended acoustical ceiling in which the board, per-forated metal, or tile is provided with small, evenlydistributed mechanical perforations through thematerial; designed to provide a desired flow of airfrom a pressurized plenum above.air door Same as air curtain.air drain An empty space left around the ex-ternal foundation wall of a building to preventthe earth from lying against it and causingdampness.air-dried lumber, natural-seasoned lum-ber Wood dried by exposure to air under nat-ural conditions; usually has a moisture contentnot greater than 24%.air drill Same as pneumatic drill.air-dry moisture content The moisture con-tent of a piece of wood after it has been exposedto its environment long enough to attainmoisture-content equilibrium without the appli-cation of heat.air drying The process of drying slowly underambient conditions of temperature and humid-ity, as in the natural seasoning of lumber or thehardening of paint.air duct A duct, usually fabricated of metal,fiberglass, or concrete; used to transfer air fromone location to another.air eliminator In a piping system, a deviceused to remove air from water, steam, or a refrig-erant.air-entrained concrete Concrete made withair-entraining cement or an air-entrainingagent. Same as cellular concrete.air entraining Descriptive of the capability ofa material or process to develop a system ofminute bubbles of air in cement paste, concrete,or mortar.air-entraining admixture An admixture thatcauses the development of air bubbles in con-crete or mortar during its mixture.air-entraining agent An addition for hydrauliccement or an admixture for concrete or mortarwhich causes air to be incorporated in the form ofminute bubbles in the concrete or mortar duringmixing, usually to increase its workability andfrost resistance.air control valve20air curtain or air doorair damper See damper, 1.air diffuser An air distribution outlet, usuallylocated in the ceiling and consisting of deflect-ing vanes discharging supply air in various direc-tions and planes, and arranged to promoteair diffuser
  • 34. air-entraining hydraulic cement Hydrau-lic cement which contains an air-entrainingagent in an amount such as to cause air to beentrained in the mortar, within specified limits.air entrainment The occlusion of air in theform of tiny bubbles (generally smaller than 1 mm)during the mixing of concrete or mortar; used toimprove its workability.air exfiltration See exfiltration, 1.air-exhaust ventilator 1. An air-exhaust unitused to carry away odors and fumes from a stove,griddle, etc.; may contain a grease-extractingdevice or an air filter; sometimes includes a fire-extinguishing device. 2. Any air-exhaust unitused to carry away dirt particles, odors, or fumes(as in an industrial plant); the ventilator may bemechanically actuated or of the gravity type.air filter Any device used to remove solidand/or gaseous pollutants from air.air filtration The use of an air filter to provideclean air.airflow vane Same as turning vane.air flue See flue.airfoil vane Same as turning vane.air-fuel ratio The ratio of the volume (orweight) of air being furnished for combustion tothe volume (or weight) of the fuel.air gap 1. The unobstructed vertical distancebetween the lowest opening of a faucet (or thelike) which supplies a plumbing fixture (such astank or wash bowl) and the level at which thefixture will overflow. 2. In a drainage system, theunobstructed vertical distance between the out-let of a waste pipe and the flood-level rim of thereceptacle into which it discharges. 3. A gap inan electric or magnetic circuit; usually acts as ahigh-resistance path in the circuit.air leakage21air grating 1. A fixed metal grille on the exte-rior of a building through which air is broughtinto, or discharged from, the building for pur-poses of ventilation. 2. An air diffuser.air grille A type of air grating.air gun 1. Same as spray gun. 2. See shotcretegun.air hammer, pneumatic hammer A por-table tool, driven percussively by air pressure,into which is set a chisel, hammer, or the like.air-handling luminaire Same as air-lighttroffer.air-handling system An air-conditioning sys-tem in which an air-handling unit provides partof the treatment of the air.air-handling unit; packaged fan equip-ment An assembly of air-conditioning com-ponents (such as fans, cooling coils, filters,humidifiers, and dampers) integrated into a self-contained package and often installed as a singleunit, which is connected to system of metalductwork that distributes the conditioned air.air heating system See warm-air heatingsystem.air hole In the foundation of a house, anopening that provides ventilation for a crawlspace.air house Same as pneumatic structure.air-inflated structure Same as pneumaticstructure.air inlet In an air-conditioning system, a devicethrough which air is supplied to the system.air intake Same as outside-air intake.air lance A rod-shaped device for directing ahigh-velocity stream of compressed air; used toclean away debris from a surface.air leakage 1.The volume of air which flowsthrough a closed window or door in a given lengthair gap,1air gap,2
