Architectural Dictionary | A

This Dictionary is an invaluable guide for anyone interested in Architectural / Construction Activity. Click on the alphabets given below, for the word you are looking for.

Abacus – Flat piece at the top of the capital. (Picture shown above).
Abattoir – A public slaughter house.
Abbey – A convent under an abbot: the church now or formerly attached to it.


Ablution Fitting- A large sanitary fitting in which several people at the same time can wash their hands, arms, or faces. Ablution fittings are made for rough use and have water sprayers, often with touchless controls or foot controls. Trough type can be set in ranges, while washing fountains have a circular pedestal bowl.
Above Ground Level– Higher than ground level, particularly with reference to the superstructure, and to work after a building is out of the ground.
Abrasion Resistance– The ability of a finish to stand up to wear from rubbing,
Abrasives – Rough, hard materials (usually powders, grits or stones) in various forms such as sandpaper, grinding wheels, or grinding discs, used to smooth or clean surfaces or to sharpen and hone edge tools. From hard to soft they include: diamond, garnet, corundum(emery), carborundum, powdered glass, and silica sand. The hardest abrasives cause others to wear the most while lasting the longer themselves. Coarse abrasives remove the most material, fine abrasives give the smoothest surface.
ABS (Acrylonitrile Butadiene Styrene)- A tough co-polymer, used to make plastic pipes for cold water supply or soil and waste drains. Pipes can have solvent welded joints, made with special ABS cement, or push-fit joint rings. Its softening point is higher than that of polypropylene, so that it can handle hot waste water up to 80 degree Cent. However, petrol, oil, and linseed oil can damage it. ABS pipe can be bent at about 125 degree Cent. ; no bending spring is needed. Like all plastics, ABS is combustible.
Absorption Rate – The speed at which water is taken up by a brick when partly immersed for one minute, used to measure initial suction.
Absorption Refrigerator – A refrigerator without a compressor which uses heat to evaporate lithium bromide from water. It is silent and not very efficient but can be run on waste heat.
Absorptivity / Absorptive Power – The relative rate of absorption of heat by a body compared with a similarly shaped black body in the same conditions.
Abstracting – Assembling data so that similar types of work are brought together under one item ready for billing. It is the first part of the working up of bill of quantities.
Abutment – An intersection between a roof slope and a wall that rises above it. (Picture shown below).

Abutment Flashing – A flashing over an abutment. At the head of the slope it is level, at the side of the slope it is raking or stepped.
Abutment Piece – A sill or sole plate.
Accelerated Weathering/ Artificial Ageing – The testing of materials by exposure to cycles of sunlight, heat, frost and wetness or dryness that are more severe than in nature.
Accelerator / Accelerating admixture – An admixture that hastens setting and increases the early strength of concrete, usually causing an increase in temperature. This allows earlier removal of formwork and may give frost protection.
Access – A way in or out, including any circulation area for walking (such as a stair, balcony or ramp), vehicle access to a site (such as a road or a way), or even hand access for inspection.
Access Chamber – A space big enough for a person to get into.
Access Floor – A floor above the structural floor, creating the space between them, for cables going to office work stations, to allow easy wire management for data, telephone, power and lighting.
Access Hole – An opening large enough for a person to get through for work on installations, or for a tool to be passed through for making adjustments. Access holes normally have a cover, such as a panel or a trap.
Accessories – Components used to fix, join, or connect building elements or services, including hardware, fixings and roof flashings.
Accordion Door – A folding door. (Picture shown below).


