Glossary of Building Terms

An A to Z of building terms & acronyms


AAV – Air admittance valve (automatic air vent). This is a device that allows air to escape from high points in a heating system
Abutment – Joint between two surfaces. Commonly used in roofing terminology to describe the likes of the joint between a roof and a wall.
Acrows – Temporary structural supports used primarily in refurbishment work
Architrave – Timber moulding fixed around outer edge of door frame
Acoustic Efficient – A technical term for materials that have soundproofing qualities
Actual – The actual size of a member, as opposed to a normal one
Adhesive – A substance that joins surfaces, objects or materials together, e.g. wood glue
Architrave – Decorative moulding used around a wall recess or opening, such as a doorway
Asbestos – Mineral composed of thin, flexible fibres, commonly found in and on older properties, which is very hazardous to your health
Attic – The room directly under the roof



Balance Flue – A duct on a gas appliance that allows both fresh combustion air in and products oif combustion out
Ballast – Sand and stones for mixing with cement and water to form concrete
Balloon Framing – Traditional method of timber-frame house construction where single vertical members stretch from ground level up to the height of the eaves
Baluster – Vertical member of a balustrade that fits beneath the handrail, offering support
Balustrade – Collective term for the handrail, balusters and baserail of a staircase
Barge Board – Fascia covering to the apex of a roof
Bat – A brick or block cut across its shortest dimension – a quarter of a brick is a quarter bat. Used to create a particular type of bond. Also the name of rigid sections of insulation materials.
Batten – Thin, square-edged timber
Bead – Decorative moulding designed to cover a join
Bearer – Supportive member, e.g. beams are the bearers that support a raised wooden deck
Benching – Sloping concrete at the base of a manhole
Bespoke – Handcrafted work that is made to measure
Birdsmouth – A section of the base of a rafter that is cut out in order so that it can fit or connect with the wall plate on an exterior wall
Bitumen – Tar-like compound commonly used as an adhesive for flat felted roofs
Blinding – A covering, usually sand, over hardcore to prevent sharp stones penetrating a damp proof membrane
Block Paving – Man-made concrete blocks of various sizes, colours and shapes commonly used for driveways, paths and patios
Block Work – Blocks laid to form the main structure of the house, usually used for the inner skin and internal walls
Bonding – The overlapping of successive courses of bricks or blocks producing a regular pattern without vertical joints from one course to the next
Bracing – Timber or metal braces usually fixed at angles to provide rigidity to the structure to which it is fixed
Bracket – Projecting supportive fixture or fitting
Building Regulations – Local authority guidelines on how to build and maintain a property safely. The regulations also include environmental standards to ensure new properties are built with good insulation and energy-efficient windows, lofts, etc
Butt – To join pieces together forming a butt-join or joint
Butter – Technique of applying mortar to the end of a brick or block before positioning it



C25 Concrete – Concrete produced to a specific design requirement, e.g. C25 is used in foundations
Capping Stone – Stone laid on the top if a wall to protect the wall from weather. Normally edges are flush with the wall, and do not overhang
Caulk – Flexible filler used for filling cracks and joints when decorating
Cavity – The gap between the inner and outer leaf of a cavity wall
Cavity Closers – Commonly a plastic insulated barrier placed between the inner and outer skin of brick and block work prior to installation of windows
Cavity Trays – A membrane laid over lintels and between the inner and outer skin of block work to deflect moisture through the weep holes
Cavity Wall – Two walls forming the structure of a building usually with a cavity space of approximately 75mm, filled with insulating material
Celcon Lightweight Blocks – Proprietary brand of lightweight block
Cement – Adhesive that is also used to bind other materials (aggregate) to make concrete. Dries to a very hard finish  
Chipboard Interlocking Blocks – Commonly used as floorboards within domestic properties
Chopsaw – Specialised saw used in construction for cutting timber
Cistern – The part of a toilet that contains the water needed for flushing
Cladding – Thin covering of overlay, e.g. of stone on a building or metal on a metal core
Combi-boiler – Combination boiler providing both heating and instantaneous domestic hot water
Compact Dumper – Motorised vehicle used for transporting earth on building sites
Compressor – Mechanical or electrical device used to produce compressed air for the operation of pneumatic tools
Concrete – A mixture of sand, stones (course aggregate) and cement
Consolidated Hardcore – Compacted rubble used as a sub-base
Consumer Unit – Main electricity intake box with fuses or circuit breakers and a main switch
Contingency – The amount set aside as a percentage of total cost of the job, to allow for unseen work, such as a structural repairs that could not be anticipated when first planning work
Coping Stone – Stone laid on top of a wall to protect the wall from the elements. The edges normally overhang the wall slightly
Cornice – Decorative moulding used at the abutment of ceilings and walls
Counterbatten – Double layer of battens, secured at right angles to each other. Commonly used in roofing or timber-frame wall structure to provide a cavity for ventilation and/or water runoff
Countersunk – To recess the head of a fixing (normally a screw) to below surface level
Course – A row of building components, such as bricks
Cutting in – Term used for painting a precise line at a junction or joint between two surfaces
Coving – Decorative moulding used at the junction between ceiling and walls



