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Glossary of terms
General Building Terminology

Aggregate - Pebbles, shingle, gravel etc. used in the manufacture of concrete, and other construction work.

Airbrick - A perforated brick used for ventilation, especially for under floor spaces.

Asbestos - A fibrous mineral used in the past for insulation. Can be a health hazard - should not be disturbed and specialist advice sought if found or suspected.

Asbestos cement - Cement with 10-15% asbestos fibre used as reinforcement, often used in the past for roofing sheets, gutter, roof tiles. It is fragile and will not bear heavy weights. Hazardous fibres may be released if cut, drilled or otherwise broken.

Asphalt - Black, tar-like material, strongly adhesive and impervious to moisture. Used on flat roofs and under tile felt.

Balanced flue - A common flue design used with gas appliances which allows air to be drawn to the appliance whilst also allowing fumes to escape.

Bat (brickwork) - A brick cut crossways to give a reduced length - commonly quarter, half or three-quarter bats. See also Closer.

Beam and Block (Floor) - Suspended floors consisting of precast pre-stressed concrete beams spaced at centres to suit the use of standard walling blocks as infill between the beams. They are a preferred solution for suspended ground floors in housing.

Bitumen - A black, sticky substance, related to asphalt. Used in sealants, mineral felts and damp-proof courses.

Brace - A diagonal member used to prevent part of a structure from sagging - can either be temporary or permanent.

Breeze block - An old type of building block made using cinders - tends to produce find black dust when drilled or cut.

Brick bond - The various styles of laying bricks to give different patterns while ensuring that no vertical joints align with those of the higher or lower row.

Cantilever - A projecting beam (or other part of a structure) that is secured at one end only.

Caulking - Sealing joints by applying a flexible compound or sealant.

Cavity wall - A method of building external walls of houses using two leaves of brick or blockwork (with wall-ties between) separated by a gap (I. e. the 'cavity') of about 50mm (2 inches). The prevents rain etc on the external leaf from penetrating into the building.

Cavity wall insulation - A method of improving the thermal insulation of a wall by filling the wall cavities with one of various materials available to provide increased thermal insulation. For retrofits often foam or pellets are inserted through holes drilled in the external walls; for new builds, insulating boards are built in as the walls are constructed.

Cement - A grey or white powdery material which is mixed with an aggregate and water to make mortar or concrete. A chemical reaction of the cement will cause the mixture to harden.

Cesspit - A watertight chamber in which sewage effluent is collected and stored for subsequent emptying, usually a service provided by the Local Authority for which a charge is made. Sometimes an outlet is provided to allow soakage of liquids from the cesspit into surrounding ground. Not to be confused with Septic Tank.

Chalk line - A length of string, coated in chalk dust, which is used to produce accurate straight lines for many decorating tasks. The line is held at both ends and 'twanged' against a surface thus transferring chalk dust to it.

Chase in - To cut a groove in a wall to take a conduit, cable or pipe so that when the wall is 'made good', it is concealed.

Chromate Primer - A paint used for priming aluminium, galvanised and other metal surfaces.

Closer (brickwork) - A brick cut lengthways to give a reduced width but full length. Used where the appearance of a full brick is required but the depth of the brickwork will not accommodate a full width - such as where a pier is inserted into a wall. A brick cut in half lengthwise is referred to as a Queen Closer, See also Bat.

Collar (in pipes) - The wider end of a pipe into which another pipe fits.

Coping stones - Stone or concrete slabs laid on top of a masonry wall as a decorative finish and to shed rainwater. The coping stones are normally wider than the wall to allow an overhang on both sides of the wall.

Corbel - A stone or timber support built into a wall which projects to support the load of a structural member, such as a beam.

Corbelling - The projection of masonry formed by building successive courses outwards by a small amount to form small steps with each additional course.

Cornice - A decorative moulding at the junction between a walls and ceiling of a room, or the uppermost horizontal moulding of a classical entablature.

Counter-bore - To insert a suitable screw into a surface so that its head does not protrude above that surface. This is achieved by using screws in a hole 'counterbored' with a flat bottomed cutter. If the counterbore is deep enough, it may be plugged with a piece of doweling to fully hide the screw head.

Counter-sink - To insert a suitable screw into a surface so that its head does not protrude above that surface. This is achieved by using counter sink screws in a hole 'countersunk' with a conical-shaped cutter.

Course - A row of bricks, concrete blocks, etc in a wall etc.

