The timber frame industry and research bodies have reacted strongly to a recent feature in Building magazine which questioned timber frame’s credentials in dealing with fire risks.

The article was based on a workshop at the Building Research Establishment (BRE) focusing on a government-funded Partners in Innovation research initiative called ‘Understanding Fire Risks in Combustible Cavities’. Its findings will be released in a report this September.

Issues arising from the BRE’s TF2000 project at Cardington were also debated.

The workshop presented evidence that badly installed plasterboard drylining and fire protection measures could lead to a fire spread through cavity walls.

But, Building says, timber frame buildings are most at risk, “because their cavities are lined with combustible materials”.

It also said test fires at TF2000 re-ignited after being put out because of smouldering timber in the wall cavity, severely damaging three flats.

It said fire protective cavity closers were either missing or dislodged in the test building.

The implications of all this, Building says, are that potentially thousands of people’s lives are endangered. And it calls the ‘revelations’ a potential disaster, raising the spectre of the 1983 World in Action television programme which severely damaged the industry’s image.

So is it a case of the timber frame industry “only having itself to blame”, as the editor of Building stated in his leader, or has the truth become muddied?

Mostyn Bullock, principal engineer of Chiltern International Fire, said Building had presented the workshop proceedings “out of context” and its report contained inaccurate, incomplete or untrue statements. He pointed out that:

  • the cavity fire research is ongoing and the workshop was an information-gathering exercise;

    &#8220 People should not worry that timber frame buildings present significantly more danger from this type of fire than buildings of other construction types.
    ”

    Deputy prime minister’s office spokesperson
  • the fire at TF2000 remained in the cavity and did not break into accommodation on any floor;

  • cavity barriers at TF2000 were not missing;

  • the workshop explained that fire in cavities incorporating combustible insulation materials are not confined to timber frame;

  • Building failed to acknowledge that the timber frame industry is heavily involved in sponsoring the work;

  • there have been no fatalities as a result of fires in wall cavities.

    The BRE said that it was as a result of the TF2000 recommendations that the government commissioned the Partners in Innovation project involving Chiltern International Fire, itself, the insurance sector, fire rescue services and others to investigate fires in cavities.

    TF2000 was focused on compartmental fire testing, not cavities. However, when a fire broke out in the cavity the BRE recommended further investigations.

    The BRE says TF2000 clearly demonstrated that multi-storey timber frame construction can satisfy fully the structural and internal fire spread requirements of the Building Regulations.

    Crucially, it adds: “At the time of the test referred to in the article, the top and bottom of the cavities were open fully due to an earlier series of structural disproportionate collapse tests and these adverse conditions, which obviously do not exist in practice, created a severe chimney effect within the external cavity.”

    For this reason, the BRE says, it is “misleading” to draw any conclusions from the limited fire spread in the cavity observed in the TF2000 test.

    Charles Grant, public relations director at the UK Timber Frame Association (UKTFA), said: “The UKTFA recognises that issues of poor workmanship are universal in the construction industry and that the detailing of cavity barriers always needs close attention. This is an industry-wide problem and not specific to timber frame.

    “For example, insurers Zurich Municipal have stated ‘most of the defects we find relate to cavity construction. About one in four properties have problems fire stopping’,” he said.

    &#8220The UKTFA recognises that issues of poor workmanship are universal in the construction industry and that the detailing of cavity barriers always needs close attention. This is an industry-wide problem and not specific to timber frame.”

    Charles Grant, public relations director UK Timber Frame Association

    Robin Davies, group business development manager of Westbury plc, added: “When you read the article it’s clear that the risk being referred to is more to do with what you fill a cavity with, rather than the fact you’re using timber.

    “The advanced timber frame products coming onto the market are extremely good at minimising the risks of serious fire.”

    Westbury’s Space4 houses have panels filled with fire-resistant phenolic foam and exterior cement particleboard cladding.

    Stewart Dalgarno, managing director of Stewart Milne Timber Systems, said: “The research project is still incomplete and has not uncovered the full extent of the causes and the solutions.

    “We are building about 1,000 homes a year and are perfectly confident in their capabilities to meet standards. The workmanship is no more or less of an issue than any other form of construction.”

    The Office of the Deputy Prime Minister, which now deals with building regulations, said the problem of poor workmanship is a problem throughout the construction industry, and not peculiar to timber frame.

    A spokesman said: “People should not worry that timber frame buildings present significantly more danger from this type of fire than buildings of other construction types.”