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BUILDING TERMS EXPLAINED

 

Although we try to avoid the use of jargon, sometimes in reports of this type it is necessary to use technical terms. Some of these are explained below. Should you be unsure of any of the terms used in your report, please do not hesitate to contact us and we will try to explain them.

 

Aggregate                                Broken stone, gravel or sand used with cement to form concrete.  Aggregates may be coarse or fine and are often used in construction of “soakaways”.

 

Airbrick                                     A perforated brick built into the wall for the purpose of providing air for ventilation purposes.  Used to ventilate the underside of a wood floor or a roof space.

 

Apron                                        A strip of lead sheet or similar built into a wall and dressed over abutment to adjoining roof.

 

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.

 

Ashlar                                       Squared and faced stone used as high quality finish.

 

Asbestos                             Material used in the past for insulation.  Can sometimes be a health hazard – specialist advice should be sought if asbestos is found. (See asbestos general information in report) 

 

Asbestos Cement                   Cement mixed with approximately 15% asbestos fibre as reinforcement.  Fragile – will not usual bear heavy weights.  Hazardous fibres may be released if cut or drilled.

 

Asphalt                                     Black, tar-like substance, designed to be impervious to moisture.  Used on flat roofs and floors.

 

Baluster                                    A vertical support to the handrail of a staircase.

 

Balustrade                                A collective name for a row of balusters or other infilling below a hand rail on a staircase.

 

Balanced Flue                          Commonly a metal device normally serving gas appliances which allows air to be drawn to the appliance whilst also allowing fumes to escape.

 

Barge Board                             Timber or plastic, sometimes decorative, placed at the verge of a roof below the edge of the roof covering; also know as “verge board”.

 

Batten (Tile)                             Timbers to which roofing tiles or slates are fixed.

 

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.

 

Benching                                  Shaped concrete slope beside drainage channel within an inspection chamber.  Also known as “haunching”.

 

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

 

Bond                                         The regular arrangement of bricks or stones in a wall so that the structure is physically joined together.  The principal types of “bond” used in domestic construction being English, Flemish, header, stretcher or garden wall bond.

 

Breeze Block                            Originally made from clinkers or cinders. The term now commonly but incorrectly used to refer to various types of concrete and cement building blocks.

 

BWPDPA                                   British Wood-Preserving and Damp-Proofing Association. The national body overseeing this type of specialist treatment.

 

Buttress                                    A support to a wall, designed to resist outward thrust and add stability.

 

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 block work usually separated by a gap (“cavity”) of about 50mm (2 inches). Normally the inner leaf is load bearing and outer leaf protects it from the weather. The two leafs are connected by metal ties. This type of wall is more resistant to damp penetration than a solid wall and has greater thermal qualities.

 

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

                                                  Beads: Polystyrene beads pumped into 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 material 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.

 

Cesspool                                   A simple method of sewage disposal comprising a watertight holding tank which needs frequent emptying. A cesspool is an ongoing financial liability. Not to be confused with “septic tank”.

 

Chimney Breast                       The part of a chimney below roof level, normally projecting into a room.

 

Chimney Stack                         The part of the chimney above roof level.

 

Chipboard                                 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 to kitchen units.

 

Cill                                             The horizontal member at the bottom of a window or door frame.

 

Collar Beam/Tie                       A horizontal tie beam of a roof, which is joined to opposing rafters to prevent spreading of the roof structure. Normally at a level about half the height of the roof. Absence, removal or weakening can lead to roof spread.

 

Combination boiler                 Modern form of pressurised boiler system which activates on demand.  With this form of boiler direct connection to mains is possible, there is no need for water storage tanks, hot water cylinders etc.

 

Coping/Coping stone              Usually brick, stone or concrete, laid on top of a wall as a decorative finish and designed to stop rainwater soaking into the wall surface below. 

Corbel (ing)                              Projection of stone, brick, timber of metal jutting out from a wall to provide support. 

 

Cornice                                     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.

 

Coving                                      Curved plaster junction between wall and ceiling.

 

Cowl                                          A cap to a chimney or flue pipe. May also describe a moveable wooden structure to an Oast House roundel.

