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Timber Frame A-Z

Anchor Straps

Stainless steel straps fixed to the timber kit & foundation of structure as dictated by structural engineer. Also known as holding down straps.

Attic Trusses

Roof trusses constructed with strong timbers to create a habitable or useful storage space in the roof.

Bird's Mouth Cut

The method of cutting the underside of a rafter (seat cut & plumb cut) to form a bearing surface for the timber rafter.

Blocking And Bridging (Strutting) Blocking

Solid pieces of timber in short lengths fixed between floor joists at ends of spans to prevent any movement.

Bracing / Wind Bracing

Lengths of timber used to brace components together to distribute loads more evenly throughout the structure to counteract forces such as wind loads.

Breather Paper / Membrane

A man made material such as woven polypropylene, generally stapled to the outside face of an external timber frame panel. It allows water vapour to pass through from the inside to the outside of a timber frame wall, but does not allow the passage of water in the opposite direction.

Brickwork Lintels

Galvanized steel lintels that are fixed to the external timber frame panel and support brickwork / blockwork over window / door openings in timber frame.

Brickwork Coursing

Swift Timber Homes try to ensure wherever practicable to position openings in timber frame such as windows and doors and soffit lines to brickwork coursing. This is to enable complete bricks to line up with the openings to avoid the bricklayers having to cut more bricks than is necessary.

Building Regulations

An area of building control that states how a building should be constructed to ensure safe and healthy accommodation and the conservation of energy. This form of control is administered by the relevant local authorities, to whom an application must be made and permission received (generally a conditional approval) before work is started.

Swift Timber Homes supply structural drawings and engineering for building control approval for the structural shell. The client or client's Architect makes the main application before work on site begins.

Canadian Lumber Standards (CLS)

CLS is timber surfaced on all four sides and has eased edges. It is produced in a limited range of sizes and is widely used in the timber frame industry. The most common sizes used are 89x38mm or 140x38mm for internal and external wall panels respectively.

Cavity Barrier

Either timber / wire reinforced mineral wool blanket or polythene sleeved mineral wool used to seal off the cavities into zones.

Chain Of Custody

Chain of Custody is a term used in the timber trade that refers to the ability to guarantee the sustainability of specific timber products.

Chipboard Flooring

This is manufactured mostly from softwood forest thinnings and timber waste from sawmills or manufacturing processes. In standard domestic dwellings Swift Timber Homes always use a board with a weather proof, non slip finish this is to reduce damage under construction and improve on safety of our sites.

Concrete Screed

An in situ flooring of cement mortar laid to an accurate flat surface by screeding. Screeds are laid on the structural floor and usually have no reinforcement - in a timber frame situation it would be laid after the structural shell has been erected (generally approx 65mm deep).

Cripple Stud

A short stud that is connected to a full height stud to form a bearing for a horizontal lintel for a window or similar opening. Also known as a jack stud.

Damp Proof Course (DPC)

A strip of impervious material that sits underneath the timber frame soleplates or brickwork / blockwork to keep out moisture. The DPC at ground level excludes rising damp but they are also used to divert rain out of the cavity, to drain through weepholes at the lintel above door or window openings. DPC comes in preformed rolls and made of flexible materials such as bitumen-polymer or pitch-polymer.

Damp Proof Membrane (DPM)

A wide layer of impervious material such as mastic asphalt or a plastic sheet underlay beneath a ground slab to create a waterproof skin. A surface damp proof membrane can also be used such as what is supplied with a floating floor.

Differential Movement

Timber being a natural resource is prone to some shrinkage across the grain although it is stable in the longitudinal section. An allowance is made in the floor where joists do have to lye across the grain. The difference between the timber frame movement and that of the external brickwork is the differential movement.

Dormer House

Also sometimes known as a one and a half storey house or room in the roof bungalow. This is where the roof space is utilized by using Attic Trusses or similar. The rooms on the first storey will have sloping ceilings and either dormer windows or velux roof lights to allow light into the rooms.


Scottish equivalent to noggin.


The eaves are the roof overhang (usually clad in fascia and soffit) which protects the brickwork, or other external cladding from rain. It generally allows air ventilation to the roof void while keeping out insects and birds.

Engineering / Engineers Certificate

Swift Timber Homes provide structural calculations (from NHBC registered engineers) providing information on the timber kit’s various structural components.

