BUILDING TERMS EXPLAINED
Broken stone, gravel or sand used with cement to form concrete. Aggregates may be coarse or fine and are often used in the construction of “soakaways”.
A perforated brick built into a wall for the purposes of providing air for ventilation purposes. Used for instance, to ventilate the underside of a wooden floor or roof space.
A moulding around a doorway or window opening. It usually covers the joints between the frame and the wall finish, thus hiding any shrinkage gaps which may occur.
Material used in the past for insulation. Can sometimes be a health hazard – specialist advice should be sought if asbestos (especially blue asbestos) is found.
Cement mixed with 15% asbestos fibre as reinforcement. Fragile – will not usually bear heavy weights. Hazardous fibres may be released if cut or drilled.
Black, tar-like substance, designed to be impervious to moisture. Used on flat roofs and floors.
See “Verge Board”.
Common metal device normally serving gas appliances which allow air to be drawn to the appliance whilst allowing fumes to escape.
A post of vertical pillar supporting a hand rail or parapet rail.
A collective name for a row of balusters or other infilling below a hand rail on a stair or parapet.
Beetle Infestation (Wood boring insects, e.g. woodworm)
Larvae of various species of beetle can tunnel into timber causing damage. Specialist treatment normally required. Can also affect furniture.
Shaped concrete slope beside drainage channel within an inspection chamber. Also known as “haunching”.
Black, sticky substance, similar to asphalt. Used in sealants, mineral felts and damp proof courses.
The regular arrangements of bricks and stones in a wall so that the units may be joined together. The principal types of “bond” used in domestic construction being English, Flemish, header, stretcher, diagonal or garden wall bond.
Originally made from clinker cinders or “breeze”. The term now common but incorrectly 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 in some cases.
A window composed of hinged, pivoted or fixed sashes.
Traditional modern method of building external walls of houses comprising two leaves of brick or blockwork usually separated by a gap (cavity) of above 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.
Foam: Urea formaldehyde foam, mixed on site and then pumped into the cavities where it sets. Can lead to problems of dampness and make replacement of wall-ties more difficult.
Fibreglass: Inert mineral fibre pumped into the cavity.
A twisted piece of metal or similar material bedded into the inner and outer leaves of cavity walls intended to strengthen the wall. 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”.
Often referred to as “particle board”. Chips of wood compressed and glued into sheet foam. Cheap method of decking to flat roofs, floors and (with Formica or Melamine surface) furniture, especially kitchen units.
Sometimes known as an “access eye” or “rodding eye”. An opening in a drain or ventilation pipe, covered by a plate, the removal of which allows the drain to be rodded to clear blockages.
Walling of damp earth sometimes mixed with cement, rammed without reinforcement into a formwork. This cheap method of walling has in the past been practiced mainly in East Anglia and the West of England.
A horizontal tie beam of a roof, which is joined to opposing rafters at a level above that of the wall plates.
Horizontal timber member designed to restrain opposing roof slopes, absence, removal or weakening can lead to spread.
Modern form of gas boiler which activates on demand usually within a pressurized system. With this form of boiler there is no need for water storage tanks, hot water cylinders, etc.
Usually stone or concrete, laid on top of a wall as a decorative finish and
Coping Stone designed to stop rainwater soaking into the wall.
Projection of stone, brick, timber or metal jutting out from a wall to support a weight above it.
A large moulding at the junction between an inside wall and a ceiling. Can also include a moulding at the top of an outside wall designed to project and throw raindrops clear of the wall.
Curved junction between wall and ceiling.
A wooden moulding fixed to the wall or capping paneling and forming the top most part of a dado. Originally designed to avoid damage to the wall where people or furniture brushed against it.
Damp Proof Course (or DPC)
Layer of impervious material (mineral felt, PVC, etc) incorporated into a wall designed 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 (Xestobium Rufovillosum)
Extremely serious insect pest which attacks 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.
Secondary: In effect a second “window” positioned inside the original window.
Double Hung Sash
A window in which the opening lights slide vertically within a
Window cased frame, counter balanced by weights supported on sash cords which pass over pulleys in the frame.
Dry Rot (Serpula Lacrymans)
A very serious form of fungus which attacks structural and joinery timbers, often with devastating results. Can flourish in moist, unventilated areas.
The overhanging edge of a roof.
Powdery white salts crystallized on the surface of a wall as a result of moisture evaporation.
Particularly strong and dense type of brick, often used as a damp proof course in older buildings.
Cheap, lightweight board material of little strength, used as a damp proof course in older buildings.
Building technique designed to prevent leakage at a roof joint. Normally metal (lead, zinc, copper) but can be cement, felt or proprietary material.
A cement mortar weathering on the top of a chimney stack surrounding the base of the chimney pots to throw off the rain and thus prevent it from saturating the stack.
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. Other proprietary flue liners are also available.
Normally concrete, laid underground as a structural base to a wall; in older buildings these may be brick or stone.
An indention, usually V shaped in the bedding face of the brick to reduce its weight. “Frog down” or “Frog up” are the generally accepted ways of describing how the bricks are laid.
Upper section of a wall, usually triangular in shape, at either end of a ridged roof.
