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MMA Surveyors

Whilst MMA Surveyors endeavour to use plain and simple English, we occasionally have to use some technical words and phrases. We have, therefore, prepared a list of the most common technical words for ease of reference. However, we are always delighted to explain or put into context anything you may not understand.



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 purpose of providing air for ventilation purposes. Used for instance, to ventilate the underside of a wooden floor or a 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.

Asbestos Cement
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.

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.

A post or 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, egg 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 has “haunching”.

Black, sticky substance, similar to asphalt. Used in sealants, mineral felts and damp proof courses.

The regular arrangements of bricks or 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.

Breeze Block
Originally made from clinker cinders or (“breeze”) – the term now commonly, but incorrectly used to refer to various types of concrete and cement building blocks.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.

Casement Window
A window composed of hinged, pivoted or fixed sashes.

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 50mm (2 inches).

Cavity Wall Insulation
Filling of wall cavities by one of various forms of insulation material:

Polystyrene beads pumped into the cavities. Will easily fall out if the wall is broken open for any reason.
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.
Inert mineral fibre pumped into the cavity.

Cavity Wall Tie
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 form. Cheap method of decking to flat roofs, floors and (with Formica or melamine surface) furniture, especially kitchen units.

Cleaning Eye
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.

Collar Beam
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 of weakening can lead to roof spread.

Combination Boiler
Modern form of gas boiler, which activates 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.

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.

Dado Rail
A wooden moulding fixed to the wall or capping panelling 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
Layer of impervious material (mineral felt, PVC, etc) or DPC) incorporated into a wall and 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 effects 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” positioned inside the original window.

Double Hung
A window in which the opening lights slide vertically within a Sash 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.

Engineering Brick
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 in ceilings or as insulation to attics.

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 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 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 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 brick are laid.

Upper section of a wall, usually triangular in shape, at either end of a ridged roof.

Ground Heave
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 a foundations in extreme cases.

See “Benching”. Also term used to describe the support to a drain underground.

The external junction between two intersecting roof slopes.

Hip Tile
A saddle shaped or angular tile fitting over the intersection of those roofing tiles, which meet at a hip.

In Situ
“In position” – applied to work done in the position where it is finally required, eg concrete may be precast in sections which are later taken to the position where they are required or it may be cast “in situ”.

Inspection Chamber
Commonly called the “manhole”. 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 RSJ’s (rolled steeled 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 sub-soil 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.

Longhorn Beetle
(Hylotrupe Bajulus). 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.

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 hand rail at the top and bottom. Also, the central pillar of a winding spiral staircase.

Rough concrete below timber ground floors.

Low wall along the edge of a roof, balcony, etc.

Parapet Gutter
A timber gutter of rectangular cross-section, usually provided with a flexible metal 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 papers. Now in widespread use for ceilings and walls.

Outer edge of mortar joint between bricks, stone, etc.

Powder Post Beetle
(Bostrychide or Lycitdae 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.

Random Rubble
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 or apex of a roof, usually horizontal.

Ridge Tile
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.

Rising Damp
Moisture soaking up a wall from below ground, by capillary action, which can cause rot in timbers, plaster, decay, decoration failure, etc.

Roof Spread
Outward bowing 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.

Septic Tank
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 powers, 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 watertight 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 conveying sewage to the drains. Its upper under is usually vented above the eaves.

Solid Fuel
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.

Stud Partition
Lightweight, sometimes, non-loadbearing 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 sub-soil.

Soil lying immediately below the top-soil.

Sulphate Attack
Chemical reaction, activated by water, between tricalcium aliminate and soluble sulphates which can cause deterioration in brick walls and concrete floors.

Tie Bar
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 a door.

The horizontal part of a step or stair.

Trussed Rafters
Method of 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.

Valley Gutter
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.

Verge Board
Timber, sometimes decorative, places at the verge of a roof; also known as “barge board”.

Wall Plate
Timber places at the eaves of a roof, designed to take weight off the roof timbers and coverings.

Wall Tie
See “cavity wall tie”.

Waste Pipe
A pipe from a wash hand basin, sink or bath to carry away the waste water into the drains.

Weather Boarding
Horizontal overlapping boards nailed on the outside of a building to provide the finished wall surface.

Wet Rot
(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 Punctatum). By far the most frequently encountered insect attack in structural and joinery timbers.


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