Back to the future – the revival of timber frame construction
From Metropolis to Minority Report, set designers have been imagining the buildings of the future for well over a century. The built environments are dominated by man-made materials such as steel and concrete. It’s ironic, therefore, that to solve Britain’s housing shortage developers are increasingly turning back to timber.
A brief history of timber frame construction
The bio-degradable nature of wood makes it extremely difficult to accurately estimate when the first wooden structures were created, however, recent archaeology discoveries show that it was already in use by the period 5600 to 4900 BC. In the UK, the oldest wooden building still in use is Greensted Church, which contains timber planks estimated to date back to 1060.
In the UK, timber frame was the dominant form of construction from the middle ages right through to the early Stuart period, with Britain’s large native woods making it a cheap, fast and affordable construction solution. This began to change by the mid-17th Century for a variety of reasons. The lack of effective building regulations meant many timber frame buildings were susceptible to rot – greatly reducing their lifespan when compared with other construction methods. Over cramping of timber buildings also exacerbated the risk of fire and was a key factor in the rapid spread of the Great Fire of London. Finally, Britain’s oak woodlands had been largely exhausted, making timber much costlier. As a result, by the Victorian period, the timber structural elements of most UK buildings were largely consigned to the roof and internal floors of the building.
It wasn’t until the 1960s that timber frame construction began to see a revival as a long-term housing solution – even then, the change was largely restricted to Scotland. The cooler, wetter climate north of the border made timber frame a logical choice – allowing buildings to be constructed rapidly and delivering improved fabric performance compared with other methods of the time. Today, around 75% of new Scottish homes are constructed using structural timber frames, and increasingly housebuilders across the UK are embracing its benefits.
Today, the most common structural timber frame approach is open panel construction. A recent survey from the National House Building Council showing that around 70% of companies surveyed had used open panel constructions in the past three years, and around half expected to use it in 2016.
In an open panel construction, the skeletal timber frame panels are pre-fabricated offsite without any vapour control or insulation. Once the panels are erected and made weathertight and the initial electrical and plumbing work is carried out, insulation can be fitted within the stud cavity. Modern, premium performance insulation products such as our Kingspan Kooltherm K100 range can achieve thermal conductivities as low as 0.018 W/m.K. This can help housebuilders meet the desired level of fabric performance with a minimal construction depth.
For example, take a typical open panel timber frame home with 89 mm deep studs with a foil faced breather membrane, Oriented Strand Board and a 102.5 mm brickwork outer leaf. In order to meet our best starting point U-value for domestic properties in England and Wales (0.16 W/m2.K) all that is required is 70 mm Kingspan Kooltherm K112 Framing Board between the studs and a further 52.5 mm thickness of Kingspan Kooltherm K118 Insulated Plasterboard internally.
As a result, housebuilders can construct highly energy efficient homes whilst preserving valuable internal space. In the next blog, we’ll take a look at best practice when installing Kingspan Kooltherm K112 Framing Board within open panel timber frame construction.
This is part two of a four part series on timber frame construction. View the others here:
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