Coving - A curved moulding at the junction between a walls and ceiling of a room - a form of cornice.

Damp-proof course (DPC) - A layer of impervious material inserted towards the base of walls to stop rising damp. In older buildings, slates was used, more modern practice used mineral felt or PVC. A new DPC can be inserted where necessary, a "chemical" form of silicone being injected into the walls.

Damp-proof membrane - Normally a layer of plastic sheeting, laid over the site hardcore of a modern building, to prevent moisture rising from the ground into the floor structure. Needs to be connected to the DPC in the surrounding walls to be fully effective.

Dormer window - The window in the vertical end of a dormer.

Double glazing - A method of thermal insulation applied to windows usually either using:

  • Sealed units using two panes of glass hermetically sealed with internal air gaps.
  • Secondary glazing where a single pane of glass is fitted inside an original single glazed window, usually fitted to the window frame.

Dowel - A short length of wood, round in section, used for a variety of purposes such as joining timbers, plugging fixing holes etc.

Downpipes - The pipe used to take water from the guttering to the drainage system. Usually round or square cast iron (on older properties) or plastic - may be Asbestos Cement.

Drip groove - A groove cut in the underside of a projection (such as a window sash or sill) to cause rainwater to drip to the ground rather than running under the projection onto the main structure.

Dry rot - A fungus which rots timber, masonry and plaster.

Efflorescence - The white powdery deposit on the surface of masonry or plaster caused by mineral salts migrating to the surface as a result of moisture evaporation. Harmless but unattractive.

Engineering brick - A strong and dense type of brick, impervious to water so ideal for use in damp areas.

Fibre Quilting - A form of thick matting used for thermal insulation. Often fibre glass based, health and safety precautions need to be taken when handling it.

Flaunching - The contoured mortar around the base of chimney pots, used to secure the pot and allow rain run off.

Floors - Three types:

Flue lining - The lining within a chimney to protect the brickwork from the effects of the waste fumes. Essential for high output gas appliances such as boilers. Often a metal tube (usually stainless steel and can be retro fitted) but can be made from special bricks and built into the flue.

Fluting - Parallel concave channels used to decorate the surfaces of stone, plaster or timber etc.

Foundations - Normally concrete, cast into the sub-soil as the structural base for a wall or building - the depth and size will depend, amongst other things, upon the size/type of building and the nature of the sub-soil. In older buildings, the foundations may just be a course or two of wide bricks or stone.

Frog - The depression in one side of a brick, should always be laid uppermost.

Gilding - A technique of applying a gold finish to a surface: usually by application of either gold paint or gold leaf.

Gold leaf - A very thin sheet of rolled or hammered gold that is used for gilding decoration.

Ground heave - The swelling affect of clay sub-soil due to absorption of moisture, can cause an upward movement of foundations resulting in damage to buildings.

Gully - An opening into a drain, normally at ground level, placed to receive water etc. from rainwater downpipes and surface water. In older properties, sink, basin and bath wastewater may have fed into a gully, however this is not allowed with more modern buildings.

Guttering - The collecting channels at the lowest point of a roof for collecting the rainwater. Usually cast iron (on older properties) or plastic - may be Asbestos cement. Various profiles are available; the two standard traditional ones being Half-round (with a semi-circular section and supporting brackets fixed to the fascia) and Ogee (a moulded pattern with a flat back, where it is made from cast iron, lengths are secured to the fascia by fixing screws through the back).

Inspection chamber - An access point to underground drains comprising a chamber (of brick, concrete or plastic) with the drainage channel at the bottom and a removable cover at ground level. Also called "man-hole".

Interlocking tiles - These, unlike plain tiles, are designed so that their edges fit mechanically one with another, to provide a weather seal.

Land Drain - A drain usually consists a pipes laid with open joints and surrounded by pea shingle or similar material through which water can seep into the surrounding soil.

Lath - Thin strip of wood used as a support for plaster on walls and ceilings in old properties.

Lath and Plaster - Traditional (Pre 1940's) way of forming plaster surface on timber partitions and ceilings. Comprises of numerous horizontal laths to which the plaster is applied.

Lintel - A horizontal beam of timber (in old properties), stone, concrete or steel (the most common modern practice) spanning doorways and window openings in a wall to support the structure above.

Load bearing wall - A wall which supports the structure of the building above. It should not be removed without professional assistance.

LPG - Liquid Petroleum Gas or Propane. Used in areas without mains gas, requires an on-site storage tank.

Man Hole - see Inspection chamber.

