Glossary

This glossary has been created to help you understand the terminology used by builders, loft converters, architects, planners, as well as others when it comes to discussing issues involved with your loft conversion. We hope you find it helpful if there is anything we have not covered below and you have a technical question please don’t hesitate to ask, call or drop us an email.

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AIRBRICK
A special brick with holes, built into an external wall to provide background ventilation.(see BACKGROUND VENTILATION)

ALTERNATIVE ESCAPE ROUTES
Escape routes sufficiently separated by either direction and space, or by fire-resisting construction, to ensure that one is still available should the other be affected by fire.

ALTERNATING TREAD
A special paddle shaped tread with the wide portion alternating from one side of the stair to the other. Designed to save space and used in both straight flights and spiral (circular) stairs.
(see SPIRAL STAIR)

APEX (Roof)
The Point at the centre of the room, often where to roof pitches meet a point.

APEX HEIGHT
The Internal height in the loft at the centre.

APPROVED DOCUMENTS
A series of technical documents explaining the practical details in The Building Regulations and how they should be interpreted.

ARCHITRAVE
A plain or moulded section around a door or window opening.

ASPHALT
Mastic asphalt applied hot in semi-liquid from as a waterproof coating to flat roofs, basement tankings and exterioir staircases.

ATTIC
The empty space in a roof. (see LOFT)

BACK ADDITION
Projecting rear wing or section of house

BACKGROUND VENTILATION
Permanent ventilation consisting of airbricks, grilles and hit-&-miss ventilators, required in all habitable rooms under the Building Regulations.(see AIRBRICK)

BALUSTER
One of several vertical members used to infill a balustrade. (see AIRBRICK)

BALUSTRADE
A protective barrier on a staircase formed by a series of balusters capped by a handrail. The height of balustrades and spacing of balusters are given in Approved Document K.(see BALUSTER, HANDRAIL)

BATTEN
A small sawn timber section fixed across the rafters on a roof to provide support for tiles or slates.(see COUNTER BATTEN)

BARGE BOARD
Sloping timber fascia to roof verge or gable end.

BASEMENT CONVERSIONS
Basement conversions can be cramped and have no natural light. A better way to add living space to your property is through a loft conversion. In the UK loft conversions are an effective way to add real value to your house. This is because loft conversions are more pleasant to use as living quarters due to the increase in natural light and airflow possible through the use of windows in the loft

BEAM
A long timber, steel or concrete member designed to carry loads over a span between supports.(see SPAN, DEAD LOAD, IMPOSED LOAD)

BINDER
A timber joist spanning across the ceiling joists to strengthen them.

BLANKET INSULATION
Insulating material loosely compressed into a flexible slab or blanket. eg. glass fibre or mineral wool.

BLOWN
Defective render of plaster lifting from base, hollow and loose

BOARDED ROOF
A roof structure in which the rafters are covered externally with boarding before the roofing felt and tile/slate battens are fixed.

BOX FRAME
A simple square frame made from four members (usually timber) joined together at to each other. e.g. around an opening for a loft access hatch* or a roof window*.

BREEZE BLOCK
Building Blocks made from cinders and cement used for internal and inner skins of cavity walls

BUILDING ACT 1984
The statutory Act of Parliament that controls the safe construction, extension and alteration to all building in England, Wales and Ireland.

BUILDING CONTROL BODY
A term used to include the local Authority Building Control department and its Approved Building Inspectors. see BUILDING INSPECTOR)

BUILDING INSPECTOR
An official of the Local Authority Building Control department, who inspects building work to ensure it complies with Building Regulations.

BUILDING REGULATIONS
The detailed rules of construction as specified in the Act and explained in the Approved Documents. (except in Scotland and Northern Ireland which have different legislation)

CASEMENT
Opoening hinged part of a window

CAULKING
Sealing to edges around bath and showers areas


CEILING
The soffit of any floor (above the ground floor) in a building which is exposed overhead and may be integral with the floor structure, or suspended below it.
(see SUSPENDED CEILING)

CHEEK
Side face to roof dormer or bay

CHANNEL
A 'U' shaped section, usually of steel, used as a structural support. (see I-BEAM)

CILL
(see SILL)

CLEARANCE
The space between two adjacent surfaces, close together but not touching. eg., a door or window and its frame.

