In association with
Timber FRAME Fast, energy efficient and convenient, it's little wonder that this is a popular construction method with selfbuilders. imber frame is the most widely used construction method in the developed world and tends to dominate in colder climates. In Scotland, more than 75 per cent of self builds use this method, and around a quarter of new homes in England are timber framed. Some half-timbered buildings from the 12th century are still in good repair today and a modern timberframed house is fully recognised for lending purposes by banks and building societies. From the outside, it’s often impossible to tell a timber-framed house from a masonry one, because external cladding is unaffected by the choice of internal walls. In a timberframed house, the outer decorative ‘skin’ is finished in the same way as any traditional block house, using bricks, stone, timber cladding or render. The Structural Timber Association (structuraltimber. co.uk), which represents the timber-frame manufacturing industry, believes that no alternative building material offers the combination of sustainability, renewable, natural, recyclable, and low embodied energy.
T
PANEL TYPES
When people refer modern timber frames, they are usually referring to building using prefabricated panels. Open-panel systems are structurally engineered panels that form the inside load-bearing leaf of the external wall, comprising studs, rails, sheathing on one face and a breather membrane. Service runs, insulation, windows and doors are then added later on site. The open-panel system is made from treated softwood timber framing, over which a structural sheet material of either ply or OSB board is fixed. Depending on the system, U-values ranging from 0.26 down to 0.15 W/m²K can be achieved. Closed-panel systems are usually more expensive than open panels, but faster to erect on site. Made from studs, rails and insulation, with sheathings and/or linings on the faces of the panel, closed panels also incorporate a vapour barrier on the warm side of the insulation and a breather membrane on the outer face of the panel. If desired, closed panels may also include fitted windows and internal service zone battens, for ease of installation and construction. This will require decisions about positioning services at an early stage. The walls, floors and sometimes even the roofs of these closed-panel systems are then delivered to site ready for erection, resulting in an airtight building envelope. Closed panels are far heavier to manoeuvre than open panels and will usually need to be craned into position.
6
BUILDING WITH TIMBER / selfbuildanddesign.com