Accreditation – An approval of one official body by a higher authority, e.g. for building products certification.
Acetal Resin – Strong, low priced synthetic resin made by polymerizing formaldehyde. Acetal plastics are used in plumbing fittings, particularly for threaded valve components and intricate shapes.
Acoustic – Pertaining to the sense of hearing or to the theory of sounds, acoustic properties of a room determining whether accurate hearing in it is easy or not.
Acoustic Board – Wall and Ceiling acoustic furnishings made with a porous core of insulating board or mineral fibre tiles and a surface that has many round holes, or is fissured or riled. It can be fixed as full boards or made into acoustic tiles. Painting can block the holes and reduce sound absorbency; careful spraying with many thin coats of emulsion paint reduces mainly the high frequency sound absorption.
Acoustic Clip – A floor clip with a flexible rubber pad to reduce transmission of impact sound through a timber floating floor.
Acoustic Construction – The improvement of sound insulation by using thick walls, heavy materials of low stiffness, or discontinuous construction such as a floating floor, which reduces noise transmission.
Acoustic Finishing – Materials inside which sound energy is lost by absorption. However they usually have high sound transmission.
Acoustic Plaster – Gypsum Plaster with light weight aggregate, used as an acoustic finishing.
Acoustic Tile – A square of acoustic board.
Acoustical Transmission – Sound or noise in buildings is controlled either by reducing transmission between rooms by the methods of construction, or by increasing absorption within the room, with acoustic finishings. In sound measurements the acoustical transmission factor is the amount of sound that passes through a type of construction, while the acoustical reduction factor is its reciprocal, implying the effectiveness of sound insulation.
Acre – Measure of land containing 4840 sq.yds.
Acropolis – Greek citadel sited prominently above the rest of a city. (Picture shown below).


Acrylic Adhesive – A fast-curing emulsion adhesive, usually white in colour and fairly non-staining. It is used wet but goes tacky quickly, and can hold down curling edges of vinyl floor tiles.
Acrylic Paints – Emulsion paints which hold their colour well, are very durable and resistant to oils, fats and grease, and have sufficient resilience to avoid cracking. They are used as fast-drying floor paints and as organic coatings on metals.
Acrylic Resins – Polymethyl methacrylate, the synthetic resin in acrylic paints, sealants, adhesives, and sheet. It however has poor resistance to alkalis.
Acrylic Sealants – Sealants that set to a tough rubbery material by solvent release. They have good adhesion to most substrates without the need for a primer, but should not be used in wet areas or in contact with cement-based products, which are alkaline.
Acrylic Sheet – Fairly strong, light weight, easily moulded plastics, mainly used for clear or tinted glazing and coloured sanitary fittings, such as baths or basins. Acrylic sheets melt and burn easily, so they are a fire hazard and have low fire resistance. However, they can be broken to allow escape and unlike glass do not splinter into sharp pieces.
Acrylonitrile Butadiene Styrene – A tough co-polymer, used to make plastic pipes for cold water supply or soil and waste drains. Pipes can have solvent welded joints, made with special ABS cement, or push-fit joint rings. Its softening point is higher than that of polypropylene, so that it can handle hot waste water up to 80 degree Cent. However, petrol, oil, and linseed oil can damage it. ABS pipe can be bent at about 125 degree Cent. ; no bending spring is needed. Like all plastics, ABS is combustible.
Active Fire Protection – Mechanical and electrical devices to warn of or extinguish fires, such as sprinklers, alarms, fire detectors, and fans or dampers for a pressurized escape route. They can be very effective but require regular inspection and maintenance, and may need standby power.

Active Leaf – The leaf of double door which is most used, held closed by latching to the inactive leaf.
Active Solar Heating – Heating systems that use solar collectors and mechanical devices such as pumps or fans.
Actuator – A mechanical linkage to create or transmit movements such as pushing, pulling, or slight rotation, which enable automatic controls to control a flow of fluids or the currents in the electric system.
Adaptor – A device which matches different objects, e.g. the connection between pipes or ducts of different sizes or sections, or between British electrical plugs and Continental ones.
Adhesion – The sticking together of components by making a chemical bond, using an adhesive, cement, or bonding compound.
Adhesive, Glue – A liquid that in hardening sticks together by adhesion. It allows joints or fixing to be made without spoiling a surface with nails or screws.
Adjudication – Adding a margin to the net price of builder’s estimate to give the tender amount. Adjudication is done by a manager after discussion with the chief estimator.
Admixture – A product or agent added in small quantities to the basic constituents ( aggregate, cement or water ) of concrete or mortar to alter a particular combination of properties while it is fresh or after it has hardened.
Adobe, Mud brick – A moulded and sun-dried brick or block of clay (or the clay itself) usually containing chopped straw reinforcement, used for the walls of earth buildings. Adobe construction is common in South and Central America and is occasionally used in semi-arid regions of the USA, Australia, and elsewhere. (Picture shown below).


