Out of ash and beech - Beer Holz's manufacturing and offices – Photo Beer Holz

Ashes to Beeches: Between a mountain and a hardwood place

The prospects and potential of engineered Swiss hardwoods is a long story,
dating back to the 1980's. After a first false dawn, since around 2010, a decade
plus of research and development centred on the Biel Wood School has
blossomed into the first Swiss engineered ash and beech materials, and their
becoming increasingly common currency in the country's latest wave of
timber buildings.

You can imagine the scene around the beech table. A half-dozen or so long-in-the-tooth Swiss timber folk, discussing with the journalist sent to write up the engineered hardwood story hidden inside the international watch brand, Swatch’s, new showcase headquarters designed by the Japanese starchitect, Shigeru Ban.

Not only had Swatch executives decided that their campus headquarters’ overhaul in downtown Biel was going to highlight Swiss timber, but they had green-lighted proposals that a significant portion of the timber for the campus’s three new buildings would use Swiss beech and other hardwood forest stands. Now the group of senior timber industry people were holding forth on the similarities between Swatch’s success at rescuing the Swiss watch industry from what had looked like terminal decline, and the prospect of these new engineered hardwoods doing the same for the Swiss timber industry.

For Thomas Rohner, and Bruno Abplanalp, founders of the Buchentisch think tank, or ‘Beech table think-tank’, this was a moment that could transform the sector’s fortunes: as Rohner told the journalist, “the forest is no longer economical, the number of sawmills are decreasing, the industry is collapsing. So, we said to each other, we’re going to think about something completely new: we’re going to found this think tank and re-launch the Swiss timber industry with new ideas, new products and new processes.”

This was 2016, and the completion of the campus was three years away. Still the interview feature for the autumn issue of Holz Revue lifted the curtain on one of the highest profile instances of a small timber revolution that had been underway in Switzerland for nearly a decade, a major effort to bring back hardwoods, and particularly beech, as tree species that could yet be part of the swelling 21st century timber tide.

Rohner and Abplanalpand the others were old hands and knew that changes on the scale of transformation being discussed didn’t come easy – Abplanalp headed up neue Holzbau (n’H), the only Swiss engineered hardwood manufacturer, and had been conducting research since the 1990s with the support of ETH Prof. Emeritus Ernst Gehri. As such they fitted the caricature of Swiss industry: small, self-starting, industrious, and overwhelmingly male, embodiments of the Protestant work ethic, as well as living up to the country’s international reputation for skilfully solving technical problems. Rohner was part of a network of researchers working at the principal timber-focused applied research department in the country, Berne University of Applied Sciences’ (Berner Fachhochschule/Haute école spécialisée bernoise) department of Architecture, Wood and Civil Engineering (AHB) a stone’s throw away from the Swatch headquarters in the Biel outskirts.

Each man knew first-hand that the attempt to rehabilitate hardwoods from their completely neglected plight, turning them into future timber materials, was more marathon than sprint. If it were to succeed, that is. The promise of hardwoods, particularly beech is its strength. The vulnerability is susceptibility to moisture and the elements. There were sheaves of challenges though, from the varied behaviour and performance of differently aged and qualities of woods, the need for new types of kit and machinery, to the need to develop and test new adhesives. All of this and much more needed many hours of R&D attention.

Creuzberg: Pollmeier's main Baubuche factory – Photo Pollmeier

Yet, from outside the perception of a threshold either reached, or within reach, made sense of the journalist’s question. n’H had established themselves as a niche producer of hardwood timber, primarily engineered ash, even if most of the materials leaving their production facilities was softwood. More dramatic was the German company Pollmeier, and their development - after considerable R&D - of beech, Baubuche, hardwood Laminated Veneer Lumber (LVL), the commercial take-up of which had grown quickly since launching in 2014. Many among the beech round table were looking to do something similar in Switzerland.

The most significant indication of the quickening pace, however, had come in the shape of National Research Programme (NRP) 66 and later on by the Federal Office of the Environment (FOEN) funding. This signal from the National Government to up the timber ante had led to a mushrooming of projects across the research and related industry sector. The programme was well advanced, by 2016 into its sixth year, including one large if discreet package focused on engineered timber hardwoods. And at its heart was the AHB department, at the time in the earlier stages of the applied research within the programme it was responsible for. So, it wasn’t surprising that there were hopes that Swatch’s specification of engineered beech and other hardwoods would help precipitate a considerably larger uptake of these homegrown woods.




A river runs through it - downtown Biel – Photo Biel Municipality town information/Ben Zurbriggen

Compared to Zurich, Biel isn’t exactly a continental cosmopolis. An industrial town with a population of 55,000 Biel is gateway to the country’s Jura watchmaking region. It’s also on the Swiss linguistic border: Biel is its German name, Bienne the French one. And, from halfway through the twentieth century on, it was host to the Swiss School of Engineering for the Wood Industry. Originally founded in 1952, in 1997 the wood school merged with the University Applied Sciences of Berne and was relaunched as an early version of what was to become the Department for Architecture, Wood and Civil Engineering (AHB.)

Monumental timber - Meili & Peter Arkitekten’s statement building for the Biel wood school
(or department for Architecture, Wood and Civil Engineering) – Photo’s Meil & Peter Arkitekten

The relaunch was also occasioned by the opening of the school’s only relatively new building thus far, a striking instance of a heavy monumental architecture, though all in timber, by the respected Zurich practice, Meili & Peter Arkitekten. The four-storey building remains both statement and presence. Since then, while there haven’t been other buildings drawing the architectural media’s attention to Biel, AHB’s influence has increasingly permeated the Swiss construction sector, a reflection of the return of the material in construction. Today the school flickers brightly on any map of the timber silicon valley network,  a shorthand description for all this Alpine and sub-Alpine German-centric timber tech activity. For Professor Andrea Frangi, head of the chair of Timber Structures at ETH-Zurich, AHB has overseen one of, if not the, most fundamental strategic developments in wood construction and buildings in the country, leading its transition from the margins to a place much closer to the centre. Comprising three schools – Materials & Wood Technology, Timber Construction, Structures & Architecture – the first two have played central roles in the research, helping solidify their positions at the forefront of the country’s timber research network. In the twenty plus years since its opening, as the Department has grown, around 1000 timber engineers have passed through the schools’ doors to be trained and graduate. This groundswell of qualified engineers has provided the capacity and backdrop for the upsurge in timber buildings in Switzerland through the last two decades, bringing it, for AHB alumni and founder of Timbatec, Stefan Zöllig – see Zollig/Timbatec feature here - and others’ eyes “to a completely different level. It is the most advanced timber and construction school in the country.”