 

Crown                                       Top of an arch or roof.

 

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. May conceal rising dampness.

 

Damp-Proof Course                (abb. DPC) Layer of impervious material (slate, mineral felt, PVC etc.) incorporated into a wall designed to prevent dampness rising up the wall or lateral dampness around windows, doors etc. A remedial chemical injection treatment can be injected into a wall to form an impermeable layer within the wall. Efficiency can vary with the type of construction.

 

Damp-proof Membrane           A sheet DPC within a solid concrete floor to prevent dampness.

 

Deathwatch Beetle                  (Xestobium Rufovillosum).  Extremely serious insect pest which attacks structural timbers especially oak. Usually effects old hardwoods with fungal decay already present.

 

Dormer Window                       A window projecting from a roof slope.

 

Double Hung Sash Window   A window in which the opening lights slide vertically within a cased frame, counter balanced by weights supported on sash cords which pass over pulleys.

 

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.

 

Dressing                                   The process of working lead/metal flashings to shape.

Eaves                                        The lower overhanging edge of a roof adjacent to guttering.

Efflorescence                           Powdery white salts crystallised on the surface of a wall or plaster 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 or in manholes.

Facia                                          A vertical board at eaves level often supporting gutters.

Fanlight                                     A light or window over a door or casement.

Fibreboard                                Cheap, lightweight board material of little strength, used in ceilings or as insulation to attics.

Fillet (Cement)                         Mortar joint used in period property to weather a joint. Prone to splits and cracks resulting in leakage. Requires regular replacement. Ideally replace in Code 4 lead flashing.

Firring                                       Tapered timbers laid on joists of a flat roof to provide a fall to gutters.

Flashing                                   Building technique designed to prevent leakage at a roof joint or base of a chimney stack.  Normally metal (lead, zinc, and copper) but can be short life cement, felt or proprietary material.

Flaunching                               A cement mortar weathering on the top of a chimney stacks supporting the base of the chimney pots to throw off the rain and thus prevent it from saturating the stack.

Flue                                           A smoke duct in a chimney, or a 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 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.

Foundations                             Also called ‘footings’, normally concrete, laid underground as a structural base to a wall; in older buildings these may be brick or stone.

Frog                                          An indent, usually V shaped in the bedding face of the brick to reduce its weight.  “Frog down” or “Frog up” is the generally accepted ways of describing how the bricks are laid.

Furniture                                  Handles, locks, etc. fitted to doors, windows and cupboards.

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

Granolithic                               Floors finish of polished crushed stone or aggregate.

Ground Heave                         Swelling of clay sub-soil due to the presence of moisture: can cause an upward movement of foundations.

Gulley                                       An opening into which rain and waste water are collected before entering the drain.

Gutters                                     (Rainwater Goods) Collects rainwater from roof coverings and discharge to down pipes.

Hanger                                      Metal bracket supporting a joint between structural timbers. Can also describe a timber upright between rafters and ceiling joists.

Hardcore                                   Broken brick rubble or stone which, consolidated, are used as a foundation in extreme cases.

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

Header                                      The end face of a standard brick.

Header Tank                             A small water storage tank which provides top-up water to a central heating system. Also called a feed and expansion tank.

Hip                                             The angled external junction between two intersecting roof slopes.

Hip Tile                                      A saddle shaped or half-round tile fitting over the intersection of two roof slopes which meet at a hip.

Hopper head                             A square or funnel shaped receptacle to connect rainwater or waste pipes to a down-pipe.

Interlocking Tiles                     Modern machine made roof tiles designed to lock together to prevent water driving in.

In Situ                                       “In position” – applied to work done in the position where it is finally required.

Inspection Chamber               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.

Jamb                                         The vertical side face of a timber door frame or window.

Joist                                          A timber or steel beam directly supporting a floor or a ceiling.  Steel beams are usually referred to as RSJs (rolled steel joists).

Key                                            A roughened surface which provides a bond for any application of paint, plaster, rendering, tiles etc.

King Post                                  A central post of a period roof framework. Can be decorative.

Landslip                                   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.

