Jargon Buster

Glossary of Building Terms

(click on any featured word below to reveal it’s definition)

A – K

Pebbles, shingle, gravel, etc. used in the manufacture of concrete, and in the construction of “soakaways”.
Perforated brick or metal/plastic grille used for ventilation, especially to floor voids(beneath timber floors) and roof spaces.
Joinery moulding around window or doorway.
Fibrous mineral used in the past for insulation. Can be a health hazard – specialist advice should be sought if asbestos is found.
Cement with 10-15% asbestos fibre as reinforcement. Fragile – will not bear heavy weights. Hazardous fibres may be released if cut or drilled.
Finely dressed natural stone: the best grade of masonry.
Black, tar-like substance, strongly adhesive and impervious to moisture. Used on flat roofs and floors.
See “Verge Board”.
Common metal device normally serving gas appliances which allows air to be drawn to the appliance whilst also allowing fumes to escape (see also “Fan Assisted Flues”).
Thin lengths of timber used in the fixing of roof slates or tiles.
(Wood boring insects: woodworm) Larvae of various species of beetle which tunnel into timber causing damage. Specialist treatment normally required. Can also affect furniture.
Smoothly contoured concrete slope beside drainage channel within an inspection chamber. Also known as “Haunching”.
Black, sticky substance, related to asphalt. Used in sealants, mineral felts and damp-proof courses.
Originally made from cinders (“breeze”) – the term now commonly used to refer to various types of concrete and cement building blocks.
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.
Standard modem method of building external walls of houses comprising two leaves of brick or blockwork separated by a gap (“cavity”) of about 50mm (2 inches).
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.

Fibreglass – Can lead to problems if becomes damp.

Foam – Urea formaldehyde form, mixed on site, and pumped into the cavities where it sets. Can lead to problems of dampness and make investigation or replacement of wall-ties more difficult.

Rockwool – Inert mineral fibre pumped into the cavity.

Metal device bedded into the inner and outer leaves of cavity walls. Failure by corrosion can result in the wall becoming unstable – specialist replacement ties are then required.
A simple method of drain comprising a holding tank which needs frequent emptying. Not to be confused with “Septic Tank”.
Also referred to as “Particle Board”. Chips of wood compressed and glued into sheet form. Cheap method of decking to flat roofs and (with formica or melamine surface) furniture, especially kitchen units. Also commonly used on floors. Tends to swell if moisture content increased.
Horizontal timber member intended to restrain opposing roof slopes. Absence, removal or weakening can lead to roof spread.
Modem 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.. but are complex and more, expensive to repair. Water supply rate can be slow.
Usually stone or concrete, laid on top of a wall as a decorative finish and to stop rainwater soaking into the wall.
Projection of stone, brick, timber or metal jutting out from a wall to support a weight.
Ornamental moulded projection around the top of a building or around the wall of a room just below the ceiling.
Curved junction piece to cover the join between wall and ceiling surfaces.
Wooden moulding fixed horizontally to a wall, about 1 metre (3ft 4in) above the floor, originally intended to protect the wall against damage by chair-backs.
Layer of impervious material (mineral felt, pvc, etc.) incorporated into a wall to prevent dampness around windows, doors, etc.. Various proprietary methods are available for damp-proofing existing walls including “electro-osmosis” and chemical injection.
Usually polythene, incorporated within ground floor slabs to prevent rising dampness.
Serious insect pest in structural timbers, usually affects old hardwoods with fungal decay already present.
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.

A fungus which attacks structural and joinery timbers, often with devastating results. Can flourish in moist, unventilated areas.
The overhanging edge of a roof at gutter level.
Salts crystallized on the surface of a wall as a result of moisture evaporation.
Particularly strong and dense type of brick, sometimes used as a damp-proof course. Usually blue in colour.
Similar to “Balanced Flue” but with fan assistance to move air or gases.
Cheap, lightweight board material of little strength, used in ceilings or as insulation to attics.
Mortar used to seal the junction between two surfaces, i.e. between a slate roof and a brick chimney stack.
Building technique used to prevent leakage at a roof joint. Normally metal (lead, zinc, copper).
Contoured cement around the base of chimney pots, to secure the pot and to throw off rain.
A smoke duct in a chimney, or a proprietary pipe serving a heat-producing appliance such as a central heating boiler.
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.
Normally concrete, laid underground as a structural base to a wall; in older buildings may be brick or stone.
A depression imprinted in the upper surface of a brick, to save clay, reduce weight and increase the strength of the wall.
Upper section of a wall, usually triangular in shape, at either end of a ridged roof.
Swelling of clay sub-soil due to absorption of moisture; can cause an upward movement in foundations.
An opening into a drain, normally at ground level, placed to receive water, etc. from downpipes and wastepipes.
See “Benching”. Also term used to describe the support to an underground drain.
The external junction between two intersecting roof slopes.
Commonly called “man-hole”; provides access 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.
Side part of a doorway or window.
Horizontal structural timber used in flat roof, ceiling and floor construction. Occasionally also metal.