Erection / Installation

The on site construction of the timber frame structural shell by a specialized team. A structural shell for an average 3/4 bed house will generally take approximately 7-10 working days to erect.

Fascia - Bargeboard & Soffit

A board which is generally timber or UPVC set on edge along the eaves. This covers the rafter ends and will usually carry the gutter.

Bargeboard: As above but used on the sloping areas of the roof. They are fixed in pairs along the edge of the gable to cover the roof timbers and protect them from rain. They can be ornately carved or moulded if required to create a feature.

Soffit board: A horizontal sheet fixed under the eaves, concealing the rafters and the underside of the roofing. It runs between the back of the fascia and the face of the outer wall. The soffit can be either flat or sloping.

Floor Joists

A wooden (or steel) beam which directly supports flooring in common with other joists (or a ceiling lining as a roof joist).

Types of floor joists generally used by Swift Timber Homes are SOLID TIMBER JOIST and I Beams - Treated softwood floor joists that Swift Timber Homes commonly use at 400mm centre spacings. The cross sectional size usually used is 220 x 44mm.


Cavity barriers such as flexible mineral fibre strips in polythene sleeves required at junction of separating and compartment wall and external wall with roof.

Gable Ladders

The structural link between trusses and gable panels that will overhang to form the eaves. They will often be used as a fixing for barge board and soffit.

Gable Panels / Spandrel Panels

Triangular external infill wall panels that form the gable ends of a dwelling and follow the roof profile or pitch.


Glued Laminated Timbers - Large section timber material for structural applications. It is an engineered product built up by gluing together layers of timber boards with staggered joints.

Ground Floor Finishes

FLOATING GROUND FLOOR: Ground floor finish laid when the structure is watertight which generally consists of Vapour barrier, rigid insulation and floor decking

POWER FLOAT FLOOR: A finished concrete floor that is laid using a power float machine before the timber frame arrives. The concrete is screeded off flat and allowed to reach initial set before work starts. This method avoids having to lay a screed or a floating floor at a later date.

Head Binder

Horizontal timber member that ties together individual wall panels.

Holding Down Straps

See Anchior Straps.

I Beams / Silent Floor

These generally use engineered timber flanges, routed to accommodate a wood fibre web. They can accommodate larger spans than standard joists and are a lightweight, uniform product. Advantages include reduced shrinkage, cupping, bowing, twisting and splitting that can be associated with standard joists. Because the I Beams are dimensionally stable they produce a ‘silent floor’ eliminating squeaky floors.

Internal Partitions

Timber wall panels that are prefabricated and generally without sheathing unless required for engineering purposes.


The materials used in walls, floors and roof space to create a warm structure to satisfy the clients requirements and comply with part L of the building regulations.

Types of insulation are:-

Timber Batts: A semi-rigid unfaced slab designed to give thermal and acoustic insulation and fire resistance. It is push fitted between studs at 600mm centres and is made from natural materials and recycled glass. (generally used for external and internal panels).

Rolls: A product that is produced from fine, non-combustible glass mineral wool and generally used in horizontal applications such as roof and floor areas.

Polyurathane: Expanded plastics that have excellent insulation properties. It is generally used as a rigid board for installation in sloping roofs or even between the studs in external wall panels. It can also be sprayed in situ as an expanding foam to follow complex shapes.

Warmcell: This is an insulation material made from recycled material such as paper. It is blown into the required area pneumatically by specialist contractors on site from a van mounted machine. It is used in wall panels / horizontal and sloping roof areas and floors and can result in high U values.

Jack Stud

See Cripple stud.

Joist Hangers

Galvanised steel hangers that can be nailed to timber or other materials that floor joists sit into for support.

MMC (Modern Methods of Construction)

Open panel timber frame is considered to be a MMC.

National House Building Council (NHBC)

An organisation that encourages better house building. It has a register of reputable house builders and includes services such as conciliation between builders and purchasers, the NHBC Warranty, ten year insurance on new houses and advice on proper site practices.

Swift Timber Homes will provide a suitably signed engineers certificate for the timber frame structure if the NHBC route is chosen by the client for insurance and warranties.

Noggins (Plasterboard)

A horizontal member fitted between 2 studs, Joists or Trusses generally to supply a fixing for plasterboard.

Notching And Drilling (for services)

It is important the joists and studs are notched and drilled for services (to run cables and pipes through) in areas indicated by the supplier only. Notching and drilling zones will be indicated by the manufacturer in their standard details so as not to impair the structural integrity of the structure. If service zones are required within the joist and studs further calculations can be carried out specific to the project.

