Modern methods of construction in general and timber frame buildings in particular came under the fire safety spotlight at a recent insurance industry event, as Ron Alalouff reports.

Recent fires on timber frame construction sites was the backdrop to several presentations at the Risc Authority’s annual seminar. While acknowledging that timber frame buildings had a role to play as a low weight, environmentally sustainable building material capable of flexibility in design and quick construction, several speakers called for greater attention to its fire safety drawbacks – especially during construction.
 

The timber frame development Beaufort Park in Colindale, north London after the fire in 2006

Niall Rowan of the Association for Specialist Fire Protection highlighted the combination of incomplete construction, a finely divided fuel source, and the potential for arson as contributing to the very rapid fire spread and major disruption caused by some recent fires. He then went on to give an example of a fire in a 5-6 storey building which started in an electricity consumer unit and spread through voids to the top of the building. As well as affecting the apartment housing the consumer unit, the fire broke into a neighbouring apartment and two apartments below. Because so much of the fire spread was hidden behind voids, firefighters had to break into the walls of several other apartments to the top in order to effectively tackle the fire.

He then gave graphic illustrations of non-existent or inadequate fire stopping – both in timber frame and other types of construction – which would contribute to failures in compartmentation in the event of a fire.

Niall Rowan said part of the problem was that specialist fire contractors were working in an environment in which main contractors were continuously trying to drive down costs. Added to this is a light touch regulatory environment, competition between local authority building control and approved inspectors, and that inadequate passive fire protection may only become apparent when it’s too late – in a fire. “The problem is poor specification, installation and enforcement, not timber frame per se.”

He called for the better design of buildings to reduce fire spread in concealed spaces, the specification of products on the basis of performance and not just price, the use of third party certificated installers and products, and the use of building inspectors and ‘qualified’ risk assessors.

Geoff Harris and Andy Brookes of Greater Manchester Fire and Rescue Service gave a graphic account of the difficulties of detecting the progress of a fire spreading through voids in a large timber frame apartment building. A fire for which the initial call to the fire service was made at around 11.15 am seemed to be under control soon after 3.00pm. But at around 6.00pm, flames started emerging again from the previously undetected spread of the fire. Even after that, the fire service had to attend fires which broke out on a further three consecutive days, before the building was demolished. The cause of the fire was a plumber carrying out soldering an external overflow pipe.

Issues for firefighters tackling such fires include the difficulty of identifying how a building is constructed, the potential for undetected fire spread, rapid fire spread and radiated heat, and the risk to crews from unstable structures, especially when cutting away burning timber.

Geoff Arnold, chairman of the UK Timber Frame Association (UKTFA), said that while responsibility for all site activities ultimately lies with principal contractors, accountability lies with timber frame manufacturers and the industry. He then outlined the measures being taken by his member companies to reduce the incidence and severity of fires on construction sites. Site Safe was a new mandatory scheme for UKTFA member companies which aims to ensure that the risk of fire is understood by all parties in the design and construction process. As such, the co-operation with principal contractors was critical to its success. He described the scheme as “a seismic change for the industry” as there has never before been a requirement for this level of commitment to fire safety.

Mr Arnold described Site Safe as an audited process to ensure member companies provide clear and concise information and assistance on fire safety to principal contractors on large timber frame construction sites. It involved a three-stage process: pre-construction planning; on-site management; and post timber frame construction. He said the process includes the contentious issue of a member company asking for a copy of the main contractor’s fire plan.

Where minor non-compliance was found, the member company would have to demonstrate future improvement. If a member company had two major non-compliances in a year, or if it did not adopt the Site Safe scheme, it would be expelled from the association.

Finally he said the association would consider the potential risks in completed timber frame buildings highlighted by previous speakers. “We were not aware of fire risks in completed buildings until [they were] raised today, but we need to take that on board.”