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Knock on wood: Timber in modern construction

With its durability, potential for prefabrication and advantageous carbon footprint, wood is increasingly being used in urban construction. Swiss Re's Franco Ciamberlano asks if insurers should reassess their attitude to wood.

As a junior underwriter, I was taught 'wood is different'. Wood is combustible, stone is not. The great fires of history spread through largely wooden cities that over 150 years ago helped trigger the creation of the reinsurance industry.

Wood was a common factor. But our urban areas were densely packed around sprawling networks of narrow alleys with open fires commonplace in homes and factories. This would give modern insurers nightmares. Thank goodness city planning has evolved since then. Unguarded fire is mostly a thing of the past, but mistrust of wood lingers.

Treehouse to skyscraper

So  it was with great interest that I listened to Tobias Hohermuth's presentation, a representative Swiss construction company Implenia. Tobias was talking to attendees at the 12th Swiss Re Engineering Underwriting Forum. His company has seen its timber construction services grow steadily within its home European markets. The popularity of wood is driven by its high industrialisation potential; the ability to prefabricate timber; a favourable cost profile; and by its sustainability and relatively low carbon footprint.

Switzerland has become a pioneer in a new generation of timber constructions. The first three-storey timber buildings were completed 20 years ago; since 2003, companies have been able to build up to six storeys in wood. Implenia is currently working on seven storey  wooden residence, with 208 apartments and a 17,000m2 rentable area.

Burning questions

Modern timber constructions don't have a high fire risk. Solid wood, evolved to withstand forest fire, will char. This char is predictable and measurable; and can be engineered to ensure adequate protection in fire. Indeed, solid wood will out-perform steel at high temperatures, even though steel is non-combustible.

Thus when it comes to modern wood structures, fire risk is actually accounted for in the engineering planning process. This includes emergency escape routes, stability of load-bearing structures, safety gaps between buildings and lightning protection. Since 2015, Swiss regulators benchmark fire protection design, not the building material. The required fire resistance of the building elements is differentiated according to geometry and usage.

Does this alter my view as an insurer? Well, we welcome how the increased use of timber contributes to sustainability goals within the construction industry. We also see that solid wood, as part of a regulated process, has a high degree of fire safety. Even though I'm not yet ready to issue a carte blanche to all timber constructions, I do think the insurance industry needs to adopt a more differentiated stance regarding the use of wood in construction.

Franco Ciamberlano is Head Engineering Medi, CEE & Middle East, at Swiss Re. Tobias Hohermuth was speaking at the 12th Engineering Underwriting Forum (EUWF), where the discussion theme was "Infrastructure: from cradle to cradle." The EUWF is a leading industry forum for engineering underwriters across Europe. For more information, please contact Franco_Ciamberlano@swissre.com

 

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infrastructure engineering

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