COLD WATER STORAGE CISTERN
An open-topped tank to store water from a rising main and fitted with a ball-valve and overflow pipe.(see TANK)

COLLAR
High level roof timber running between opposing rafters to prevent spread.(see TIE)

COMBINATION BOILER
‘Combi Boiler provides heating and hot water directly from the mains with no need for staorage tanks

CONDENSATION
Water droplets deposited from warm, damp air when it comes into contact with any cold surface.

CONDUIT
A rigid tube or duct to carry and protect electrical, telephone and computer wiring.

CONSERVATION AREA
Any area of natural beauty and resources which requires protection, preservation and sustained management. eg. The National Parks, The Broads etc.

CONSUMER UNIT
The assembly of separate fuses with an isolation switch in a protected enclosure, connected to the incoming electricity supply. (also known as a FUSEBOARD)

COPING
Brick, stone or tile finish to top of parapet

CORNICE
DEcritive plaster or rendered moudling at a junction of wall and ceiling or below an external parapet

COUNTER BATTEN
A small sawn timber section fixed over a boarded and felted roof in the opposite direction to and providing support for the tile/slate
battens and allowing natural ventilation. (see BATTEN)

CUT OR OPEN STRING
A string with the upper edge cut away to the shape of the treads and risers so that their profile can be seen from the side.

DCLG
The Department for Communities and Local Government (which now supercedes the ODPM - Office of the Deputy Prime Minister)

DEAD LOAD
The load due to the weight of all walls, permanent partitions, floors, beams, roofs and finishes including services and all other permanent elements of construction.
(see IMPOSED LOAD)

DOOR LINING
An alternative to a door frame in a stud partition, which uses a section of 25mm (nominal) timber to the full thickness of the partition.

DORMER WINDOW
A structure projecting above the roof slope to let in light and provide ventilation to a loft conversion and also to provide additional headroom. (see ROOF WINDOW)

DRY ROT
A fungal growth that attacks and destroys timber by absorbing its moisture. It also has the ability to spread rapidly and, if untreated, can cause serious damage to the building structure. Dry rot is usually caused by poor ventilation. (see WET ROT)

DRYWALL
A term from the USA/Canada, to describe the construction of stud partitioning covered with plasterboard. (see STUD PARTITION, PLASTERBOARD)

EAVES
The lowest part of a roof around its periphery, which projects beyond the face of the wall below.

ESCAPE ROUTE
Any route forming part of the means of escape from any point in a building to the final exit. (see FINAL EXIT)

ESTIMATE
A price given by a builder or trade company which is approximate. Not to be confused with a Quotation. (see TENDER or QUOTATION)

EVES LOFT CONVERSION
When the loft conversion is within the existing roof pitch. Sometimes call a velux conversion.


EXPANSION PIPE
An open ended pipe designed to discharge over-heated water from a hot water cylinder and which usually terminates over an expansion tank. (see OVERFLOW PIPE)

EXPANSION TANK or HEADER TANK
A small open-topped cistern (tank) containing water with which to top up a central heating system.

EXTRACT VENTILATION
Any means of extracting stale air from a bathroom or kitchen. (see PSV, also Approved Document F)

FASCIA
A vertical board or trim fixed along the eaves to cover the ends of the rafters and on which to fix the gutter. (see GUTTER, RAFTER)

FEASIBILITY STUDY
The feasibility study is the way to determine the most efficient, cost effective way of carrying out your loft conversion. An experienced surveyor will visit your property and inspect your roof space discussing specific issues with you that arise without obligation

FELTING
Felt sheet soaked in bitumen and used over the rafters to line the roof before the tile/slate battens are fixed.

FINAL EXIT
The termination of any escape route from a building giving access to a passageway, street or open space and sited so that persons are not in any danger from fire or smoke.

FINISHED SIZE
The actual size of a timber member after it has been machined. e.g 50mm x 100mm nominal timber will machine to 45mm x 95mm actual size. (see PAR TIMBER, SAWN TIMBER)

FIRECHECK DOOR
A door designed to withstand the passage of fire for a given period of time. eg. an FD20 door will resist fire for 20 minutes.

FIRE RESISTANCE
The ability of any component of construction to satisfy, for a stated period of time, some or all of the criteria specified in the relevant part of BS.476.

FLASHING
Any weatherproof material, usually galvanised steel or lead, used to cover the gaps between two adjoining materials, for example on a roof or chimney stack or around openings such as doors and windows.

FLIGHT
The series of consecutive treads and risers which make up a stair. (see TREAD, RISER)

FLUSH FIT
Any element of construction or finish with at least one face that does not project beyond the face of any adjacent element(s).

