A-Z of Building Terms Addition A projecting structure, or wing, which is part of the original building rather than a subsequent extension. Airbrick A perforated brick built into a wall for providing ventilation. Used, for instance, to ventilate the underside of timber ground floors, blocked fireplaces or a roof space. Architrave 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. Asbestos Material used in the past for insulation and fire protection. Can be a health hazard. Specialist advice should be sought if asbestos is found. Asphalt Black, tar-like substance, designed to be impervious to moisture. Used on flat roofs and floors. Back Addition The narrower part of a building, or wing, which extends rearwards beyond the “main“ structure, being an original feature rather than a subsequent extension. This is sometimes called an “outrigger“ in different parts of the country. Back Gutter The lining and flashing arrangement at the back of a chimney stack (on the upslope side) to divert rainwater away from the stack. Bargeboard Timber, sometimes decorative, placed along the verge of a roof at a gable end. Baluster A post or vertical pillar supporting a handrail or parapet rail. Balustrade A row of balusters, or other infilling, below a handrail on a landing, stair or parapet. Batten Thin strips of timber, commonly used to support roof tiles or slates. Bellcast Thickening out of render, in a curved shape, to form a drip to deflect water. Usually found at the base of a wall, above the damp-proof course. Brace Diagonal support in a timber door. Bracing The arrangement of timbers spanning across roof trusses to provide lateral stability Bressumer A lintel, often timber, over an opening such as a fireplace or bay. Buttress A brick or stone support to a wall designed to resist lateral movement. Capping The weather-proof finish formed with tiles, or stone or concrete copings, over a wall, parapet or chimney. Casement A window composed of hinged, pivoted or fixed sashes. Cavity tray A moisture barrier inserted above a window or door opening to deflect moisture that transfers across the outer leaf of brickwork back to the outer face rather than letting it cross the cavity at lintel level causing dampness internally. In many cases, the lintel itself acts as a cavity tray though this arrangement is not always appropriate. Cavity Wall Traditional modern method of building external walls of houses comprising two leaves of brick or blockwork usually separated by a gap ("cavity") of about 5Omm (2 inches). Chase To cut into plaster, brickwork etc. to receive cables and pipes. Combination Boiler A central heating boiler that also provides hot water “instantaneously“ on demand, usually within a pressurised system. With this form of boiler there is no need for water storage tanks, hot water cylinders etc. Coping/Coping Stone Usually stone or concrete laid on top of a wall as a decorative finish and designed to stop rainwater soaking into the wall. Cornice A moulding at the junction between a wall and ceiling. Can also include a moulding at the top of an outside wall designed to project and throw raindrops clear of the wall. Coving Curved junction between wall and ceiling ie. a type of cornice. Creasing Projecting course of tiles to a wall or chimney to prevent rain from running down the face of the brickwork. Dado The bottom one metre or so of wall clad with timber, originally designed to provide protection to the wall, and also covering the area most likely to be affected by rising damp. The top edge is finished with a Dado Rail. Damp-Proof Course Layer of impervious material (bitumen felt, PVC, slate etc) incorporated into a wall and designed to prevent dampness rising up the wall, and lateral dampness penetrating around windows, doors etc. Various alternative methods are available for damp-proofing existing walls including "electro-osmosis" and chemical injection. Damp-Proof Membrane Horizontal layer of impervious material (usually polythene or bitumen) incorporated into floors or slabs. Dormer A construction with a window that projects from a sloping roof. Eaves The lower edge of a roof. Engineering Brick Particularly strong and dense type of brick, often used as a damp proof course in older buildings. Fascia A board fixed to the rafter ends along the roof eaves. Flank wall A side wall. Flashing A sheet cover formed over a joint, such as between a roof covering and a chimney or wall, to render it waterproof. Normally formed in metal (lead, zinc, copper) or cement. Flue A smoke duct in a chimney, or a proprietary pipe serving a heat producing appliance such as a central heating boiler. Footings Older, usually shallow, form or foundation of brick or stone. Foundations Normally concrete, laid underground as a structural base to a wall. In older buildings these may be brick or stone. Gable Upper section of a wall, usually triangular in shape, at each end of a ridged roof. Grout Used for filling the joints between wall and floor tiles. Gully