It is not often that one sees a whole city burning, although much of Fort McMurray did in Canada in 2016 from a fierce forest fire. But could it happen in the City of London, that part now known as the financial centre? On 4th Sept 2016 – the 350th anniversary of the 1666 Great Fire of London – a magnificent 120 metres long wooden replica of the original 17th century walled city, moored on the River Thames, was deliberately set on fire. That was all part of the ‘Totally Thames Festival’ which included ‘London’s Burning – Great Fire 350’ and other celebrations. It raised some burning issues for today’s built environment.

When London burned from 2nd to 5th September 1666, about 436 acres of the city were destroyed, including 13,200 houses and 84 churches, vividly described by Mr Samuel Pepys in his famous diaries. 52 Livery Company Halls were lost. However only 6 people died but more than 100,000 people were left homeless for years.  Pepys described ‘10,000 houses all in one flame’, most of which were wooden and thatched houses in a totally chaotic and very overcrowded area. There was no fire service and the authorities were slow to act. It changed London for ever.

The Great Fire gave way to both good and bad consequences. On the one hand the fire cleared slums and the architect Sir Christopher Wren was able to oversee the redesign of the city including such iconic buildings as St Paul’s Cathedral as we know it today. But the fire did no good for wood, which was virtually banned by building regulations for the next three centuries or more. Whereas in the USA and Scandinavia wood has been a prime construction material throughout history, it was impossible to obtain a bank loan in Britain for any home not built in bricks and mortar until quite recently. The real consequence is that for all this time financiers, developers, architects and engineers have ignored what we now know as the most environmentally beneficial construction material, low in embodied energy, storing atmospheric carbon and requiring less energy to construct – wood.  The latter is largely because lighter buildings require less foundation material.

There are other issues too. When wood burns it tends to form insulating charcoal outside and maintain the integrity of the structure for some time. Firemen will tell you that a life-size building on fire, constructed of wood, will creak, speak and groan before it finally fails. Nobody is suggesting that the Twin Tower attacks in New York might not have ended in massive loss of life, but at a certain temperature steel melts and instantly collapses, when many firemen have no chance to evacuate in time. There are other advantages. It came as no surprise 20 years ago when the world-renowned engineers Arup came up with research showing that the volume to strength ratio of laminated American white oak was superior to steel, when wood was specified for Portcullis House atrium roof at Westminster in London. This reduced the volume of support sections thus allowing more light into the courtyard below.

We can regenerate forests and plant trees indefinitely and when we do so the carbon impact of producing lumber pales into insignificance compared to the energy required to produce steel or the unsustainable and polluting effects of mining and drilling. Building technology for wood is advancing fast with high-rise buildings literally growing all over the world from Australia to Canada and, despite the history, now also in London as well. A turning point for the UK came in 1999 when the Building Research Establishment (BRE) built a 6-story building and burned it under test, reporting to the Timber Frame Association that the fire was contained; and regulations to prohibit wooden structures were then relaxed.  So now the burning of this magnificent model of the old city in London made of softwood and Chinese poplar plywood, surrounded by its competing materials of steel, concrete and glass, was merely a reminder, at least for this observer, of the end of some prejudice against the increased use of wood in construction.

Michael Buckley 2016©