Dabs – Blobs of mortar or adhesive, e.g. to fix lining boards to masonry
Dado – Lower area of a wall surface
Dado Rail – Rail that divides the dado and the upper wall. Commonly positioned 1m from floor level
Damp-proof Course (DPC) – Membrane laid between brickwork courses at ground-floor level, usually 150mm above external ground level, to prevent rising damp
Deep-proof Membrane (DPM) – Sheet of impervious material positioned under floors to prevent moisture rising into the house structure. Edges can be built into surrounding walls to act as a DPC
Data Cabling – Cabling used for TV, computer, telephones, alarms, etc.
Decking – Decorative garden structure commonly made of wood
Door Liners – Timber frame fixed into a structural door opening onto which the door is hung
Dormer Window – A window set vertically in a structure projecting through a sloping roof
Double Side Tooth Plate Connector – Structural component used to prevent two timbers from moving
Dowel – Small peg, normally wooden, partially inserted into two adjacent surfaces strengthening the joint. Also a thin strip of wood that is round in cross section
Drip Groove – Small channel in the underside of sills, thresholds, and other exterior projections, that prevents water running back to the wall surface by making it drip down to the ground
Drainage Gulley – Pre-formed clay or plastic unit into which surface water or waste water flows
Dry Lining – Plasterboard used to line walls instead of plaster or render
Dry Rot – Caused by a fungal growth that thrives in damp conditions. It can cause considerable damage to timber areas, which will need replacing
Dry Vent Ridge System – System used within roofing to ventilate roof space (loft)



Eaves – The lower border of a roof that overhangs the wall
Edge Cutter – Type of a bit used with a router to create decorative profiles along the edge of a board
Electrical Breaker – Miniature circuit breaker that opens in the event of excessive current, which has to be manually closed when the overloading problem has been investigated and repaired
Elevation Drawings – A representation of the front, back or side of a building
Elasomeric Sheeting – A cover for a roof that expands and contracts under the sun without cracking or distorting
Estimate – A verbal or written assessment of how much a job will cost. The amount can go up or down if the job changes in any way
Expansion Vessel – A small tank that allows water from a heating system to enter and leave as the water expands on heating and contracts on cooling



Faceplates – Word commonly used to describe light switches, sockets, etc.
Fascia – A flat, horizontal piece of stone or board protecting the eaves
Female – The joining part of a fitting that the male part fits into. A male thread screws into a female thread
First-fix – The early stages of a construction job, e.g. first fix carpentry includes erecting studs and fixing rafters, first fix plumbing or electrical work involves routing the pipes or cables to where fixtures or fittings will be placed
Flashing – A waterproof sheet found between the roof and a wall, designed to stop water entering a property. The flashing is generally made of lead
Flaunching – Sloping mortar, usually surrounding a chimney pot, to direct rainwater from brickwork
Float – Type of trowel with a rectangular blade used for finishing a render or plaster coat
Floor Joists – Structural timbers spanning from wall to wall onto which the floorboards are fixed
Flush – Level with an adjacent surface
Footings – Commonly used to refer to foundations. It is the base of a structural wall
Foundation – The base on which to build or support a structure
Frog – The wedge-shaped depression in the surface of a brick