An opening into which rain and waste water are collected before entering the drain. Gutter A channel along the eaves of a roof or the edge of a path for the removal of rainwater. Hardcore Broken bricks or stone which, consolidated, are used as a base under floors and patios. Hip The sloping angle where two roof planes meet to form a ridge. Hip Tile A saddle shaped, angular or half round tile fitting over the junction of the roof slopes at a hip. Inspection Chamber Commonly called a manhole. An 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. Joist A timber or steel beam directly supporting a floor or ceiling. Lantern Light A roof light constructed like a lantern with fixed and/or opening glazing. Lean-to A structure, the sloping roof of which abuts a higher wall. Lining The wood finish to a window or door jamb. Lintel 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. Mastic A generic term for any sealant used in the building process. Mezzanine A floor between the ground and first floors, often accessed off a half landing. Mortar Mixture of sand, cement (or lime), and water used to join stones, blocks or bricks, and for pointing and general filling. Mullion Vertical bar dividing individual lights in a window. Newel Post supporting a staircase handrail at top and bottom. Also, the central pillar of a winding spiral staircase. Oversite The finish to the ground surface beneath suspended floors. Parapet Low wall along the edge of a roof or balcony, or extending over the roof slopes above a party or gable wall. Parapet Gutter A gutter behind a parapet usually provided with a flexible metal or other impervious lining. Party Wall The wall which separates, but is shared by, adjoining properties. Pier A vertical column of brickwork or other material, used to strengthen the wall or to support a weight. Pitch The angle of slope to a roof. Plinth The projecting base of a wall. Pointing Outer edge of mortar joint between bricks, stones etc. Racking The distortion, or tendency to distort, laterally as in changing a rectangle to a non-rectangular parallelogram. Rafter A sloping roof beam, usually timber, forming the carcass of a roof. Raked Pitched, sloping. Render Smooth or rough cast cement or lime based covering to a wall, either internally or externally, sometimes with pebbledash or other textured finish. Retaining Wall A wall built to hold back a bank of soil. Reveal The side or top faces of a window or door opening. Ridge The highest part or apex of a roof where two slopes meet. Ridge Tile A specially shaped angular or half round tile for covering and making weather-tight the ridge of a roof. Rising Damp Moisture soaking up a wall from the ground by capillary action. RSJ Rolled Steel Joist. Rough Cast A rough render finish to external walls. Screed Final smooth finish of a solid floor; usually cement or concrete. Septic Tank Private drainage installation whereby sewage is collected into a chamber and decomposes through the action of bacteria, with remaining solids requiring removal periodically, and liquids running off to a water course or soakaway. Skylight A window set into a roof slope. Soakaway A pit, filled with broken stones etc., below ground to take drainage from rainwater pipes or land drains and allow it to disperse. Soffit The underside of an arch, beam, staircase, eaves or other feature of a building. Soil Pipe A vertical pipe that conveys sewage to the drains. Its upper end it usually vented above the eaves. Soldier Course A horizontal course of bricks set on end over a window or door opening. Stop Cock A valve on a gas or water supply pipe which is used to cut off the supply. Stop End The end piece of a gutter. Stud Wall Lightweight wall construction comprising a framework of timber faced with plaster, plasterboard or other finish. Sub-Soil Soil lying immediately below the topsoil. Tie Bar Metal bar passing through a wall, or walls, in an attempt to brace a structure suffering from structural instability, normally lateral. Trimmed Joist Cut joist where an opening is formed in a ceiling, roof or floor, for example a roof hatch or stairwell. Truss A prefabricated triangular framework of timbers used in most modern roof constructions. Underlining A lining of felt, PVC, or similar, laid over the rafters and beneath the tiles and battens, to provide a second line of defence to a roof against weather penetration. Underpinning Method of strengthening weak foundations whereby a new, stronger foundation is placed beneath the original. Verge The edge of the roof, especially over a gable, or around a dormer window or skylight. Wall Plate Timber normally fixed on top of a wall to receive floor joists or roof rafters. Wall Tie Usually a piece of metal bedded into the inner and outer leaves of a cavity wall to provide a physical connection between the two. Waste Pipe A pipe from a wash hand basin, sink or bath to carry away the waste water into the drains.
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