  • 35. of time as a result of the difference in air pressureon its opposite faces. 2.In ductwork, air whichescapes from a joint, coupling, etc. 3.The unde-sired leakage or uncontrolled passage of air from aventilation system. 4.The flow of uncontrolled airthrough cracks or openings in an enclosure withina building (such as a HVAC plenum) or throughthe surfaces which enclose the building.airless spraying, hydraulic spraying Thespraying of paint by means of high fluid pressureand special equipment.air lift 1. Equipment for lifting slurry or drypowder through pipes by means of compressedair. 2. The use of compressed air, introduced inwater at the bottom of an open-ended cased pileor cell of a cofferdam, to rid it of loose material.air-lift pump A type of pump for raising waterfrom a well, consisting of a pipe which surroundsanother of smaller diameter; compressed air isinjected into the smaller pipe, causing water torise up the larger pipe.and egress from one room to another while per-mitting minimal air movement between rooms.air-lock strip The weather stripping which is fas-tened to the edges of each wing of a revolving door.air maintenance device A valve required tointroduce air into a tank which stores waterunder pressure.air meter A device for measuring the air con-tent of concrete and mortar.air-mixing plenum In an air-conditioningsystem, an enclosed volume in which recircu-lated air is mixed with fresh air for distributionthroughout the system.air monitoring During the removal of asbestosin buildings, the measurement of asbestos fibercontent in the air.air motor An air-operated device used to openor close a damper, 1 or valve.air moving device See fan.air outlet In an air-conditioning system, adevice at the end of a duct through which air isexhausted.air permeability test A test for the measure-ment of the fineness of powdered materials, suchas portland cement.air pipe A seldom-used synonym for vent pipe.airplane bungalow A Craftsman style bunga-low having a gable whose face is parallel to themain ridge of the roof; its second floor is a singleroom.air pocket An air-filled volume within a sec-tion of piping (or an apparatus) which is nor-mally filled with liquid.air pressure-reducing valve See pressure-reducing valve.air pressure relief vent A relief vent.air pump A pump used to exhaust or to com-press air, or force it through another apparatus.Also see air compressor.air purge valve A device which eliminatestrapped air from a piping system.air quality See indoor air quality.air receiver On an air compressor, the air stor-age tank.air register Same as register.air regulator A device for regulating airflow, asin the burner of a furnace.airless spraying22air-lift pumpair-light troffer In an air-conditioning system,a unit which combines the functions of a lightfixture and an air terminal unit.air line A duct, hose, or pipe that suppliescompressed air to a pneumatic tool or piece ofequipment.air lock 1. A space which is designed to isolatean air conditioned space from another space towhich it is connected. 2. In a pump or piping sys-tem, the stoppage of flow resulting from the pres-ence of trapped air. 3. An enclosure with controldoors between two rooms that permits the ingress
  • 36. air reheater In a heating system, any device usedto add heat to the air circulating in the system.air release valve A valve, usually manuallyoperated, which is used to release air from awater pipe or fitting.air right The legal property right for use of thespace above a specified elevated plane; usuallyincludes the right to ground support but excludesother rights to ground use, e.g., the right to con-struct a building over a railroad track.air-ring In the placement of shotcrete, a perfo-rated manifold through which air is introducedinto the flow of material.air scrubber See air washer.air-seasoned lumber See air-dried lumber.air separator An apparatus for separatingground-up materials pneumatically into varioussizes.air-set To allow material to harden under nor-mal atmospheric pressure and temperature.air shaft, air well A ventilating shaft; a roof-less enclosed area within a building or betweenbuildings; may have openings such as windows.air shutter A device for regulating the quantityof