Compared to the watch industry, though, timber construction is thin on the ground in Biel. The town’s close proximity to the western Jura region, where beech forests are at their most plentiful and widespread (Jur means forest), and its edging the country’s central plateau, which is dappled with mixed deciduous and conifer forests, makes sense of the wood school’s locale. Beech is the most prolific of deciduous trees in Switzerland; oak, ash, maple and chestnut are also found, the latter in the warmer south. As in other parts of central Europe, the great hardwood forests were historically a mainstay of traditional building culture. Indeed, these deciduous trees are entwined in central European identity, prospering in continental climates. Beech woods proliferated across all of central Europe. The wood was used for both interiors and some construction uses. For foresters, and others with beech stands, the timber cut from forests ensured a secure livelihood and financial security.

Sihlwood, outside Zurich, is one of the very few old growth
beech forests in Switzerland Photo Marcel Porschmann/Wikipedia cc

But that was then. Throughout Switzerland’s recent history woodlands have been intensively worked, in fact so much so that by the mid-19th century only 10% was wood covered. This only changed in 1876, when legislation was enacted after a town where protective forest stands had been cut down was engulfed by an avalanche, resulting in hundreds of deaths. The new laws required nearly one third of Swiss forests to be maintained, ensuring towns and other mountain habitations weren’t so vulnerable to avalanches, floods and other potential disasters. This, though, didn’t influence many forestry stands in the 20th century being given over to intensive monocultural softwoods, primarily Norway spruce. Today over half (56%) of all forests are for commercial uses, and over two thirds of these are conifer, whilst slightly under one third are deciduous. Of these 44% comprise spruce, followed by 18% beech, and 15% silver birch. In 1991, national government passed legislation focused on biodiversity, and there has been a gradual, ongoing shift to ‘Close to Nature’ forestry practice, with more mixed deciduous and conifer forests promoted and grown. Small amounts of land (3.5%) are now left to grow naturally, although 90% remains managed woodlands. The Forestry and timber sectors have been slow to adapt, with spruce remaining the industry’s mainstay material. As elsewhere, engineered timber is essentially a softwood story. Beech, and the other hardwoods, have, despite their potential strength, been a backwater material, causing difficulties and despondency to Swiss and other central European foresters, their harvests relegated to firewood and low-cost exports to Asian countries. At the same time, available hardwoods have been on the increase. In Switzerland, by the late 1970’s, there was an annual increment of 200,000 tonnes of beech. Between the country’s first national forest inventory in 1985, and the second in 1996, the proportion of hardwoods in Swiss woods grew by 12%.

While nearly all the sector uniformly ignored the issue, including its abundant waste, a few began voicing their belief that Swiss hardwoods could become a core part of the country’s timber construction palette. This was given further heft by the first waves of environmentalism in the 1970s and 80s. Through subsequent decades Climate Change research and modelling underlined that the sorts of changes in store were likely to happen across Alpine regions at twice the average rate, emphasising how vulnerable softwoods, and particularly Norway spruce would be to increasingly warm, drier climates. A consensus began emerging regarding continental European hardwood forests, that hardwood tree species would be generally more robust as temperatures warmed compared to spruce and were likely to replace softwoods forests as the main source of timber through the 21st century. If in time this would cause division between environmentalists and the forestry sector, the climate was immediate grist to the mill for hardwood industry advocates and was soon being integrated into their arguments.

Life Cycling in Dornbirn – Hermann Kaufmann’s Life Cycle Tower – Photos Hermann Kauffmann Architekten

The main point for the hardwood timber lobby was the woods’ strength. Engineered hardwoods held out the prospect of far stronger building materials, double spruce’s C24, C26, and C28 standard strength codes, to what are known for beech and ash as GL40 and GL48, up to GL60. A pan-European growth in timber construction was already clear including, by the mid-2000s the first tall timber projects. London’s eight storey Murray Grove and Berlin’s E3 Brettstapel six storey mid-rise were both completed in 2008. Closer to home, the Swiss timber engineering community only needed to look over the border, eastwards into Vorarlberg (Austria), where an eight storey timber-concrete hybrid Life Cycle Tower was being planned for Dornbirn, the state capital. If Swiss fire safety regs had been revised in 2005 to allow timber buildings up to six floors, there weren’t any actual planned projects to demonstrate this. There was also awareness that the German company, Pollmeier, was well advanced in developing just such a stronger material, a laminated veneer lumber or LVL, using beech veneers to create considerably stronger structural components.  It was clear that Swiss hardwoods, whether oak, beech, ash, or other leafed tree species could provide these stronger materials to build with, but there was a mountain of research needed, particularly if the resulting materials were to pass the testing standards required for European product certification, the hoop that opened up its use beyond Switzerland’s non-EU borders. The harvesting process includes assessing each tree’s contained different strength potentials and related properties, much of which is done mechanically. But unlike softwoods, the technology to grade strengths hadn’t been developed. All sorts of work towards making optimal hardwood and hybrid connectors were needed. Adhesive research for engineered hardwoods was only in its early stages. Swiss sawmills and manufacturers weren’t equipped with appropriate technology, and again, some of this kit needed developing. Among the hardwoods, beech came with a mixed reputation. At an English language conference, Hermann Blumer, arguably Switzerland’s leading timber engineer and a beech advocate – see the Hermann Blumer profile feature here - had remarked graphically that the wood is “known for its wild behaviour when drying.” Exposed to humidity, beech isn’t durable, and tends to swell and shrink. Such unpredictability was also found during kiln drying processes: under compression the beech was liable to crack.