FORCED VENTILATION
(see EXTRACT VENTILATION)

FUSEBOARD
(see CONSUMER UNIT)

GABLE
The triangular upper portion of a wall below the ends of the roof slopes.)

GOING
The horizontal distance between the risers of two consecutive stair treads.
(see TREAD, RISER and also Approved Document K)

GUARD RAIL
A safety rail fitted around an opening in a floor (eg. a loft access hatch) or where there is a change of level.

HABITABLE ROOM
A room used, or intended to be used, for dwelling purposes, including a kitchen but not a bathroom.

HANDRAIL
The member fitted along the top of a stair balustrade to provide support for any person using the stair.

HATCH*
An opening in a ceiling to provide access into a loft space and usually fitted with a hatch door.

HEAD
The top member of a stud partition or the frame of a lining around a door or window. (see STUD PARTITION)

HEAD OF WATER
The vertical distance between the water in a storage tank or cistern and any appliance it feeds. eg. a shower which will require sufficient 'head' of water for it to operate correctly.

HEADROOM
The clear height in a room or doorway to allow a person to stand without bending.

HELICAL STAIR*
(see SPIRAL STAIR)

HIP
The junction between the two outer slopes of a pitched roof. (see RIDGE,VALLEY)

HIP TO GABLE LOFT CONVERSION
A ‘hip to gable' conversion is an alternative to a side dormer. Your decision on this can be assisted by our Surveyor who will explain the various benefits of each possible solution.

HIT-&-MISS VENTILATOR
A special ventilator grille built into an external wall to provide background ventilation and which can be opened and closed. (see RAPID VENTILATION)

I-BEAM
A structural member with a central spine and two flanges in the shape of a letter 'I'.(see CHANNEL)

IMPOSED LOAD
The load produced by the intended occupancy or use, including the weight of all movable partitions, furniture, persons, distributed, concentrated, impact and snow loads, but excluding wind loads. (see DEAD LOAD)

JAMB
The side members of a frame or lining around a door or window.

JOIST
A structural member of timber or steel and spanning between supports and designed to carry loads.

JOIST CENTRES
The distance between joists (in a floor or ceiling) measured from centre to centre of each one.

JOIST HANGER
A metal bracket designed to support the ends of timber joists where they cannot be built into the supporting wall or other structural element.

JUNCTION BOX
An enclosed box in which electric cables are joined together.

LADDER
An arrangement of treads supported by side members and used as a means of access from one level to another.

LANDING
A level platform at the top of a flight of stairs or at a change of direction in a stair.

LATH & PLASTER
The traditional method (now obsolete) of covering walls and ceilings, in use until the 1950‘s (approx) when it was replaced by plasterboard sheeting. (see DRYWALL, PLASTERBOARD)

LINTEL
A timber, steel or concrete structural member used to span an opening and support a load. eg. over a window or door.

LIVE LOAD
(see IMPOSED LOAD)

LOAD BEARING
Any structural part of a building designed to carry imposed loads. eg. a brick or concrete wall, steel or concrete pillar or timber, steel or concrete floor.

LOFT
The space below the rafters in a roof and above the ceiling, which may be of use as habitable space.

LOOSE FILL INSULATION
Insulation, such as mica pellets, used for heat insulation around hot water cylinders and between ceiling joists.

MANSARD
A roof Dormer conversion with a sloping front of 70° which can take either roof lights in the slope of the new roof or new vertical windows. It can have brick cheeks to keep in character with the property

MEANS OF ESCAPE
A protected route used in the event of fire to provide egress for persons to a place of safety.

MINIMUM HEADROOM
The buildings regulations do not specify a minimum height requirement for new rooms, however, there is a requirement of a minimum height of 2m from the top of the stairs.

MOE WINDOW
A special 'means of escape' roof window which complies with the dimensions set out in the Building Regulations (see Approved Document B)

NEWEL CAP
The square or round block on the top of a newel post, sometimes fitted with a decorative finial.

NEWEL POST
Accommodates the strings, handrails and treads/risers of stairs. A structural member of a staircase either plain or decorative.

NOGGING
A short horizontal member fitted between the studs in a framed partition.
(see STUD PARTITION)

NOSING
The front edge of a stair tread, often rounded.

OPEN RISER
A stair in which all the vertical risers are omitted.

OVERFLOW PIPE
An open-ended pipe designed to discharge water from a tank or cistern when it oveflows. eg. a toilet cistern.