air being mixed with gas for combustion.air-slaked Said of a surface that is wetted by theexposure to moisture in air.air slaking Absorption by quicklime or cementof moisture and carbon dioxide from the atmo-sphere, causing the material to change its chem-ical composition.air space The space above private property orpublic property for which air rights may begranted.air-supported structure See pneumaticstructure.air tap Same as air vent.air terminal In a lightning protection system,the combination of a metal rod and its brace orfooting, on the upper part of a structure.air terminal unit In air-conditioning, same asterminal unit.air test A test that applies uniform air pressurethroughout a drainage system being tested forleakage. This test is recommended in lieu of awater test when there is a danger of water freez-ing during the test.air test, pneumatic test A test for leaks indrainage systems, in soil, waste, and ventilatingpipe systems, or in ductwork; all openings aresealed, and compressed air is introduced into thesystem; air leakage is indicated by means of a U-gauge or other suitable pressure gauge.air tight Said of an enclosure or barrier thatdoes not permit the passage of air.air-to-air resistance The resistance pro-vided by the wall of a building to the flow ofheat. See thermal conductance and thermalresistance.air-to-air transmission coefficient Seethermal transmittance.air trap Same as trap, 1.air valve A valve used to admit or discharge airfrom a pipeline.air vent In a water distribution system, a ventfor releasing trapped air; usually located at thehighest point in the system.air ventilation The quantity of air which mustbe supplied to maintain the desired quality of airwithin a space.air vessel 1. An enclosed volume of air whichuses the compressibility of air to minimize waterhammer. 2. An enclosed chamber using theair vessel23air terminalair test
  • 37. compressibility of air to promote a more uniformflow of water in a piping system.air void A space which is filled with air incement paste, mortar, or concrete. Also seeentrapped air, entrained air.air washer A water spray system or device forcleaning, humidifying, or dehumidifying the air.air-water jet 1. A jet of air and water mixed,which leaves a nozzle at high velocity; usedin cleaning the surfaces of concrete or rock. 2. Incleaning concrete or rock surfaces, a high-velocityjet consisting of a mixture of air and water.air-water storage tank A water storage tankin which the air, above the water, is compressed.airway A passage for ventilation between ther-mal insulation and roof boards.ajaraca In southern Spain, an ornament inbrick walls, formed of patterns, a half brick deep,more or less complicated.a jour, ajouré Pierced, perforated, or cut out toform a decorative opening in wood, stone,metal, or other material.AL On drawings, abbr. for aluminum.ala 1. An alcove or small room opening off theatrium of an ancient Roman house. 2. A smallroom on each side of a cella.alabaster Fine-grained, translucent variety of verypure gypsum, generally white or delicately shaded.A-labeled door A door carrying a certificationfrom the Underwriters’ Laboratories, Inc. that itmeets the requirements for a class-A door.alameda A shaded public walk or promenade.alarm system An electrical system that isinstalled in a building as a protective measureagainst fire or unauthorized entry. In the eventthat the system is activated, an alarm (such as anaudible signal or flashing light) is turned on; seefire alarm system and burglar alarm system.alarm valve See wet alarm valve.alatorium 1. A piazza, corridor, or coveredwalk. 2. The flank of a building.albani stone A pepper-colored stone used inbuildings in ancient Rome before the introduc-tion of marble.albarium A white lime used for stucco; madeby burning marble.albronze Same as aluminum bronze.album In ancient Roman architecture, a spaceon the surface of a wall covered with white plas-ter, located in a public place, on which publicannouncements and records, etc. were written.alburnum Same as sapwood.alcazar A Moorish or Spanish fortress or castle.alclad A metal product clad with an aluminumor aluminum-alloy coating, usually as a protec-tion against corrosion.alcove A small recessed space, opening directlyinto a larger room.alder A moderately light-colored, light-weighthardwood that changes to flesh color or lightbrown when dried; often stained to simulatecherry, mahogany or walnut; often used as ply-wood core and crossbanding.air void24air well See air shaft.AISC Abbr. for “American Institute of SteelConstruction.”AISI Abbr. for “American Iron and SteelInstitute.”aisle 1. A longitudinal passage between sectionsof seats in an auditorium or church. 2. In achurch, the space flanking and parallel to thenave; usually separated from it by columns,intended primarily for circulation but sometimescontaining seats.aisle access way A continuous, unobstructedaccessible route around seating, furniture, ordesks so as to provide adequate clearance for thedisabled.aisleway A passage or walkway within a fac-tory, storage building, or shop permitting theflow of inside traffic. Also see aisle.AITC Abbr. for “American Institute of TimberConstruction.”aiwan A reception hall in an ancient Parthianbuilding.airway
