Timber Frame Fires

Advocates (mostly those with a vested interest or inbuilt prejudice it should be said) of so called 'traditional' methods of construction are very quick to point out that timber burns.  Well spotted.  In HA Magazine today (November 2011) there is a lovely advert (p7) for precast flooring.  Does the picture show the benefit of the product being promoted - large spans, thinner floors, good sound insulation?  No - its a (quite shocking admittedly) picture of the Colindale fire on a timber frame site in July 2006.  Clearly the Precast Flooring Federation have no confidence in the benefits of their own product that they resort to sensationalist and very negative advertising knocking the competition.  'Sour grapes', I hear you cry!  Well OK maybe I am a little disappointed at this approach but lets face it this isn't the first time this sort of advertising has been used.  Who can forget the 'floating house' (wood floats as well everyone) or the 'matchstick house' adverts over the last 10 years.
Lets face it, a reduction in the amount of combustible material (fuel) on a building site will undoubtedly reduce the risk of a fire taking hold - that's a no brainer.  But lets be realistic boys and girls, the majority of residential building sites in the UK use timber in large quantities (no matter how they are built).  Why?  Apart from being aesthetically pleasing where exposed, it is THE most environmentally friendly and commercially viable building material that we have available, FACT.  Lets not pretend that fire doesn't damage steel or concrete, in fact the timber frame boys would argue strongly that the effects of fire on a steel or concrete building are pretty catastrophic.
The UK Timber Frame industry I know is taking a responsible, professional and practical approach to product development and system methodology to ensure fire risk is reduced and readers should visit www.uktfa.com for further useful information.  Publication is eagerly awaited of UKTFA further guidelines on assessing and mitigating the fire risk when using timberframe construction methods within the next few months.  Many UK manufacturers are already offering cost effective and practical systems which address the fire risk during the construction process - engage with them and find out.

Now don't get me wrong, heaven forbid I might be advocating timber over brick and block or steel frame (wink wink) - they all have their place and one solution does not necessarily fit all - but do not expect many product suppliers or manufacturers to take such a responsible and considered view.  After all they are all embedded in a the most difficult market place that most of us have known and gloves are off in the 'winning new business' stakes.  Beware, sensationalist approaches and 'competition knocking', in my experience, this nearly always hides some fundamental weaknesses - you've been warned!  Oh yes and one final thing - if you want an impartial view of the right approach to a particular building email us or visit our website!! 

But just to redress the balance a little these pics show the effects of fire on buildings built using steel or concrete.

[These views are those held by the author only and are not in any way connected with any of the organisations mentioned in this blog!!]


Concrete Building on Fire

Effects of Fire on Steel Framed Building

Light Steel Frame v Timber Frame?

Having completed 39 light steel frame (LSF) flats over 4 storeys in Peckham, Excel are about to commence another scheme of 44 flats over 4 storeys in Camberwell for the same contractor. Both schemes had been partially constructed in timber frame before suffering well publicised fires last year. There is no doubt that a timber frame solution is well suited for this type of building and, provided adequate site protection is provided, can be as safe as any other method of construction. There is significantly less 'fuel' on a LSF site during construction - a significant factor when assessing fire risk.

There are few, if any, tangible and usable sustainable characteristics that benefit one system over another. Both external wall constructions are typically A+ rated by the BRE Green Guide. Chain of custody certification for timber frame, if properly applied by the supplier, can gain additional points under Mat 2 in the Code for Sustainable Homes. There can also be some benefits in reduced waste on site with the LSF solution.

Timber frame shrinks in service. As well as careful design detailing and control of following trades, the sequence and timing of various applications during the construction process is critical to managing the risk of potential defects occurring from this shrinkage (plus non-elastic deformation and compression of joints between timber). Contractors often plump for joint fillers which do not demonstrate suitable compression characteristics to account for differential movement. This is rarely well managed by architects and contractors (sorry chaps!) and subsequent defects are experienced.

There is no shrinkage in LSF structures - a major benefit to build programme can be delivered because of this and risk of potential remedial defects can be significantly reduced.

Whilst initial prime costs for light steel frame may be higher, the sequence of build allows contractors to value more works earlier in the process delivering a notable cash flow improvement. Arguably, light steel frame can be built over a shorter contract period as brickwork can be installed before cladding dead loads (roof tiles, plasterboard etc) are applied or windows fitted. This will obviously be subject to the contractor arranging following trades appropriately.

What about New Building Regs Part L? Well we await accredited construction details with eager anticipation but my view is live with the default value for thermal bridging or let us calculate and provide the psi/Y values for the SAP assessor.

What is really interesting is how we have been able to discuss a number of potential solutions with our clients without being driven by a manufacturing business that offers one basic solution. There can be a varying number of influences on each project. As previously noted 'one size does not fit all'. 'Horses for courses' and all that..... (anyone got any tips for the Grand National?)