Aerated Concrete – Lightweight and highly insulating cellular material made from a mix of fine sand, pulverized fuel ash, and chemical admixtures, cast into moulds and autoclaved to make lightweight concrete blocks. It is easy to saw and drive nails into, although metal fixings do not hold well and may corrode needing the use of resin anchors. Aerated concrete has high moisture movements.
Aesthetics – The principle of taste and of art : the philosophy of fine arts.
A-frame Building – A building with beams straight from the ground to the roof ridge, that form the shape of an A. The lower part of the roof slope usually takes the place of the wall.
African-Mahogany – Timber from West Africa, generally Nigeria or Ghana,
After tack – The defect of a paint film which has been tack-free and then becomes tacky
After-flush – The small quantity of water remaining in the cistern after flushing a water closet. It trickles slowly down and remakes the seal
Ageing – The storing of a material to improve its quality. Varnish that has been aged has improved gloss and reduced pin-holing and crawling. Ageing is done before use, unlike maturing and curing.
Aggregate – Any granular material used as the main constituent of concrete, mortar and plaster. Aggregate is defined by its size, as coarse, fine, or all-in, its source (natural or artificial) and its shape, e.g. rounded or angular.
Agora – Greek forum or market place.
Agreed Levels – A survey of natural ground levels before the commencement of groundworks, marked on a drawing and signed by the site engineer and the clerks of works.
Air Admittance Valve – A device to let air into the sanitary pipe, used in addition to the soil vent, to relieve minor differences in air pressures.
Air Balancing – Adjusting air conditioning dampers so that air is evenly distributed to rooms. It is necessary at commissioning or when partitions are moved.
Air brick – A special brick with perforations through it so that it can be built into wall to ventilate a room or a space under floor. Air bricks can be of normal size, two course high, or made to be laid as a brick-on-edge. (Picture shown below).


Air brush – A small spray gun.
Air change – A quantity of fresh air equal to the volume of the room being ventilated. The ventilation rate is the number of air changes per hour. Offices need about 30 changes, boiler houses and laundries 10 to 20, classrooms 6, reading rooms 2 and store rooms 1.5. Kitchens often have high air-change rates, although if heat and smoke are withdrawn through hoods, excessive rates can be avoided.
Air Conditioner (Window)– A small to medium capacity packaged air treatment unit or cabinet, usually without ductwork and often mounted in a window.
Air Conditioning – The process of treating air so as to control simultaneously its temperature, humidity, cleanliness and distribution to meet the requirement of conditioned space or,
The supply of cool or warm, dry and filtered air using mechanical services to maintain conditions of temperature and humidity within the comfort zone, with an indirect benefit of a quiet environment, as windows are kept closed to reduce traffic noise. Automatic controls operate the air-treatment plant and determine the setting of air-handling equipment
Air curtain – A strong flow of warm air directed towards a doorway from the outside, to stop cold air entering in winter when the door is left open. Small air curtains are drawn from the sides, but larger units have a high velocity air current from overhead and the return duct in the floor.
Air diffuser – An air terminal unit that controls the direction of supply air for distribution into room or occupied area.
Air distribution – The supply of treated air from a central air-conditioning plant by blowing it through ductwork to air terminal units and into space
Air dried timber – Sawn timber that has had natural seasoning, by stacking cut planks in the open air, usually with stickers between them.
Air Eliminator – A plumbing fitting for the automatic release of gases, as from a cold water supply pipe, to prevent an air lock
Air Gap – The height of water above the rim of sanitary fitting to prevent backflow from contaminating the supply pipe.
Air grille, air grating – A simple type of air terminal unit: a perforated metal plate that allows air to pass, while acting as a sight screen. (Picture shown below).