Sometime in 2009 the Swiss Timber Codes Committee met with n’H’s Bruno Abplanalp and Thomas Strahm. René Steiger, Chair of the Committee, and senior timber researcher at the Swiss Federal Laboratories for Materials Science and Technology (Empa), recounts the meeting while talking with me on the phone: “They came to the Committee to propose work on standardising hardwood timber codes for Swiss buildings, as there were no design values for hardwood.” The pair pitched that, with their n’H research and testing, they could prepare the required hardwood values for the codes. The small yet adventurous outfit had already been producing engineered hardwoods since the turn of the century. Though interested, there was agreement around the Committee table that considerably more solid testing, data and stats regarding hardwood glulam were required than n’H could offer before the Swiss codes step could be considered. Although the Committee rejected n’H’s overture, the meeting triggered a discussion about how and what kind of research programme was needed to demonstrate engineered beech hardwood’s performance and properties which could confidently pass the code standards.

It happened to be good timing. The Federal Office for the Environment (FOEN) had recently announced the major research programme "Aktionsplan Holz". A submission focused on engineered hardwood, with a final goal of certification standards, fitted right in. “This was the beginning of the research bid.”

Steiger, along with the head of ETH-Z’s Timber Structures, Andrea Frangi, worked on developing a submission, emphasising engineered hardwood’s potential as high-performance industrial materials, which, in Steiger’s words, could ultimately compete with the “domain of steel and concrete structures.” As the team waited for the Federal Office's response, there was the feeling that the time was right. “We felt there really was momentum…not only to the main focus but trying to fill the gaps in knowledge.”




Flee market under the experimental beech space frame in the Arbon hall building  - Photo Joanna Rutko-Seitler

The irony was that Swiss timber had been here before. Through the 1970s and 80s and up to the close of the 90s, ongoing (if smaller-scaled) research on engineered hardwoods had been conducted at ETH-Z. An earlier generation of timber engineers had considered the potential of beech and ash, and had sought to develop the conditions for the research. The time, however, hadn’t been right, even if a company committed to hardwood research had emerged out of this period of hardwood research flux, n’H.

Flee market under the experimental beech space frame in the
Arbon hall building  - Photo Joanna Rutko-Seitler

At the time that he joined in 1999, n’H’s senior engineer, Thomas Strahm, knew nothing of the hardwood research that had been ongoing at ETH-Zurich for over ten years. And it was only a while later that he realised that his first days at the timber specialists were also those of Professor Ernst Gehri. The ex-head of ETH-Z’s timber engineering, Professor Gehri had led the hardwood research there up until his retirement, whereupon he began a consultancy role at n’H, arriving, Strahm recounts, the same week as the young novice engineer. Within a year, Strahm would be thrown into engineered ash hardwood research, as n’H’s first significant ash glulam project was worked on and completed through 2000. There was also beech, and although the beech research would get underway over the next decade, ash was better suited for working with because its tannin colour was similar to spruce and lamination thicknesses could be kept in the same range, so that soft and hardwood could easily be combined. This was the rationale for its use at Schnidrig, the relatively small project that kicked off n’Holzbau’s latest phase of research and development into engineered ash materials.

For the retired Professor Gehri, the news about the Empa-ETH-Z and AHB major funding bid must have felt like vindication. Born in 1934, Gehri had spent thirty plus years at ETH-Z, mainly leading the precursor department to the Timber Engineering department, almost a lone voice in the technical institute’s sea of concrete. A few others, including the then unknown Blumer, were also convinced that engineered beech was part of the future of timber construction. The use of hardwoods wasn’t exactly brand new either. The history stretched right back through the decades: in the 1930s both birch and beech had been used for high performance LVL and plywood in aircraft construction, reprised in the 1950s with glued-laminated wooden shell designs for European jet fighters and in the US, glulam oak was deployed on keels and frames of UK Navy ships’ hulls.

The space frame system, the space frame under construction, and the connector – Photos Ernst Gehri

Gehri initiated a series of research experiments within the department, with a particular focus on beech, beginning with strength testing and the species’ mechanical properties. 6 m boards from different beech were dried and pre-planed at four strength levels, and a series of finger joint profiles and surface gluing options were tested. The results weren’t exactly encouraging: the tensile strength values reached 70 Nmm2. By comparison steel pin connectors attained tensile strength values of 100 Nmm2 (N/mm2).

Research on a live building project was a next step, with an experimental space-frame roof system developed in 1984 for an assembly hall, Seeparksaal in Arbon, close to Lake Constance. The space frame deck, using large numbers of individual, short length beech rods, provided the testing context. The shortness of the rods, joined to steel connectors, ensured that the challenge of points of weakness in the timber, such as the finger-jointing joins, was side-stepped. A follow up project, this time a bridge, examined the types of protection that would effectively protect the beech components, with coal tar oil proving effective.

n’H hardwood testing machinery – Photo n’H

The research continued, including a focus on laminated veneers, and the beginning of a beam system, featuring the gluing of threaded rods into load-bearing wood components, based partially on the work of an ETH-Z PhDs, Andrea Bernasconi, and completed in 1996. But by the time Professor Gehri was preparing to retire and leave Zurich’s industrial knowledge factory, the progress towards certifiable engineered hardwoods had likely not advanced nearly as far as he’d envisaged when he’d been starting out in the late 70s.

According to Gehri’s student and eventual professorial successor, Andrea Frangi, the original work was “very nice research, but too early and not the right time to implement.” One main consequence, however, was that it provided an opening to consider hardwoods as high performance materials, capable of attaining strengths of up to 100 N/mm2. And further, the research also established that hardwood wasn’t so much a substitute, rather a potential complement to work with softwood. “It was an extension of what could be possible, making larger and taller timber buildings more normal. The recent research is actually similar to Professor Gehri’s 1970/80s work.” Still, at ETH-Z Gehri’s departure slowed activities for several years, only really returning in the second half of the noughties.