Mitre - A joint where the two parts are each cut at 45 degrees so that the make a neat rightangle.

Mortar - Mixture of sand, cement, (sometimes lime) and water, used to bond stones and bricks.

Mullion - Vertical fixed member between a window sill and the window lintel. Usually of stone or precast reinforced concrete.

Oversite - The concrete below timber ground floors - the level of the oversite should be above the external ground level.

Parapet - Low wall along the edge of a roof, balcony etc. , can be purely decorative.

Pier - A vertical column of brickwork or other material built into a wall, used to strengthen the wall at the ends and at intervals along it as appropriate.

Plasterboard - A 'sandwich' of plaster with paper/card on either side. Widely used for ceilings and walls etc.

Pointing - The finish applied to the outer edge of mortar joint between bricks, blocks, stones etc. .

Rendering - The vertical plaster (internally) or mortar (externally) covering of a wall.

Rising damp - A building defect resulting from moisture soaking up a wall from the ground by capillary action in the structure - can lead to rot in timbers, plaster decay, decoration failure etc.

Screed - Final, level, smooth surface of a solid floor onto which the floor covering is applied - usually of mortar, or fine concrete.

Self-levelling compound - A special compound poured over an uneven floor to produce a level surface.

Septic Tank - A sewage disposal system normally consisting of two or three linked chambers within which bacterial processes breakdown the effluent, the final result being a liquid which can be fed into a land drain or soakaway. Occasional emptying of the chambers may be necessary, but depends upon their usage and the soil conditions. Care needs to be taken on what is fed into a Septic Tank - use of chemicals such as bleach, biological washing powders etc can cause the bacterial processes to stop. Not to be confused with Cesspit.

Sill - A sloping projection below a window or door opening to allow rainwater to run off.

Soakaway - An arrangement for draining rainwater into the ground. Usually a large hole dug and filled with broken bricks, rubble or similar 'waste' materials into which the rainwater is piped. Its effectiveness largely depends upon the type of soil surrounding the hole.

Solid Floor - Usually built up of layers of aggregate, damp-proof membrane (in modern floors) and concrete finished with a layer of screed.

Spirit Level - A tool used to establish true vertical and horizontal lines by looking at a bubble in spirit filled vials.

Straightedge - A length of timber or metal with at least one edge truly straight for marking out, checking levels etc.

Stretcher - A brick or stone block laid so that one of its long faces is to the outside of wall - i. e. it is visible.

Stringcourse - A horizontal strip of moulded stone or special bricks set into a wall.

Stucco - See Rendering

Subfloor - The surface beneath a floor covering, usually of concrete or timber, and sometimes covered with hard board.

Sub-soil - The soil immediately below the top-soil, into which foundations usually bear.

Suspended timber floors - The joists supporting the floor boards or chipboard are themselves supported by small "sleeper" walls at ground floor level or wall hangers at other floors. Older properties may have the joists built into the masonry walls which can lead to the ends of the joists rotting.

Suspended concrete beam floors - Usually consist of precast pre-stressed concrete beams spaced at centres to suit the use of standard walling blocks as infill between them. See beam and block.

Tie bar - Heavy metal bar passing through walls to brace a structure suffering from structural instability. The ends are often visible outside a building by the large metal 'S', 'X' or circular plates which spread the load over the external walls.

Tiler's spike - A sharp pointed tool for scoring through the glaze of ceramic tiles prior to cutting.

Timber frame - A method of building construction where the internal walls, floors, roof etc are manufactured in sections using timber off site and are erected onto a completed base built up from the foundations. In modern timber framed buildings, the inner timber construction is often covered by using an outer skin of brick or similar materials to give a traditional appearance.

Timber framed wall - A wall composed of structural wooden components, sheathed on both sides or infilled with masonry or wattle and daub.

Triple glazing - A type of window providing thermal insulation by using three panes of glass hermetically sealed with two internal air gaps.

Undercutting - Cutting away material from the edges of a recess to provide a key for new material.

Underpinning - A method of strengthening weak foundations by supporting the walls, digging underneath and inserting a new foundation.

Vapour barrier - A layer of impervious material, often heavy gauge polythene sheeting) used to prevent the passage of moisture through the structure.

Vinyl Flooring - A soft flexible and cushioned flooring available in sheets or tiles.

Wall Tie - Metal connector built into masonry walls to provide a structural link between the inner and outer skins.

Wet rot - Decay of timber due to wet or damp conditions.