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There seems to be some unrest in the market about warranties for new oak framed homes with some well established insurers starting to get the jitters! To be clear this is nothing to do with buildings insurance but, typically, 10 year building warranties. Companies such as NHBC are getting nervous about oak frames but they're muddying the waters because they're not being clear about what it is that bothers them. If you can get under the skin of it the real problem seems to be infill panels that try to emulate those used in period buildings.
With infill panels the oak frame punctures the wind and weather tight envelope dozens and dozens of times. Perhaps hundreds (typically four edges around every panel) of water tight seals have to be made and stay intact against oak that will move and shrink. Whilst some manufacturers claim to have a solution to this the insurance industry now seems to think otherwise.
So if you want infill panels in an oak frame and want a building warranty either use a builder who is accredited by the insurance company you want to use or get an architect who will do your working drawings, oversee the project and sign it off for you.
More blogs by Andy Parker
The annual conference in London hosted by Trada (Timber Research and Development Association) brings together lots of building professionals with a common interest in timber construction from across the UK and Europe. Delegate numbers were up on last year showing that even in a recession we are all very positive about the future. The focus of the conference was on design, distinguishing between design Architecturally and structurally.
Our first speaker Simon Smith, a structural engineer, took us through a number of interesting projects, mainly focussing on educational buildings. Interesting was the combination of structural timber frame (glulam) with concrete floors for lightness of structure and thermal mass. In the early days, standard hollowrib steel deck permanent shuttering for the concrete floors was simply supported on the frame. However research with Cambridge University has moved on timber / concrete floor design so that the composite action of sheer studs directly fixed to the timber integrating the two materials, has resulted in reduced timber dimensions and slab thicknesses, producing economies for the timber design. Simon's message to the UK construction industry "buy more German Technology with Scandanavian thinking".
Mark Soutar, until very recently "head of environmental construction" for Tesco, explained what I'd heard in the press about the supermarkets building in timber. The supermarket giants are all battling with each other to be greenest. Everything they do is customer led, and they've discovered that customers feel good about and want to be greener, and look to companies to set the example. Building in timber is more expensive, but top of Mark's list for reasons to build in timber is services. Supermarkets are designed and built around the services, and holes and fixing service runs are greatly simplified and much quicker in a timber building. However the value of the Euro has now priced timber (temporarily we hope) out of the market for Tesco.
Alison Brookes, an Architect, spent most of her presentation recalling her days of steel frame construction and use of tropical hardwoods to produce complicated shapes in her designs which gave no shelter to the exposed external timber finishes. I must admit to wondering for a long time why she had been invited to speak at a timber conference until rather near the end of her presentation she seemed to get to the point. She explained that she was forced by client economics on a large speculative private housing development into using timber panel construction instead of steel with a light timber infill, and as an alternative to endangered tropical hardwoods, treated stained Siberian larch. These new materials could do everything she wanted artistically producing a much quicker site build at a fraction of the price! Alison was the project Architect with Feilden Clegg who designed the award winning Accordia site in Cambridge that Cowco have been heavily involved with.
Michael Keller, a structural engineer and timber consultant from Germany, spending many years with Finnforest Merk, brought some fascinating European timber projects to our attention, the most interesting of which to me was the Centre Pompidou - Metz, an impossibly shaped glulam gridshell costing euro 6M to cover a 8000m2 space. Michael's message to the UK - get in the euro and start producing your own glulam and cross laminated panels. Tesco he reminded us, because of the currency fluctuations have reverted back to building supermarkets from steel (which is probably why Mark has moved on).
Hugh Mansfield-Williams, Technical Manager for Trada, gave us a clear succinct pathway through the new Eurocodes, explaining that it was a phenomenal piece of work presenting a common basis for structural design throughout Europe amalgamating a mind boggling amount of legislation into a single document.
I'm sorry to say that due to another work appointment I missed Richard Harris' talk, as Richard, Technical Director of Buro Happold, is one of the UK's very own timber structural engineering gods!
The message I took from the conference is Britain historically way behind Europe and Scandinavia in building in heavy timber frame, is catching up with the schools (public) and supermarkets (private) initiatives, but has been recently temporarily wrong footed by the strength of the Euro, because we don't yet have our own indigenous engineered timber production. With the uncertainty in recent years about the world price of steel, engineered timber was seen for a while to be a very credible alternative. Pity our government didn't take the Olympic opportunity to champion the uk industry!
However I'm sure it is only a hiccup.
More blogs by Scott Fotheringham
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