  • 38. aleatorium In ancient Roman architecture, aroom in which dice games were played.ale house In an early British or American com-munity: a village tavern licensed to sell alco-holic beverages.alette 1. A minor wing of a building. 2. A doorjamb. 3. A rear pilaster, partially visible withina cluster of columnar elements. 4. The wing ofthe pier on both sides of an engaged column.aligning punch25alidade The part of a surveying instrumentwhich consists of a sighting device, with index,and reading or recording accessories.alienation The transfer of title to real propertyby one person to another.aliform Having a wing-like shape or extensions.aligning punch A punch used for lining up mat-ing holes prior to riveting or bolting; a drift punch.alettes,4 CalfizAlexandrian work Same as opus Alexan-drinum.Alexandrinum opus Same as opus Alexan-drinum.alfiz A decorative molding enclosing a door orarch.alhambresqueAlhambra A fortress and palace built by theMoorish kings of Granada in southern Spain,completed in the 14th century.Alhambresque Ornamentation that resem-bles the fanciful style used at the Alhambra.alicatado Tile work which is executed withazulejos; used to decorate pavements and walls,especially in patios. aligning punch
  • 39. alignment 1.An adjustment in a straight line. 2.The theoretical, definitive lines that establish theposition of construction (such as a building) or theshape of an individual element (such as a curved orstraight beam). 3.In highway and other surveys,the ground plan depicting direction of the route asdistinguished from a profile, which shows the ver-tical element. 4.In prehistoric building, formalalleys of standing stones, as at Carnac in France.alipterion In ancient Roman architecture, aroom used by bathers for anointing themselves.alite A principal constituent of portland-cement clinker; primarily tricalcium silicate, butincludes small amounts of magnesium oxide,aluminum oxide, ferric oxide, and other oxides.alive Same as live, 1.alkali Any of the various chemically activebases such as the soluble salts of metals, e.g., thewater-soluble salts of sodium and potassiumwhich occur in constituents of concrete andmortar that may result in deleterious expansion.alkali-aggregate reaction A chemical reac-tion in mortar or concrete between alkalies fromportland cement or other sources and certainconstituents of some aggregates; under certainconditions, deleterious expansion of the con-crete or mortar may result.alkalinity See pH.alkaline soil Soil containing soluble salts ofmagnesium, sodium, or the like, and having apH value of between 7.3 and 8.5.alkali reactivity Of a concrete aggregate, itssusceptibility to alkali-aggregate reaction.alkali resistance 1. The degree to which apaint resists reaction with alkaline materials suchas lime, cement, plaster, soap, etc.; a necessaryproperty for paints in bathrooms, kitchens, laun-dries. 2. The degree to which a porcelain enamelwill resist attack by aqueous alkaline solutions.alkali-silica reaction In portland cement, thereaction between the alkalies and particularsiliceous rocks and/or minerals which arepresent in some aggregates; may result in abnor-mal expansion and cracking of concrete underservice conditions.alkali soil A soil, with salts injurious to plantlife, having a pH value of 8.5 or higher.alkyd paint A paint using an alkyd resin as thevehicle for the pigment.alkyd resin One of a group of thermoplasticsynthetic resins; used in bonding materials, inadhesives, and in paints and varnishes.allée A broad walk, planted with trees on eitherside, usually at least twice as high as the width ofthe walk.allège A part of a wall which is thinner than therest, esp. the spandrel under a window.alignment26allègeallegory: Cathedral of Worms, 13th cent. The beast withfour heads symbolizes the Four Gospelsallegory A figurative representation in whichthe meaning is conveyed symbolically.Allen wrenchAllen head A screw having a hexagonallyshaped recess in its head.Allen wrench A wrench for Allen headscrews; a steel bar, hexagonal in shape, which isbent to form a right angle.
