Andrew Orriss of the Structural Timber Association explains the basics around choosing structural timber, and why it holds so much promise for self-builds, particularly on sustainability grounds
Structural timber is now used across over a quarter of all new homes in the UK. For self-builders, the material offers an exceptionally cost-effective and sustainable construction option. What’s more, structural timber excels in terms of design potential, aesthetic value and speed of construction, making it particularly well-suited for those building their own homes.
WHAT IS STRUCTURAL TIMBER?
Structural timber refers to any timber solution used within a building’s structure. Normally, structural timber homes are built around a load-bearing timber frame. The timber frame then transmits weight evenly to the building’s foundations and ensures long-term, stable performance. For self-builders, this form of construction offers a genuine alternative to those manufactured from steel frame, or concrete blockwork.
WHY USE STRUCTURAL TIMBER?
It’s clear to see why structural timber is becoming such a popular option for self-builders, especially in an era of greater environmental awareness. Structural timber solutions help to create energy efficient buildings, as the systems have inherent properties which can incorporate very high levels of thermal insulation, and prevent heat being lost through the fabric of a building. Likewise, structural timber buildings are more sustainable than other construction methods. For example, structural timber can act as an effective ‘carbon store,’ with timber harvest crops absorbing more carbon during their growth than what’s emitted during the manufacturing process.
Solutions manufactured from structural timber are often ideal for those self-builders wishing to embrace offsite construction methods. For self-builders, such ‘modern methods of construction’ can significantly reduce the need for onsite labour. As such, project management is greatly simplified, with integral building elements manufactured in factory-controlled conditions away from the site. In turn, this helps those utilising the technique to achieve better quality on their finished projects. Finally, structural timber can contribute to those wishing to exceed current Building Regulations on thermal insulation and acoustic performance.
WHAT ARE THE MAIN CONSTRUCTION METHODS?
There are a lot of ways to utilise the latest structural timber technologies, but for self-builders, the most popular methods tend to be open panel timber frame, closed panel timber frame and structural insulated panels (SIPs). All types of structural timber construction methods offer self-builders excellent insulation levels, despite having thinner walls than those associated with traditional construction. What’s more, structural timber construction methods deliver exceptional construction speed onsite. In fact, many timber frame kits can be typically erected in under two weeks.
Each of the aforementioned methods is slightly different. In open panel timber frame developments, the open panel system provides the structural frame, to which site installed insulation, services and plasterboard elements are added. In closed panel timber frame buildings, the structural frame is the same as an ‘open panel’ construction, but includes factory-fitted insulation and inner sheathing boards to close off the panel.
Finally, the SIPs building method utilises timber panels, which are bonded to insulation and combine to provide structural strength.
If these options don’t seem suited to your build’s needs, there are other methods which may be useful. For example, glue-laminated timber can be integrated into the structural design of any construction technology, and helps when looking to form large openings and spaces.
WHAT ABOUT THE ENVIRONMENTAL IMPACT?
Structural timber construction delivers the lowest carbon emissions of any construction material. As well as helping to reduce the construction sector’s dependence on finite raw materials, structural timber can be extracted from nature sustainably. Most notably, for every tree the structural timber sector fells, it plants five more. Furthermore, it should be noted that all timber used by STA members comes from well-managed sources and does not use any timber from tropical deforestation.
Moreover, because trees absorb CO2 as they grow, structural timber buildings contribute to the de-carbonisation of the environment. What’s more, with structural timber homes able to achieve high levels of thermal efficiency, running costs are also lowered, through reduced energy consumption for the finished building.
Currently, the construction industry represents around 10 per cent of total UK carbon emissions and directly contributes to a further 47 per cent. In looking to improve these figures, the sector must be willing to begin adopting more sustainable, low-carbon solutions, such as timber. In fact, when used instead of other building materials, a single cubic metre of timber will save around 0.8 tonnes of carbon dioxide emissions. Therefore, structural timber represents an effective and reliable way to ensure that properties are built in an environmentally conscious manner.
HOW CAN I BE SURE THAT I’M GETTING GOOD QUALITY?
As with any other material, it’s paramount that self-builders only source structural timber solutions from reputable suppliers. The Structural Timber Association is committed to making sure this process is as simple as possible, which is why it has developed the STA Assure Scheme. Members
of the scheme are committed to the highest quality standards on all structural timber. To this end, the scheme is designed to benefit both clients and members by ensuring the highest quality standards maintained by the individual STA member companies. This scheme offers reassurances to the construction community that the organisation’s members meet or even exceed current legislation and regulatory requirements.
Andrew Orriss is Assure director at the Structural Timber Association (STA)