Timber frame construction uses timber studs and rails, together with a structural sheathing board, to form a structural frame that transmits all vertical and horizontal loads to the foundations.

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At its most basic, a timber frame structure features walls consisting of timber studwork fixed in place (typically) with OSB or plywood. The strength and rigidity is supplied by the board, which, when nailed to the studwork, makes a very rigid box known as an open panel — the panel is ‘closed’ once insulation has been introduced.

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The frame is wrapped on the outside with a waterproof barrier and then wrapped around this are the external wall elements, which can be either built up out of the ground (brick or stone), or hung off the timber frame walls — as would happen with timber cladding or tiles.

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Timber frame tends to work best with simpler-shaped structures and it really comes into its own when combined with lightweight wall claddings such as timber, tiles or render on boarding. This can reduce wall widths by up to 150mm, which adds a sizeable amount to internal floor areas.

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Timber frame homes can be built on site (known as a ‘stick’ build), but the UK’s self-build timber framing industry is based around off-site construction — the timber frame panels are prefabricated in a factory and rapidly assembled on site.

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Factory prefabrication is by far the most popular route chosen by self-builders, as manufacturers have to work to strict quality control methods, ensuring the correct specification of materials are used and a high degree of dimensional accuracy is achieved.

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There are a number of ways of developing timber frame structures:-

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• A commonly-used method for constructing timber frames is the platform frame, in which each storey is formed by floor-to-ceiling timber panels and a floor deck which then becomes the platform for constructing the next storey.

• SIPs (structural insulated panels) consist of a layer of oriented strand board (OSB) bonded onto each side of an insulating foam core. These composite engineered products can be used as a structural loadbearing element.

• CLT (cross-laminated timber) uses wood panels in which the thickness is made up of a number of narrow widths of timber laid together with each layer at right angles to the previous layer. These panels can be pre-cut in the factory to form wall, roof and floor elements.

• Engineered stud is a simple way to allow a large depth of insulation to be installed between the loadbearing timber studs used for timber frame wall panels. A number of different types of engineered stud are available, using either I-joist or metal web joist designs. 

• Twin stud is two timber frame stud walls in parallel, separated by a cavity, but only one of these carries the vertical load of the building.

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Open Panel And Closed Panel Construction - The Two Main Construction Methods

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Open panels - are manufactured ready for external joinery (doors and windows) to be placed, and are delivered to site together with flooring elements and roof trusses. The panels are delivered without insulation or vapour control layers in an open format, hence the name. Once the building is weather tight and the electrical and plumbing carcassing has been completed, the insulation can then be installed between the studs before a vapour-proof barrier is tacked up, followed by the internal lining with plasterboard

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Closed panels - are delivered to site with insulation already factory fitted. The external cladding, windows and doors may be fixed, as may electrics and plumbing. Alternatively, a service void may be added for self builders undecided on their electrical and plumbing scheme. The service void within the panels provides convenient access for the plumber and electrician to carry out their 1st fix which will also reduce their time on site and their costs. Not only this, but the service void also provides improved thermal performance to the panels.