Glossary

The following is a list of common terms used in the building industry. Whilst many may be self-explanatory some are not so obvious. We strive to make all our correspondence as clear and understandable as possible but there are times when “only the proper name will do”. Hopefully this glossary will be of assistance.

Barge Board

Wide board (on older work often carved) fitted below tiles of overhanging verge to gable.

Battens

Timber members to which roof tiles are fitted.

Bridles

See "collars" below.

Cavity Wall

Perforated wall, comprising inner and outer "skins", of either brick or some form of block with space between of about 2". "Skins" linked by wall ties, which should be kept clean of mortar droppings during construction, otherwise "bridging" can occur, leading to dampness internally. Properly constructed cavity walls are more resistant to damp penetration than solid walls and thermal insulation is also higher. In modern timber framed dwellings, timber framing forms an inner "skin" then often clad with an outer skin of brick or similar to give a traditional appearance.

Cavity Wall Insulation

In recent years cavity filling with insulation materials has come into use to preserve warmth in buildings. Not always suitable for exposed positions. Unless properly done can form "bridge" between skins of wall across which moisture could pass. Some doubts have also been expressed as to the possibility of toxic fumes emanating from some forms of foam insulation. There is no evidence that this is a significant problem in this country, but this type of insulation is not generally suitable for timber framed walls. It is essential that work is done by an experienced and reliable company.

Cesspool

Watertight chamber in which sewage effluent is collected. Has to be emptied at regular intervals, a service
usually provided by the Local Authority for which a charge is made. Sometimes outlet provided from cesspool to allow soakage into surrounding ground.

Cill

Sloping area below a window or door opening to facilitate rainwater run off.

Collar (in roof)

Timbers around a chimney breast within roof structure, sometimes referred to as "Bridles" or "Trimmers".

Collar (in drain)

Wider end of pipe into which another pipe fits.

Dado

Externally the area of wall usually below damp proof course level often having an alternative finish to the brickwork or roughcast on the sections above damp course level.

Damp-Proof Course (DPC)

Layers of impervious material to prevent passage of water. Either horizontal, inserted at base of walls to stop rising damp, or vertical, e.g. where room is below ground level to prevent lateral passage of water from ground into wall. In older buildings, slates often used. When inserting a new DPC in older buildings, a "chemical" form is frequently used consisting of impregnating wall at ground floor level with silicone, which percolates walls and forms barrier against rising damp.

Damp-Proof Membrane

Similar to DPC, but in solid ground floor to prevent rising damp rising up through floor. Should be connected to DPC in surrounding walls to be fully effective.

Downpipes

Round or square cast iron or plastic tubing to take water from the gutters to the drainage system.

Eaves

Projecting edge of a roof.

Fascia

Vertical board at eaves level to which guttering often attached.

Fibre Quilting

Glass fibre insulation. It should be noted that there is some medical evidence to suggest this form of insulation may be carcinogenic.

Fresh-Air Inlet (FAI)

Perforated brick or grating set into wall to provide ventilation. Most frequently used at the base of walls to ventilate areas beneath joist and boarded ground floors.

Flashing

Method of weather-proofing joist between roof covering and brickwork; formed in lead (in good quality work) or other metal.

Floors

Two types:

Suspended or solid. Suspended means system of joists covered with floor boarding or chipboard supported by small "sleeper" walls on the solum at ground floor level. Cavity between solum and floorboarding should be ventilated by air bricks set into external walls to avoid formation of stagnant pockets of damp air, conducive to growth of rot. Suspended can sometimes also be concrete beam or reinforced concrete particularly in flats.

Solid floor usually formed and incorporating a damp-proof membrane with surfacing of cement screed.

Gable

Side end of property.

Gutters

Open piping at lowest point of roof for the collections of rain water and formed in plastic or cast iron in older properties and to two standard designs. Half-round; a semi-circular section, fixed to fascia with brackets. Ogee; a moulded pattern commonly sitting on the wallhead. In more recent times, plastic guttering commonly used, these have the advantage of not requiring painting, but can fade and/or become brittle.