  • 40. alley 1. A service way providing a secondarypublic means of access to abutting properties; anarrow passageway between or behind buildings,sometimes permitting traffic for only one lane ofcars. 2. A garden walk between rows of trees; anallée.all-heart lumber Lumber that is all heart-wood, entirely free of sapwood.alligator hide A surface condition on porce-lain enamel, characterized by an extreme rough-ness; a severe case of orange peel.alligatoring 1. The splitting of a film of paintin a pattern resembling an alligator skin, causedby shrinkage of a coat of paint applied over asemiplastic or thermoplastic undercoat; alsocalled crocodiling. 2. Surface cracking, due tooxidation and shrinkage stresses, which showsas repetitive mounding of an asphalt surface in apattern resembling the hide of an alligator;occurs only in unsurfaced bitumen exposed tothe weather.alligator shears, lever shears Wide-jawedshears, resembling the jaws of an alligator,used to cut sheets of metal; operated by a footlever.alligator wrench A wrench having V-shaped,fixed serrated jaws; used to turn cylindrical parts,esp. in fitting pipe.all-in aggregate See bank-run gravel.all-in contract Same as turn-key job.allotment garden Any privately or publiclyowned garden area which has been dividedinto plots for assignment to individuals fortheir use.allover A pattern covering an entire surface;usually one which is repeated.ALLOW. On drawings, abbr. for “allowance.”allowable bearing value, allowable soilpressure, allowable bearing capacityThe maximum permissible pressure on founda-tion soil that provides adequate safety againstrupture of the soil mass or movement of thefoundation of such magnitude as to impair thestructure that imposes the pressure.allowable load The load which induces themaximum permissible unit stress at a critical sec-tion of a structural member.allowable pile bearing load The maximumpermissible load on a pile that provides adequatesafety against movement of such magnitude thatwould endanger the structure supported by thepile.allowable pile load The allowable concentri-cally applied load which is permitted along thecentral axis of a pile.allowable soil pressure See allowable bear-ing value.allowable stress In the design of structures,the maximum unit stress permitted under work-ing loads by codes and specifications.allowance 1. See cash allowance. 2. See con-tingency allowance.alloy A composition of two or more metalsfused together, usually to obtain a desiredproperty.alloy steel Steel containing one or more alloyingelements other than carbon, such as chromium,molybdenum, or nickel, which have been added(in an amount exceeding a specified minimum)to impart particular physical, mechanical, orchemical properties.all-risk insurance On a construction project,insurance that protects the policyholder againstall risks other than those which are specificallyexcluded by the policy.all-rowlock wall See rowlock cavity wall.all-stretcher bond A masonry bond, 6 show-ing only stretchers on the face of the brick wall;same as stretcher bond.allure See alure.alluvial deposit Earth, sand, gravel, or otherrock or mineral materials transported and laiddown by flowing water.alluvium Gravel, sand, silt, soil, or other mate-rial that is deposited by running water.ALM On drawings, abbr. for “alarm.”almariol A storage place for ecclesiastical vest-ments; an ambry.almary See ambry.almehrabh In Arabian architecture, a nichein a mosque which marks the direction ofMecca.almemar, almemor 1. A bema, 2. 2. In asynagogue, a desk on which the Torah is placedwhile being read to the congregation.almena An indented trapezium serving as anembattled parapet. (See illustration p. 28.)almena27
  • 41. almery See ambry.almocarabe Same as ajaraca.almond An aureole of elliptical form.almonry A building or part thereof where almsare distributed.almorie Same as almariol.almorrefa In Hispanic architecture, brickworkintermixed with azulejos; used as flooring.almshouse 1. A building in which charity wasdistributed to the poor; found in England and insome early American settlements and cities; alsosee poorhouse. 2. An almonry.alpha brass An alloy containing 51 to 61%copper and 39 to 45% zinc; used in hot-watersystems because of its corrosion resistant pro-perties.alpha gypsum A specially processed gypsumhaving low consistency and high compressivestrength, often exceeding 5,000 lb per sq in.