INTERNAL FEATURE DEFINITIONS OF BUILDINGS

CEILINGS AND WALLS

Lath and Plaster.
Laths are thin strips of timbers which are fixed to the structure. Wet plaster is applied to the laths, usually in several layers. The plaster forms a key as it is forced between the laths. This plaster, once dry, is given further coats and often a decorative finish. If plasterwork is referred to as having ‘lost it’s key’ it has become separated from the lath structure and is in danger of falling from the wall or ceiling.
Plasterboard
The usual name for Gypsum plasterboard which is building board with a core of aerated gypsum, usually enclosed between two sheets of heavy paper, used as a dry lining.
Dry Lining (Old Properties)
This technique is usually used on solid walls particularly where dampness is occurring. In older properties, where the internal wall is not flush, battens would be added and then lath and plaster. In more modern properties, the walls may be lined with plasterboard on battens or plaster dabs .
Dry Lining (Modern Properties)
Within modern properties, dry lining is a technique used to give an improved drying out time, the plasterboards have a taper to the edge and this is taped and filled, the finish is then sanded smooth. This reduces the amount of moisture as no actual plaster is used and so decoration can commence rapidly. This has obvious benefits for homebuilders.
The term comes from the fact that plasterboard is dry and used as an inner lining within the property. Prior to this a wet plaster was used and required drying out periods which slowed the construction process down. Therefore almost universally in modern properties dry lining is used both as a finishing to internally line the walls and ceilings.
Blown Plaster
This is where the plaster has come away from its base leaving a hollow area. Often caused by a build up of salts behind the plaster as a symptom of rising damp
Bressummer Beam
A bressummer, or breastsummer Beam, in a british building is a large beam which holds up multiple other beams, in the inner parts of a building, such beams are called "summers". in victorian houses this beam is often found in a bay window where the beam holds up the floor of the upstairs room and masonry over the bay area. Breastsummer is an alternate spelling and was from the summer beam in a chimney breast above the fireplace opening.
Sudwork
Usually a timber frame, clad in either lath and plaster or plasterboard and used to divide areas. Studwork can be structural, i.e. load bearing, or alternatively non-structural depending upon its construction. Modern Building Regulation requirements also require minimal sound transfer and this is usually adhered to by the incorporation of insulation material between the studs.
Stud wall
A wall constructed from studwork as opposed to a solid wall of brick, Block or stone

FLOORS

Suspended Timber Floor Construction .
A suspended timber floor usually consists of timbers spanning the ground floor, supported on piers (usually brickwork), vented via air bricks within the walls.
Beam and Block Flooring Construction .
This form of construction uses concrete beams to span the floor in between which blocks are fitted.
Chipboard Flooring/Boarding Construction.
This is formed from small particles of timber which are bonded together into a board normally 1200 x 2400mm (2' x 8') which are then fitted over or secured to the joists forming a floor vented via air bricks within the walls.
Floating Floor Construction .
This type of flooring is relatively modern (last 20 years). It consists of a chipboard flooring (chipboard is formed from small particles of timber which are bonded together into a board), on a vapour barrier on a solid insulation board on a damp proof membrane onto a concrete floor slab. A floor void is not present in this type of construction.
Joist and Floorboard Construction.
Sometimes referred to as suspended floors or timber deck floors These are usually consisting of joists suspended from the external walls, either built in or, in more modern times, sitting upon joist hangers, sometimes taking additional support from internal sleeper walls beneath the floor, with floorboards fixed down upon it.

DOORS

Hollow Core Doors
This is a modern door which uses hardboard as its outer surface and a cardboard latticework as its inner surface. It is very common on modern properties and relatively cheap, but they do damage easily.

WITHIN THE ROOF SPACE

Sarking Felt/Underfelt
This is the felt that sits between the roof covering and the timber battens and forms an additional protective layer to stop the wind lifting the roof and to stop the elements from penetrating the structure. This was first used in the late 1940's/early 1950's and is a requirement for current Building Regulations, though now we have moved onto breathable membranes such as Tyvek whih allow air through but not moisture.
Close Boarding
These are timbers positioned on the common rafters which are butt jointed together. They add to the wind resistance and water-tightness of the roof together with the overall structural integrity of the roof. Usually this type of roof does not have an underfelt, this can lead to problems if the roof is not cross-battened as wet rot can occur to the underside of the timbers. This is very difficult to identify.
Feather Edge Boarding
These are timbers positioned on the common rafters which form the slope of the roof. These timbers are butted together but they are cut at an angle, or feather edged, to give a lip for the nibs of the tiles to sit upon.
Fire Walls
Fire walls help prevent the spread of fire through roofs and are a relatively recent Building Regulation requirement .
Purlins
The purlin is the horizontal timber member usually running from gable end to gable end and parallel with the walls which supports the jack or common rafters (the angled rafters forming the slope to the roof).
Ridge Board
The ridge board forms the apex of the roof and usually denotes that the roof was constructed on site and joins the jack rafters or common rafters together. These are the rafters that form the slope to the pitch of the roof.
Common Rafters
The rafters form the slope to which the battens are secured and in turn the roof covering is also secured too.
Principle rafters
These are the larger rafters which can form part of a roof truss that in turn supports the purlins, principle rafters generally sit on top of a king post at their top ends, they are named principle rafters as they follow the same line as the common rafters, they do however serve a different purpose alltogether.
Couple Roof
A traditional pitched roof with rafters and no tie beam, used for short spans up to 3m, assuming standard joist centres.
Close-Couple Roof
This is a traditional framed roof with common rafters joined at the wall-plate level with a tie beam, also used for ceiling joists, used for spans up to about four metres, assuming standard joist centres.
King Post Truss
A traditional timber roof truss with a vertical post from the apex to the centre of the bottom tie beam, suitable for spans up to about 11m, but like the queen-post truss not now used for new work in Britain.
Prefabricated Truss
This is a roof truss made in a factory using gang nails at the joints, it is then transported to the site and normally lifted into place. This type of construction has been used for about the past 30 to 40 years.
Wall Plates
Wall plates are the horizontal members normally timber, although they sometimes can be metal RSJ's, fixed to the top of the wall within the roof space. They hold the common rafters from the roof in place but can be susceptible to dampness.
Battens
A small section, normally of timber, to which the slates and roof tiles are fixed.
Wind Bracing
These are timbers fixed across the roof structure to stop movement when it is windy.