Asymmetric Truss: A truss with two rafters meeting at the apex, having a different pitch on both sides.
Attic Trusses: Roof trusses constructed with strong timbers to create a habitable or useful storage space in the roof.
Birds 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):: 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: 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 vapour in the opposite direction.
Breathing Wall (Panelvent / Bitvent): These boards manufactured from wood chips, selected wood waste and forest thinnings have been designed as a sheathing board for the timber frame industry and a sarking board in most forms of construction. In normal situations they do not require a breather paper or vapour barrier. This allows moisture migration from the inside to the outside of the structure.
Brickwork Coursing: Taylor Lane 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.
Brickwork Lintels: Galvanised steel lintels that are fixed to the external timber frame panel and support brickwork / blockwork over window / door openings in timber frame.
Bridging: solid pieces of timber generally at mid spans of floor joists to prevent twisting of timber.
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. Taylor Lane supply structural drawings and engineering for building control approval for the structural shell which are generally completed approximately 2 weeks before the delivery of the frame. The client or client's Architect makes the main application before work on site begins.
Cantilever: The part of a structural member or truss which extends beyond one or both of its bearings.
Cavity Barrier: Either timber / wire reinforced mineral wool blanket or polythene sleeved mineral wool used to seal off the cavities into zone.
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.
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 lie 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 utilised 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.
Eaves: 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: Taylor Lane currently employs 3 structural engineers (all NHBC registered) to provide structural information on the size and nature of the various components that make up structural timber frame kit. Structural calculations, assembly drawings and details are supplied by Taylor Lane for submission to the Local Authority by the client or the client's representative. N.H.B.C. HB353B Certificate/Engineers Structural Certificate, provided by Taylor Lane.
Erection / Installation: The on site construction of the timber frame structural shell by a specialised team that usually include for their own mechanical handling and accommodation whilst working. A structural shell for an average 3/4 bed house will generally take approximately 7 - 10 working days.
External Joinery: The windows and doors etc. produced from high quality planed timber or UPVC.
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. Taylor Lane's standard detail is to bring the soffit line down to the head of window to avoid brickwork / blockwork lintels above openings.
Firestops: Cavity barriers such as flexible mineral fibre strips in polythene sleeves required at junction of separating and compartment wall and external wall with roof.
Firrings: A tapered timber member used to give a fall to flat roof areas or to adjust the pitch on a roof truss.
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 Taylor Lane are- SOLID TIMBER- Treated softwood floor joists that Taylor Lane commonly use at 400 centre spacings. The cross sectional sizes usually used are 195 x 44mm/ 195 x 70mm and 195 x 90mm.
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 House and follow the roof profile or pitch.
Girder Truss: A truss comprising of two or more individual trusses fixed together and designed to carry exceptional loads such as those imparted by other trusses.
Glu-lam: 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 / 60mm Polystyrene and 18mm V313 Moisture resistant floor decking POWER FLOAT FLOOR - A finished concrete floor that is layed 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.
Hanger: A metal component designed to provide a connection between a truss or other component and its support.
Head Binder: Horizontal timber member that ties together individual wall panels.
I Beams / Silent Floor: These generally use laminated veneer lumber flanges, routed to accommodate an OSB centre 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.
Imposed Load: The load produced by occupancy and use including storage, inhabitants, moveable partitions and snow, but not wind. Can be long, medium or short term.
Insulation: 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.
Internal Partitions: Timber wall panels that are prefabricated and generally without sheathing unless required for engineering purposes.
Jig: Equipment used in laying out, and clamping in position, the components of a truss prior to pressing.
Joist Hangers: Galvanised steel hangers that can be nailed to timber or other materials that floor joists sit into for support.
King Post: Internal member which connects the apex to the bottom chord / ceiling tie on a truss.
Loose Timber: Members not forming part of a truss but necessary for the formation of the roof.
Moisture Resistant Chipboard (v313): This is manufactured mostly from softwood forest thinnings and timber waste from sawmills or manufacturing processes. Taylor Lane always use the moisture resistant form that is generally recommended for bathrooms and other potentially wet areas.
National House Building Council (NHBC / NHBC Builder): 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. Taylor Lane 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.
Oriented Strand Board (OSB): Timber board generally used to sheath external panels 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.
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.
Parallam: 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 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 are 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).
Plywoods: 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 floor decking or as sheathing boards.
Post and Beam Construction: Differing Timber frame construction method to the panel construction that Taylor Lane use. 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.
Purlins: 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 Resistance: 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.
Rafters: 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.
Remedial Detail: A modification produced by the designer to overcome a problem with the design after its manufacture.
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.
Sarking: 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.
Scab: Additional timber connected to a truss to effect a splice, extension or local reinforcement.
Scaffolding: 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.
Sheathing: 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 OSB or plywood generally used for panels).
Soleplate: A horizontal timber member fixed to the ground floor slab to which the wall panels are then nailed to. It is generally treated with a powerful preservative.
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.
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.
Studs: A vertical timber (generally 90x38mm 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.
TCB: 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.
Tile Battens: Small timber members spanning over trusses to support tiles, slates, etc.
Timber Types: The majority of timber used in the Timber Frame Industry is Scandinavian softwood. We ensure that all of our timber suppliers source their materials from renewable resources and properly managed forests.
Top Plate: Horizontal timber rail that ties together studs in a wall panel.
TRADA Quality Assurance Scheme: Formalised method of quality control, administered by the Timber Research and Development Association.
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 N.H.B.C. and the Building Regulations 1995. The various types of timber used in different areas will be treated with a different material such as Tanalith or Vacsol.
Trimmer: 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.
Truss Shoe: A metal component designed to support and provide a structural connection/support of a truss to a girder or beam.
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, Taylor Lane generally use125mu, 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 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.
Wall Panel Thicknesses: External wall panels generally consist of 90x38mm or 140x38mm timber studs, a 10mm sheathing board, breather paper and tape that is factory fixed. The internal panels are usually studwork (some internal panels are sheathed with a 10mm board for engineering purposes) The 140mm external panels are used instead of the 90mm 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.
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 Taylor Lane for submission to the Local Authority by the client or the clients representative. N.H.B.C. HB353B Certificate/Engineers Structural Certificate, provided by Taylor Lane.
Windbracing: A structural tie (generally made up of 100 x 25mm timbers) giving lateral bracing to roof trusses.