ABUTMENT  An intersection usually between a roof and a wall.

AIRBRICK  A perforated brick built into a wall to ventilate a   room  or the underside of a wooden floor.

APRON (WALL OR PANEL) That section of a wall below a window.

BAKELITE   One of the earliest plastics.

BALL VALVE (BALL COCK) Valve operated by a ball floating in a cistern.

BALUSTER   A post in a balustrade

BALUSTRADE   Collective name to the whole infilling from handrail down to floor level at edge of a stair.

BARGE BOARD   A sloping board built along a gable edge of a roof.

BAY WINDOW   A window formed in projection of the wall beyond its general line and carried on foundations.

BEAM   A structural component spanning an open space and designed to carry the weight of the structure above.

BLISTERING   Air bubbles below bituminous felt, asphalt or painted surfaces usually indicating imminent failure of the material.

BONNET ROOF   A roof over a bay window.

BONNET TILE   A hip tile with a bonnet-like appearance.

BRESSAMER A large timber beam more commonly found in older buildings.

CASEMENT WINDOW  A window in which one or more lights are hinged to open.

CAVITY WALL   A wall comprising two leafs of brick or blockwork tied together, with an air gap/insulation between.

CEILING JOIST  A joist which only carries the weight of the ceiling beneath it.

CENTRAL HEATING  Heating of a building comprising a central boiler distributing hot water to heat the radiators.

CLADDING   The non-loadbearing external skin of a wall or roof used to keep the weather out.

CLOSED VALLEY  A gutter at the junction of two roof where the slates or tiles are cut to meet on the valley line.

COLD DECK ROOF  Used to describe a flat roof in which the insulation is placed below the deck.  (See also WARM DECK ROOF).

COLLAR   Horizontal timber spanning between rafters of a pitched roof preventing outward movement thereof.

CONCRETE TILE  A roof tile made of concrete rather than of the  traditional clay material.

CONDENSATION  Surface condensation is seen as dew drops or damp  patches on indoor surfaces caused by the release of moisture from air as it is cooled below its dew point.

CONDUIT   Usually a metal or plastic tube used to protect electrical cables.

COPING   The top of a wall.  Usually finished with a concrete moulding or bricks laid on edge.

CORBEL   Usually a brick or masonry projection from the wall face either used for decoration or a support for a  beam or other structural component.

COURSE  A horizontal layer of bricks, blocks, slates etc. including any mortar laid with them.

COVER FLASHING  A vertical flashing overlapping the vertical upturned parts of a roof covering or other flashing.


CRAZING  Hairline cracks on the surface of concrete, cement render or plaster usually of random pattern over a large area or the whole surface.

DADO RAIL  Usually a timber moulding around the perimeter of a room approximately three feet above skirting level.

DAMP PROOF COURSE  (DPC) A horizontal layer of impervious material laid in a wall to prevent moisture rising to a higher level.  Vertical damp proof courses are used in cavity wall construction.

DAMP PROOF MEBRANE (DPM) A layer of polythene or other similar material laid over a concrete ground floor slab to prevent moisture rising to higher level.

DIFFERENTIAL MOVEMENT  Movement of different intensity either within a single material or between varying materials.

DORMER  A vertical window through a sloping roof provided with its own small pitched or flat roof.

DORMER CHEEK  The vertical side of a dormer.

DOUBLE GLAZING  A double layer of glazing separated by an air space for thermal and accoustic insulation.  Usually provided as sealed units commonly set in hardwood,   aluminium or pvc frames. (See also SECONDARY GLAZING).

DOUBLE HUNG SASH WINDOW  A pair of vertically sliding sash windows.

DOWNPIPE   A vertical pipe which brings rainwater to ground level from roof gutters or waste water from hoppers.

DRAIN   Underground system of piping to discharge water and sewage away from the building.

DRIP or THROAT  A groove under an overhanging edge (e.g. window cill) designed to stop water running down the face of the building.

DRY ROT   Decay of timber due to the fungus Serpula Lacrymans.  Usually considered to the most serious timber decay.

EAVES   The lowest edge of a sloping roof.

