By Jim Glockling, Technical Director of the Fire Protection Association and RISCAuthority
The drive to achieve net-zero by 2050 will inevitably mean a rise in the use of timber as a structural building component, and this will include large buildings such as hospitals. However, while sustainability is rightly a key factor in building design, safety is a primary concern, and massive timber construction presents challenges over insurability.
Cross laminated timber (CLT panels), laminated veneer lumber (LVL), Glulam and other engineered wood products can all be used as load bearing materials in massive timber construction. The shift to the use of these materials – and the changes in the ways they are assembled and the additional events that the insurance policy therefore needs to cover – presents a number of challenges and impacts the core established insurance principals for assessment and risk measurement.
For some construction methods, predominately those reliant on combustible materials, compliance with building regulations does not necessarily mean that the building is insurable. Compliance with regulations does not ascertain 
that the scale of loss in the event of a fire would be less than 100%, which is what insurers need to be able to conclude. The current lack of property protection measures in UK building regulations means that this must be considered in the building design.
Fire safety challenges, potential for water damage and the combination of combustible materials and voids are key areas of concern over timber construction. In the domestic and residential sector, escape of water alone is the biggest category of loss – greater than fire and security combined. Water leaks occur more frequently than fires meaning water damage is a particular concern to insurers and, as timber is more susceptible to water damage, there is a risk of structural deterioration from prolonged, hidden water exposure.
So, what are the solutions?
A potential solution is the hybridisation of traditional and modern building methods and materials. For example, if half of the structure of multi-storey buildings are non-combustible this reduces flood and fire risk. The first floor of a mass timber building should be constructed with concrete, and subsequent floors should alternate between timber and concrete. It’s important that all electrical intake, bathrooms and kitchens are located in the concrete construction. Moreover, to reduce the potential for water damage during delivery and construction, a CLT panel waterproofing membrane should be used.
The presence of combustible voids creates one of the greatest challenges for building safety, and as a result the insurer, as these combustible voids in cavities and roof spaces enable the invisible spread of fires. One solution is for all timber to be encapsulated and protected from fire exposure by a material such as gypsum, which resists fire and prevents its spread. Any combustible voids should be either lined, sprinkler-protected or filled.
These are just a few examples which show that progress can be made in order to achieve the best route forward to satisfying both property insurers and all stakeholders involved in timber construction projects.
Innovative solutions are already being found, often involving the hybridisation of new and old building methods and materials, to minimise the risk posed by fire, water exposure and flood, to timber buildings. However, legal requirements could go further and include property protection requirements withing building regulations.
RISCAuthority’s whitepaper provides a definitive description of the insurance challenges of timber construction methods based on insights from 24 major UK insurers. To learn more about how buildings can be designed and constructed so that they are both sustainable and insurable, download the whitepaper here.