Zurich’s loss was, as the newbie engineer Thomas Strahm was realising, n’H’s gain. Gehri had taken on the consultant role at the small company, which included use of a research lab and machinery for in-house testing. Soon enough Strahm, who’d arrived direct from Biel’s AHB timber engineering department, was thrown into a research programme which took up from where ETH-Zurich had left off.

The space frame system, the space frame under construction, and the
connector – Photos Ernst Gehri

Within the first few months a live pilot project, a farm building which included a beech glulam truss holding a roof spanning 15.5 m, each girder 4 m apart, and supported by softwood spruce glulam columns, was built in the rural district of Lauenen, after Government funding had been received. The farm shed confirmed much of what was already known about beech glulam’s behaviour, deteriorating once exposed to humidity, and also shrinking and swelling. The level of challenges that came with beech, plus the absence of research grants, was enough for n’H to back away from beech research, and concentrate primarily on ash, a much easier hardwood to work with. Containing comparable strengths to beech, ash is also less unpredictable. This makes the wood easier to combine with spruce, along with its other advantage, that its tannin colour is similar to Norway spruce.

Over the next early noughties years, n’H continued researching ash-based lamellas, focused primarily on gluing and glue-lamination issues. In collaboration with Frangi’s ETH-Z’s timber engineering chair, n’H also focused on connections. The results helped as they provided the basis for n’H to begin properly producing engineered ash hardwood, even if they were doing so on machinery which had been designed for softwood. With a small selection of components commercially available, the subsequent ten years saw a trickle of projects with ash included in the structural specification - about one or two a year, said Strahm. “They weren’t really important projects, we tested what was possible. Nearly all the questions were answered. There was always the problem of price though, ash couldn’t be as cheap as spruce.” As ever, commercial considerations trumped all others. Like other industries Swiss timber was always looking to the bottom line. For the vast majority, the apparent lack of commercial viability, or to turn the point around, the knowledge, experience and familiarity around softwood glulam as well as the familiarity of Norway spruce was, and continues to be, a key reason for the overwhelming indifference, until recently, to engineered hardwood.  It’s tempting to ask that impossible question of the business mindset: what if there hadn’t been the cost implications, and to wonder what might have been unfolded.  It was never like that of, course, and the research was nothing if not applied and pragmatic. Much of the next decade’s work revolved around refining and improving on the solutions that Gehri, Strahm and the n’H team had come up with, and where problems were identified, often from the live projects, these spurred further in-house research. “Only the glue was the problem.”

In parallel another member of Gehri’s team, Alessandro Fabris, had completed his PhD in 2001. Together with Andrea Bernasconi’s earlier PhD in 1996, the two theses laid the groundwork for developing more fully the anchor system that Gehri, joined by n’H, had begun developing through the past decade. Physics, timber testing, research into adhesives, steel rods, and beech and ash’s behaviour under various conditions were drawn together in Fabris’s PhD, enabling the threaded rods to be glued into load-bearing ash components. Steel rods running through the interior of engineered ash and bonded by an especially developed resin adhesive – a combination of pur bonding and epoxy – made for an extremely strong and rigid connection anchor. n’H titled the high-performance connector under the patented name, GSA technology - GSA translates as ‘thread rod anchor.’ Launched commercially in 2000 the connection anchor has proved a success story. Through the last two decades this GSA technology system, also supported by test series performed at Empa, has been refined, broadened and developed into a family of anchor connections. Equally important, though, and maybe more significant, was that with GSA technology’s development, engineered hardwoods could be used in structural contexts such as basements in multi-storey timber buildings, which hitherto were the preserve of steel and concrete.

One key moment was in 2010, when a ski centre and hall in Arosa, Graubünden, decided to commit to an all ash building. Strahm: “This was the first really big ash construction.” Though the ground floor was concrete, the upper level was timber. Arosa, a tourist town popular for skiing holidays and with many timber houses, experiences large amounts of snowfall, which needed to be engineered for, along with other building physics issues. The ski school building, designed by Lutz & Buss Arkitekten, featured a wide spanning roof joining two linked but separate buildings. An ex-ETH-Z’s engineer, Michael Bueeler, who’d, while working on his Master Thesis project at ETH-Zurich and Empa, helped with the tests on ash and beech glulam, was working on the engineering, and could see the potential for engineered ash providing the strength needed for the deck’s 24 metre span. Bueeler made the case to the ski school to explore the different new wood. It turned into a pilot for both glulam ash and the GSA technology: with snow loads of one tonne per square metre the engineering needed careful attention, as did, given the amounts of wood being used, the finger-jointing in the timber. Not only this but given the narrow mountain roads, the timber had to be transported by rail, another logistics lesson. “It wasn’t so easy to build so we developed a special joint for the project, everyone working together; architect, engineers, it was an adventure.”

Arosa ski centre and hall – Photos (and above) n'H

Arosa was immediately followed by a less ambitious hall in Sargans, another Graubünden town, where beech was also specified and was important for Strahm and n’H for the learning they brought away from it. “Being able to see the buildings has been really important with ash. We can show the wood to architects and engineers and show what is possible in ash, and now beech. It is really different compared to softwood. People must believe.”

The all ash Ekkharthof restaurant and community
centre – Photo Lukas Imhof Arkitekten

Projects such as the Arosa parking garage have shown that ash enabled solutions if special requirements are required from wooden structure, such as small cross-sectional dimensions with high loads. While a niche terrain, the engineered ash and beech developed by n’H expanded glulam’s repertoire to include stronger, higher performance categories, opening up new applications in hitherto uncharted territory. For n’H, projects have continued, growing in number and scale, including their own new workshop, the Ekkharthof community restaurant – featured in this Annular Unstructured edition see here - and in Britain, a major Cambridge University building in Magdalene College by Niall McLaughlin Architects.

