Why might such research be important and have far reaching implications? Consider the modern art gallery, museum or archive collection in which rigorous control of environmental factors are applied to protect the artefacts on display or in storage. The twentieth century approach to these challenges generally involved extensive use of - and expensive to run - mechanical systems to deliver a specific and strictly monitored internal environmental quality. All too often, however, these systems were introduced to mitigate problems created by designs that demanded the use of materials inappropriate to the building’s actual purpose and functional effectiveness. As such, many of the solutions applied can nowadays be seen not only to be insufficiently protective to the materials they are there to environmentally defend, but which - albeit unintentionally - have sometimes also proven to have deleterious effects entirely contrary to modern conservation practice.
In this context, therefore, what difference can cross laminated timber construction make? The first thing to consider is external wall thickness. The material is conventionally used in large scale panels of 100-150mm thickness which are then insulated and clad to achieve weather protection and the required U-values. In the UK the walls are invariably also lined internally to provide a non-timber surface finish, but which completely negates the hygroscopic benefits of the material. Additionally, this type of build-up of different materials may still not deliver the levels of thermal performance demanded by curators, thus necessitating the introduction of mechanical air handling systems. This then, might be described as the use of an advanced building material in wall systems that simply replicates traditional construction techniques.
An alternative and highly innovative approach was taken recently in the unlikely location of a Somerset farmyard where the owner sought to house his collection of historic and contemporary architectural drawings. Hugh Strange Architects (whose own ‘Strange House’ in London had previously won multiple design awards for its innovative use of cross laminated timber) were commissioned to work within the wall remnants of a derelict farm structure, with the client’s brief as to the required environmental qualities resulting in some very sophisticated new thinking by the architect about the physics of the new building. Recognising the inherent, but hitherto under-utilised, thermal potential of solid timber construction, Hugh Strange elected to use cross laminated timber panels of 300-420mm thickness for the walls, i.e. more than twice the usual depth. At around 3.6 tonnes each, these were also considerably greater in weight than normal, with the heaviest panel on the absolute limit of the lifting crane’s capacity. Why so big therefore?