(352 kg per sq cm).ALS Abbr. for “American Lumber Standards.”ALT On drawings, abbr. for “alternate.”altana A light ornamental structure on a roofthat serves much the same function as a gazebo.altar 1. An elevated table, slab, or structure,often of stone, rectangular or round, for religiousrites, sacrifices, or offerings. 2. The Communiontable in certain churches.altar frontal An ornamental hanging or panelfor the front of an altar.altar of repose In a Roman Catholic church, aside altar, repository, or storage niche where theHost is kept from Maundy Thursday to GoodFriday.altarpiece A decorative screen, painting, orsculpture above the back of an altar.altar rail A low rail or barrier in front of thealtar, running transversely to the main axis ofthe church and separating the officiating clergyfrom the other worshipers.altar screen A richly decorated partition ofstone, wood, or metal, separating the altar fromthe space behind it.altar slab, altar stone A flat stone or slabforming the top of an altar.altar tomb A raised tomb, or monument cover-ing a tomb, whose shape resembles an altar.alteration Construction in a building whichmay change the structural parts, mechanicalequipment, or location of openings, but does notincrease the overall area of dimensions of thebuilding.alterations 1. A construction project (or por-tion of a project) comprising revisions within orto prescribed elements of an existing structure,as distinct from additions to an existing struc-ture. 2. Remodeling.alternate A change in work, 1 described in thecontract documents for a building that gives theowner the option of selecting various products,materials, or systems, and/or the right to add ordelete portions of the work, 1.alternate bid The amount stated in the bid tobe added to or deducted from the amount of thebase bid if the corresponding change in projectscope or alternate materials and/or methods ofconstruction is accepted.alternating current An electric current thatvaries periodically in value and direction, firstalmery28altaralmena
  • 42. flowing in one direction in the circuit and thenflowing in the opposite direction; each com-plete repetition is called a cycle, and the num-ber of repetitions per second is called thefrequency; usually expressed in Hertz (Hz).alternating Flemish bond A brickwork pat-tern which is produced by laying alternatecourses of Flemish bond and common bond.alternating sprinkler system A fire sprin-kler system that can be changed from a wet-pipesprinkler system in the summer to a dry-pipesprinkler system in the winter.alternator A generator of alternating currentwhich is produced by the turning of its rotor.ALTN On drawings, abbr. for “alteration.”alto-rilievo, alto-relievo See high relief.alum A chemical compound added to gypsumplaster to make the plaster harden faster.ALUM. On drawings, abbr. for aluminum.alumina The oxide of aluminum; an importantconstituent of the clays used in brick, tile, andrefractories.aluminium British term for aluminum.aluminize, Brit. aluminise To apply a surfacecoating of aluminum to another metal or otherbase material, usually by spraying or dipping inmolten aluminum. On steel, such coatingsgreatly increase corrosion resistance.aluminous cement See calcium aluminatecement.aluminum, Brit. aluminium A lustrous,silver-white, nonmagnetic, lightweight metalwhich is very malleable; has good thermal andelectrical conductivity; a good reflector of bothheat and light. In construction, most aluminumis used in alloy form because of added strength;further strengthened by heat treatment; used inextrusions, castings, and sheets. Excellent resis-tance to oxidation; often anodized for bettercorrosion resistance, surface hardness, and/orarchitectural color requirements.aluminum brass Brass to which aluminumhas been added to increase its corrosion resis-tance.aluminum bronze A copper-aluminum alloy,usually with 3 to 11% aluminum; may containadditional additives; has good corrosion resis-tance and may be cast or coldworked.aluminum door A door having aluminumstiles and rails; usually glazed.aluminum foil Very thin aluminum sheet (lessthan 0.006 in. or 0.15 mm); usually used forthermal insulation and vapor barriers.aluminum oxide Same as alumina.aluminum paint A paint made with alu-minum paste and a film-forming vehicle (such asa varnish); a good heat and light reflector; hasgood water impermeability.aluminum powder Small flakes of alu-minum metal obtained by stamping or ball-milling foil in the presence of a fatty lubricant,such as stearic acid, which causes the flakes toorient in a pattern to give high brilliance. Usu-ally supplied in paste form wetted with mineralspirits.aluminum primer An aluminum-basedprimer,1 that has excellent water-resistant prop-erties.aluminum-silicon bronze An alloy con-sisting chiefly of copper with aluminum andsilicon added to give it greater strength andhardness.aluminum window Any window constructedprincipally of aluminum, the components ofwhich usually are extruded.aluminum-zinc coating On a metal surface,a corrosion-resistant coating having propertiessimilar to galvanizing.alure, allure, alur A gallery or passage, asalong the parapets of a castle, around the roof ofa church, or along a cloister.alure29alure A
