According to the UCAS admissions service, this year has seen the highest level of entrants recorded with almost 410,000 students already accepted on to full-time undergraduate courses. With this rise in attendance, comes an ever-increasing need for more student accommodation that is affordable and sustainable.
In recent years there has been a marked shift towards timber, due to the advantages it offers.
For the universities themselves, the ultimate aim is to achieve a good standard of build in as small a timeframe as possible – with many wanting construction to take place during the summer holidays. In addition, they are looking for a sustainable build; one that meets a responsibility to minimise energy use and environmental impact.
Building with timber offers significant advantages due to the ability to prefabricate components in a safe off site environment. One of the advantages is the reduced ‘time on site to weather tightness’ process – open panel timber frame solutions take roughly 55% less time than masonry construction.
The reduction of onsite wastage is another plus point when it comes to prefabrication. With the building frame being put together off site, the construction site itself is kept relatively clear, meaning reduced cost and time when clearing up afterwards.
The offsite manufacturing of timber frame means it can be constructed with precision and accuracy, eradicating any potential onsite defects and allowing for the construction of a perfectly airtight structure. The construction time is also significantly reduced, which in turn, reduces the labour and skill requirements of the labourers, as the timber frame structure simply needs to be put together like a jigsaw upon its arrival on site.
With less time on site for construction workers, there is in turn a reduced amount of time working at height. Working at height remains one of the biggest causes of fatalities and major injuries, however, with workers not being in high-up or precarious situations for long, this reduces the chance of accidents.
Finally, inclement weather can cause many problems to construction sites, delaying work and sometimes damaging components. With the prefabrication of timber frame, the weather elements are taken out of the equation and allow for the planned time frame of construction to remain.
There are a number of modern methods of timber construction. These include open panel, pre-insulated panel, closed panel, CLT, volumetric, and SIPs.
Open panel systems provide the structural frame, from which, site installed insulation, services and plasterboard elements are added. The buildings wall and floor plans are divided into panels, which can be assembled on site to provide a weather tight working environment, once windows are installed.
A pre-insulated panel is an open panel with factory-installed insulation. A closed panel is the same, but with inner sheathing boards to close it off. Advanced closed panels include pre-fitted services and windows, the advantage here being that they have added value in the factory, quicker assembly on site, and produce less waste.
CLT (Cross Laminated Timber) is used for walls, floors and roofs. It consists of perpendicular alternating laminations of softwood, which create a solid panel. The advantages of CLT are that there is a reduced structural depth compared to joisted floor beams, meaning more space and quicker fitting on site.
Volumetric frames, consisting of large portions of a structure completed off-site, are delivered to site whole. This could be a whole room, including its fixtures and fittings, offering quick erection of repetitive design layouts.
Structurally Insulated Panels or SIPs are a particularly popular method as they arrive to site pre-insulated –offering the client the quickest, most cost effective and most robust means of achieving the U-values required by building regulations.
Used in walls, floors and roofs for all kinds of timber structures, SIPs consist of two parallel faces, normally made of sterling board, which sandwiches a rigid core of Polyurethane (PU) foam. Being pre-insulated, SIPs offer huge advantages over other forms of construction where the insulation is installed on site – a lengthier process that is also subject to the weather.
Of course, in addition to the many practical benefits of building with timber, wood is also effectively carbon neutral, with structural timber benefiting from the lowest embodied CO2 of any building material. Structural timber also benefits from being the only organic, naturally renewable building material, whilst minimising energy consumption during the manufacture process.
Andrew Carpenter is Chief Executive of the Structural Timber Association.