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Can timber work hand in hand with MMC?

by BDigital_Admin
TDUK Chief Executive Dave Hopkins

On 22 September, Timber Development UK became the largest timber supply chain body in the UK following the merger of the Timber Trade Federation and TRADA, bringing together more than 1500 businesses. As TDUK looks ahead to the future of the timber trade sector, TDUK Chief Executive Dave Hopkins asks whether timber has a role to play in the latest construction innovations

Timber may be one of humankind’s oldest building materials, but it can also play an important role in the future of construction.

Regular readers of Build in Digital are likely aware of the emergence of Modern Methods of Construction (MMC) based on platform systems and offsite construction. But they would be forgiven if they have not yet made a connection between timber and the cutting edge of construction innovation.

In the UK, and England in particular, concrete and steel are firmly established as the de facto choice for construction, despite their problematic environmental credentials, whilst timber construction is seen as something of a specialist area.

Despite misconceptions about the limitations of timber, we are in a unique moment in time where focus on embodied carbon and whole-cycle carbon targets is forcing the industry to reconsider the materials we build with. This shift is pushing innovators look for options which can help them increase the viability of MMC.

MMC and timber – a natural fit

Sustainably sourced timber is a natural fit for offsite construction because it has the advantage of being significantly lighter than steel or concrete, which reduces transportation costs of pre-made assemblies once prepared.

Housing construction sites are already filled with trussed rafters manufactured in local offsite factories and delivered to site to be quickly erected. This is nothing new – traditional timber frames have long been prepared offsite and constructed on-site and as a result the timber industry is well-versed in prefabricated approaches to construction.

These established techniques are exactly what platform and modular construction companies are currently aiming to achieve.

That said, it’s the latest innovations in engineered timber where wood may be really ready to come into its own.

Engineered timber

Engineered timber is an increasingly popular material, both in the UK and around the world. These modified timbers are stronger and more durable, diversifying the potential uses of timber for construction.

Engineered woods have had their properties modified to give the timber added strength, allowing them to be used in place of more energy-intensive materials like steel. These products can then be engineered to precise performance specifications, and often will be cut to measure offsite before being transported and erected at great speed.

One of the most commonly known is cross-laminated timber (CLT) but there are many other forms of this engineered wood, such as glulam and laminated veneer lumber (LVL).

Some engineered woods are pound for pound stronger than steel with the same carbon-saving advantages as standard timber.

Engineered timber is extremely versatile and well suited to be applied to a range of MMC solutions. CLT can be used for load-bearing beams or cut into wall panels with spaces for doors and windows pre-made. It is also ideally suited for wall and ceiling cassettes due to its insulating properties, which can then be transported to site pre-assembled.

The striking Metropol Parasol in Barcelona is one of the world’s largest timber structures (credit: Turismo de Sevilla)

Because you can cut CLT sheets into almost any shape you can also be extremely creative, and we have seen some dramatic examples, such as the Metropol Parasol in Barcelona (pictured).

CLT offers a range of options for modular or platform construction schemes, allaying fears of dull, uniform architecture becoming the norm.  

In smaller projects, you can create ‘flat-pack’ buildings including floors, walls and roofs which can be constructed without the need for multiple specialist trades on site in a manner similar to Ikea furniture.

A great example was Tsuruta’s Architect’s Wooden Annex building which was entered into last year’s Wood Awards. During construction, over 1222 individual CLT pieces were produced, using CNC milling, for the structure and envelope. These were delivered as flat packs and then assembled on-site using traditional carpenters’ skills.

Building tall with timber

As sustainable construction becomes more important, timber has been growing in popularity, and over the last 15 years, growing in height. Timber skyscrapers are being constructed around the world using engineered timber.

The UK were early leaders in constructing these timber towers with Waugh Thistleton and Hackney Council building a 29m, nine-story apartment building in Murray Grove in just 49 weeks. This has become a world-renowned example of timber construction.

“Some engineered woods are pound for pound stronger than steel”

By selecting timber these projects are helping reduce carbon emissions and setting a standard for what is achievable with MMC and timber.

From Sweden to Canada and all the way down to Australia, many countries can now boast of their own multi-level timber buildings.

In July 2022, the Council on Tall Buildings and Urban Habitat officially proclaimed the Ascent building in Milwaukee, US, as the world’s tallest timber and concrete hybrid structure.

Standing 25 stories and a total of 86.6 meters, the tower surpasses Norway’s Mjøstårnet Tower, the former record holder, by 1.2 metres. However, the Mjøstårnet is not a hybrid structure – it was entirely built using CLT so can still claim the title of world’s tallest timber-only building.

Whether hybrid or pure wood, many timber buildings, even taller than both the Mjøstårnet and Ascent, are already in the works as the possibilities of this versatile building material reach new heights.

The timber supply chain

So, what needs to happen if timber is to play a role in the future of MMC?

MMC is all about high volume flow. Once MMC adoption starts to become the accepted way to build, the reliance on the supply chain will be of key importance. This is why the timber industry needs to prepare now if it is to play a major role.

The fragmented nature of the timber supply chain is one issue which we hope the formation of TDUK will begin to address. Whilst the other supply chains such as concrete are dominated by a few large corporations, there are many thousands of businesses of all sizes in the timber supply chain.

Traditionally, this can make collective action and response to market trends difficult. It can also make it difficult for businesses trying to innovate in the construction space to engage with timber materials.

We will also need to secure the supply of timber if demand increases. The war in Ukraine has highlighted how imports are vulnerable to world events. We would do well to encourage the government to press on with targets around tree planting, whilst increasing our own supply capability through the development of more sustainable forests.

Upskilling for timber construction

Perhaps the biggest hurdle in the UK is education.

Understanding of timber: how to build with it, its properties, and how it relates to existing building regulations, is a real problem at all stages of construction – from architects to engineers and beyond.

Until only recently, structural timber was caught up in a blanket ban on combustible material allowed for buildings up to 18 metres, before the government admitted a more nuanced approach was needed after hearing responses from the timber industry.

Further reading:

Timber Development UK is working with Edinburgh Napier University and NMITE to provide extensive resources to designers and the industry at large, but it’s clear a significant cultural shift will need to take place in the UK if timber is to become a first-choice building material.

All the knowledge and information we need exists, as many countries outside the UK have embraced timber construction. However, as noted earlier, concrete and steel construction is well established in Britain and colours the choice of materials in many projects.

The emergence of MMC techniques seems to be a good opportunity to explore new material solutions which can help deliver efficiency and carbon savings alongside the other benefits of MMC. With this in mind, we would encourage innovators to take another look at timber.

At Timber Development UK we will be keeping a close eye on progress in MMC as we help ensure the sector is ready for the call.

Image: TDUK Chief Executive Dave Hopkins (supplied)

Read next: TDUK teams up with academics to close timber construction ‘knowledge gap’

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