  • 43. ambrices In ancient Roman construction, thecross laths inserted between the rafter and tilesof a roof.ambry, almary, almery, aumbry 1. A cup-board or niche in a chancel wall for the utensilsof the Eucharist; an armarium. 2. A storageplace, storeroom, closet, or pantry.ALV30amadoALV Symbol for alarm valve.alveated Having the vaulted shape of a beehive.alveus In ancient Rome, a bath constructed inthe floor of a room, the upper part of it project-ing above the floor, the lower part being sunkinto the floor itself.ALY On drawings, abbr. for alloy.amado In traditional Japanese architecture, atype of shutter made of sliding wooden panelswhich (when not in use) slide into a box-likestorage cabinet attached to the exterior of thebuilding at one side of the opening; usually set inplace in the evening.ambry, 1AMB Abbr. for “asbestos mill-cut board.”ambient lighting In any given area, the gen-eral background illumination.ambient noise The all-encompassing, averagebackground noise associated with a given envi-ronment, often a composite of sounds frommany sources near and far, of many differenttypes, e.g., the general background noise in aneighborhood or in an auditorium.ambient pressure In a water distribution sys-tem, the normal operating pressure at any partic-ular location in the system.ambient temperature The temperature ofthe surrounding air.ambitus 1. A small niche in undergroundRoman or Greek tombs, forming a receptacle fora cinerary urn. 2. In the Middle Ages, such aniche, but enlarged to admit a coffin. 3. In theMiddle Ages, the consecrated ground surround-ing a church.ambo, ambon 1. In early Christian churches,a pulpit for reading or chanting the Gospels orthe Epistles. 2. In contemporary Balkan orGreek churches, a large pulpit or reading desk.ambo,1
  • 44. ambulatory church A church having adomed center bay which is surrounded on threesides by aisles.AMCA Abbr. for “Air Movement and ControlAssociation.”AMD On drawings, abbr. for “air-moving device.”amended water Water to which a surfactanthas been added.amendment A modification to a building’scontract documents.American basement A floor of a buildingpartly above and partly below grade level, oftenserving as the entrance level to the building. Alsosee basement. Also called a walk-out basement.American bond Same as common bond; sameas English garden-wall bond.American Bracketed style A term occa-sionally used for the Italianate style.American Chateauesque style See Chateau-esque style.American Colonial architecture A termusually applied to colonial buildings constructedin America by English immigrants to the NewWorld; often classified according to region inAmerica.In early colonial New England, the typicalhouse was timber-framed with hewn-and-peggedjoints; exterior walls were sometimes coveredwith hard plaster, then clad with clapboardor weatherboards. Unpretentious houses com-monly had a single room with a loft space above;more prosperous houses, often one and a half ortwo stories high and one or two rooms deep, usu-ally were built on the hall-and-parlor plan, withone room on each side of an interior wall con-taining a massive, centrally located fireplace anda large high chimney; on the façade, drops wereoften suspended from the underside of an over-hanging second floor. Many of these early houseshad a steeply pitched gable roof and a side gable,or a hipped roof with eaves having no significantoverhang; unglazed window openings were cov-ered with solid-wood shutters, later replaced bynarrow casement windows having small quar-rels; heavy battened doors. Also see saltboxhouse, stone ender, whale house. Occasionallycalled Early Colonial architecture.In the colonial South and along the mid-Atlantic coast, single-room houses of the earlysettlers were often similar to the one-room planhouses in New England, with a clay-and-stickschimney. Later, as the houses became larger,they usually followed a hall-and-parlor plan or