Tom Wright of George Barnsdale explores the use of timber in ‘minimalist’ designs
“We must recognise the importance of timber in overcoming our climate challenge,” David Warburton wrote to his fellow MPs recently. On paper, politicians are making the right noises, having enshrined into law a commitment to reduce carbon emissions by 78% versus 1990 levels. The MP goes on to predict that we will move from a “20th century built environment comprising concrete and steel, to a 21st century that lives in harmony with nature.”
Modernist architects often ask whether it is possible for a timber window to look right in a minimalist project, and the response is always ‘yes.’ People are increasingly incorporating timber into contemporary designs, combining modern Passivhaus standards with sustainable, carbon reducing materials. A great example is Hackbridge Passivhaus Plus Primary school, which is described as a modernist log cabin. Using contemporary machined timbers that are sleek and modern, unlike the rustic timber frames of the past, it is possible to achieve a minimalist aesthetic. Engineered timber is much less likely to twist and warp, meaning symmetry and form are easier to achieve than was the case with old timber buildings.
As timber window manufacturers, the increased use of timber in the built environment is heartening, but we still regularly face questions about the durability of timber windows and doors. This is a hangover from the poorly made, cheap wood windows used in low cost housing of the 1960s and 1970s which gave timber a bad name, ably fuelled by the strong marketing messages of the PVCu market. In fact, modern engineered timber windows are scientifically proven to last 65 years or more with minimal maintenance if made to approved standards. However, there is a role that architects can play in ensuring they last a lot longer than this.
The modernist styles of buildings incorporating flush windows and flat roofs is far from ideal when it comes to protecting buildings in a four season, temperate climate with wide variation in rainfall and temperature. In fact, water ingress is responsible for a high percentage of claims against architects. The technology developed in modernist design would have impressed architects of the late 19th century, but they would be surprised at the abandonment of precedent in vernacular design and detailing gleaned over centuries of trial and error.
There are a few things to consider when it comes to successfully incorporating timber windows and doors into a design. Where possible, protecting the building from rain and harsh sunlightis the key. From the foundations up, the act of displacing water away from the building extends the life of the windows as well as protecting the walls. For instance, overhanging eaves are great for helping to control temperature inside the building, as long as you can avoid cold bridging.
While traditional details may be at odds with the clean lines of modern building projects, there are lots of ways of achieving the same result using contemporary architectural language and design elements. Peter Barber Architects for example have mastered the art of combining a British vernacular with the demands of contemporary architecture.
When it comes to positioning the windows, they should ideally be set back in the reveal – this helps to protect them further from adverse weather. The Orsi Kaneh building in Iran is a great example of how a timber building can be optimised to deal with extreme weather whilst retaining a contemporary feel.
It is advisable to try to set the windows on stone, tile or aluminium and avoid extended cills. Much of the damage that occurs to windows starts on the cills and in the bottom joints where water sits and eventually moves up the grain of the timber if they aren’t made correctly. Whilst modern engineered windows incorporate precision joints, end grain sealing and modern breathable coatings, sitting them on stone would help preserve them even further and reduce maintenance. Of course, there are considerations around the sourcing of the right sustainable materials here too.
Timber doors can prove a challenge. In order to satisfy Part M of the Building Regulations (covering accessibility), there is a tendency to create a contradiction between the need for level thresholds, and the demands of a sustainable future. Many architects have a habitual cognitive bias against timber in favour of aluminium, due to the outdated perceptions of timber. There are gains to be made environmentally by going for timber doors – which are usually more competitively priced too.
While there is no perfect solution to the climate crisis, as hosts of COP26, Britain needs to be leading the way when it comes to the most sustainable building material available – timber. The creativity and vision that architects possess should enable them to overcome the connotations of old fashioned, traditional timber designs to create modern, sleek, stylish and contemporary buildings that are also kind to the environment and more pleasant to live in.
Tom Wright is managing director at George Barnsdale