Air Handling Equipment – Equipment in an air-conditioning system for moving air into and out of rooms, usually by blowing with fans through ducts. The supply air from the air treatment plant goes to air terminal units discharging into the spaces where air is distributed.
Air Handling Luminaire – A luminaire through which extract air is drawn, to reduce the cooling load on the air conditioning system as well to improve light output and improve lamp life
Air Handling Unit (AHU) – A packaged air conditioner either a large individual unit for a special environment, such as a kitchen or computer room, or a simple fan coil unit
Air House (pneumatic structure) – A balloon structure either air-supported or air-inflated. Air houses pay for themselves quickly when used for temporary shelter, because they can span large areas, are inexpensive and easy to transport, and allow fast erection or demounting. In case of fire the burn hole can provide both a means of escape and ventilation
Air lock – A bubble of air, trapped in a high point of a pipe, obstructing the flow of water, OR
Any device for preventing the flow of air, often merely a lobby with two doors far enough apart so that the first closes behind a person before a second is reached. Air lock doors should open in one direction.
Air Receiver, Air Vessel – A pressure vessel connected to a outlet from an air compressor for storage of compressed air until used. One may be connected to the delivery side of a pump to extract air from water.
Air Release Valve, Pet Cock – A small valve for bleeding air from pipework, a pump casing, pressure vessel etc.
Air right – The right of the owner of a low city building with fewer floors than allowed by the plot ratio to sell the space above for another building to be stacked on top. However, this may mean also allowing foundations and columns to be built under and through the property to provide support
Air Seasoned Tmber – Air dried timber
Air Set – Warehouse set.
Air Shaft – A light well.
Air Space – A cavity.
Air Supported Structure – A type of air house with a single membrane carried by low pressure air. The edges need anchorage from concrete beams in the ground or sandbags, and the entrance needs an air lock. (Picture shown below).

Air Terminal Unit – Equipment on the end of air conditioning ductwork to distribute supply air into a space or collect return air
Air Termination Network – The parts of lightning protection system on a roof. Flat roofs have roof conductors. Ridges or high points have a sharp tip to emit ions and neutralize the high static voltages which cause lightning strikes. Both lead any discharge that does occur to the down conductors.
Air test – A drain test using air pressure. The pipe run is blocked at the top and bottom with screw plugs, then air is pumped in until 100 mm of water gauge is shown on glass U-gauge. The test is satisfactory if the pressure does not drop below 75 mm within 5 minutes. Air tests are used for gravity pipes, e.g. the sanitary pipework above ground
Air treatment – Altering the air temperature and humidity, and removing dust and impurities with filters, to make it suitable to be used in an air conditioning system. In winter, air treatment involves normal heating, which may be shared with radiators in a split system and use of humidifiers. In summer or damp weather a chiller runs the cold coils and dehumidifiers are used.
Air valve – A valve for bleeding air from water pipe
Air vessel – An air receiver
Air void – A blowhole
Air Washer, Wet Air Filter – A chamber in which air is mixed with water, removing contaminants such as dust and gases. Suited to industrial exhausts, it is no longer used for air conditioning, supply air owing to costly maintenance and because it is a possible source of bacteria.
Air-blast Cleaning -The flushing of rubbish away from the work surface using a blow gun supplied with compressed air.
Air-entraining Agent – An admixture for concrete.
Airless Spraying – Painting by a spray gun by a miniature high-pressure pump forcing paint through a fine nozzle. With this method there is almost no spray mist and less overspray than with compressed-air spraying
Airtight Inspection Cover – A cast Iron plate over an Inspection chamber. Covers are removable, non ventilating and bolted down to a frame, which has a groove filled with grease. They may be required over a soil drain indoors and are made to resist flooding
Aisle – Subsidiary part of a church or other large building parallel to the main body of the building.

Alarm – An alarm system is an automatic communications installation to indicate fir, intruders etc. A fire alarm may be set off by a manual call point or an automatic fire detector and usually operates a warning bell.


