Timber framed building fires raise doubts about the method of construction once again
Once again, the issue of using of timber framed construction in both residential and institutional premises has raised its head. Five fires in a period of just over two months destroying an assisted living residence, two hotels and two residential apartment blocks have made over 200 dwellings and 100 hotel rooms unfit for occupation and have once again raised the question of safety in buildings where a high reliance is placed on timber as the principal constituent of structural material.
While these high profile, high consequence incidents attract a great deal of media attention, raising questions of their constructional suitability, is it possible that once again press concerns drive an agenda that is both inappropriate and unduly raises concerns and worry for citizens? Or is it coincidence that these fires have occurred in another great British summertime where the sun shines and ambient temperatures are elevated for extended periods?
Beechmere Care Home Blaze
The largest incident was a fire at the Beechmere assisted living home in Crewe on Thursday, August 8 at a retirement complex for around 150 residents. The fire, which is believed to have started somewhere in the roof area of the three storey ‘H’ shaped complex, 110m x 80m, and the first call to Cheshire Fire and Rescue Service (CFRS) was made at around 16.33.
In the early stages of the incident residents were supposed to follow the ‘stay put’ policy as previously instructed following the fire risk assessment. On arrival of the first attendants, it was clear to the initial incident commander (identifying a dissonance between what he expected to be happening and what was happening in reality) that ‘stay put’ was unlikely to be appropriate as large numbers of residents were leaving the building, some supported by the complex’s duty staff. It became apparent that allowing residents to remain in their flats while the firefighters contained the fire was not appropriate or safe and so, almost immediately recognising the potential for a major loss of life, the watch commander made the decision to evacuate the whole premises.
Assisted by a diverse group of individuals and neighbours, the building was eventually cleared of residents, a task which nevertheless took almost 50 minutes. Some of the residents had mobility issues or were non-ambulant and so, just after the time they all eventually left the building, the front of the property had started to collapse.
In an attempt to contain the fire to the area of origin, breathing apparatus (BA) teams were committed to all floors using jets. Whilst attacking the fire, flames were noticed emerging from external air vents 20m behind the BA teams on the top floor, threatening to block off escape routes and also indicating that the fire was indeed “in the walls”. BA teams were withdrawn and an external attack begun.
The fire became well developed in the roof space and spread rapidly into both parts of the ‘H’ shaped building. As the roof timber collapsed, the external skin of the walls appeared to part from the inner framework and bowed outwards extensively, forcing a 15m hazard are to be declared around most of the building perimeter. This key decision was proved correct as the wall faces did start to collapse not long after.
At its height, 20 pumps, two aerial ladder platforms and other appliances were used to control the fire. The fire, believed to be accidental, is thought to have started in the roof space and spread rapidly involving the walls of the building that allowed the fire to extend into and cause progressive collapse of those walls. One hundred and fifty residents of the complex were now having to seek alternative accommodation as the whole of the premises had been destroyed. To quote Mark Cashin, Chief Fire Officer of Cheshire Fire and Rescue Service: “We saw a £20 million plus building reduced to dust in less than 14 hours!” He also believes that had the fire started a few hours later, after sunset, that there could have been a significant body count, due to the rapid spread of fire, limited visibility and the potential for confusion among the elderly residents.
The building itself was one of five such complexes, and was opened in 2009 through a private finance initiative (PFI) contract between Cheshire County Council and a commercial developer. Designed and built using extensive timber frame technology, and having facings of brick, block and render and timber, it was reported by Inside Housing magazine, to ‘have the largest timber content of any on-site housing project in Europe’, using some 1,700 m³ of timber frame.
Like many fire and rescue services, Cheshire has 180 larger timber framed buildings within its area, which are registered under the Safe Site Scheme (a requirement to be registered with the National Fire Chiefs Council if the timber framed building is over 600m2). This is intended to support manufacturers and builders in ensuring compliance with all aspects of the design, build and occupancy of a building including the provision of Building Regulation requirement for passing information to the occupiers (Regulation 38).