Gasket – Shaped piece of sealing material that prevents liquid or gas leaking from joining surfaces
Gluelam – Laminated sections of timber used to create structural elements such as beams and lintels
Go Off – The gradual process by which an adhesive or wet substance dries to a hard finish, a substance that has “gone off” is not yet fully dried
Going – The tread on a staircase
Grinder – Electrical tool generally used for cutting blocks, steel and forming slots for cabling
Grout – The substance used to fill between tiles to finish the look and prevent water getting to the adhesive and wall



Hand/Handed – When a fixture or fitting is designed to work in one direction by rotating one way, or opening from one edge, e.g. it is possible to buy handed ceramic-disk valves for taps, and handed rising butt-hinges for doors
Hardcore – Broken bricks and rubble laid under a concrete foundation
Header – End of a brick
Header Tank – An open water tank that feeds water into a central heating system
Hip – Outside sloping joint where two angles of a pitched roof meet
Hydraulic Working Platform – Mechanised platform for working at heights


Indirect Hot Water Cylinder – A vessel usually made of copper that allows water for the hot taps to be heated by water from the heating system. The heating water passes through a coil in the cylinder so it does not mix with the water that goes to the taps.
Intumescent Mastic – A filter that expands when in contact with heat so preventing the spread of smoke and retarding the spread of fire



Jigsaw – Electrical tool used for cutting out shapes
Joist (Rafter) – Timber used for the construction of roof or floor


Kango – Electrical tool used for breaking up concrete or hard surfaces



Lath – Thin, wooden strip nailed to studs or joists used in old buildings to create a framework for the application of lime plaster. Also a small sheet of plasterboard
Laying Off – Technique of using a tool such as a paintbrush to lightly skim a surface, creating a flat, even finish
Lighting Circuit – The electrical circuit that connects the light fittings and switches around the house
Lintel – A horizontal architectural member spanning and usually carrying the load
Load-bearing Wall – A support structural wall
Low-e Glass – Low emissivity glass, i.e. coated glass with improved thermal performance.  



M12 Bolt – A specific diameter of a bolt, i.e. M12 – 12mm
Making Good – Putting right any flaws or problems with a finish after a job
Male – The joining part of a fitting that inserts into the female side, e.g. a male screw thread fits into a female thread
Mastic Sealant – A sealant which provides a waterproof joint, e.g. window frame and a wall
MCCB – Moulded case circuit breaker. Modern replacement for a fuseholder in a Consumer Unit which breaks the circuit on detection of overload but can be manually reset
MDF – Medium density fibreboard. A dense board resistant to warping and capable of being intricately shaped, used in joinery and furniture making
Member – Structural element or section of a building
Membrane (Breathable) – e.g. roofing felt which allows air flow out of the roof structure but will not allow water to penetrate it
Membrane (Polythene) – e.g.  a membrane laid over the entire area of an extension to prevent moisture from rising
Metre Head Position – The point at which electrical cabling enters the property
Microporous – Waterproof yet allowing moisture vapour to be released (breathable)
Mineral Wool Insulation – Material used to meet the insulation qualities required for building control compliance
Mitre – A joint using angled cuts. Most mitres consist of two members with ends cut at 45 degrees so they form a right-angled joint
Mortar – Mix of sand, cement and sometimes additives to bond brickwork or coat internal brickwork before the application of finishing plaster
Mortar Joint – The cement joint between the horizontal and vertical joints of brick or block work
Mortise – Rectangular cavity in wooden joints or in security devices such as locks or latches
Much Away Lorry – Vehicle used for removing large quantities of excess earth, debris, etc.
Mullion – Vertical dividing section to windows



Newel – Post at the start and end of a staircase, used to provide structure for the banister and spindles
Newel Post Cap – Decorative cap used on the principle post supporting either end of a staircase handrail
Noggin – A horizontal timber, e.g. to affix a radiator onto a timber wall
Nominal – A size of a member that may not be completely accurate in terms of measurement, but is informative in terms of estimation for building purposes. The nominal size of a brick, e.g. includes mortar on the short and long side to make estimation of quantity requirement easier. The nominal size of timber cross-section may not be its actual size because it has dried out or been planed down from its actual size
Nosing – Front edge of a staircase thread