Land Drain                               (or French Drain) A drain laid with open joints or a trench filled with gravel to dispose of surface water.

Lap                                            The amount by which a slates or tiles overlap each other to prevent water ingress in high winds.

Lath                                           Thin strip of wood used in the fixing of roof tiles or slates, or as backing to plaster, as in lath and plaster.

Lintel                                         A beam over a door or window opening carrying the load of the wall above. May be timber, brick, stone, concrete or steel depending on the age of the building. Often lintels can be partially or completely hidden from view.

Longhorn Beetle                      (Hylotrupe Bajulus).  A serious inspect pest mainly confined to the extreme south-east of England, which can totally destroy the structural strength of wood.

Louvers                                    Glass slats fixed or pivoting to allow ventilation. Often found on older poor quality replacement timber windows. Now considered to be a security risk and should be replaced.   

LPG                                            Liquid Petroleum Gas or Propane.  Available to serve gas appliances in areas without main gas. Requires a storage tank or cylinders.

Mansard Roof                           A roof with two pitches, steep at lower level and flatter to the upper part. This is a design which allows accommodation to be formed in a roof space.

Masonry                                    Brickwork, stonework or block work.

Mastic                                       A generic term used for a flexible sealant. Used around window and door openings to prevent water ingress.

Mezzanine                                A floor introduced between principle floors.

Mortar                                       Mixture of sand, cement and water used to join blocks or bricks. In period buildings lime can be used.

Mullion                                      A vertical bar dividing individual lights in a window.

Newel                                        Vertical post supporting a staircase handrail at top and bottom of the flight.

Noggin                                      Brick infilling to a timber frame or timber struts between joists to prevent twisting strengthening the structure.

Oriel Window                           A self-supporting projecting window not having any brickwork below.

Oversite                                    Rough concrete below timber ground floors.

Parapet                                     A wall above the edge of a roof or balcony etc.

Parapet Gutter                         A timber gutter of rectangular cross-section usually providing with a flexible metal or other impervious lining.  Used behind a parapet wall or sometimes at a valley.

Parquet Floor                           Strips of hardwood laid in an interlocking pattern on a solid floor.

Partition                                    An internal timber, brick or block work wall forming rooms in a building. Can be load bearing or non-load bearing.

Pier                                            A vertical column of brickwork or other material, used to strengthen a wall or to support a beam or other structure.

Pitch                                          The angle or slope of a roof covering.

Plasterboard                             Stiff “sandwich” of plaster between coarse paper.  Now widespread used for ceilings and walls.

Plinth                                         The projecting base of a wall or structure.

Pointing                                     The neat finishing of mortar joints between bricks, blocks or stone etc.

Powder Post Beetle                 (Bostrychide or Lyctidae family of beetles). A relatively uncommon pest which can cause widespread damage to structural timbers.

Purlin                                         A horizontal beam in a roof upon which rafters rest and normally supported by load bearing party walls.

Quoin                                         The external angle of a building, or specifically, bricks or stone blocks often contrasting, forming the corner of walls.

Rafter                                         A sloping roof beam, usually timber, supporting the roof covering and forming the carcass of a roof.

Random Rubble                        Basic early method of irregular stone or brick wall construction with no attempt at bonding or coursing.

Rendering                                 Vertical covering of a wall either plaster (internally) or sand/cement (externally), sometimes with pebbledash, stucco or Tyrolean textured finish. Can also describe the first coat in plastered walls.

Reveals                                      The side faces of a window or door opening.

Ridge                                         The highest part or apex of a pitched 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.

Riser                                          The vertical part of a step or stair. 

 

Rising Damp                             Moisture from the ground soaking up a wall by capillary action which can cause rot in timbers, plaster decay, decoration failure etc.This is controlled by an effective damp-proof course.

 

Roding Eye                              Sometimes know as an ‘access eye’ or ‘cleaning 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.

Roof Spread                            Outward bowing of a wall caused by the thrust of a badly restrained roof framework (see “collar”).

Rot                                            Fungal growth which causes breakdown of the cellulose which gives strength to timber. Can be wet or dry rot.