(EDGE) DETAILING  The intricate construction around the perimeter of a flat roof.

EFFLORESCENCE  Powdery white salts left on a wall surface as it dries out.  Usually associated with new brickwork.

EXPANSION TANK  Small tank required for most central heating installations to provide water for the central heating installation and overflow therefrom.

FASCIA BOARD  A vertical timber board fixed to the rafter end or wall plate or wall to carry the gutter at the eaves.

FILLET   A narrow strip of wood or cement fixed to the angle between two surfaces.

FIRE RESISTANT or FIRE RESISTANCE Period of time for which an element of theconstruction will resist the penetration of fire. Usually measured in periods of half an hour.

FLASHING   A strip of impervious material usually flexible metal that excludes water from the junction between a roof covering and another surface.

FLAT ROOF   A roof which slopes at less than ten degrees to the horizontal but which should not be truly horizontal.

FLAUNCHING   A cement mortar fillet around the top of a chimney stack to throw off the rain.

FLOOR JOIST   A joist which supports a floor and in the case of upper floors, also supports the ceiling to the room below.

FLUSH PIPE   The pipe between a WC cistern and bowl.

FRACTURE   Another term for a wide crack the cause for which is usually structural in nature.


GABLE   The triangular part of a wall under the edge of a sloping roof.

GULLEY   A fitting of the underground surface water or waste water drain over which downpipes or other above ground drainage discharge.  There are various types e.g. open gulley, back inlet gulley.

HEAD   The upper horizontal member of a door frame, window frame, partition frame etc.

HIP   The external edge at the junction between two roof surfaces.

HIPPED END   The sloping triangular end of a pitched roof.  It is an alternative to a gable end.

HIP END SLOPE  The triangular slope at the end of a pitched roof.

HIP RAFTER   The rafter below the hip.

HOPPER (HOPPER HEAD) An enlarged top usually to a vertical pipe where it receives water from rainwater or waste pipes.

INSPECTION CHAMBER Another term for a manhole located over an underground drainage installation to allow access for  cleaning and other maintenance.

INTERSTITIAL CONDENSATION Condensation which occurs within the thickness of a material rather than on its surface.

JAMB   The vertical post of a door or window frame.

JOIST   A (timber) beam supporting floorboards or ceiling.  Usually arranged at max. 600m centres.

KERB   A profile fixed to a flat roof deck abutting an adjacent wall but not fixed to it.  Usually of shaped timber construction.

LATH   Small section timbers at very close centres which form the backing for plaster on ceilings or timber framed partitions   usually in older buildings.

LEAN-TO   A roof sloping one way only, who's upper edge is supported on a wall higher than the top of the roof.

LINTEL   A small beam over a door or window.

LOAD BEARING  Term usually applied to walls or other structures which carry a load from walls, floors or roof at higher level.

MANHOLE   See inspection chamber.

MANSARD ROOF  A pitched roof which has, on each side, a shallower upper slope and a steeper lower slope and often contains dormers.

MASTIC   A permanently flexible waterproofing material mostly used for sealing external or water-vulnerable joints in building or glazing etc.

MATCH BOARD   Flat boards laid side by side with mouldings or rebates on each edge.  The term is usually applied to wall or ceiling linings.

MORTAR   A mixture of sand and cement used for laying bricks, blocks etc.

MORTICE LOCK  A lock set within the door thickness.

MULLION   An intermediate vertical component to a window frame.

NEWEL POST   The vertical post at the foot or top of a timber flight of stairs, between which the balustrade spans.

OPEN VALLEY   A valley gutter in which the slates or tiles are so cut that the metal sheet or other waterproof  material laid under them in the valley, is exposed.

PARAPET   A section of an external wall rising slightly above a pitched or flat roof, and finished with a coping.

PARAPET GUTTER  The gutter behind a parapet wall between the wall and the roof.

PARTITION   A wall between rooms usually non-load bearing.

PATENT GLAZING  Large area of glazing set within long glazing bars.

PIER   Projecting load-bearing brick or blockwork on each side of an opening usually carrying a beam.