Alarmed Door – A door with an alarm set off by built in detectors, which show when it is opened or forced.
Alburnum – Sapwood
Alkali – Resistant Glassfibre – Special glassfibre with upto 20% by weight of Zirconium dioxide, for glass reinforced concrete.
Alkali – Resistant Paint – Few Paints are alkali- resistant and there is a risk of failure if applied to young concrete or any product containing cement in the first year or two. Oil paints have little alkali resistance and suffer saponification, but emulsion paints can resist mild alkali attack. The main alkali resistant paints are cement paints, masonry paints, bitumens, epoxy paints
Alkali – Resistant Primer – A primer used under oil paint on concrete
Alkyd Paint – Durable exterior oil paint or varnish with varying percentage of alkyd resins, usually in gloss, which are easy to brush. They are fast drying and have good weather and abrasion resistance, as well as low permeability to water vapour. Since alkyd paint, widely used for site decoration of timbers, tend to become brittle with age, external joinery should be repainted every three or four years.
Alkyd Resin – A synthetic polymer resin made from an alcohol combined with an acid, used in alkyd paints.
All-Air, 100% Air – Air conditioning in which the sir is used only once, then rejected to outside.

All Glass Door – A frameless door with a leaf of solid toughened glass and patch fittings
All in Contract – A design built contract
All in Material – Aggregate with all sizes up to a stated maximum, but without accurate grading, mainly used for bedding drain pipes and to make non structural concrete.
Altar – An elevated place or structure, block or stone, or the like on which sacrifices were offered.
Alteration – A change from one occupancy to another, or a structural change, such as an addition to the area or height, or the removal of any wall, partition, column, beam, joist, floor, or other support, or a change to or closing of any required means of ingress or egress or a change to the fixtures or equipment.
Alternate Bay Construction – Ground slabs cast in two stages, often like the squares of a chequer board, to form contraction joints in the concrete.
Alternate Lengths Work – Underpinning under old foundations, placed in two stages so that support is continuously available. Each length (or stool) is about a metre long, with “odds” and “evens” excavated, concreted and pinned up separately.
Aluminium – A lightweight and fairly strong metal, normally used as an alloy, in form of castings, sheet or extrusions. Aluminium has good corrosion resistance unless in contact with dissimilar metals. It is soft and easily worked with woodworking or carbide tipped tools, or joined by welding
Aluminium Cable – Electrical cable with aluminium conductors. It is cheaper and lighter than copper cable, but because special electrical terminals are needed which do not crush soft aluminium, it is not used in house wiring.
Aluminium Foil – Aluminium sheet which is thinner than 150 microns, often only 20 microns.
Aluminium Paint – A finishing paint made by leafing aluminium powder or foil and blending with a suitable medium.

ECS 2003

Aluminium Primer – A wood priming paint noted for its high water resistance.
Aluminium Roofing – Durable Sheet roofing. The commonest is self supporting about 0.8mm thick, profiled (corrugated) for stiffness, and organic coated.
Aluminium Windows – External windows, mostly factory- made with gasket glazing.
Aluminium Zinc Coatings – Corrosion protective coatings for sheet steel roofing.Ambient Conditions – The quality of surrounding air, lightening and acoustics.
Ambient Counter – A survey at room temperature, not heated or chilled.
Ambulatory – Internal extension to a circular or semicircular building, often forms the east end of a Cathedral.
Amendment – A revision or modification to a contract document made to correct an error or to show a variation in the works.
Amphitheatre – An oval or circular edifice having rows of seats, one behind and above another round an open space, called the arena, in which public spectacles are exhibited.
Analogue Detector – A fire Detector which gives electronic signals to represent what it senses, e.g. a data code. The central computer decides if there is a fire.
Anchor – A primary fixing permanently built into a structure, to hold components, either directly or through secondary fixings. Anchor types include expansion bolts and resin anchors and/or
A secondary fixing made from a short length of angle, or from a steel plate, such as L-shaped clip or metal cleat. Anchors have bolt holes for connections to the primary fixing and the component to be secured.
Anchor Plate – A steel floor paving, about 305 x 305 mm and 2-3 mm thick, with downward projecting lugs or cross flanges. It is fully bedded in mortar 40 mm thick and is used for very traffic and impact loads
Anchorage – A system for securing a component against a force, such as the uplift from a pressurized air house or the tension in a tendon for prestressed concrete
Angiosperms – A large group of flowering plants that includes deciduous trees, therefore all hardwoods, but not pine trees.
Angle – A change in direction or space between two lines or surfaces such as internal or external angles.
Angle Bead, Plaster – A thin line of metal trim for protection of the outer arris of a plaster corner against knocks. Large holes in the metal provide bond and are used for nailing. They are plastered over, using bead edge.
Angle Block – A small wood block, usually shaped like a right angle triangle, glued and screwed into an angle as a stiffener
Angle Brace – A bar fixed across a angle in a frame to stiffen it
Angle Cleat – An L-Shaped anchor to hold purlins to a roof truss
Angle Closer – A brick cut specially to complete, i.e. close, the bond at the corner of a wall
Angle Fillet – A triangular strip or moulding in the corner between two surfaces, often in cement or asphalt. It makes two sharp 45 degree angles
Angle Float – A plasterer’s tool for shaping an internal corner
Angle Grinder – A power tool with a right angle drive, used with rigid abrasive discs, for the hand grinding and cutting of metal or masonry, for which different abrasive wheels are available.
Angle Gauge – A template made for setting out or checking angles
Angle Joint – A carpentry joint at a corner, not a lengthening joint.
Angle Rafter – A hip rafter

