Fabric first

When considering the benefits of utilising timber as the core fabric of a building, it is time we look past the obvious and highly publicised environmental advantages. Geoff Arnold, chairman of the UK Timber Frame Association explains.

BY NOW, just about everyone from architects to builders understands the unrivalled sustainability and green credentials of timber, but to become the number one construction method of choice, it must face its rivals head on addressing more than just the obvious ‘green’

We must now consider how timber works in real world situations; its thermal performance;
the financial benefits of choosing timber frame and how easy it is to work with if we are to truly
understand why timber is not just the future of the construction industry, but the here and now.

Timber frame is going to win the argument, not with rhetoric or vitriol aimed at highlighting the deficiencies of its competitors, but with cold, hard, indisputable figures; so lets start with a few. Timber frame’s share of the construction market continues to increase year on year,
currently the share of the market reads as; 25% or 1 in 4 of all new builds utilise timber frame.

This figure alone indicates timber frame must now be considered a mainstream method of
delivering quality construction.

A two year continuous assessment of timber frame homes built at the BRE Innovation Park
has shown unequivocally that timber frames are ideally suited to the Code for Sustainable Homes (CfSH). It came as no surprise when the first homes reaching Code levels 5 and 6 were timber frame buildings. Timber frame is a perfect fit with the low carbon agenda and more and more house builders are beginning to appreciate the benefits, finding it much easier to achieve very high insulation levels, fewer defects and increased air tightness, all with extremely low embodied energy.

It is obvious to most observers that the most important aspect of successful construction is getting the fabric right; this is great news for timber frame. Forget about sourcing fancy renewable energy systems to bolt onto leaky, poorly built homes with high embodied carbon - the emphasis should now be on putting the fabric first. That’s why the UKTFA has recently launched its Fabric First campaign, a new initiative designed to highlight the importance of using timber frame as the core fabric in a building to deliver a host of key benefits including sustainability, high performance and cost efficiency.

The CfSH is shaping the future of construction and the government’s target to see all new homes reach Code Level 6 by 2016 is possible but only if the right choices are made now. To achieve the right amount of credits to demonstrate compliance with the code, the construction method chosen by architects and developers alike appears to be affected by two key factors: energy efficiency and the environmental rating and sourcing of the building materials themselves. The environmental argument has already been won by timber, so the emphasis should now be placed on energy efficiency and the financial implications of ignoring timber’s advantages.

A report commissioned by the UKTFA and ‘wood for good’, discovered many technical benefits for choosing timber over masonry when aiming for code compliance. The ‘Comfort and Cost’ report based on research by ESD and Buro Happold, explains how to gain credits in relevant sections of the code, particularly heat loss parameters. Importantly, the report measured the costs of compliance, comparing timber frame with more traditional construction methods. The higher the Code Level attempted the more it will cost; that’s obvious, but what’s not obvious is the percentage uplift in cost for each Code Level will always be higher for masonry buildings than with timber frame buildings. To uplift from the current building standard to Code Level 5 will cost 8-24% more in timber, but 10-30% in masonry; a not inconsiderable amount when multiplied by tens of thousands of new buildings.

This report also highlights that timber frame dwellings generally show a lower additional cost to achieve compliance with a Heat Loss Parameter (HLP) of 1.3, 1.1 and 0.8 than a typical masonry dwelling, with the cost differential assumed to be in the order of 2.2 to 5.2%, depending on the type of building.

It would be simple to think the case for timber is overwhelming and conclusive, but every genius has a flaw and timber frame is no different. In recent months, fires on construction sites have brought into question the use of timber frame in multistorey buildings. Firstly, it has to be stated that most constructions site fires, irrespective of construction method are treated as arson and therefore the problem is not an inherent issue with timber as a construction material.

Secondly, the timber frame appears only to be vulnerable for a small window of opportunity during the construction process and the UKTFA has initiated its SiteSafe campaign to educate the industry to this danger and how a few simple steps will dramatically reduce the risk of fire on construction sites.

It would be easy to point to fire risk as a reason to reject timber, but that would be missing the point and focusing on short term issues rather than long term benefits. Whilst not underestimating the impact of fire in the local community, are we to ignore the global community and the need to cut energy use and focus efforts on using sustainable building products for the benefit of the entire planet?

For more information on the UKTFA’s Fabric First campaign visit http://www. fabricfirst.co.uk.