PACKING
Any material used to fill a gap between two adjacent surfaces.

PAR TIMBER
PAR (planed all round) timber which has been machined on all four faces to precise dimensions. eg.. 50mm x 100mm sawn timber will reduce to 45mm x 95mm (approx) after machining PARTITION. (see STUD PARTITION)

PARTY WALL
A wall built on the boundary between two buildings (as in semi-detached houses) which is common to both and subject to legislation in the Building Regulations and The Party Wall etc. Act 1996

PITCH
The degree of slope of a structural member or roof especially when expressed as the ratio of height to span. (i.e, a 30° pitch.)

PITCHED ROOF
A roof with a slope greater than 150 to the horizontal.

PLANNING PERMISSION
The approval required from a Local Authority for permission to do work on any building under the Town & Country Planning Act 1962.

PLASTERBOARD
A sheet material consisting of compressed gypsum plaster between two sheets of tough building paper.

POLYCARBONATE
A transparent unbreakable thermoplastic resin used for domed roof lights.

PROTECTED STAIRWAY
A stair that discharges to a final exit and place of safety, and is adequately enclosed by fire-resisting construction. (see FINAL EXIT)

PSV
'Passive stack ventilation' is a system of ventilation that uses ducts from the ceilings of rooms to terminals in the roof and operates by a combination of the natural movement of warm air, and the effect of wind over the external surface of the roof.(see also Approved Document F)

PURLIN
The horizontal timber or steel beam which provides support for the rafters in a roof.

RAFTER
One of several parallel sloping timber or steel members which form the roof of a building.

RAIL
The horizontal member fitted between the two vertical stiles in a framed and panelled door.

RAMP
A sloping surface connecting two other surfaces at different levels.

RAPID VENTILATION
A permanent method of ventilation, such as a window, that provides a natural flow of air. (see also Approved Document F)

RIDGE
The apex of a pitched roof at the junction of two slopes.

RIDGE BOARD
The horizontal timber member which spans the length of the roof and supports the ends of the rafters.

RING MAIN or RING CIRCUIT
(see CONSUMER UNIT)

RISE
The vertical distance between two consecutive treads in a stair.
(see GOING, also Approved Document K)

RISER
The vertical member which separates and connects the treads in a stair.
(see TREAD)

RISING BUTT HINGE
A special type of hinge which operates as a self-closing mechanism when a door is open.

RISING MAIN
The supply of mains water to a building which usually terminates in the roof in a cold water storage tank.
(see COLD WATER STORAGE CISTERN)

ROOF DOME
A clear plastic dome (normally made from polycarbonate)

ROOFLIGHT
A dome light, lantern light, skylight, ridge light, glazed barrel vault or other element intended to admit daylight through a roof. (see ROOF DOME, ROOF WINDOW)

ROOF TRUSS
A framed assembly of structural members consisting of ceiling joists, rafters, struts and ties. Not to be confused with trussed rafters. (see TRUSSED RAFTER)

ROOF WINDOW
An opening window fitted into the roof slope and parallel with it. Also available as an alternative means of escape MOE* window. (see MOE WINDOW, also ApprovedDocument B)

SARKING
A felting sheet laid over the rafters to provide a weatherproof barrier under the tile/slate battens.

SASH
The opening part of a casement or sash window into which the glazing is fixed.

SAWN TIMBER
Timber in its rough state prior to being machined. Sawn sizes are nominal, whereas machined sizes are actual and. referred to as PAR. (see FINISHED SIZE, PAR TIMBER)

SIDE DORMER
If your house is Semi-detached with a ‘hip-ended' sloping roof at the side it may be necessary to add a side dormer. This will provide much needed headroom above the new staircase. Pinnacle Loft Conversions will suggest a design for this extension which is sympathetic to the style of your house.

SILL
A horizontal member made of timber, brick, stone or concrete onto which a door or window frame is fixed.

SKEW NAILING
A method of nailing at an angle when constructing stud partitions.

SKIRTING
A narrow timber member fixed around the base of internal walls to protect the wall finish from being kicked or damaged. In a kitchen or bathroom the skirting can also be of tiles.

SKYLIGHT
A window inserted in a flat or pitched roof to provide natural light to the room below. (see ROOF WINDOW)

SLATE
A fine-grained rock capable of being easily split into very thin layers and used for roofing and flooring tiles. (see TILE)

SOFFIT
The underside of an overhanging part of a building, typically between the fascia board and the external wall and below the roof.