Sutton Flats Fire
On September 9, a fire occurred which involved a four storey block of 20 flats in Sutton, London. The block was all but destroyed in the fire which broke out at around 01.00 in the morning and required 20 pumps and aerial platforms to contain. Around 60 residents have been made homeless although, despite occurring in the dark hours, there were no serious injuries and fire protection measures to evacuate residents worked effectively.
What is being seen to be particularly worrying is that this is the second block of flats in London to have been destroyed in recent months. The ten-year-old block, designed in the New England style and called the Hamptons, was wooden clad and according to Building Design magazine, reported to have a timber framed structure as well.
As FIRE went to press, a further fire involving a timber framed structure occurred on September 20 at around 20.00 in the evening. The property, a three-storey, 12 apartment social housing block in Pankhurst Avenue, Brighton, lost its roof and second floor during the fire, which was described by one firefighter as being “unbelievable how quickly it spread”. No-one was hurt but residents have been evacuated to a rest centre. The two adjacent blocks, of similar construction and design, and owned by the same social housing landlord, have been evacuated of residents until further investigations into the structure and fire precautions have been investigated.
Timber Clad Balconies
It is not only timber framed buildings that are causing fires: an even earlier fire, involving the Samuel Garside House in Barking on June 9, occurred when timber clad balconies were set on fire destroying 20 flats and seriously damaging a further ten. This fire is perhaps worrying in that the block is an early phase of one of the UK’s largest residential regeneration schemes which will eventually create nearly 11,000 homes in Barking Riverside.
Despite complying with Building Regulation requirements (for not having combustible materials on external walls and buildings taller than 18m – this building was marginally less than the threshold), the fire quickly spread externally and involved the whole of the block. Again, the same experts have been quick to get out their shrouds and wave them about with one expert speculating that had the fire occurred 12 hours later there would have been a death toll to “rival Grenfell”. If that were not enough, on September 16, a suspicious fire at a six storey block of flats in Clapton, East London, required 80 firefighters to contain the fire after it spread from the ground floor up via the balconies to all six storeys. Once again, timber cladding on the balconies was considered to be at fault.
Undoubtedly, there will be many conclusions from the investigation of these fires which will replicate those of the past. It will be concluded that like any building project, the standard of workmanship is of crucial importance when providing the required level of fire resistance. This can include the correct standard of nailing plasterboard to timber structural members, the correct location and fixing of cavity barriers within the cavities between timber frame and outer skin, the provision of fire stopping around gaps and holes made by second fix of electrical, heating and water systems within a structure.
There is also concern that with age, timber may dry and shrink, deform and sag if not treated correctly. While this may not necessarily cause a major structural problem, it may affect the security and integrity of the cavity barriers and other fire protection measures. As has been the case in the past, like the massive expansion of the housing industry in the 60s and 70s to meet the demands of the country to build 300,000 homes in a single year, it has led to a lack of effective quality control by the construction industry, as well as insufficient oversight by enforcing authorities and building control.
The consequences of inadequacies in the building process from design to sign off and occupancy led to events such as Ronan Point, the premature demolition of homes less than ten years old due to damp ‘concrete cancer’, dangerous installation of electricity and gas, and critical failures in the construction themselves.
Timber Framed Boom
The use of timber framed construction in the 1960s and 70s was virtually unheard of in the mass housing market. But things have changed: with the increasing demand for homes for the 21st century in the UK, timber framed houses are becoming more commonplace and incidents such as those above create an unease both for individuals and government as the scale of building means that getting it wrong can cost millions, if not billions to put right. With the housing industry set to expand the number of timber framed homes prefabricated every year, doubts about the construction and its safety record could have a serious impact on the capacity for the construction industry, affect resale values and cause worry for owners and occupiers.
There are, however, many good reasons why timber framed buildings could be used to provide effective housing not only on an individual dwelling basis but also as larger units with multiple apartments. The use of timber can be more energy efficient than more traditional types of construction. Traditional brick and block construction comprises about 30 per cent of the lifetime energy use of the building which is embodied within the structure. Timber used in construction of the structure reduces this quantity significantly and is more energy efficient. In addition, timber stores carbon and can help reduce the production of carbon dioxide in the atmosphere. In terms of thermal transmission, wood can be a more efficient insulator and reduce energy costs from heating, helping to create a more sustainable building.