PITCHED ROOF  A roof with two or more slopes at more than ten degrees to the horizontal meeting at a central ridge.

POINTING   The surface mortar between brickwork to a depth of approximately 19mm with one of several profiles.

PURLIN   A horizontal beam in a roof construction at right angles to and supporting the rafters.

RAFTER   A sloping timber extending from ridge to eaves of a roof.

REAR ADDITION  That narrower section of usually Victorian properties extending beyond the main rear wall of the house.

RENDER   Cement based plaster usually applied externally to the face of a wall.

RETURN SLOPE/ROOF  A slope of a pitched roof usually aligned at right angles to the main slope.  A return roof is the smaller pair of slopes at right angles to the main roof.

REVEAL   A visible edge of a door or window opening in a wall not covered by the frame.

RIDGE   Apex of a pitched roof at the junction of a pair of slopes.

RISING DAMP   The upward movement of water within a wall or floor from the ground.

ROOF DECK   The timber or ply boarding to a flat roof below the waterproof layer.

ROOF VOID   The unused space between the roof and the ceiling of the highest storey.

SARKING FELT  Bituminous felt laid across rafters of a pitched roof.

SASH   One sliding window in a pair forming a 'double hung sash window'.

SCREED   A layer of mortar laid over a concrete floor slab.

SCRIM   Coarse canvass or cotton mesh used for bridging the joint between plasterboard sheets to prevent cracking.

SECONDARY GLAZING  An additional layer of glazing fixed in its own frame within a window opening.

SETTLEMENT   Downward movement of a structure or element of construction due to its own weight.

SOFFIT(E)   The under surface of a projecting eaves, staircase, beam etc.

SOIL VENT PIPE  A vertical wide pipe into which toilet and other waste appliances discharge which is ventilated at its upper end to prevent syphonage.

SOLDIER ARCH  A flat arch of uncut bricks on end.

SOLID FLOOR   A concrete floor slab.

SOLID WALL   A wall of solid brickwork usually 9″ or 13.5″ thick.

SPALL(ING)(ED)  Removal of the face or edges of bricks or other materials by weathering processes.

SPANDREL  A triangular section of wall below the outer string of a staircase.

SPINDLE   See 'baluster'

STRING   The timber beams running up each side of a flight of stairs.  That one fixed to the wall is the 'wall string'; the other is the 'outer string'.

SUBSIDENCE   Downward movement of structural walls and foundations due to a cause other than self weight of the structure.

SURFACE WATER Another term for rainwater.

TELL-TALE  A glass slip or proprietary product fixed across a crack to monitor movement usually of a crack in a wall.

THERMAL MOVEMENT  Movement induced within a single material or between differing materials by thermal expansion or contractions.

THROAT   See also Drip.

TRAP   A U shaped bend in a waste pipe, soil pipe or gulley containing enough water to seal the air downstream of the U, from that above it.

TRUSS   A triangular frame to carry a roof usually at 600mm   centres.

TRANSOM   A horizontal intermediate member of a window or door frame.

UNDERPINNING  A process of providing an additional stronger foundation below an existing wall or foundation.

VALLEY   An internal intersection between two slopes of a pitched roof towards which water flows (i.e. the opposite of a hip).

VERGE   The edge of a sloping roof which overhangs a gable and is usually finished by a barge board.

WALL PLATE   A horizontal timber in or at the top of a wall supporting floor joists, ceiling joists or rafters.

WARM DECK ROOF  The opposite of a cold deck roof.  Insulation is placed between the 'roof deck' and waterproof covering of a flat roof and thus the deck is on the warm side of the insulation.

WASTE PIPE   A pipe to carry water away from a basin, bath or sink.

WATER BAR   A small metal bar rising above the level of threshold to a door to prevent water blowing below it.

WEATHER STRIP  Moulding fitted at the base of an external door to throw water clear from the threshold below.

WET ROT   Decay of timber caused by which will only affect damp timber and unlike dry rot will not spread to seek and destroy other timber.

WOODWORM   Common term for infestation of timber by wood boring beetles such a common furniture beetle, Deathwatch beetle etc

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