SOIL PIPE
A pipe designed to carry away effluent from bathrooms and kitchens on one or more floors of a building. (see SOIL VENT STACK)

SOIL VENT STACK
A pipe designed to carry away effluent from one or more floors of a building, which terminates above the eaves level of the roof and provides ventilation to the foul water drain into which it discharges. (see SOIL PIPE)

SPAN
The clear distance between two supports or bearings measured along the length of a structural member

SPIRAL STAIR*
A staircase with tapered treads assembled around a central column. Also referred to as a helical stair.

STAIR or STAIRCASE
A structure made from a series of steps held between and fixed to two side members (strings) to provide access between two different levels. (see RISER, TREAD, STRING, also Approved Document K)

STRING or STRINGBOARD
The two structural side members of a stair into which the treads and risers are fixed. (see TREAD, RISER)

STAY
A metal bar designed to hold a window sash in the open or closed position.

STILE
The two vertical side members which make up a framed and panelled door.

STRUT
A structural member designed to resist compression stresses and used in a roof to support the purlins. (see TIE)

STUD
A vertical timber used in the construction of stud partitions.

STUD PARTITION
A series of vertical studs and horizontal noggings nailed together to form a framed partition and usually covered with plasterboard on both sides. (see DRYWALL, STUD, NOGGING)

SUSPENDED CEILING
A non-structural element fixed below the soffit of the structural floor, and which lowers the height of the room and may contribute to fire resistance. (see CEILING, also Approved Document B)

TANK
A closed cistern similar to a hot water cylinder but rectangular. Often mistakenly termed a cistern. (see CISTERN)

TAPERED TREAD
A stair tread that is wider at its outer edge and used in spiral stairs.

TCPA
The Town & Country Planning Act, 1962, a statutory Act of Parliament which controls the planned development of both rural and urban areas in the UK.

TEMPLATE
An exact pattern used as a master for cutting repetitive and awkward shapes such as alternating treads. (see ALTERNATING TREAD)

TENDER or QUOTATION
A firm price given for work by a builder or trade company. Not to be confused with an estimate. (see ESTIMATE)

THERMAL CONDUCTIVITY
A measure of the rate at which heat passes through any material or structure and expressed in watts per metre thickness per degree of temperature difference ( = W/m/K) (see also Approved Document L)

THERMAL TRANSMITTANCE
(see ‘U’ VALUE)

TIE
A structural member designed to resist tension stresses and used in roof trusses.
(see STRUT)

TILE
A durable weatherproof material used for roofing and normally made from burnt clay, or concrete with integral nibs on the lower side which hook over the tile/slate battens. (see SLATE)
TRANSOM
Any horizontal member fixed across an opening such as a window frame.

TRAP
The bend in a waste or soil pipe which forms a water-seal to prevent foul gases escaping into the building. Traps are designated 'P', 'S' or 'U' according to their shape.

TRAP DOOR
An access door into a loft space usually hinged and fixed into a frame.

TREAD
The horizontal member in a stair that separates and connects the risers.
(see RISER)

TRIMMER
A structural member normally of timber which spans between two other structural members to form an opening. eg. for a stair or ladder.

TRUSSED RAFTER
A method of roof construction (post 1960) using pre-fabricated triangular frames made with small section timbers fixed together with metal plates. The frames are placed at regular intervals (normally 600mm) along the supporting walls of the building and replace the traditional purlin and rafterconstruction.

'U' VALUE
The ‘U’ value or thermal transmittance is a measure of the rate at which heat passes through one metre° of any material or structure, when the air temperature on either side differs by one degree. The value is expressed in watts per metre square temperature difference. (U = W/m2 /K)
(see also Approved Document L)

VALLEY
The junction between the two inner slopes of a pitched roof which form the valley gutter.

VENTILATION OPENING
Any means of ventilation which opens directly to the external air, such as a window, door, airbrick, or louvred ventilator.

WALL PLATE
A load bearing timber member laid on top of a structural wall onto which the floor, ceiling and rafters members are fixed.

WASTE PIPE
A pipe which carries waste water from a basin, bath or sink and either discharges over an external gully or into a soil stack.
(see SOIL PIPE, SOIL VENT STACK)

WET ROT
A fungal growth which survives on wet conditions and attacks timber. The growth will usually cease when the building dries out. (see DRY ROT)

WINDER
A tapered tread which allows a change of direction in a stair and used where space is restricted.