Do you know your Ashlar from your Asphalt?
Do you know the difference between a Cesspool and a Septic Tank?
What about; Benching, Flashing, Flaunching, or, Haunching?
Whether you’re buying a property and requiring a surveyor’s report, or you’re planning on extending your home and needing to get quotes from builders, it is important to familiarise yourself with some of the terminology you may come across.
So, to make things easier and a little less daunting, at John O’Connell Building Solutions, we have produced a ‘Glossary’ of terms commonly used within the construction industry across the UK.
Aggregate: Pebbles, shingle, gravel, etc. used in the manufacture of concrete, and in the construction of soakaways.
Airbrick: Perforated brick used for ventilation, especially to floor voids (beneath timber floors) and roof spaces.
Architrave: Joinery moulding around window or doorway.
Asbestos: Fibrous mineral historically for insulation. Can be a health hazard. Specialist advice should be sought immediately if asbestos (especially blue asbestos) is found.
Asbestos Cement: Cement with 10-15% asbestos fibre as reinforcement. Fragile and will not bear heavy weights. Hazardous fibres may be released if cut or drilled.
Ashlar: Finely dressed natural stone – the best grade of masonry.
Asphalt: Black, tar-like substance, strongly adhesive and impervious to moisture. Used on flat roofs and floors.
Barge Board: (See Verge Board)
Balanced Flue: Common metal device normally serving gas appliances which allows air to be drawn to the appliance whilst also allowing fumes to escape.
Beetle Infestation: (See also Woodworm) Larvae of various species of beetle which tunnel into timber causing damage. Specialist treatment normally required. Can also affect furniture.
Benching: Smoothly contoured concrete slope beside drainage channel within an inspection chamber. Also known as Haunching.
Bitumen: Black, sticky substance, related to Asphalt. Used in sealants, mineral felts and damp-proof courses.
Breeze Block: Originally made from cinders (‘breeze’), the term now commonly used to refer to various types of concrete and cement building blocks.
Carbonation: A natural process affecting the outer layer of concrete. Metal reinforcement within that layer is liable to early corrosion, with consequent fracturing of the concrete.
Cavity Wall: Standard modern method of building external walls of houses comprising two leaves of brick or blockwork separated by a gap (‘cavity’) of about 50mm (2 inches).
Cavity Wall Insulation: Filling of wall cavities by one of various forms of insulation material: Beads: Polystyrene beads pumped into the cavities. Will easily fall out if the wall is broken open for any reason. Foam: Urea formaldehyde form, mixed on site, and pumped into the cavities where it sets. Can lead to problems of dampness and make replacement of wall-ties more difficult. Rockwool: Inert mineral fibre pumped into the cavity.
Cavity Wall Tie: Metal device bedded into the inner and outer leaves of cavity walls to strengthen the wall. Failure by corrosion can result in the wall becoming unstable specialist replacement ties are then required.
Cesspool: A simple method of drain comprising a holding tank that needs frequent emptying. Not to be confused with Septic Tank.
Chipboard: Also referred to as ‘particle board’. Chips of wood compressed and glued into sheet form. Cheap method of decking to flat roofs, floors and furniture, especially kitchen units.
Collar: Horizontal timber member intended to restrain opposing roof slopes. Absence, removal or weakening can lead to roof spread.
Combination (Combi) Boiler: Modern form of gas boiler which activates on demand. With this form of boiler there is no need for water storage tanks, hot water cylinders, etc. and generally the pressure is much better for showers.
Condensation: Occurs when warm moist air meets a cold surface. The water in the air then either settles as water droplets on the surface (as it does on windows for example), or, if the surface is absorbent, it soaks into the surface. In the latter case condensation is often unnoticed until mould appears. (See also Ventilation)
Conversion: Can be defined as a change in function or change in use, such as converting an office block and making it suitable for residential use.
Coping/Coping Stone: Usually stone or concrete, laid on top of a wall as a decorative finish and to stop rainwater soaking into the wall.
Corbell: Projection of stone, brick, timber or metal jutting out from a wall to support a weight.
Cornice: Ornamental moulded projection around the top of a building or around the wall of a room just below the ceiling.
Coving: Curved junction between wall and ceiling.
Dado Rail: Wooden moulding fixed horizontally to a wall, about 1 metre above the floor, originally intended to protect the wall against damage by chair-backs, but now very much a decorative feature.