Angle rafter

Angle Section – A steel angle

Angle Staff – An angle bead
Angle Tie – An angle brace
Angle Trowel – A plasterer’s trowel, either with upturned edges for working internal angles, or vee shaped for working external angles.
Angle Valve – A screwdown valve with it’s outlet at a right angle to the pipeline
Angled Tee – A pipe fitting, such as a junction, with the inlet leg at a shallow angle, used at drain connections
Anhydrous – Containing no water, usually from heat e.g. Quicklime
Animal Black Paint – Pigment made by heating animal products, such as bone.
Annealed Glass – Ordinary sheet glass that has not been toughened
Annealing – Softening a metal or glass by heating and slow cooling
Annual Ring – One ring of springwood and summerwood added to a growing tree each year.
Annunciator -An indicator panel
Annular – Shaped like a ring
Anodizing – A hard and attractive coating to aluminium. It is used on self finished items such as windows
Anti-climb Paint – Paint that stays soft and slippery, applied above normal reaching height to drain pipes on the outside of walls
Anti-condensation Paint – A coating containing cork dust or vermiculite, put on pipes as insulation and to absorb moisture. It has little effect on really heavy condensation, which needs lagging as well as a vapour barrier and good ventilation.
Anti-corrosive Paints – Paints which contain inhibiting pigments to delay corrosion of metal surfaces. Metal Primer for steel is anti-corrosive, but needs to be sealed by the later coats of the complete paint system.
Anti-dust Product – A dust Proofer
Anti-frost Agent – A frost proofing admixture, or a cold-weather concreting aid
Anti-graffiti Treatment – A textured finish with enough small stones to discourage markings with felt pens, lipstick etc.
Anti-siphon Trap – A waste trap which resists unsealing, usually by having a deep seal of water in it, achieved by having a lower dip. In the single stack system of internal pipework these traps may save the expense of branch vent
Anti-siphonage Pipe – A branch vent
Anti-slip Paint – A paint containing hard sand, cork dust or similar material used for finishing wood floors or decks
Antistatic Flooring – An electrically conducting floor finish, such as flexible PVC or carpet, that can earth static, used in computer rooms and operating theatres.
Anti-Sun Glass – Solar control glazing
Anti-Theft Glass – Security glazing that delays access through a window for a short time, such as 10 mm thick laminated glass. This type of glass is not bullet resistant.
Anti-vibration Mounting – A flexible pad (often rubber) for mechanical equipment to prevent transmission of equipment noise to the fabric of the building.
Apartment – A flat or a similar dwelling
Appliance Ventilation Duct – A ducted Flue
Applicator – A tool used for placing adhesive, plasters etc, and/or Somebody trained to place special coating, sealing etc.


