A new report on fire risks posed by timber-framed buildings is a positive first step towards greater collaboration between the insurance and construction industries

Traditionally, the construction industry has delivered buildings and insurers have covered these without the two ever meeting.

Concrete, brick and steel are materials that shrug off fires and floods – the risks that exercise insurers – and a robust checking regime has largely ensured decent build quality. The two parties did not need to meet.

Tom Lane NEW with path grey

Thomas Lane is Building’s group technical editor

New forms of construction have changed all that, however, by introducing flammable materials such as foamed plastic insulation, plastic cladding panels and timber structures. The clerk of works has disappeared from construction sites and competition has been introduced into building control to cut costs.

The insurance industry has also become concerned about increasing losses after fires took hold in cavities full of combustible materials, making these difficult if not impossible to extinguish.

The perception was that insurers were over-reacting to the risks, unreasonably blocking progress towards tackling global warming

Then the tragedy at Grenfell Tower happened. Insurers took fright and refused to provide cover on large timber-framed buildings, much to the frustration of those trying to reduce the industry’s contribution to carbon emissions. The perception by many in the industry was that insurers were over-reacting to the risks,  unreasonably blocking progress towards tackling global warming.

>> Also read: Insurers call for hybrid structures to make timber buildings easier to insure

A report published today aims to change all that. RISCAuthority, a research organisation which carries out research on behalf of insurers, wants to set the record straight by saying that insurers want to provide cover for sound business reasons. It explains the risks peculiar to timber-framed buildings and proposes some solutions to make these easier to insure.

The risks include fire spreading uncontrolled inside cavities resulting in disproportionate losses. Concerns extend beyond cladding cavity fires to modern methods of construction, which include horizontal and vertical cavities, for example between modules, with minimal fire protection.

A surprise was water damage worries as claims exceed those for domestic fire and burglary. Insurers are concerned that water can spoil surface finishes and there is a risk of engineered timber products delaminating.

The report proposes a hybrid solution which includes building a concrete core, a concrete structure up to first-floor level and alternating concrete and CLT floor slabs above that

There is also concern that timber structures are at greater risk from long-term water seepage with the potential for building collapse.

The report therefore proposes a hybrid solution which includes building a concrete core, a concrete structure up to first-floor level and alternating concrete and CLT floor slabs above that.

A concrete core offers non-combustible service voids and reduces the risk of water damage if kitchens and bathrooms are in the core. A concrete structure up to the first floor reduces the risk of damage from arson during construction and offers protection from flooding. Alternating concrete floors provides more robust compartmentation in the event of a serious fire.

The report also makes the point that regulations in other countries pay more attention to protecting buildings. The US, for example, requires all timber elements to be protected with non-combustible boards.

Some of the suggested solutions should not be an issue, for example buildings over six storeys – the size of building of particular concern to insurers because of the potential for greater losses – will include a concrete core for stability reasons. But calls for alternating concrete and CLT floors and a concrete structure up to first-floor level will be harder to swallow as this means that well over half of the building would be concrete.

The reality is that the net zero agenda and skills shortages mean the move towards timber construction and MMC is becoming unstoppable. In time there will be low or zero carbon concrete and steel alternatives but, in the meantime, timber provides a readily available, low carbon solution.

Many in the industry, particularly housebuilders, are turning to MMC because of skills shortages which again will not be solved quickly. And MMC has the potential to improve quality and reduce cost.

How can this gap between insurers and the industry be closed? This report is a positive first step towards greater collaboration between the construction and insurance industries, which need to develop mutually acceptable solutions.

A more rigorous approach to quality is needed across the board

This includes borrowing the experience of countries that have a long tradition of timber construction, such as Scandinavia. This includes analysing their test data and construction experience. If there are gaps, then insurers and industry need to collaborate on material testing and assembly.

New forms of construction are less forgiving of poor build quality. A key reason for the insurance industry’s mounting claims bill is down to poorly installed – or missing – cavity barriers, turning small fires into big ones.

This issue is being tackled through the Building Safety Bill, which will help in the case of tall residential buildings, but a more rigorous approach to quality is needed across the board. Hopefully the requirements in the Building Safety Bill will filter through to other building types and the CLC’s industry skills plan should improve overall competence.

The main thing now is that insurers and the industry are talking. They need to maintain this dialogue and look forwards rather than backwards.