And yet, for hardwood advocates n’H was only really starting out. All through these years Professor Gehri had continued to give presentations at conferences. Included in many, such as the 2014 Vienna Glued Timber Symposium, was a section rather ruefully devoted to engineered hardwoods asking, “Why are we still at the beginning?”




Bern Canton Beech forests near Solothurn, Bern Canton – Photo Tanja Kohli, Juradog, Switzerland

The country’s forests and what to do with forester’s harvested but unwanted wood had been climbing Switzerland’s political agenda through the new century’s first decade. Not only were larger, and in a few cases, taller timber buildings increasingly in evidence across the Continent, but climate change considerations were becoming more pressing. Each year the increment of unused felled trees grew. And each year much went to biomass and firewood, for some a sustainable use, but still a frustrating one. The forests also grew, and as they did, they grew older and, from a forester’s perspective, past their prime. Signs of change were becoming more evident and obvious. In Alpine countries, tree lines moved up the mountain side, signalling the advance of warming, and drier summers. More visibly the hastening rate of glacier melt was another signal of the advancing new normal. For foresters, the question of what to do with some of their unused wood remained an ongoing thorny issue, begging questions of what to do, indeed, how to make better use of hardwood.

The Swiss Aletch glacier melt left to right 1979, 1992 and 2002
Composite photo Zuecho/Wikipedia  - CC BY-SA 3.0

If both Frangi’s Structural Timber ETH-Z department and Steiger at Empa had been running smaller individual research projects on hardwoods, all sorts of light bulbs must have begun brightly blinking when they got wind that the National Government was preparing the major National Research Programme (NRP) and the Programme "Aktionsplan Holz" by the Federal Office for the Environment focused on the future of Swiss timber. NRP66 Resource Wood, as the programme was titled, was to be applied, solution-oriented research, sought to be inter- and trans-disciplinary and to be focused on pressing national problems. The Resource Wood NRP announcement was made in 2009, with a call for projects, included an 18 million Swiss Franc budget, and research would last for five years, focused on four core themes: New Developments in Timber construction, Novel ways of bio-refining wood, Innovative wood-based materials, and Provisioning and sustainable use of wood.

NRP66 and Aktionsplan Holz must have felt something like manna from heaven for the country’s timber research network, not least those around engineered hardwood research. Led by Steiger and Frangi, the three institutional partners, Empa, ETH-Z, and the University of Applied Science Berne’s Biel AHB department, in collaboration with n'H and some of the major Swiss hardwood sawmills worked up an eight-module research programme. Submitted under the first ‘Timber Construction’ theme the project was accepted by the Aktionsplan Holz Funding within the wider programme.  The focus spanned a variety of technical challenges, ranging from wood selection, strength grading, finger-jointing and gluing of laminations, products performance testing, standards and the slew of ways hardwood glulam could be utilised. Pollmeier’s work underway with Baubuche LVL was noted, influencing an early decision given the availability of respective production plants in Switzerland to emphasise glue-laminated hardwood, though, according to Steiger, the research agenda wasn’t ever intended as either LVL or glulam. Rather both worked in parallel rather than compete with Pollmeier, by developing LVL veneers. Today, Steiger casts his mind back to the meeting with n’H. Without their initial approach, he says, it was their motivation and energy that really propelled the research into manifesting. “Without n’H the research wouldn’t have got off the ground.”

The actual research period was for the five years between early 2012 and the end of 2016. Further dissemination of the research and product development continued through 2017 and ended in 2018. The budget value was over 1 million Swiss Francs, 50% from the Federal Office for the Environment, and the three partners sharing the budget’s remaining half.

The first step, covered by the first module, was for the partners to meet, review, amend where relevant and finalise agreed objectives for the project. Once decided, the project was to move into the second two modules, the first developing strength-grading methodologies for the raw beech material as it arrived from the sawmill.

Densified woods – examples from Biel’s Institute for Materials and Wood Technology
research – Photos AHB/BFF

ETH-Z, Empa and AHB’s three-way partnership began to assign different aspects of the programme to their respective pools of researchers. Generally, the work continued and built on already completed smaller individual pieces of research. For instance, the head of AHB’s Institute for Materials and Wood Technology, Professor Frédéric Pichelin, an adhesives and bonding specialist, had already been working with fellow (though recently retired) ETH-Z Professor Peter Niemz, on ash and beech related adhesives and bonding research, including a three year (2011-2014) project. This had led to combining both ash and beech into several single experimental glulam materials, generally using hollow beech cases, and integrating ash into the material assemblage. Once NRP66 and Aktionsplan Holz were up and running the bonding research expanded into moisture issues in hardwood structural elements, and the different considerations needed compared to existing glulam and cross-laminated timber (CLT).

Overall, AHB’s central role in the programme focused primarily on three parallel problems: one was the unresolved challenges around fire resistance, another dealing with the gluing process and finally structural issue were also addressed. The fire resistance focus spanned started at the microscopical level. Thomas Volkmer, one of Pichelin’s wood materials departmental colleagues, sought to modify wood at the cellular level. Collaborating with Pichelin, the pair developed a new non-toxic mineralisation approach to modifying and improving the resistance of the wood against fire. Several water-soluble minerals were introduced into the woods cell structure, which reacted with insoluble materials also in the wood. Settling in the cells and on the cell walls, the resulting insoluble inorganic minerals strengthened the woods resistance to fire, including slowing the spread of flames and charring.

Wood mineralisation - at a cellular level (upper picture) and (below) illustrating the
improved fire resistance after mineralisation. Photos AHB/BFF

The gluing issues were mainly focused on the development of a fast bonding technology. No researcher had so far cracked how to stop the phenolic glues used in hardwood glue lamination producing a dark reddish hue appearing when the glues and hardwood were mixed. “That was the biggest problem, the aesthetics. The architects wanted to see white.”
In Volkmer and Pichelin’s mineralisation process the glues turned an almost invisible white, with the wood looking much lighter and clearer, as well as being highly stable.  “When we tested it on the House of Natural Resources (see below) you didn’t see the white line.”