Offering Up – Holding a fitting or material in place to check for appropriate fixing points, level positioning, or aesthetic appeal
Olive – Metallic ring used to create a watertight seal in a compression joint between pipes
Opaque – Describes a surface or substance through which light cannot pass
Outerskin – The brickwork that forms the outer surface of a cavity wall structure
Outriggers – Part of a tower scaffold to provide stability



Packing – Material, often wooden wedges or slivers) used to fill in a gap during construction or to wedge a member or fitting into position, normally so that it is level or securely fixed
Padstone – Dense material used to transfer the load of a beam to surround masonry
Parapet – Top of a wall where it rises above roof level
Partition Wall – A wall divided by two rooms
Party Wall – A common wall that is shared between neighbours, such as the wall that divides semidetached houses
PAT Test – Portable Appliance Test (for electrical tools and equipment)
Pendant Light Fitting – One that hangs from the ceiling
Percussion Drill – An electrical device for drilling into hard surfaces such as concrete and brick
Pier – A supportive pillar common in garden-wall construction
Pilot Hole – A guide hole made for fixing (normally a screw)
Plant – Term commonly used to describe machinery, e.g. dumpers, diggers, forklift trucks, concrete mixers
Plasterboard – Board with a plaster core used as a substitute for plaster on the interior walls, onto which plaster is usually added
Platform Frame – Timber-frame house construction where panelled timber frames are erected in storeys. Each floor forms the base for the next storey
Plug/Wall Plug – A plastic or metal sleeve used in the masonry or cavity walls to provide a secure insertion point and housing for a fixing
Plumb – Exactly vertical
Pneumatic Drill/Breaker – Compressed-air operated tool for breaking up surfaces such as thick concrete
Pointing – Mortar or cement used to fill joints in brickwork
Point Loading – The transfer of weight down to a specific point
Polypropylene – Any of various plastics or fibres that are polymers of propylene
Practical Completion – The point at which a project is virtually complete
Pricework – Work that is carried out at an agreed overall cost, or on a rate per square metre. It is also known as a ‘quote’.
Profile Board - A batten nailed to two wooden stakes, with nails positioned along its top edge to indicate foundation and/or wall width. String is attached between the nails of opposing boards to provide guide lines for foundation and wall width
Prop – Adjustable, heavyweight pole used to support the weight of structures during construction
PTFE Tape - Tape used on the male threaded plumbing joints to create a watertight seal. Polytetrafluoroethylene may also be supplied as a paste
Purlin – Horizontal roof member that supports the rafters
PVA – Polyvinyl acetate, a synthetic resin used as an adhesive in its neat form, or, when diluted with water, as a sealer for porous surfaces
PVC-u – Polyvinyl chloride unplasticised, commonly used in the manufacture of windows, doors and other building materials



Racking/Racking Back – Building up the corners first when constructing a brick or block wall
Radon – radioactive gas
Raft Foundation – Where a reinforced concrete floor slab is integrated with a reinforced shallow foundation strip and ‘floats’ on the subsoil
Rafter – Sloping timber members that carry the covering of a pitched roof
Rebate – A groove or step cut into the edge of a piece of wood
Reducer – A connection that joins pipes of different diameters
Reinforcement Mesh – Steel mesh used to reinforce concrete
Render – A sand and cement mix used as a base coat under plaster internally instead of plasterboard. It can also be used externally.
Repointing – Replacing the mortar between bricks on a wall
Retaining Wall – A wall used to hold back earth
Retention – Money held back until a job is completed
Reveal – Sides of a door or window opening
Ridge – The apex of a pitched roof.  A ridge board is a horizontal timber member that runs the length of the roof to which the rafters are connected at either side
Ring Main – The electric circuit that connects plug sockets to each other
Riser – The vertical pieces between the treads on a staircase
Rising Main – Cold water main, it usually rises to the roof space to feed cold water tanks
Roof Trusses – Timber frames designed and manufactured from plan to form the shape of the roof
RSJ – ‘Rolled Steel Joint’, this is a large beam used to support the ceiling or roof across an open span


