Mass timber: challenges and potential solutions

Phase 1 report available for download here: https://asbp.org.uk/project/asbp-tah

1 Introduction
2 Standardised design
3 Executive summary
4 Mass timber solutions
5 Mass timber challenges
6 Insurance and policy
7 Opportunities for collaboration
8 Conclusion and full report
9 Related articles on Designing Buildings

[edit] Introduction

A report published in May by the Alliance for Sustainable Building Products (ASBP) in May 2022 sheds light on the major challenges faced by developers in their attempts to reduce carbon emissions in new building projects. It recommends a series of potential solutions that could unlock significant carbon savings through an increase in the use of mass timber.

The report, “Mass Timber: Challenges & Potential Solutions”, presents a summary of the research carried out through the ASBP’s Timber Accelerator Hub (TAH), a project initiated in response to the unfavourable market conditions that engineered wood products have been facing in recent years.

The project investigated the primary barriers preventing the wider uptake of mass timber and outlined how industry might overcome difficulties obtaining insurance, and the prevailing negative perceptions around fire performance and prohibitive regulation.

[edit] Standardised design

The report draws attention to a number of industry-led initiatives seeking to overcome these barriers, documenting a thriving ecosystem of organisations working to unlock mass timber construction through research, design innovation or cross-sector collaboration.

An example is the New Model Building, a project led by Waugh Thistleton Architects and funded by Built By Nature, which aims to create a pre-warrantied standard design for a six-storey mass timber housing block. The New Model Building approach could spark a renewed use of mass timber in UK residential development.

The report urges developers and building designers to collaborate to define further design standards and common approaches to mitigating risk that could address insurer’s concerns.

Elaborating on this, the report’s author Joe Giddings emphasises that “the urgent need to address the climate emergency combined with the necessity of adequately addressing fire safety concerns creates an imperative to act fast and demonstrate fire performance through testing, especially given the timescales involved in undertaking large-scale fire tests and creating appropriate standards and regulations.”

[edit] Executive summary

As the UK built environment sector seeks to transition towards greater use of timber and other bio-based materials to reduce the embodied carbon emissions of new buildings, major challenges are being experienced. These are leading developers, clients and their design and construction teams to turn back to more carbon intensive construction methods before the project starts on site.

[edit] Mass timber solutions

The group of engineered solid wood products known in the UK as ‘mass timber’ demonstrate enormous potential for carbon reductions in major developments, due to their structural strength, versatility, lightness, high degrees of precision and low-carbon manufacturing. These attributes mean that mass timber products are technically suitable for structural use in medium and high-rise buildings, as demonstrated up to 24 storeys in Austria1, 18 storeys in Norway2 and Canada3, and 10 storeys here in the UK4 .

Calling for the mantra in coming years to be “test, test, test”, the report calls on Government to work hand-in-hand with industry and rapidly scale-up fire testing programmes and provide clarity, following a string of divergent standards and policies released or drafted by the Greater London Authority, the British Standards Institute and the Government itself that have fuelled negative perceptions around timber’s fire performance.

Whilst some research is underway, test evidence often remains out of the public domain, having been produced on a project-by-project basis for a client. This can be enough for singular projects to gain approval, but this piecemeal approach will not overcome systemic barriers and negative perceptions. Industry-wide collaboration and coordination should be a priority to unlock mass timber for all.

[edit] Mass timber challenges

Despite this potential, mass timber construction faces particularly acute challenges in the UK. These are significant enough to be stymying its wider uptake and following an early growth period which saw the successful completion of many mass timber buildings, there have been many reports that the advance of mass timber has ground to a halt in certain sectors, particularly residential.

The primary obstacles currently preventing the wider use of mass timber are shared across the industry, with three issues particularly being reported by private developers, Local Authorities and Government clients alike: Severe difficulties obtaining affordable construction and property insurance for mass timber buildings. A prohibitive regulatory environment precluding the use of combustible materials in certain building types. Prevailing uncertainty around the fire performance of mass timber causing doubt amongst industry stakeholders.

...mass timber construction faces particularly acute challenges in the UK. These are significant enough to be stymying its wider uptake.

Developers and their design teams might overcome one or more of these only to find the next obstacle insurmountable. The greatest challenge is currently insurance. Costs of insurance for a completed building using mass timber for its primary structure have been reported to be up to 800% higher than conventional construction methods. In some cases, insurers have opted to refuse cover.

[edit] Insurance and policy

The fact is that insurance providers’ assessment of mass timber as a risk leads to disproportionate price increases for cover. Their concerns can be grouped into broad areas; susceptibility to fire and moisture damage, durability and repairability, concerns over quality of design and construction, and concerns over competency of professionals. There are several emerging and established solutions to these risks and competent design teams can demonstrate this. But at the time of writing unfavourable insurance market conditions persist.

The insurance sector has now been very clear about its concerns, with the RISC Authority publishing a white paper on mass timber in February 2022. Engagement with the insurance sector towards a common approach to risk mitigation in mass timber buildings has tentatively begun. This should be top of the priority list for all stakeholders aspiring to reduce the carbon footprint of construction through an increase in mass timber products.

Aside from property protection, the Grenfell tragedy highlighted the tragic consequences of neglecting building safety. Given the scale of fatality witnessed in London in June 2017, the onus is well and truly on the timber industry, the wider construction industry and the Government to demonstrate clearly that this group of combustible products are safe to use.

The wider policy context has shifted dramatically since 2017 with the UK now legally committed to net zero emissions by 2050. The Government is well aware that to get there, the construction industry will need to dramatically reduce embodied carbon and there is now wide recognition that mass timber has an important role in this.

[edit] Opportunities for collaboration

This demonstrates that despite the challenges, we’ve arrived at a moment of great opportunity and potential for mass timber construction in the UK: Ministers speak publicly about the need to reduce embodied carbon emissions; the Conservative MP Duncan Baker has introduced a private member’s bill for embodied carbon regulation to Parliament; the Government has kickstarted a policy process to increase timber use; the UK’s largest private developers are working together to unlock mass timber for their projects. And crucially, insurance brokers and underwriters are taking note and beginning to respond.

In the medium to long term, industry needs to work closely
with Government towards the development of more advanced regulations, standards and statutory guidance documents that encourage mass timber construction whilst ensuring the highest degree of building safety and property protection in mass timber buildings. We’re not there yet, but ultimately the ambition to mitigate constructions contribution to climate change will require us, somehow, move beyond the prohibitive regulatory environment we currently have. This report proposes a potential roadmap for this.

Casting our view further afield, there are many industry-led initiatives seeking to overcome the challenges outlined here. This report documents a thriving ecosystem of projects and organisations attempting to unlock mass timber construction. Over the past year, the TAH has coordinated some of these efforts through cross-industry working groups. Going forward, greater collaboration and coordination can really take advantage of this moment and generate further momentum towards the nature-based transformation of the UK built environment sector that we so need.

[edit] Conclusion and full report

In conclusion, it seems clear that efforts to decarbonise the construction sector in the UK with natural materials, such as mass timber, are being stifled by an inability to overcome the twin challenges of gaining insurance & demonstrating fire safety. Anybody with an interest in mitigating the sector’s impact on climate change should consider focussing on resolving these challenges, as a matter of priority.

Mass timber is an incredibly useful tool in the fight to mitigate climate change, but it is a tool which is currently unattainable for many. We must change this.

The text above is made up from the ASBP press release dated May 5 2022 as well as extracts from the report. The full report is available for download from the ASBP website, where you can also find out more about the Timber Accelerator Hub project https://asbp.org.uk/project/asbp-tah