At first Pichelin and Niemz and n’H worked together, n’H preparing the finger jointing beech, though the collaboration slackened off once the bonding research team moved from the phenolic glues used by the hardwood manufacturer to the materials scientist’s experimental new bonding method: a microwave heat pressing combined with a melamine-based adhesive that quickly bonded the lamellas. An assessment of Pollmeier’s gluing challenges with Baubuche had precipitated this heat-based approach, AHB also developed the technologies needed for heat bonding tests and experiments. In correspondence, Pichelin describes the approach as ‘holistic’, adding that the research came with “very different challenges.”  By 2020 the testing had arrived at a stable product, an optimised beech plate, currently planned to be launched in the summer of 2021.

Biel’s structural focus was on smaller, shorter beams and rods, with a young structural engineer, Steffen Franke, working on connections and fasteners as the main second structural part for the practical use of hardwood in the construction sector. Franke concentrated on mechanical behaviour at a structural level, filling in gaps in the knowledge across the research community, including the properties and capacity of the connections, the number and types of fasteners: dowels, screws bolts, or glued-in rods, helping the adaptation of these at n’H and Fagus Suisse.

Timber testbed - ETHZ’s Structural Timber Institute’s testing machinery lab – ETH-Z

If equipped with far fewer researchers, Empa's Structural Engineering Research Laboratory and ETH-Z’s Structural Timber institute included larger, chunkier and just more testing kit, and so was the principal site for investigating the mechanical characteristics and structural properties of larger glulam beech beams. These included both earthquake and fire safety issues in taller timber buildings. Demonstrating how engineered beech and ash could be combined with softwood glulam, as hybrid soft and hardwood components for various uses including columns, was a key challenge for the Empa and the ETH-Z team, who none the less developed tests, experiments, and other applied approaches which illustrated the potential of these hybrid component systems. Some forty beech beams were delivered by n’H to test the components and connections properties, including tensile steel dowel connections, and specifically what happened under various loads and force levels. At Empa René Steiger was also engaged in structural timber research, specifically focused on taller timber buildings and the implications of horizontal forces originating from earthquakes and wind.

Key to the research’s progress, according to Steiger, was a young Austrian PhD Student, Thomas Erhart, who had arrived from the epicentre of CLT research, professor Gerhard Schickhofer’s TU Graz’s timber engineering department – Further see profile piece on Schickhofer here - bringing a mission-driven motivation to the early start-up phase of research and through the rest of the programme. Erhart worked on developing human eye and machine methods of visual strength grading, including a picture-taking machine which could partially automate and confidently grade beech boards into different classes.

Some of ETH-Z’s work on hardwood research flowed into the lighthouse House of Natural Resources project. The building provided various timber engineering opportunities to showcase the experimental hybrid soft and hardwood components research – such as a prototype post-tensioned beam-column timber joint, using engineered ash to strengthen spruce glulam at key points. A second prototype developed for the House of Natural Resources included a timber-concrete composite floor using beech LVL, and a biaxial floor system made of CLT slab elements made of beech wood connected with studs to a grid of LVL beech lamellas. Once completed the House of Natural Resources was among the awardee’s of the 2015 Schweighofer prize.

ETH Zurich's House of Natural Materials with below, and above the biaxial CLT slab – Photos ETH-Z

Vison Wood in the upper right section of
experimental building - Empa
NEST's Hydrophobic water basin – Photo Empa

Empa also developed a parallel showcase, in partnership with ETH-Z's Wood Materials Science department. NEST, an experimental building of multiple parts, constructed on Empa's Dübendorf campus, brought together a spectrum of research experiments in discrete units, together creating a multi-storey NEST experiment. Vision Wood, one of these units and a single strand in Empa's NEST research, is a box of beech surprises, with a sample of one-off examples to demonstrate the 21st century future of hardwoods. These included structural CLT beech optimised for prefabrication and speedy module construction, internal beech panel walls and, to highlight the research collab>oration's wood materials and green chemistry credentials, a treated hydrophobic beech basin sitting in the building's bathroom, doubtless intended to vividly remind those pondering beech's particular vulnerability to the watery elements could be negotiated if high-tech routes were considered.

Despite the novelty of hydrophobic basins, at the engineering level the materials technicians and scientists couldn’t fully resolve beech’s vulnerability to the element. “There were problems with moisture, and changes in climate can cause changes in the glulam, including higher stress, and compromising of glue lines.” Beech glulam (and other hardwoods) can only be used internally, notes Steiger. “Or at least that is the recommendation.”




Boningen rail maintenance and repair depot for engines where engineered beech is used for crane rails - Photo Architekten Schwaar & Partners

Inevitably the Resource Woods NRP66 and Aktionsplan Holz programme’s overall objective was about turning applied research into commercial results whether, like the hydrophobic beech basin, it was novel and exotic, or like engineered beech, potentially more standardised and conventional. As it was, AHB had already been approached by a group of forest managers and owners in the Jura in 2014 who were looking for new uses for their forest stands. One of the group, Corbat Holdings, one of the larger Jura wood industry companies, owned large tracts of beech forest. The limits about what to do with the wood had long been clear to the foresters, harvested stands either going to low value uses such as biomass, firewood, or railway sleepers, or left unharvested. They could also see, however, how timber in construction was taking off. A timely approach, meetings and discussions continued, before Fagus Jura, a project company was formed, and began overseeing testing and other trials of beech within the Jura company’s facilities. The next step, a first production line for engineered hardwood, was instigated by Corbat Holdings in 2016. This was, says Pichelin, the beginnings of Fagus Suisse (Swiss Beech), the company that has since emerged out of the extensive beech research.

Working with Martin Lehmann the AHB in Biel, research included the structural testing, glue, sub-dividing woods, with n’H’s production facilities, using polyurethene adhesives, and other applied areas. The fact that Pollmeier, the German Baubuche ‘beech’ manufacturer, had already gone through a comparable R&D process, provided a test bed and exemplar to learn from and attempt to avoid making the same mistakes. “They had needed to fight at a technical level,” says Pichelin. The aim, like Pollmeier, was to identify and develop a dedicated market. Out of the structural work came one of Fagus Suisse’s eventual components Stabschichtholz (SSH), a super-strong glulam beam in both ash and beech, graded at between GL40 and 60, with solid lamellas replaced by battens of 40 x 40 mm, using an entirely different manufacturing process to Baubuche.

