A worthy manual for a future of timber diversity

BauBuche engineered beech hardwood used on IttenBrechBeuhl’s Scott Sports HQ – Photo IttenBrechBeuhl Arkitekten

dRMM’s Jonas Lencer reviews a recently published guide to the emerging field of engineered hardwood.

Building with Hardwood, Konrad Merz, Anne Niemann, Stefan Torno, Detail Practice 2021.

Building with Hardwood is a comprehensive, well-balanced manual for current practices on building with hardwood species. Its biggest contribution to the construction industry, however, will be its usefulness in promoting a future of diversity in timber growth and building innovation.

The book pinpoints the position of hardwood today, outlining its history, uses, and benefits through uncomplicated text, clear diagrams, and well-chosen case studies. A holistic timeline in its first chapter is particularly useful, providing a broad picture on the past and present context of hardwood in terms of both forestry and product development, and how these have fared against changes in climate over time.

In its outline of historic hardwood uses, the book triggers ideas on how hardwood can be utilised more boldly in present and future construction, showcasing past case studies where its strength yielded expansive spans and structural compositions. It summarises the tools and processes needed to help support its use with objective clarity, outlining pitfalls that build clearer ideas on how, and in what contexts, hardwood is best swapped out for other timber products.

Along the way, the authors give commentary on changing approaches to forestry and timber harvesting. It is in these passages that the book captures the biggest potential for how practitioners could and should be thinking about hardwood. It paints a robust picture of where hardwood comes from, and how it must be grown to ensure its proliferation is sustainable as it becomes more widespread in construction.

Old techniques and structures – furniture makers steam bending beech and Stirling Castle Great Hall Ceiling – Photo’s left Tom Raffield, right Wikipedia/Wknight94

The Fagus Suisse factory in Les Breuleux – Photo Fagus Suisse

This is where the book aligns with the most urgent decision-making process facing the UK and its treatment of timber production – forest management. In Europe, the mistake of focusing on deciduous forestry has been made and learned. In the UK, the danger of monocultural growth currently looms.

The consequences of single-species forestry practices are a focus point for our studio (dRMM), becoming a central part our recent three-part essay on trees and timber in construction (Treelogy). As such, we have outlined how species diversity in UK forestry must be prioritised as the first step in a positive domino effect of sustainable timber construction. 

Understanding the link between diversity and sustainability is fundamental for growing trees, which are eventually used for timber products. I grew up in Germany, where generations of people lived with the forest and looked after it for prosperity, planting trees to be harvested two or three generations later, helping trees to develop, and cutting them down as they were needed to make buildings or furniture. This life cycle remains unchanged. What has changed – and this is outlined clearly in Building with Hardwood – is demand.

Timber is a commodity. As a material, it offers significant inroads into decarbonising the construction industry and built environment. But its growing use must tally with an awareness of three important considerations: how to grow it sustainably without wiping out ecosystems and biodiversity; how to work with and make best use out of trees that are not uniform in shape and size; and how to ensure that the timber we use in construction can have a third life once its primary function is dismantled.

The first speaks to the point on multi-cultural forestry. Forestry’s greatest environmental value is the process of photosynthesis. Diverse forests yield better canopy cover and healthier ecosystems and therefore serve this crucial function best. Organisations like Continuous Cover Forestry (CCF) have been working for years to promote the transformation of single species plantations into biodiverse woodlands, with more and more foresters signing up to join their work in silviculture and sustainable forestry.

But aside from what forests do to help regulate climate, diversity in their management can also have significant commercial gains. Monocultural planting is a risky model when responding to changing industry specification; multi-species planting offers greater variety of product and is by nature nimbler in addressing variety in market demand. For this reason, communication between architects and foresters should be strengthened. In 2021, the Architects Climate Action Network (ACAN) and the Construction Declares Steering Group responded to consultation for England’s Tree Strategy in an open letter, calling for the UK government to “​make firm commitments to building publicly funded and partnered buildings with homegrown timber​ to give confidence to nurseries, foresters and construction supply chains of future demand”. dRMM was one of 249 signatories who lent support to this call.

The second consideration addresses the issue of hardwood species’ physical characteristics, which differ from softwoods’ highly regular, vertical growing patterns – an issue that is well documented in the book. At dRMM, we have become increasingly interested in the possibilities of digital design in working with organic and/or irregular shaped materials. With emerging technology in scanning, customised manufacture and assembly, the construction potential for less tidy timber species is becoming more and more exciting. 

Continuous Cover forestry in Cumbria, with 85 year old Douglas Fir Photo Wikimedia/WikiForester

The Endless Staircase – dRMM’s first exploration of American Poplar hardwood – Photo dRMM

IDC/ITKE’s 2010 experimental pavilion uses birch ply
at the University of Stuttgart – Photo ICD/ITKE

The final point is about the consideration of timber as a material that can be re-used over several lives. The case for recycling timber products is made strongly within Building with Hardwood, outlining the intensity in strength and performance of recycled hardwood timber. As architects and makers, this book compels us to stretch our knowledge and inventiveness in terms of eliminating obstacles (such as fixings or glues) that prevent the re-use of timber in the afterlife of buildings. As such, the idea of a ‘circular re-use culture’ for timber is an exciting prospect that this book competently lays ground for.

Overall, Building with Hardwood presents a starting point for a new movement in sustainable construction. Through its fact-driven content on the attributes of a recently resurging material, it outlines a way in which biodiversity can become commercially viable. Without actively setting out to, this book points out that now is a time in our society where we can make a series of right decisions, helping us to move towards significantly more sustainable development. Timber, in all its variety, is at the heart of that change.

Engine depot using engineered hardwood  Zweisimmen – photo ASP Arkitekter/Rebekka Affolter

Jonas Lencer is a director at dRMM. He is one of the director’s responsible for the practices new Berlin studio.

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