Appraisal – The examination and testing of building materials or processes and the assessment of their suitability for a particular use, often as a step towards approval.
Apprentice – A young person who agrees to work under a skilled master on a small pay for a given number of years in order to learn a craft
Apprenticeship – The time served by an apprentice, according to a written agreement called the indenture
Approval – Approval to build, alter or demolish that is obtained from the local development authority.
Approximate Quantities – Preliminary bills of quantities used where the extent of the work is difficult to measure.
Appurtenant Works – All labour and materials required for the satisfactory completion of a job, which are included even if not described in detail in an item
Apron – A horizontal or vertical panel, e.g. the inside wall behind a window spandrel, a fascia, or a flat in front of a dormer.
Apron Flashing – A one piece L-shaped flashing usually on the lower side of a chimney
Apron Lining – Joinery casing over the vertical face of a stair well
Apse – Semicircular recessed end to a church sanctuary or chapel and/or
An arched recess, especially at the east end of the choir of the church.
Arbitration – When a dispute over a building contract has reached deadlock, both parties may agree to its settlement by an arbitrator named in the condition of contract. Arbitrators may call expert witnesses, but evidence is not taken under oath
Arcade – A walk arched over: a covered passageway lined with slopes on both sides and/or,
Corridor of arches on piers or columns.
Arch – A curved structure so built that the stones or other component parts support each other by mutual pressure and can sustain a load, of the foot, the part from head to toes of the body structure, normally having an upward curve.
Arch Bar – A flat steel bar or an angle to carry the bricks of a window arch.
Archeology – A knowledge of ancient art, customs, the science that studies the extinct relics of ancient times.
Architect – One who designs designs buildings and supervises their erection.
Architectural Concrete – Concrete with a textured surface, either direct finish or the result of surface treatment after forms are stripped.
Architectural Drawings – Contract documents prepared by the architect, showing the layout and details of the work of the new building.
Architectural Metalworks – Decorative or ornamental metalwork, such as gates, railings, staircases, balustrades, screens and ducts
Architectural Sections – Drawn, extruded or folded shapes made of aluminium or stainless steel, used as decorative trim around the outside of windows, the porches of industrial or commercial buildings.
Architrave – Lowest of the three main parts of an entablature. Also, the moulded frame around a door or window. Collective name for the jambs, lintels and other parts surrounding the door or window, or,
Joinery trim which is planted to cover the small gap between a door frame (or jamb lining) and the wall finishing. It has mitred joints and may be fixed with nails or architrave adhesive.