The Fagus Suisse factory in Les Breuleux – Photo Fagus Suisse

There were other physical results too. It was Fagus Jura that manufactured the test beech CLT used in the Empa Vision Wood module-building. They also collaborated with AHB on developing a beech wood-concrete composite ceiling prototype system, with researchers carrying out measurements on structural performance characteristics, sound absorption levels and airborne and impact sound insulation. In 2017, Fagus Suisse emerged, chrysalis- like, out of Fagus Jura. By then a completely new facility in the Jura town of Les Breuleux was underway, and other projects showcasing Swiss beech began to materialise.

The launching of Fagus Suisse, followed by the opening of a new production plant in November 2020, is now considered, a, if not the, key milestone in the research project, the applied fruition of so much of the programme’s energies. With the core research complete, AHB are now monitoring the quality of the manufactured hardwood glulam. Lehmann: “We are looking at how good the glues and sorting machines are” - from which data and other information will provide insights on what works and what doesn’t.

The Fagus Suisse factory in Les Breuleux – Photo Fagus Suisse

Today, midsummer 2021, Les Breuleux is, according to Fagus Suisse’s man in charge of the factory, Eric Mueller, producing ash, beech and a small amount of oak, though when invited to say how much, he declines to provide any figures, stating these are confidential. He says that, in the main, this timber is going into Swiss projects, although some is crossing the border into north-eastern France. These range from small residential homes to large buildings. There are challenges: compared to softwoods, working with hardwoods requires far more precision. Although new, the facilities machinery has been modified and it is early days, they are learning as they proceed. Mueller believes that teething issues will likely take a couple of years to work their way through. They are also preparing to submit the woods to European product certification. Research continues too, including a hardwood-concrete hybrid with a new synthetic concrete composite developed by Empa.

The final results of the main research findings are being co-ordinated by Lignum - Holzwirtschaft Schweiz, the Swiss wood sector’s main communications organisation, with all research institutes and both n’H and Fagus Suisse involved, and are being published as official documentation. Likely, though not yet definitely, to feed through into Swiss Code and European certification, the documentation, according to Steiger, is intended to provide all relevant data, information, statistics and other engineering information required regarding engineered hardwood products made of beech, ash and chestnut. And so that engineers and architects “can start designing.”

Outside and in - Boningen rail maintenance and repair depot for engines
– Photos Architekten Schwaar & Partners

Actually, the designing is well underway. Projects featuring engineered beech began to seep into the Swiss timber landscape from around 2016-2017. These were generally demonstration buildings, where the application of the new materials is often specific and tied to research questions.  Research into hardwood crane supporting structures is one example.  So Architekten Schwaar & Partners’ 2017 rail maintenance and repair depot for engines in Bönigen features glulam frames with a craneway.  The craneway’s supporting girders are an early iteration of Fagus Suisse’s beech veneered plywood. Likewise, two cranes at timber manufacturers Beer Holzbau’s new production hall in Ostermundigen, just east of Berne, sitting high on the ground floor of the three-storey timber building, also employ engineered beech supports for the craneway. For the Beer Holz project vibration properties and acoustic considerations for the offices and apartments in the floors above were monitored. The whole building is also held up by clamped beech supports. Testing how effective engineered beech support beams are for crane rails will be another research concern in a project by Empa, n'h, and this time, Gersag Krantechnik AG launching summer 2021.

New administration building for the Federal Department of Environment, Energy and
Transport – Photo’s Berrel Berrel Kräutler Architekten

In Muttenz, outside Basel, the largest energy wood center in the Basel region is currently being built on an area of ​​7,500 m2, equipped with warehouses for assortments of waste wood and forest energy wood, as well as a three-story office building for the Raurica Group, who are shareholders in Fagus Suisse. The load-bearing structures of this building and the roof structures of the warehouses are from regional beech wood. More recently, sections of a new administration building for the Federal Department of Environment, Energy and Transport by Berrel Berrel Kräutler Architekten in Ittigen, again near Berne, and completed in 2020, includes Fagus Suisse engineered beech and composite timber-concrete while in the Jura town of Porrentruy, an ice-hockey rink featuring both ash and beech is close to being completed. Also, in its stages is a new satellite centre to Biel’s AHB wood school – completing 2023 - currently titled the Smart Living Lab in close by Fribourg, designed by Stuttgart’s big name studio, Behnisch.

Render of the Fribourg Smart Living Lab, by Stuttgart veteran’s Behnisch – Render Behnisch Studio

Zug’s 80 metre Pi Project timber tower – Duplex Arkitekten

The most dramatic illustration of the increasing specification of engineered hardwoods is Switzerland’s latest entry in the tall timber race, an eighty metre residential high rise in Zug, announced in 2018, currently titled Pi. But here, the hardwood is currently planned to be Pollmeier Baubuche. Mueller hints that another seventy metre tower will be announced before long, this time using Fagus Suisse material. Zug’s winning design by Duplex Architects and Engineering Office Walt+Galmarini envisages an engineered beech inner and outer frame (known as a tube-in-tube system), joined to an innovative biaxial beech-concrete composite floor system, which is a further development of the uniaxial beech-concrete composite floor system implemented in the ETH House of Natural Resources. Statically acting as biaxial slab, and covering large spans without visible beams, the composite floor system and the tube-in-tube system will stiffen the 27-floor building against horizontal forces (wind, earthquake), rendering the usual large concrete stiffening cores unnecessary and cutting the carbon emissions associated with traditional concrete buildings. With an ‘as far as technically and financially feasible’ caveat in the press release, the project’s current completion date is 2025.