Downsides of using timber can be fairly predictable. The use of unseasoned timber may result in warping and distortion of the structure, which may result in the collapse of the outer face of the building. Distortion of the outer face brick work would at the least have significant impact on the aesthetic aspects of construction and at worse lead to major reconstruction or even demolition of the building. Ineffective treatment of timber can also lead to rot and decay of the building frame, again requiring major repair and remediation. It is important not to view these deficiencies as being specific to timber frame buildings: more traditional forms of construction have also had to deal with poor workmanship, poor material selection, poor fabrication and incorrect mix of concrete, all exacerbated when there has been a significant growth in housebuilding in the UK.
While timber framed construction has been an easy target for scaremongers and “experts” seeking to make a name for themselves or proving a narrow point, it has its supporters including the Royal Institute of British Architects (RIBA). RIBA has stated that the spate of recent fires in multi-storey blocks of dwellings has provided evidence that the government’s ban on combustible materials on the exterior of residential buildings 18m and above ‘may need to be extended’. Some architects, however, have already seen a change in attitude on the part of councils and other social landlords who had shown a ‘marked push away from exterior cladding and all components were in any way combustible’ following the Grenfell Tower fire including flooring, balconies, timber trim and any form of plastics. Unfortunately, many fear that the cladding issue will have an impact on the use of structural timber within a building’s structure.
If properly designed, specified and constructed using the proper materials and good workmanship, fire should not be able to get into the cavity within a timber frame building. Even where this does occur, fire stopping and cavity barriers should limit the development of fire within the building. While some are advocating the use of sprinklers to be a requirement in all new and converted residential buildings, as well as retrofitting an existing residential buildings above 18m upon refurbishment, RIBA argue that the Worcester Park fire shows how there is a need for automatic suppression systems in residential buildings as well as fire warning systems in individual flats and not just the communal areas. But as Jane Duncan, Chair of RIBA’s expert advisory group on fire safety, points out “sprinklers should not be used to compensate for other crucial fire safety measures”, recognising automatic suppression systems are part of the solution and not the panacea advocated by many.
Swedish Timber Model
One of the most advanced countries in its use of timber frame buildings is Sweden, which has had extensive experience of building timber framed and timber clad buildings for centuries. Since 1994, when performance-based building regulations were introduced, building multi-storey houses using this form of building technology has grown significantly. Modern wood construction is defined as apartment buildings that have two floors and can include student homes and residential care premises. By 2014 there were more than 10,000 apartments in wooden framed buildings. Between 1998 and 2014, there were nearly 49,000 fires in Sweden. While statistically at least there should have been around 73 fires in wooden buildings in this period, in fact there were only 22 which could lead to several conclusions including the supposition that Swedes are more conscious of the fire risk in these buildings and take more care; it is also possible that standards of construction are higher in Sweden. The empirical evidence suggests something may be happening over there and is worthy of further research.
There is a danger that misreading what is happening in the world of the timber framed building may play havoc with the wider housing economy and make homes built of wood relatively valueless and unwanted by potential home owners as a result. Irresponsible scaremongering and shroud waving can raise concerns and worry among those living in such buildings, despite the fact that if following the design and construction processes used in those countries that have used timber as the principle means of home building for centuries, these buildings can be as safe as those built of brick or stone. It may be something as simple as having properly designed structures, effective quality assurance, supervised construction and on-going monitoring of a building will do that.
Of course, the current regime is already organised to do this, is it not? Then if not, why not? The culture of ignorance and indifference, cited by Judith Hackitt, as being a plague on the building regulatory system (and by extension, the construction industry) in England, is at its most prevalent and most dangerous where dwellings are concerned. There is no reason why timber framed buildings have to be any more risky than other means of construction – the Swedes show this to be true – it is the systemic failure to enforce the law and its regulations that is at fault and not inherently the building.
Thanks to Mark Cashin, CFO Cheshire Fire and Rescue Service, for his help in preparing this article.