acenter-hall plan. Exterior walls were usuallybrick, with hand-split shingles on the roof; amassive decorative brick or stone exterior chim-ney at one or both gabled end walls, with cor-beled chimney caps. Pent roofs were common inthe mid-Atlantic area. For colonial architectureconstructed by immigrants other than theEnglish, see Dutch Colonial architecture,French Colonial architecture, German Colonialarchitecture, Spanish Colonial architecture.American Colonial Revival An architec-tural mode usually based on architectural proto-types in the English colonies in America, butoften including features not found or rarelypresent in those prototypes. Buildings in thisclassification are usually characterized by afaçade often featuring a Classical cornice;cupola; widow’s walk; colonial detailing; bevelsiding or a smooth brick wall finish with finejoints; brickwork often set in a Flemish bondpattern; splayed lintels; a hipped, gabled, orgambrel roof covered with slate tiles or woodshingles; louvered shutters; double-hung rect-angular sash windows with multiple panes inboth the upper and lower sashes; symmetricallyAmerican Colonial Revival31ambulatory,2ambulatory 1. A passageway around the apse ofa church, or for circumambulating a shrine. 2. Acovered walk of a cloister.
  • 45. arrayed windows in the façade; a fanlight overthe main entry door and sidelights on each sideof door; the front door commonly crowned by apediment, extending forward and supported oncolumns so as to form an entry porch.American four-square house 1. A one- ortwo-story house having a square floor plan con-sisting of four rooms (one in each corner), ahipped roof, and an off-center entry door; mostpopular from about 1905 to 1915. 2. A Prairiebox, primarily in the years between about 1900to 1920, having a low-pitched hipped roof and asymmetrical façade.American Institute of Architects (AIA)A professional organization, founded in 1857,whose purpose is to establish and promote pro-fessionalism and accountability on the part of itsmembers, and to promote architectural designexcellence. Address: 1735 New York AvenueNW, Washington, DC 20006.American International style See Interna-tional style and Contemporary style.American linden See basswood.American Mansard style A seldom-usedsynonym for Second Empire style. Also seeMansard style.American method of application A meth-od of applying rectangular roofing shingles whichprovides double coverage with a head lap, but noside lap.American National Standards InstituteAn independent organization of trade associa-tions, technical societies, professional groups,and consumer organizations; establishes andpublishes standards; formerly known as theUnited States of America Standards Institute(USASI or ASI), and previously as the AmericanStandards Association (ASA).American oriental carpeting An Americanloom-made carpet, of Axminster or Wiltonweave, manufactured in color and patterndesigns similar to those of oriental rugs.American Renaissance Revival A termoccasionally used for Italian Renaissance Revival.American Rundbogenstil Same as RoundArch style.American Society of Landscape Archi-tects (ASLA) The professional organizationof landscape architects in America, founded in1899. Address: 636 Eye Street, NW, Washington,DC 20008.American Society for Testing and Materi-als A nonprofit organization that establishesstandard tests and specifications for constructionmaterials; such tests and specifications usually arereferred to by the abbreviation ASTM followedby a numerical designation. Address: 100 BarHarbor Drive, West Conshohocken, PA 19428.American standard beam A type of I-beamof hot-rolled structural steel; designated by theprefix S placed before the size of the member.American standard channel A C-shapedstructural member of hot-rolled structural steel;designated by the prefix C placed before the sizeof the member.American four-square house32American standard channelAmerican standard pipe threads In theUS, standard pipe threads for commonly usedsizes of pipe for water, gas, or steam; formerlycalled Briggs standard pipe threads.American Standards Association SeeAmerican National Standards Institute.Americans with Disabilities Act (ADA)A federal law, enacted in 1990, requiring thatpublic accommodations be accessible to thosehaving physical disabilities; this law mandatesthat existing physical barriers be replaced ormodified so there are no impediments to accessby the physically disabled. For detailed infor-mation, write the US Equal EmploymentOpportunities Com