Though not involving Hermann Blumer, a variant of the double façade strategy protecting the strong yet element- vulnerable beech looks to have been taken up, aspects of the system used in the Ban buildings becoming part of a putative Swiss tall towers approach. With an ‘as far as technically and financially feasible’ caveat in the press release, the project’s current completion date is 2025. So it seems, at least some of the secrets of the Ban/Blumer beechwood experiments have made their way into this next generation of spectacular timber projects.

Not surprisingly given the homegrown hardwoods focus, the broader NRP and Aktionsplan Holz programmes featured public and professional dissemination, the former a campaign titled WoodVetia, promoting the virtues of locally sourced wood. AHB’s Thomas Rohner, during the beech round table with the journalist, observed what he wanted, that “every community that owns forests and wants, for instance, to build a kindergarten, automatically thinks: ‘We own beeches, I want to build my kindergarten with my beeches.’ That’s what we want to achieve.” Whether, and to what extent this has been achieved is an open question. Like the general move from 20th century concrete and steel to timber, the homegrown element is discussed within the language of reduced carbon footprints and overall sustainability. Underlining this is the environmental argument of developing hardwoods as alternatives to steel and concrete and, for the time being as complement to softwood sources, particularly spruce, even as the species is increasingly stressed by rising temperatures.

Beech trees turning brown earlier in the summer 2018 - Ulrich Wasem/WSL

As it is, climate change seems to be outpacing the forestry’s sectors adaptation plans. In 2017 a new wave of major bark beetle infestations were recorded, and has since continued each year. The bark beetle’s proliferation is a result of longer, drier and hotter summers, multiplying the stresses on spruce, and beech, which is also vulnerable. Add to this stronger storms and forest fires, and what has become known as Waldsterben 2.0, the return of the decimation of central European forests - by Acid Rain, retrospectively garnering the title Waldsterben 1.0 - in the 1970s and ‘80s. There are other pests, and diseases including ash dieback (chalara fraxinea), which has taken hold across many forests. The first year was bad, but the conditions did not fundamentally change in 2018 and all subsequent years have seen great swathes of the central European forests lost to WaldSterben 2.0’s mix of symptoms. The crisis has been declared the worst in 200 years, with forest industry figures stating that by 2020, 250 m3 of productive woods had been lost, and another 500 m3 likely to disappear over the next four years.

Many environmentalists blamed the forestry sector for its short-termism, focusing on growing spruce and disregarding the cultivation of more mixed, healthy and resilient, if less profitable woodlands. At the same time alternative approaches to forestry which sought to recreate the healthier biodiversity of old ancient woodlands, such as Protective Process Forestry, a central European approach close to rewilding, originating in Lubeck, Northern Germany and today lauded by the Naturwald Akadamie (Natural Forest Academy). Embraced by parts of the German Green party, these Protective Process Forestry and related approaches have been increasingly portrayed as a deeper green, more fully ecological response to the dying forests crisis. Never mind the sorts of technical wizardry that NRP66 and Aktionsplan Holz had brought to the fore to help support its growth, the forest sector was seen as part of the problem.

The clamour has been most heated in Germany, but the schism is also evident across Switzerland. Native engineered hardwoods weren’t going to help some decades from today if the country’s hardwoods were dying out. For n’H’s Thomas Strahm, ash will likely be a short-term material as pervasive ash dieback means there won’t be meaningful amounts of ash in the future. Beech is another matter, which Strahm, like others, seemed more confident about. Still, Waldsterben 2.0 is an illustration of the wreckage that climate change brings. These current difficulties have occurred in the early years of the 21st century. What about in twenty, thirty, fifty years?

Lukas Imhof’s all ash Ekkhartoff Community centre and restaurant – Photo Lukas Imhof Arkitekten




“We are done,” says Steiger, of the research on structural application of beech and ash, before running through a few further issues that are receiving continued attention. AI machine learning is being applied at Empa to the Erhart camera machine and similarly research into machine learning is informing strength grading. Further investigation is needed on issues around connections and shear strength. The eventual longer-term aim is to transfer the results into European Harmonisation Product Standards at the Euro level.

Smart Living Lab

The research programme may be over but the arrival of engineered beech and ash as new members in the extended family of structural timber materials is a chapter which is only really beginning. The Swiss effort sits within wider European and North American contexts. In Germany, Göttingen University includes a major hardwoods agenda;  the Bavarian Forestry and Wood Clusterincludes Hardwood Innovation Cluster connected to TU Munich, which recently co-ordinated the publication of an overview of the emerging hardwood construction agenda, Building With Hardwoods. In the US there’s been considerable energy committed to developing Tulipwood, a poplar hardwood tree indigenous across much of the eastern seaboard, for construction purposes. Switzerland, however, sought to advance the research in a single integrated piece of research programme. The most significant difference from past research in Europe, says Steiger, was that “we tested specimens at a much larger size, and the testing was much more extensive.”  Biel’s AHB department is looking to expand. While a whole new campus is apparently, post-Covid, on ice, the focus has moved to Fribourg Smart Living Lab. Applications within large, large-scale contexts like the 80m Zug high-rise, may demonstrate its mass use take-up, and a convergence of design principles that draws upon both the Swatch buildings’ double skin approach and that of the research programme, in the guise of ETH-Z’s House of Natural Resources. In some ways, tall timber, with its showcase spotlight on a minuscule proportion of buildings, is a massive distraction from the on-the-ground 21st century timber transformation. Still by the time the Swiss timber tower is finished, there ought to be a clearer sense of whether the mainstreaming of these new family additions to engineered timber is happening at scale, or if other factors - from a fresh slew of technical challenges to broader concerns of Waldsterben 2.0 and accelerating climate change - will turn this early 21st century research effort at industrial sustainable construction into yet another once hopeful, yet overtaken future. Meanwhile, the ash and the beech continue to grow, even as their future increasingly looks as if it may sit in the balance.

Many thanks to those I spoke to while researching this piece, including Olin Bartlome, Andrea Frangi, Steffan Franki, Lukas Imhof, Eric Mueller, Frederic Pichelin, Rene Steiger, and Thomas Strahm