L – Z

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.
Thin strip of wood used as a backing to plaster.
Horizontal structural beam of timber, stone, steel or concrete placed over window or door openings.
A serious insect pest mainly confined to the extreme south-east of England, which can totally destroy the structural strength of wood.
Liquid Petroleum Gas (or Propane). Available to serve gas appliances in areas without mains gas. Requires a storage tank.
Traditionally a mixture of lime and sand. Modern mortar is a mixture of cement and sand.
Vertical bar dividing individual lights in a window.
Stout post supporting a staircase handrail at top and bottom. Also, the central pillar of a winding or spiral staircase.
Rough concrete below timber ground floors; the level of the oversite should be above external ground level.
Low wall along the edge of a flat roof, balcony, etc..
A vertical column of brickwork or other material, used to strengthen the wall or to support a weight.
Stiff “sandwich” of plaster between coarse paper. Now in widespread use for ceilings and walls.
Smooth outer edge of mortar joint between bricks, stones, etc..
A relatively uncommon pest which can, if untreated, cause widespread damage to structural timbers.
Horizontal beam in a roof upon which rafters rest.
The external angle of a building, or, specifically, bricks or stone blocks forming that angle.
A sloping roof beam, usually timber, forming the carcass of a roof.
Primitive method of stone wall construction with no attempt at bonding or coursing.
Vertical covering of a wall either plaster (internally) or cement (externally), sometimes with pebble-dash, stucco or Tyrolean textured finish.
The side faces of a window or door opening.
The apex of a roof.
The vertical part of a step or stair.
Moisture soaking up a wall from below ground, by capillary action causing rot in timbers, plaster decay, decoration failure, etc..
Outward bowing of a wall caused by the thrust of a badly restrained roof structure (see “Collar”).
Final, smooth finish of a solid floor; usually mortar, concrete or asphalt.
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..
General disturbance in a structure showing as distortion in walls, etc., usually as the result of the initial compacting of the ground due to the loading of the building.
Naturally occurring cracks in timber; in building timbers, shakes can appear quite dramatic, but strength is not always impaired.
Small rectangular slabs of wood used on roofs instead of slates, tiles, etc..
Sheet metal (usually lead, copper or zinc) at the junction of a roof with a vertical surface of a chimney stack, adjoining wall, etc.. Associated with flashings which should overlay soakers.
The under-surface of eaves, balcony, arch, etc..
Heating fuel, normally coal, coke or one of a variety of proprietary fuels.
Space above and to the sides of an arch; also the space below a staircase.
Lightweight, sometimes non-loadbearing wall construction comprising a framework of timber faced with plaster, plasterboard or other finish.
Ground movement, possibly as a result of mining activities, clay shrinkage or drainage problems.
Soil lying immediately below the top-soil, upon which foundations usually bear.
Chemical reaction, activated by water, between tricalcium aluminate and soluble sulphates. Can cause deterioration in brick walls, concrete floors and external rendering.
Heavy metal bar passing through a wall, or walls, to brace a structure suffering from structural instability.
Mortar applied on the underside of roof slates or tiles to help prevent moisture penetration. Not necessary when a roof is underdrawn with felt.
Horizontal bar of wood or stone across a window or top of door.
The horizontal part of a step or stair.
Method of roof construction utilising prefabricated triangular framework of timbers. Now widely used in domestic construction.
Method of strengthening weak foundations whereby a new, stronger foundation is placed beneath the original.
Horizontal or sloping gutter, usually lead or tile-lined, at the internal intersection between two roof slopes.
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.

The edge of a roof, especially over a gable.
Timber, sometimes decorative, placed at the verge of a roof; also known as a “Barge Board”.
Wood panelling or boarding on the lower part of an internal wall.
Timber placed at the eaves of a roof, to take the weight of the roof timbers.
Decay of timber due to damp conditions. Not to be confused with the more serious “Dry Rot”.
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.