insurer opens door to more engineered timber buildings

The company, one of the largest insurance firms in the UK, said it was increasing its underwriting capacity for schemes using products such as cross-laminated timber (CLT) and glulam following a recent pilot.

Insurers’ nervousness over timber in construction is regularly cited as one of the reasons concrete is not being replaced by more sustainable wood products. Some brokers were reportedly quoting teams up to 800 per cent more for insurance on schemes featuring engineered timber compared with traditionally built buildings.

But Aviva has said it wants to ‘commit underwriting capability towards’ the development of more environmentally friendly construction.

Its UK & Ireland General Insurance chief executive Adam Winslow said: ‘There are a growing number of developers looking to build more sustainably, both by using sustainable materials like engineered timber, and by adopting modern methods of construction.

‘Aviva wants to embrace both; widening our underwriting appetite to insure commercial buildings using engineered timber, and using our risk management expertise to minimise associated risks.’

Chetwoods director Andrew Hall is behind one of the largest timber-framed buildings being constructed in the UK, a three-storey 2,800m² office headquarters at Baytree Logistics Properties’ Nuneaton development.

He welcomed Aviva’s decision to extend its insurance cover, describing it ‘as a big step forward for our industry’.

Hall told the AJ: ‘This change should encourage further developers to consider the use of the material as barriers are reduced.’

LOM Architecture and Design associate director Tom Hofton and his colleague Charlie Brett said: ‘Many of our clients are keen to use timber and CLT built frames in commercial developments, and this commitment from insurers will encourage the construction industry to invest in designing safely with engineered timber.’

Aviva‘s move comes in the wake of the recently published Mass Timber Insurance Playbook, launched in May by the Alliance for Sustainable Building Products (ASBP).

The alliance said it hoped the guide would promote a collaborative approach between construction teams and insurers and pave the way for more ‘equitable insurance for mass timber buildings’ which have often faced difficulty securing cover, especially since the Grenfell Tower disaster.

Responding to Aviva’s announcement, ASBP associate director Richard Broad said it was ‘great news’ the insurer was expanding its underwriting scope. He told the AJ: ‘Our guidance has only been live for three months but we would certainly hope that the playbook – alongside other projects funded by Built by Nature and our precursor Timber Accelerator Hub project – is helping to open up new doors and encourage insurers (such as Aviva) to insure more mass timber buildings.’

The AJ has asked other insurers whether they will be following Aviva’s direction on engineered timber in commercial buildings.

A spokesperson for Zurich, which contributed to and sponsored the ASBP Mass Timber playbook, said it would continue to look at buildings on a project-by-project basis.

They said: ‘We recognise the role mass timber can play in a move to more sustainable construction methods. Due to the individual nature of mass timber risks, we consider each on its own merits, taking into account a project’s scale, size, quality and risk mitigation measures.’

AXA Commercial’s director of mid-market and customer risk management, Dougie Barnett, said: ‘[We have] been working with architects and developers for the past two years on a number of large projects incorporating engineered timber components.

‘Essential to this engagement has been a focus from the outset that we will commit appropriate risk engineering input to guide the design, ensuring that we have an acceptable risk during both the build and the occupancy phase of the project.’

He added: ‘Each case is considered on its individual merits to assess what capacity we are willing to commit. One of the developers we’re working with is keen to engage further on AXA’s considerations of ESG in the built environment so we can jointly explore thinking and challenges.’

Comment: ‘This may be a false dawn’

Peter Drummond, chair of RIAS practice committee

The decarbonisation of the construction process poses a great many challenges for the sector, and there is an understandable focus on how we might make greater use of timber. Other European countries, such as Denmark, have shown what might be done.

We should not, however, underestimate the technical issues.

Large cross-section structural timbers burn relatively slowly, charring of the outer layers and providing a measure of insulation to the core.  Lightweight framing and cladding timbers are an entirely different matter.

Such untreated timber will typically have a Euroclass rating between D and E, igniting fairly easily with a fairly rapid spread of flame.

That is potentially disastrous in a medium-to-high-risk building and a chemical fire retardant treatment is therefore typically applied to bring it down to class B or C.  Such treatments do, however, also have an environmental footprint which needs to be taken into account along with things like long-term effectiveness.

There is also the fundamental problem of poor workmanship on sites: missing or ineffective fire and cavity barriers, interlinked cavities and substitution with inferior materials. Quality control should improve significantly as the Building Safety Act and Compliance Plan Manager measures come to the fore in England and Scotland respectively, but it will not be an overnight transformation.

We cannot afford to take our eye off public safety in the meantime.

I am no expert on insurance but I would imagine that underwriters will need to find a way to quantify the risks before they can reach a view on the extent of cover (if any) and premium arising.

If the construction sector is wrestling with this issue then, in my personal view, there is a risk that suggestions of market appetite may be a false dawn. More work needs to be done on these issues to ensure public safety and, thereafter, put in place appropriate levels of insurance.