Perfect for those who love the feel and character of period properties but who don’t love the more ‘traditional’ performance and properties of older houses, new oak frame homes have carved out a considerable following for themselves in the past 20 years.
Although most providers (the industry is dominated by a handful of package companies) provide traditional designs, there is no reason why an oak frame home cannot be contemporary — indeed the leading suppliers offer a range of options and many even provide SIPs wrappings for their frames, minimising the amount of exposed exterior oak while at the same time improving performance.
While Tim Crump from oak frame package supplier Oakwrights calls his frames “reassuringly expensive” it’s easily possible to build an oak frame home for around £1,000/m².
ICF (Insulated Concrete Formwork)
Using a polystyrene mould which is then filled with pumped concrete (and usually reinforced) on site is an incredibly fast route to getting the superstructure up — and it provides an impressively efficient wall structure, with most systems providing a U-value of around 0.2. In addition to the speed and efficiency benefits, an ICF (insulated concrete formwrk) house contains far fewer elements than in a regular blockwork house — no lintels, fewer wall ties and so on. There aren’t any significantly long lead-in times as the polystyrene moulds are easily available as are the other components. It’s important to get the ready-mix right, and it’s important to ensure that there is sufficient support and bracing to the walls as the pour occurs. But this is a highly attractive alternative that in return for attention to detail on site provides exceptional results.
SIPs (Structural Insulated Panels)
Structural insulated panels (SIPs) are essentially a sandwich: the filling is a solid thickness insulation, and the bread is made of rigid building boards such as plywood or orientated strand board (OSB). These layers are bonded together which has the effect of making the panels extremely robust. In many ways, the technique is similar to how aircraft wings are designed, with two skins wrapped around a lightweight core and then welded together to form a single element. They can be used to provide walls or roofs.
Timber frame package supplier Custom Homes began offering SIPs a couple of years ago. Steve Hunt from Custom Homes says, “Once we offered our potential clients the option and explained to them the benefits, there was no looking back.” Although standard timber frame is still offered as an option, according to Steve, 100% of Custom Homes clients opt for SIPs.
“Adding insulation into a structure on site, whether it be a timber frame or blockwork structure, is almost bound to be less satisfactory than a factory-fitted insulation. Fibreglass fitted into a cavity will ultimately drop an inch or so at the top, while rigid insulation is cut on site by tradesmen who might not always endeavour to fill every last bit of wall. A standardised factory finish is much preferable to these onsite solutions.”
Custom Homes’ standard SIPs – produced in their own factory in Fife – achieve Uvalues of 0.28 which can easily be improved to 0.22 by upgrading to what they call their ‘Premium’ polystyrene. That’s on a wall thickness of just 119mm (if you want a SIPs roof this will increase to 169mm).