Header Tank

Small storage tank linked with the central heating system to top up water in that system (normally independent of main cold water storage tank).

Hip

External angle formed by roof instead of ending in a gable.

Joists

See "Floors" above.

Land Drain

Method of disposal of water beneath ground. Usually comprises a drain laid with open joints and surrounded by pea shingle or similar material through which water can disperse into surrounding soil.

Lath and Plaster (Brander and Plaster)

Traditional way of forming plaster surface in ceiling or timber partitions. Comprises a number of horizontal battens or laths, which form a key for the plaster. Now largely obsolete and replaced by plasterboard but regularly found in properties built pre-1940.

Lintel

Beam normally of concrete or metal (sometimes timber) spanning doors and window openings in a wall to support the building materials above.

Mullion

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

Parapets

Sections of wall protruding above the external wallheads. Usually with internal parapet gutters behind. In older properties, these are commonly of lead in good quality work. Normally only found in Victorian or older properties.

Pointing

The seal between window frames and adjacent walls.

Purlins

Horizontal timbers in roof space, which provide intermediate support to rafters.

Rafter

Inclined timber immediately beneath the roof covering to which the tiling battens or sarking for sloping roofs are fixed. (Sometimes referred to as a "Spar").

Reveal/Ingoe

Vertical side of face of an opening for a window or doorway between the frame and face of the wall.

Ridge

The horizontal line at the apex of a roof. Usually has tile, zinc or lead covering.

Roof Truss

Triangular framework of structural members supporting a roof, carrying horizontal members (purlins)[see Purlins] which in turn support common rafters.

Sarking

Material laid on top of rafters to which slates/tiles are fixed.

Septic Tank

Sewage disposal system normally comprising two or three linked chambers within which self purifying (bacterial) process takes place, beyond which is an outfall to drains (land) or soakaways [see Soakaways], for the purified liquid effluent. Occasional emptying may be needed, but dependent upon soil conditions and method of use, septic tanks can remain undisturbed for a number of years. New land drainage or soakaways may also be required, but on average probably at intervals of not less than 10 years.

Skews

Wallhead details normally above slating level.

Soakaways

Method of water disposal usually for surface water, i.e., hole dug in ground and then filled with brick, rubble or similar material, and covered over. Disperses water from drains leading to it, provided surrounding soil conditions are suitable.

Solum

Top of soil or groundlevel

Soffit

The underside of an overhanging eaves.

Strut

Load bearing timbers normally supporting purlin [link to Purlins] and fixed at an angle down to a wall or some other load bearing point.

Threshold

The area at the base of a door or window opening often incorporating draught excluder strips or similar.

Trimmers

See "Collars (in Roof)"

Underfelt

A secondary barrier against wind-driven rain penetration at roof level and also acts to conduct any rainwater which may get access beneath the slates back into the gutters. Laid between the external roof covering and sarking.

Valley/Valley Gutter

Angle formed by the outside surfaces of two adjoining roof slopes. Can be tiled or formed in lead or, less durably, in felt or zinc, particularly between two parallel adjacent sloping roofs.

Vapour Check/Barrier

An impervious layer, usually heavy gauge polythene sheeting, used to prevent passage of moisture in vulnerable parts of a structure.

Verge

Edge of a roof which runs from eaves to ridge at a gable (usually cement pointed).

Wall Head

The upper most section of an external wall.

Wall Plate

Horizontal timber at top of wall on which roof timbers, rafters or joists rest.

Wall Tie

Metal or plastic connector used to provide structural link between inner and outer skins of cavity walls

This glossary is far from being a complete guide to buildings, building works and architectural detail but we hope that you have found it useful and interesting. If, at any time, you hear or see a term or phrase which you think requires explanation please ask and we will endeavour to explain and then add it to the glossary.