Oriented Strand Board (OSB)

Timber board generally used to sheath external panels and internal panels (where required by the structural engineer) of timber frame. It is manufactured by flakes of timber 'snowed' into a mat using a small electrical charge so the resulting board has a specific strength.

OSB is strength graded and used as required for purpose. The standard of Swift Timber Homes is 9mm of OSB3 to external or racking walls.

Over Fascia Vents

An eaves vent that runs along the top of the fascia. They can have different size openings depending on the ventilation requirements of the roof (generally 10 - 25mm)

Panel Construction

In a panel system the structural studs are spaced at 400 / 600mm centres and carry the loads down to the foundations via the soleplate.

Timber frame external walls (and internal loadbearing) are required to carry the dead and imposed loads acting on the structure and transmit them to the foundations. On average the panels can vary from around 2 metres in length upwards if a crane is being used on site.


This is a beam created from shards of timber formed longitudinally in line with the length of the beam. This product is stronger than conventional timber and is generally used as lintels above windows or beams in floor zones.

Party Floor

A separating floor between flats that has to perform similar duties to the party wall above. A party floor has to give more consideration to impact sound insulation as well as airborne sound.

Party Spandrels

Internal infill wall panels that form a separating roof space between dwellings.

Party Wall / Compartmentation

A separating wall between two dwellings that must fulfil two main requirements:

  1. To reduce the passage of sound between the dwellings to levels set out in Part E of the building regulations.
  2. To comply with regulations as to give adequate fire protection between the buildings right up to the roof and through the cavities.

Timber frame party walls perform well above building regulation requirements and the main components that improve sound and fire insulation is the type and mass of plasterboard used, the addition of insulation and adequate cavities between structures.

Platform Frame

Most timber frame construction in the UK is generally platform frame. It is where a structure is built sequentially upwards in platforms (floor by floor).


These consist of an odd number of thin layers of timber with their grains alternating across and along the panel or sheet. They are then glued together to form a strong board which will retain its shape and not have a tendency to shrink, expand or distort. Generally used for roof decking or as impact resistant sheathing boards.

Post And Beam Construction

Differing from panel construction more commonly used. It is where heavy structural timber posts and beams are used (generally 150 x 150mm or larger) to transfer all the loads of the structure down to the foundations. Historically these timbers have been Oak but more recently Glulam has been utilised as an engineered solution.


Horizontal heavy section timber, steel or glulam that run at right angles to the underside of the roof rafters. They carry the load of the roof to the gable ends of a house and also generally supported on internal panels which transfer the loads to the foundations.

Racking Resistence

The wall panel studs (generally set at 600mm centres) carry the vertical loads from the floor / roof down to the foundations. The studs must be restrained using a sheet material such as plywood or oriented strand board to provide resistance to racking and stiffen the structure.


A sloping roof beam that generally runs from eave to ridge. Most roof elements are generally pre-fabricated trusses but rafters are used for infilling and for other areas where prefabrication is not practical. This term can also be applied to the principal rafter of a truss.

Roof Trusses

These are triangulated plane roof frames designed to give clear spans between the external supporting walls. They are delivered to site as prefabricated components and fixed to wall plates generally at 600mm centres. They receive lateral stability through wind bracing timbers that are fixed through them to bind them together.

SAP Rating

The standard application procedure that defines the energy efficiency of a structure by taking into account items such as heating systems, the position of the site and the makeup and materials of the structure.


A material such as plywood applied to the upper surface of rafters on a roof to give a continuous panel support. A system that is used as standard in Scotland, but uncommon in England and Wales.


These are temporary working platforms erected around the perimeter of a building to provide a safe working place at a convenient height.

With timber frame the scaffolding is generally erected around three sides of the building before the kit is delivered. It is then enclosed at a suitable time. The scaffolding is erected far enough away from the external wall panels so it can stay up throughout the build for use by bricklayers and roofers etc.


Boards laid side by side - tongued and grooved boarding is used for flooring (generally 18 or 22mm moisture resistant chipboard or plywood) and close boarding for timber frame panels and roofs (9mm OSB3 or plywood generally used for panels).


A horizontal timber member fixed to the ground floor slab to which the wall panels are then nailed to.