Swelling of clay sub-soil due to the presence of moisture; can cause an upward movement of foundations in extreme cases.
An opening into which rain and waste water are collected before entering the drain.
A channel along the eaves of a roof or the edge of a path for the removal of rainwater.
Broken bricks or stone which, consolidated, are used as foundation in extreme cases.
See “Benching”. Also term used to describe the support to a drain underground.
The external junction between two intersecting roof slopes.
A saddle shaped or angular tile fitting over the intersection of those roofing tiles which meet at hip.
“In position”. Applied to work done in the position where it is finally required, e.g. concrete may be precast in sections which are later taken to the position where they are required or it may be cast “in-situ”.
Commonly called the “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.
Vertical side face of a doorway or window.
A timber or steel beam directly supporting a floor and sometimes alternatively or additionally supporting a ceiling. Steel beams are usually referred to as RSJs (Rolled Steel Joists).
The roughness of a surface which provides a bond for any application of paint, plaster, rendering, tiles, etc. or spaces between laths or wire meshes which provide a grip for plaster.
Downhill movement of unstable earth, clay, rock, etc. often following prolonged heavy rain or coastal erosion, but sometimes due to subsoil having poor cohesion.
Thin strip of wood used in the fixing of roof tiles or slates, or as backing to plaster.
A horizontal beam over a door or window opening usually carrying the load of the wall above. Often lintels can be partially or completely hidden from view.
(Hylotrupe Bajulus) A serious insect pest mainly confirmed 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.
Mixture of sand, cement, water and sometimes lime used to join stones or bricks.
Vertical bar dividing individual lights in a window.
Stout post supporting a staircase handrail at top and bottom. Also, the central pillar of winding spiral staircase.
Rough concrete below timber ground floors.
Low wall along the edge of a roof, balcony, etc.
A timber gutter of rectangular cross section usually provided with a flexible meal or other impervious lining. Used behind a parapet or sometimes at a valley.
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.
Outer edge of mortar joint between bricks, stones, etc.
Power Post Beetle
(Bostrychide or Lyctidae family of beetles) 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.
Basic early 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 pebbledash, stucco or Tyrolean textured finish.
The side faces of a window or door opening.
The highest part of apex of a roof, usually horizontal.
A specially shaped tile for covering and making weather tight the ridge of a roof. These tiles may have a rounded or angular cross section.
The vertical part of a step or stair.
Moisture soaking up a wall from below ground, by capillary action which can cause rot in timbers, plaster decay, decoration failure, etc.
Outward bowling of a wall caused by the thrust of a badly restrained roof framework (see “collar”).
Frequently used abbreviation for a Rolled Steel Joist.
Final, smooth finish of a solid floor; usually cement, concrete or asphalt.
Drain installation whereby sewage decomposes through the action of bacteria, which can be slowed down or stopped altogether by the use of chemicals such as bleach, biological washing powders, etc.
All properties settle to some extent, and this can show as cracking and/or distortion in walls. Very often minor settlement is not of great significance to the building as a whole.
A large, underground pipe or drain used for conveying waste water and sewage. The Local Authority is usually responsible for the sewers, which collect the effluent from various drains, the drains being the responsibility of the land owners.
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 tiles, slates, etc.
A pit, filled with broken stones etc. below ground to take drainage from rainwater pipes or land drains and allow it to disperse.
Piece of flexible metal fitted to interlock with slates or tiles and make a water tight joint between a wall and a roof or at a hip or valley. Stepped flashings are used over the soakers at a joint against a wall.
The underside of an arch, beam, staircase, eaves or other feature of a building.
Soil Pipe/Soil Stack
A vertical pipe conveys sewage to the drains. Its upper end is usually vented above the eaves.
Heating fuel, normally wood, coal or one of a variety of proprietary fuels.
Space above and to the sides of an arch; also the space below a staircase.
A valve on a gas or water supply pipe which is used to cut off the supply.
Lightweight, sometimes non-load bearing wall construction comprising a framework of timber faced with plaster, plasterboard or other finish.
Ground movement, generally downward, possibly a result of mining activities or failure of the subsoil.
Soil lying immediately below the top-soil.
Chemical reaction, activated by water, between tricalcium aliminate and soluble sulphates which can cause deterioration in brick walls and concrete floors.
Metal bar passing through a wall, or walls in an attempt to brace a structure suffering from structural instability.
Mortar applied on the underside of roof tiles or slates 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 utilizing 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 the ground level.
Roofs: Necessary to disperse condensation within roof spaces; achieved either by airbricks in gables or ducts at the eaves.
The edge of the roof, especially over a gable or around a Dormer window or skylight.
Timber, sometimes decorative, placed at the verge of a roof; also known as “barge board”.
Timber placed at the eaves of a roof, designed to take the weight of the roof timbers and coverings.
See “Cavity Wall Tie”.
A pipe from a wash hand basin, sink or bath to carry away the waste water into the drains.
Horizontal overlapping boards nailed on the outside of a building to provide the finished wall surface.
(Coniophora Puteana) 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 (Anobium Pumctatum); by far the most frequently encountered insect attack in structural and joinery timbers.