Almost two decades after cross laminated timber first made its appearance in the UK, it and several of the other modern engineered timber products that have been transforming much of the country’s construction remain, for many in the industry, something of an unknown quantity and to be avoided until they are “more proven”. Whilst there are several hundred projects now in existence that ably demonstrate the efficacy of modern solid timber technologies, independent, objective information on their various properties and uses has not always been so easy to come by and have often been the source of frustration amongst designers and other potential specifiers. With the publication of Mass Timber - an introduction to Solid Laminate Timber Systems, this is no longer the case. Written by Dr Robert Hairstans, head of Edinburgh Napier University’s Centre for Offsite Construction and Innovative Structures (http://cocis.napier.ac.uk) and an acknowledged expert in the field of timber engineering, the book explores the different glued and non-glued products available, through a detailed examination of the various manufacturing processes, together with their individual properties and performance characteristics.

In response to the endlessly repeated question as to why these products are not manufactured from UK-grown timber, the book provides a highly informative selection of case studies of research and development work undertaken by Dr Hairstans and other colleagues at Edinburgh Napier University into the potential of the various tree species available from the UK forestry sector to be fabricated into commercially viable solid laminate timber systems and products. The answer is that they unquestionably can be and there is sufficient resource to do so: what is required is greater confidence in the future market and investment in the necessary manufacturing facilities, both areas in which UK industry has traditionally been sadly deficient.

For those who have used some of the products - whether in glued forms such as cross laminated timber (CLT), glulam or laminated veneer lumber (LVL), or in non-glued variants such as dowel laminated timber (DLT) and nail laminated timber (NLT) and who may feel reasonably knowledgeable on the subject, the book has other surprises in store. The world of advanced timber technologies and that of solid laminate timber systems is continuously evolving and no more so than in their manufacture from hardwoods, in an industry historically dominated by the use of softwoods. Why should this be so? First, hardwood production worldwide is forecast to rise as a result of climate change and increased planting and second, the strength relative to weight of hardwoods allows for more slender proportions to be achieved. Further case studies in the book highlight recently completed projects that make exemplary use of cross laminated timber, glulam and laminated veneer lumber fabricated from hardwoods and the potential of these relatively new products and systems to introduce a new dimension to timber design and construction.

Take the Warner Stand at Lord’s Cricket Ground in London, where the structure of the new roof canopy is formed from 11 double-tapered glulam beams of up to 23.4 metres in length. Designed by Populous Architects and ARUP Engineers, the beams have been fabricated from American white oak, the first occasion the species has been engineered to form glulam on this scale. Doing so was not simply a case of using a hardwood instead of a softwood - the technical challenges are quite different and, in this instance, required extensive research, development and testing to be carried out by the engineers and the manufacturer, Hess Timber. Adhesives that work perfectly well with softwood, for example, could not be absorbed by the white oak due its density, a significant problem for finger-jointed connections but one ultimately successfully solved by the use of a modern melamine adhesive, a solution that would not have been possible a decade ago.

The use of hardwoods in the manufacture of large-scale glulam elements and other solid laminate timber products is relatively new territory in which further research and development will likely lead to wider commercial production and consequent new architectural and engineering possibilities. The Warner Stand’s hardwood glulam beams, as well as other projects highlighted in Mass Timber - an introduction to Solid Laminate Timber Systems, have undoubtedly pioneered the way for even more advances in the use of the latest developments in timber technology: time now for new creative design thinking about how these might be used in construction.

(www.cocis.napier.ac.uk)

‘Mass Timber - an introduction to Solid Laminate Timber Systems’ can be obtained from Arcamedia www.arcamedia.co.uk, price £20.00 inc.p&p

Imperceptible perhaps, but a whole range of bio-based materials are now being used in conjunction with modern engineered timber products on some very sophisticated buildings. Sophisticated, that is, in their low energy, carbon storage and life cycle credentials rather than the conventional use of that word as an indicator of complex technical specifications and high-tech components. This is not the hand-knitted world of straw bales and mud with attendant construction imperfections that conflict with the technological apparatus that now surrounds us 24/7: new architectural thinking about the way contemporary and traditional technologies can be combined is beginning to alter perceptions about the potential of natural materials in construction.

The Enterprise Centre at the University of East Anglia is a prime example of a large, non-domestic building in which locally-manufactured engineered timber products have been combined with other bio-based materials: Whilst this may seem to be a radical approach, it has delivered the client’s and architect’s aim of achieving a ‘BREEAM Outstanding’ rating as well as full Passive House Certification through its innovative use of vernacular techniques and locally available materials. As the building’s client, the University’s Adapt Low Carbon Group raised a very simple question: why had no-one previously tried to create a large-scale ‘bio-building’? The answer now stands in the Norwich Research Park and sends a highly pertinent message to every university in the country: they need to lead in the research and development of new construction approaches and technologies through the refurbishment and expansion of their own estates. This particular client group has no requirement to build speculatively or for subsequent sale: it has specific needs which can - and should - inform and support significant academic research programmes designed to drive the construction industry forward.

So what exactly is radical and innovative about UEA’s Norwich Research Park’s new gateway by architects Architype? The brief was fairly conventional: a 300 seat lecture theatre, an innovation lab, teaching and learning facilities and flexible workspaces as well as business hatcheries and incubator units for SMEs and start-up businesses in the low-carbon sector. This last criterion provided the impetus to combine new timber technologies with other bio-based materials in the creation of what has been described as “the most sustainable large building in Britain”.

The building’s most obviously unusual characteristic is its use of thatch, a traditional building material in East Anglia which, in this instance, is made from local straw varieties such as Foster Special, Maris Huntsman and Yeoman Wheat. The thatch is, however, applied in prefabricated form: 300 panels/cassettes (in 14 variations) assembled in local joinery shops by six thatchers during winter months when they would normally have no opportunity to work. Thatch is not known for having an extended lifespan but in a brief that required the building to stand for 100+ years, its use in vertical rainscreen cladding panels suggests it could last well over 50 years, with any panels requiring renewal simply unclipped and replaced.

The Centre’s timber frame too charts new territory in that it is largely manufactured from Corsican Pine grown in Thetford Forest, just 30 miles from the Enterprise Centre site. After initial sawing at Thomson Sawmills north of Norwich, the material was sent to specialist timber frame manufacturer Cygnum to be kiln dried, planed and strength graded to meet the structural engineer’s requirements. This highly localised use of home grown material creates new, higher-value possibilities for a species normally only considered suitable for low grade purposes (fencing and decking products) but which now offers a local solution to the region’s ever-increasing housing demand. Similarly, larch sourced from Brandon Fields Estate in Suffolk has been fabricated into glulam beams.

The walls use a twin frame system in which each structural stud plane has been filled with 140mm of cellulose insulation produced from recycled newspapers. With breathable wood fibre to the exterior and 18mm oriented strand board (OSB) acting as an airtightness layer, the building achieves a remarkable 0.21 air changes per hour, whilst the thermal insulation strategy delivers a U-value of 0.11 W/m2K that results in a minimal energy requirement (≤ 120KwH/m2) meaning that the building requires virtually no heating.

So, does this building offer new avenues for engineered timber products in combination with natural building technologies and the possibility of new bio-based construction components and systems? The answer to both questions must be yes, with the added bonus that craft skills can be employed to deliver solutions normally associated with serial production processes. The new Enterprise Centre easily demonstrates that true sustainability doesn’t stop at the outer skin of a building, but can be reflected in design approaches that recognise the opportunity to use local resources and thereby help sustain good quality employment in local communities.