Damp Proof Course (DPC): Course layer of impervious material (mineral felt, PVC, etc.) incorporated into a wall to prevent dampness rising up the wall or lateral dampness around windows, doors, etc. Various proprietary methods are available for damp proofing existing walls including ‘electro-osmosis’ and chemical injection.
Deathwatch Beetle: Serious insect pest in structural timbers, usually affects old hardwoods with fungal decay already present.
Double Glazing: A method of thermal insulation usually either – Sealed unit: Two panes of glass fixed and hermetically sealed together; or Secondary: In effect a second ‘window’ placed inside the original window.
Downpipes: Drainage pipes from guttering.
Dry Rot: A fungus that attacks structural and joinery timbers, often with devastating results. Can flourish in moist, unventilated areas.
Eaves: The overhanging edge of a roof.
Efflorescence: Salts crystallised on the surface of a wall as a result of moisture evaporation.
Engineering Brick: Particularly strong and dense type of brick, sometimes used as damp-proof course.
Fibreboard: Cheap, lightweight board material of little strength, used in ceilings or as insulation to attics.
Flashing: Building technique used to prevent leakage at a roof joint. Normally metal (lead, zinc, copper) but can be cement, felt or proprietary material.
Flaunching: Contoured cement around the base of chimney pots, to secure the pot and to throw off rain.
Flue: A smoke duct in a chimney, or a proprietary pipe serving a heat-producing appliance such as a central heating boiler.
Flue Lining: Metal (usually stainless steel) tube within a flue essential for high output gas appliances such as boilers. May also be manufactured from clay and built into the flue.
Foundations: Normally concrete, laid underground as a structural base to a wall. Older buildings may use brick or stone.
Frog: A depression imprinted in the upper surface of a brick, to save clay, reduce weight and increase the strength of the wall. Bricks should always be laid frog uppermost.
Fused Spur: Power socket that does not have a plug going into it, instead the cable from an appliance like a fridge, radiator, burglar alarm, etc. and has a fuse socket built into it.
Gable: Upper section of a wall, usually triangular in shape, at either end of a ridged roof.
Gang: Referred to for power points – 1 gang: 1 single socket; 2 gang: 1 double socket.
Ground Heave: Swelling of clay sub-soil due to absorption of moisture. Can cause an upward movement in foundations.
Gully: An opening into a drain, normally at ground level, placed to receive water, etc. from downpipes and wastepipes.
Haunching: See Benching. Also, term used to describe the support to a drain underground.
Hip: The external junction between two intersecting roof slopes.
Inspection Chamber: Commonly called ‘man-hole’. Access point to a drain comprising a chamber (of brick, concrete or plastic) with the drainage channel at its base and a removable cover at ground level.
Jamb: Side part of a doorway or window.
Joist: Horizontal structural timber used in flat roof, ceiling and floor construction. Occasionally, also metal.
Landslip: Downhill movement of unstable earth, clay, rock etc. often following prolonged heavy rain or coastal erosion, but sometimes due entirely to sub-soil having little cohesive integrity.
Lath: Thin strip of wood used in the fixing of roof tiles or slates, or as a backing to plaster.
Lintel: Horizontal structural beam of timber, stone, steel or concrete placed over window or door openings.
LPG: Liquid Petroleum Gas or Propane. Available to serve gas appliances in areas without mains gas. Requires a storage tank.
Mortar: Mixture of sand, cement, lime and water, used to join stones or bricks.
Mullion: Vertical bar dividing individual lights in a window.
Newel: Stout post supporting a staircase handrail at top and bottom. Also, the central pillar of a winding or spiral staircase.
Oversite: Rough concrete below timber ground floors. The level of the oversite should be above external ground level.
Parapet: Low wall along the edge of a flat roof, balcony, etc.
Pier: A vertical column of brickwork or other material, used to strengthen the wall or to support a weight.
Plasterboard: Stiff sandwich of plaster between coarse paper. Now in widespread use for ceilings and walls.
Pointing: Smooth outer edge of mortar joint between bricks, stones, etc.
Powder Post Beetle: A relatively uncommon pest that can, if untreated, cause widespread damage to structural timbers.
Purlin: Horizontal beam in a roof upon which rafters rest.
Quoin: The external angle of a building – or, specifically, bricks or stone blocks forming that angle.