Architrave Bead – Metal trim used as a stop bead for plaster, fixed to the wall beside a door and a window opening and covered by the architrave
Architrave Block – A block at the foot of a door architrave against which the skirting board also fits
Architrave Trunking – A hollow architrave to carry wiring in skirting trunking across a door opening
Archway – An arched or vaulted passage.
Arena – Part of the ancient amphitheatre strewed with sand and used for the combats of gladiators and wild beasts.
Arena Stage – A stage which can have the audience all around it.
Architecture – Art and science of building.
Arm – The outreach arm of a lighting column or a bracket for caring light fittings and/or
The dipper arm of a backhoe or similar excavator.
Armour Mechanical – Protection such as steel steeling on a fire door
Armoured Cable – An electrical cable with stainless steel strip or galvanized wire wound over the conductors and insulation, often with an outer plastics sheath (or serving) for main distribution supply and buried feeders.
Array – A repetitive series of similar components
Arris – The edge at a corner or angle, particularly of finishing such as joinery or plasterwork. A sharp arris in hardwood can cut a person’s skin and its prone to damage, as is any paint applied over it, which becomes thin from surface tension. Arrises are unusually eased or penciled rounded.
Arris Gutter – A V shaped wooden Yankee Gutter
Arris-wise, Arris-ways – Diagonal with reference to laying bricks, slates or tiles or sawing timber
Arrow Diagram – A programme on which activities are represented by arrows, joined to show their sequence and logical relationships, usually worked out by the critical path method. The length of each arrow could be time scaled to show activity duration, with the head and the tail of each arrow being at an event. Arrow Diagrams are used on site for detailed planning or as a basis for simpler bar charts.
Art – Human skill as opposed to natural agency, skill, knack acquired by study and practice, taste and skill; artistry.
Articulation – A hinge or pin joint in a framework to allow angular movement, instead of continuity or, An event on an arrow diagram where several activities meet
Artificial – Synthetic fibres and reconstituted materials (e.g. Marble) and/or
Of finishing, an imitation of an expensive material using a cheap one
Artificial Ageing – Accelerated weathering
Artificial Aggregate– Nearly all light weight aggregates except pumice, but sometimes also blast furnace slag and clinker
Artificial Stone – Cast Stone
As drawn wire – Steel Wire that has been hardened by being drawn through a die, without further treatment. It is used for reinforcement fabric
As dug aggregate – Quarry material that has not been crushed or screened, but loaded directly for delivery
Asbestos – A mineral crystal consisting of thin, tough fibre like textile, which can withstand high temperatures when pure.
Asbestos Encapsulation – In place treatment of sprayed asbestos with a durable and impact resistant coating to seal in the asbestos fibres, used in cases where asbestos removal is impractical.
Asbestos free Boards – Building Boards with fibre reinforcement and a binder such as calcium silicate or cement
Asbestos Removal – Specialist work for removing asbestos placed in buildings.
As-built Drawings – A record Drawing made by the builder after works have been completed and showing the effects of all drawing revisions
Ashlar – Walls or facings of stonework laid in courses of evenly dressed stone with thin joints about 3mm thick, which should be raked out 20mm and pointed during cleaning down.
Ashlering – A low wall usually about 1 Mt high, in the side of an attic, from the floor to part way up the sloping ceiling, often in blockwork
Asphalt – A mixture of bitumen and sand, clay or other inert mineral filler, such as limestone. It is hard at normal temperatures, but flows stiffly when heated
Asphalt Mixer – A machine for heating and mixing asphalt before laying
Asphalt Roofing – Membrane roofing made with two or three coats of asphalt work, sometimes taken to include bitumen-felt roofing
Asphalt work – A specialist trade that uses mastic asphalt for tanking, asphalt roofing and waterproofing
Assembly – Putting together several components or elements or the resulting set or unit
Assembly gluing – Constructional gluing on site, particularly of timber work or joinery units that were factory fabricated by primary gluing
Astragal – A small semicircular moulding or bead encircling a column.and/or
A glazing Bar, especially overhead, and/or
A strip of timber or metal fixed to the edge of a door leaf to cover the gap between it and the door frame and to improve security or reduce noise and draughts
Atomisation – A very fine pulverization of a liquid, as in spray painting or a boiler rotary cup burner
Atrium – A tall internal courtyard with a glazed roof that lets in daylight, often used in multistory hotels with balcony access.
Attached Column – A structural column partly projecting from a wall, as does a pilaster. It is therefore partly engaged
Attendance – Plant and equipment provided by the main contractor, or builder’s work in connection done for other trades working on site, usually sub contractors. It can be general attendance or special attendance
Attenuation – A reduction in sound level during transmission from one place to another, often through a wall or duct work
Attenuator – A silencing unit in air conditioning ductwork to reduce transfer of equipment noise, mainly from fans into a occupied space or to an exterior
Attic – A low storey above the cornice that terminates the main part of an elevation, a room in the roof of a house.


Auger – A carpenter’s tool used for boring holes in wood.
Autoclave – A pressure vessel for treatment using steam at high temperature and pressure e.g. for curing calcium silicate bricks or aerated concrete
Automatic Sprinkler System – An arrangement of piping and sprinklers, designed to operate automatically by the heat of fire and to discharge water upon that fire and which might also simultaneously give audible alarm.
Auto-suppression system – An automatic fire extinguishing system which is activated by fire detectors
Avenue – The main approach to a country house usually bordered by trees, a double row of trees, a street, means of access or attainment.
Awl – A small tool with a plain pointed steel shaft and a straight handle, mainly used as a scriber for marking hard surfaces
Awning – An external blind of fabric, such as canvas, that can be put up for protection against sun or rain
Axonometric Projection – Geometrical drawing
in three dimensions.
Axe – A bricklayer’s hammer
Axed Work – A bush hammered finish
Axminster Carpet – Patterned carpet with cut wool pile woven into the backing

This Dictionary is an invaluable guide for anyone interested in Architectural / Construction Activity. Click on the alphabets given below, for the word you are looking for.


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