Rough Cast                              A rough rendered finish to external walls usually sand/cement with gravel.

RSJ                                            Frequently used abbreviation for a rolled steel joist used to support structure over openings.

Sash                                          A sliding window frame usually vertical.

Screed                                       Final, smooth finish of a solid floor; usually sand/cement, concrete or asphalt.

Secondary Glazing                  In effect a second “window” positioned inside the original window. Often used to reduce noise transmission and improve thermal insulation.

Septic Tank                              A tank or tanks sunk below ground to dispose of sewage by purifying it, unlike a cesspool which is only for collection/storage and must be emptied regularly. It usually comprises two or three chambers to allow bacteria to purify the liquor, and an outflow to a land drain or soakaway. It can require emptying of solid matter on an infrequent basis dependent on usage. They can be slowed down or stopped altogether by the use of chemicals such as bleach, biological washing powders etc. Regular maintenance is required.

Settlement                                Structural movement caused by compression of the ground beneath a building. 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.

Sewer                                       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.

Shakes                                      Naturally occurring cracks in timbers; in building timbers, shakes can appear quite dramatic, but strength is not always impaired.

Shingles                                    Small rectangular slabs of wood, usually cedar, used on roofs and timber framed buildings instead of tiles, slates etc.

Sleeper Walls                           A wall beneath a suspended timber ground floor providing support to floor joists. Often built with gaps to allow ventilation.

Soakaway                                 A pit, filled with broken brick/stones etc, below ground to take surface water drainage from rainwater goods to allow it to disperse. Can be prone to silting up in time and require replacement.

Soaker                                      Lead components used to waterproof the joint between a pitched roof and a chimney stack.

Soffit                                         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.

Stopcock                                  A valve on a gas or water supply pipe which is used to cut off the supply.

String                                        The sloping side timber board to both sides of the staircase, supporting the treads.

String Course                          A projecting or feature course of masonry.

Stucco                                      A type of external decorative plasterwork.

Stud Partition                          Lightweight, normally non load bearing wall construction comprising a framework of timber faced with plaster, plasterboard or other finish.

Subsidence                             Ground movement, generally downward, possibly as a result of mining activities, drainage leaks or failure of the subsoil.

Subsoil                                     Soil lying immediately below the topsoil.

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

Terracotta                                Earthenware components made of baked clay.

Throat                                       The narrowing of a chimney flue above a fireplace.

Tie Bar                                      Metal bar passing through a wall, or walls in an attempt to brace a structure suffering from structural movement, usually outward movement of the walls.

Tilting Fillet                              A timber member inserted to raise the edge of tiles or slates.

Tingles                                     Metal strips used to secure loose slates or tiles. An indication of failure of nail fixings (nail rot) and a roof covering at the end of its useful life.

Torching                                  Mortar applied on the underside of roof tiles or slates to help prevent moisture penetration.  Not necessary when a roof is under drawn with felt, again an indication of age.

Tread                                        The horizontal part of a step or stair.

Trussed Rafters                      Modern method of roof construction utilising prefabricated triangular framework of timbers.

Underpinning                          Method of strengthening weak foundations whereby a new, stronger foundation is placed beneath the original.

Valley Gutter                           Sloping gutter, usually lead or tile lined, at the internal intersection between two roof slopes.

Vapour Barrier                        An impermeable layer, often of polythene, fixed to prevent condensation causing rot and decay in a timber structure.

Ventilation                               Necessary in all buildings and sections of the structure to disperse moisture resulting from bathing, cooking, breathing etc, and to assist in prevention of condensation. 

Verge                                        The edge of the roof, especially over a gable or around a dormer window or skylight.

Wall Plate                                 Timber placed at the top of a wall, designed to take the weight of the roof or floor timbers.

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 Board                         A timber section fixed to the bottom of a door to prevent rainwater driving in.

Weep holes                              Small holes or open vertical brick joints in a wall to allow moisture to drain out.

 

Wet Rot                                     (Coniphora Puteana). Decay of timber due to damp conditions.  Not to be confused with the more serious dry rot.

 

Woodworm                              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.