Soleplate Layout

One of the first jobs to be done by a timber frame company after receiving an order is to issue a soleplate layout. This is an accurately dimensioned drawing for the ground workers to set out the foundations precisely. It indicates the load bearing and non-loadbearing panels.

It is important that the foundations are constructed accurately to the timber frame soleplate to ensure a successful and smooth running project.

Soleplate Ties / Fixings

The soleplate fixings serve two purposes, to locate the plates accurately during construction setting out the superstructure. They also transfer wind loads down to the foundations once the building is completed.

The soleplates may be fixed by shot-firing through the timber into the concrete slab or using stainless steel soleplate fixing shoes. Soleplates may also be fixed to brickwork substructures using stainless steel straps.

Solid Timber Joist

Treated softwood floor joists that Swift Timber Homes commonly use at 400mm centre spacings. The cross sectional size usually used is 220 x 44mm.

Sound Insulation

The reduction of the sound transmission from one space to another especially significant through walls and floors between separate dwellings (see party wall / party floor)

Stick Built

A method of timber frame where a structure is built on site from loose materials as opposed to in the factory. This type of construction is more common in the United States and Canada than in Britain.


A vertical timber (generally 89x38mm or 140 x 38mm) that forms the wall panels and is the height of the required wall.

Tank Platform & Walkway

Timber bearers and floor decking such as chipboard or plywood that are installed in the roof space to form a walkway and take the load of the storage water tank.


A non combustible material (generally flexible mineral fibre strips in polythene sleeves) which cuts off the path of smoke and fire. It is mainly used vertically either side of party walls and up the lengths of the eaves on gable ends.

Fire Barrier consisting of 300 x 50mm x 4m wire backed insulation, single folded at floor & ceiling zones, rafter zone and vertically at external junctions and is also used in party wall /floor situations.

Timber Types

The majority of timber used in the Timber Frame Industry is CLS this is made from whitewood species graded at C16. We ensure that all of our timber suppliers source their materials from renewable resources and properly managed forests. This is done by Swift Timber Homes by using the FSC and PEFC chain of custody schemes, both of which are Tier 1 recognised in The Code for Sustainable Homes.

Top Plate

Horizontal timber rail that ties together studs in a wall panel.

Treatments Of Timber

It is important that all timber used in the structural shell is sufficiently treated against insect attack and general decay and comply with the requirements of the NHBC and the Building Regulations. The various types of timber used in different areas will be treated with different materials.


Cross member between joists or studs to form an opening. A typical example is to trim out an opening in a floor around a staircase.

U Value

The measure of the thermal insulation of a material or group of materials. Timber frame achieves excellent U values such as the ones listed below that are typical for external walls. (based on insulated timber frame panel / 50mm cavity & 100mm brickwork external skin).

External panel thickness 90mm 140mm 140+45mm

U Value (0.41)W/m2oK (0.29)W/m2oK (0.22)W/m2oK

Valley Set

A set of diminishing trusses that will infill an area of roof between two different roof directions.

Vapour Barrier

Usually a layer of polythene, supplied in rolls which is installed to restrict the passage of water vapour, e.g. on the inside of external wall panels on the warm side of insulation.

Wall Panel Thicknesses

External wall panels generally consist of 90x38mm or 140x38mm timber studs, a 9mm sheathing board, breather membrane and tape that is factory fixed. The internal panels are usually studwork (some internal panels are sheathed with a 9mm board for engineering purposes). The 140mm external panels are used instead of the 89mm so that higher insulation values can be achieved.

Wall Ties

Stainless steel brackets and nails installed to tie back and brace the external brick or block cladding to the timber frame. Polypropylene tape fixed to the outer face of external wall panels indicate where the studs are so that the ties can be fixed back at approximately 5 per m2. wall ties provide lateral restraint but do not carry the weight of the wall which is self supporting.

Wall Cavities

The void between the timber frame wall panel and the external skin such as brickwork or blockwork. The standard timber frame cavity is 60mm below dpc and 50mm above as 10mm is used up by the external sheathing board of the timber frame.

Warranties Of Timber Frame

House builders are required to get adequate insurance and guarantees on what they are building whether it is through the NHBC or through a company such as Zurich Municipal. Structural calculation, assembly drawings and details are supplied by Swift Timber Homes for submission to the Local Authority by the client or the clients representative.


A structural tie (generally made up of 100 x 25mm timbers) giving lateral bracing to roof trusses.