Air Brick

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.

Barge Board

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

Cavity Wall

External wall, comprising inner and outer "skin", each either brick or some form of block with space between of about 2". Properly constructed, it is more resistant to damp penetration than solid wall. Thermal insulation also higher. In modern timber framed dwellings, timber framing forms the inner "skin", then often clothed with outer skin of brick or similar to give traditional appearance. 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 a "bridge "between skins of wall across which moisture could pass. Important that work done by experienced and reliable company.

Cesspool

Watertight chamber in which sewage effluent is collected. Has to be emptied at intervals ­ service usually provided by Local Authority for which a charge is made: can be substantial annual outgoing if frequent emptying needed. Sometimes outlet provided from cesspool to allow some soakage into surrounding ground ­ not strictly in accord with Local Authority regulations but most "turn a blind eye".

Collar (in roof)

Timber that ties across between rafters on either side of a roof at some point above the feet of the rafters.

Collar (in drain)

Wider end of pipe into which another pipe fits.

Damp Proof Course

Layer 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. Most common material used today is bituminous felt, or (increasingly) heavy-duty polythene. In older works slates often used (two courses set in cement mortar). Rarer form, cheaper and ineffective in long term, was just a layer of bitumen. When inserting new d.p.c. in old building, "chemical" form used consisting of impregnating wall at ground floor level with chemical, which percolates walls and forms barrier against rising damp.

Damp Proof

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

Dry Rot / Wet Rot

Fungus growth which causes breakdown in fibrous texture of timber. Conditions conducive to growth of dry rot are damp, coupled with stagnant air, e.g. if sub-floor ventilation is lacking (see "air brick" above and "floors" below). Wet rot thrives in similar conditions also in external joinery unless maintenance is meticulous. Does not worsen after damp source removed, unlike dry rot which will continue to spread and affect new timber or adjoining areas if not properly treated.

Eaves

Projecting edge of a roof.

Fascia

Vertical board at eaves level to which guttering often attached.

Fillet

Method of weatherproofing joint between roof covering and brickwork, e.g. around the base of chimney. Most frequently in cement but sometimes of tile set in cement. Less satisfactory than flashing (see below) because of inflexibility and liability to crack.

Flashing

Method of waterproofing joint between roof covering and brickwork by lead (in good quality work) or other metal.

Floors

Two types: timber suspended (or joint) and solid. Timber suspended means system of joists covered with floor boarding or chipboard in modern, cheaper work, at first floor level suspended between walls and resting in them, at ground floor level, most often supported by small "sleeper" walls on over-site concrete. Cavity between concrete and floor boarding should be ventilated by air bricks set into external walls to avoid formation of stagnant pockets of damp air, conducive to growth of dry rot. Solid floor usually formed of hardcore, surmounted by 4" to 6" concrete, thence damp proof membrane with final surfacing of cement screed and tiles or woodblock. Cement screed is often left uncovered for covering with carpet.

Gable

Triangular part of an exterior wall beneath two roof slopes.

Gutters

Formed in cast iron in older properties and of two basic designs (i) half round ­ semi-circular section fixed to fascia with brackets (ii) Ogee ­ a different pattern with vertical rear side screwed direct to fascia ­ disadvantage is that it restricts decoration of fascia and rear face of gutter: rusting and failure of gutter can result, and in extreme cases, rot in fascia and feet of rafters. In more recent times, vinyl guttering and downpipes commonly used and have advantage of not requiring painting, but can fade and/or become brittle.

Hanger

Vertical timber fixed between rafters and runner (see below) to provide additional support to ceilings.

Header Tank

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

Hip

External angle formed by roof when end slopes backwards instead of ending in a gable. Usually protected by tiles (hip tile) even on slate roof.

Land Drain

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

Lath & Plaster

Traditional way of forming plaster surface in ceilings or timber partitions. Comprises number of horizontal battens or laths which form a key for the plaster. Now largely obsolete and replaced by plasterboard.

Lintel

Beam normally of concrete or metal ­ sometimes timber ­ spanning opening in a wall to support the wall above.

Purlin

Horizontal timber in roof space which provides intermediate support to rafters.

Rafter (common rafter)

Inclined timber immediately beneath the roof covering to which the tiling battens or boarding for sloping roofs are fixed.

Reveal

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

Ridge

The horizontal line at the apex of a roof. Usually has tile covering (ridge tile).

Roof Truss

Triangular framework of structural members supporting a roof, carrying horizontal members (purlins) which in turn support common rafters. (See also "Trussed Rafter" below).

Runner or Binder

Horizontal timber placed at right angles to and above ceiling joists to stiffen ceiling and provide additional support.

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 a soakaway (see below) for the purified liquid effluent. Occasional emptying may be needed, but dependant upon soil conditions and method of use, septic tank can remain undisturbed for number of years. New land drains or soakaways may also be required but on average probably at intervals of not less than ten years.

Soakaway

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

Soffit

The underside of an overhanging eaves or archway. Sometimes used to describe sloping section inside a house beneath a roof or staircase.

Strut

Load bearing timbers normally supporting purlin (see above) and fixed at an angle down to a wall or some other load bearing point.

Stud Partition

Wall formed of pieces of timber (stud) covered plasterboard or lath and plaster in older work. Unless specially constructed, unlikely to give sound insulation of solid (brick or block) partition.

Tie Bar

Metal bar inserted across (old) building to tie outer walls together, i.e. to arrest movement in structure and improve stability.

Trussed Rafter

Derivative of roof truss (see above). Factory made timber framework used instead of common rafters joined together by metal connectors or adhesive.

Valley

Internal angle formed by the outside surfaces of two adjoining roof slopes. Can be tiled or formed in lead or, less durably, in felt. May be called "valley gutter", particularly where horizontal, i.e. between two parallel adjacent sloping roofs.

Verge

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

Wall Plate

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

Wall Tie

Metal connector used to provide structural link between inner and outer skins of cavity wall.

Woodborer Infestation "Woodworm"

Insect that attacks structural timber and joinery. Eggs are laid by the insect. Resulting grub eats away within the timber for several years before emerging as ­ adult insect (completing the life cycle) through distinctive and characteristic flight holes in spring/early summer. Serious infestation can ultimately result in breakdown of timber but is relatively slow process. Most usual attack is by common furniture beetle. Other species are more voracious such as Deathwatch Beetle and House Longhorn Beetle. Latter particularly damaging in a short term.