Rafter: A sloping roof beam, usually timber, forming the carcass of a roof.
Random Rubble: Primitive method of stone wall construction with no attempt at bonding or coursing.
Rendering: Vertical covering of a wall either plaster (internally) or cement (externally), sometimes with pebbledash, stucco or Tyrolean textured finish.
Reveals: The side faces of a window or door opening.
Ridge: The apex of a roof.
Riser: The vertical part of a step or stair.
Rising Damp: Moisture soaking up a wall from below ground, by capillary action causing rot in timbers, plaster decay, decoration failure, etc.
Roof Spread: Outward bowing of a wall caused by the thrust of a badly restrained roof carcass. (See Collar)
Screed: Final, smooth finish of a solid floor, usually cement, concrete or asphalt.
Septic Tank: Tank Drain installation whereby sewage decomposes through bacteriological action, which can be slowed down or stopped altogether by the use of chemicals such as bleach, biological washing powders, etc. Not to be confused with Cesspool.
Settlement: General disturbance in a structure showing as distortion in walls, etc., possibly a result of major structural failure, very dry weather conditions, etc. Sometimes of little current significance. (See also Subsidence)
Shakes: Naturally occurring cracks in timber – in building timbers, shakes can appear quite dramatic, but strength is not always impaired.
Shingles: Small rectangular slabs of wood used on roofs instead of tiles, slates, etc.
Soakaway: Arrangement for disposal of rainwater, utilising graded aggregate laid below ground.
Soaker: Sheet metal (usually lead, copper or zinc) at the junction of a roof with a vertical surface of a chimneystack, adjoining wall, etc. Associated with flashings, that should overlay soakers.
Soffit: The under-surface of eaves, balcony, arch, etc.
Solid Fuel: Heating fuel, normally coal, or one of a variety of proprietary fuels.
Spandrel: Space above and to the sides of an arch. Also, the space below a staircase.
Stud Partition: Lightweight, sometimes non-load bearing wall construction comprising a framework of timber faced with plaster, plasterboard or other finish.
Subsidence: Ground movement, generally downward, possible a result of mining activities or clay shrinkage.
Sub-soil: Soil lying immediately below the topsoil, upon which foundations usually bear.
Sulphate Attack: Chemical reaction activated by water, between tricalcium aluminate and soluble sulphates. Can cause deterioration in brick walls and concrete floors.
Tie Bar: Heavy metal bar passing through a wall, or walls, to brace a structure suffering from structural instability.
Torching: Mortar applied on the underside of roof tiles or slates to help prevent moisture penetration. Not necessary when a roof is underdrawn with felt.
Tread: The horizontal part of a step or stair.
Trussed Rafters: Method of roof construction utilising prefabricated triangular framework of timbers. Now widely used in domestic construction.
Underpinning: Method strengthening weak foundations whereby a new, stronger foundation is placed beneath the original.
Valley Gutter: Horizontal or sloping gutter, usually lead or tile lined, at the internal intersection between two roof slopes.
Ventilation: Necessary in all buildings to disperse moisture resulting from bathing, cooking, breathing etc. and to assist in prevention of condensation. Floors: Necessary to avoid rot, especially dry rot: Achieved by airbricks near to ground level. Roofs: Necessary to disperse condensation within roof spaces; achieved either by airbricks in gables or ducts at the eaves. (See Condensation)
Verge: The edge of a roof, especially over a gable.
Verge Board: Timber, sometimes decorative plastic material, placed at the verge of a roof. Also known as Barge Board.
Wainscot: Wood panelling or boarding on the lower part of an internal wall.
Wall Plate: Timber placed at the eaves of a roof, to take the weight of the roof timbers.
Wastepipe: Drainage pipe for baths, basins, WCs.
Wet Rot: Decay of timber due to damp conditions. Not to be confused with the more serious Dry Rot.
Woodworm: Colloquial term for beetle infestation – usually intended to mean Common Furniture Beetle – by far the most frequently encountered insect attack in structural and joinery timbers.
If you can’t find what you’re looking for here, try our Jargon Buster.
This is by no means a complete index – Oxford’s Dictionary of Construction, Surveying and Civil Engineering has over 8,000 entries – and we welcome any comments and suggested additions.
This Glossary has been compiled to help people with UK property terminology. We advise that this information is for guidance only and cannot be relied on for accuracy and that you should consult a qualified legal representative if you require full explanation.