Sand Blinding – A layer of sand applied to hardcore on which polythene membrane is laid
Sarking – Sheathing boards fixed to rafters before felt and battens, although the term is sometimes used to refer to the felt layer alone
Screed – A mixture of sand and cement applied to a floor to give it a level surface
Scribing – Method of creating a cutting guide line on a material so that it will perfectly fit against a surface. A pointed wooden offcut is used with a pencil to trace a guide line that matches the profile of the surface
Sealant – Flexible substance used to create a waterproof seal along a junction, or a liquid painted onto a surface to seal it
Second Fix – The final stages of construction, e.g. a carpenter fitting skirting boards, a plumber fitting radiators, or an electrician fitting switches and sockets
Semi-Engineering Bricks – Non-porous brick used for foundations, drains and other wet or damp conditions below ground. It is also used in structural brickwork for its strength.
Septic Tank – A tank in which the solid matter of continuously flowing sewerage is disintegrated by bacteria
Sheathing – Boards used on a roof before felt, battens and tiles. Also the boards fixed to timber-frame walls in timber-frame house construction
Skim – a thin decorative coat of plaster applied to ceilings and walls before decorating
Skip – A large open container of waste and rubble
Skirting – A board, often with decorative moulding, that is fixed along the base of an interior wall
Snagging – Items of work requiring remedial work or completion prior to final acceptance of the work as being complete
Soffit – The underside of an overhanging part of a building, staircase, arch, etc.
Soil Stack – A 10cm diameter pipe that carries plumbing waste to the sewerage system
Soldier Course – A row of bricks standing vertically
Solvent – The base of a substance. Water is the solvent for emulsion paint. The solvent of a substance is also used as a cleaning agent
Spreader Boards – Boards used to distribute load
Square – Describes the position of an object that is exactly aligned so that is level, vertical, parallel, or at right angles to a surface
Strapping – Commonly used to secure roof structures and timber to brickwork
Stretcher – The long side of a brick
String – Sloping edge of a staircase
Stud – Wooden (or metal) member used in the construction of walls  
Stud Wall – An internal, non-supporting wall made from wood battens and covered with plasterboard
Subfloor – Floor material below decorative flooring, e.g. plywood sheets below ceramic floor tiles
Subsidence – Movement of the ground below or around a building that can lead to foundation and structural damage
Support Props – Temporary supports used during construction work (e.g. excavations and refurbishment)
SVP – Soil vent pipe. Same as a waste stack. Vertical pipe that takes the likes of waste water from plumbing apparatus to the drain


Tank – Technique of creating a waterproof layer or layers on a wall or floor to prevent the ingress of damp
Telescopic Air Vents – Vents inserted into the brick and block work to form an airflow beneath ground floors
Timber Studs – Upright timber framework onto which plasterboard is usually fixed
Tolerance – An allowable variation from a standard dimension
Topcoat – Final coat of a material, e.g. plaster or gloss paint
Tower Sections – Part of a lightweight access scaffold
Translucent – Allowing a proportion of light to pass through. Transparent materials allow all light through
Transome – Horizontal dividing section to windows
Trap – The curved section of pipe (sometimes chrome) found under plumbed items such as basins and toilets. It holds a small amount of water to prevent odours returning to the room. You can remove it to find items dropped down the plughole
Trickle Vent – A ventilation unit commonly found in modern windows
Trip Switch – Mechanism which cuts off the flow of electricity in the event of over-loading


Undercoat – Preparatory coat for topcoats
Underpinning – Building or adding strength to existing foundations of a building, normally to counteract subsidence
Universal Beam – ‘l’ shaped beam often called an RSJ
UPVC – Unplasticised Polyvinyl Chloride, a synthetic compound, i.e. plastic



Vermiculite – Granular material used as loose-fill loft insulation. Also mixed with cement to make lightweight concrete with fireproof qualities, commonly used as backfill behind the fireback in a fireplace



Wainscoting – The use of wooden panelling at dado level
Wall Plate – A plate fixed to the top of a wall which secures roof trusses
Wall Tie – A manufactured metal component used to tie the inner and outer skin of brickwork
Weathered Struck Mortar Joint – A type of pointing
Weep Holes – Holes left in the vertical joints of brickwork to allow moisture to escape

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