The safety of timber frame buildings is once again in the spotlight – this time in the architects’ professional magazine, RIBA Journal.

Writing in this month’s issue, building safety campaigner and architect Sam Webb questions whether the results of a full-scale fire test on a six-storey timber frame block of flats in 1999 – part of the TF2000 programme carried out by BRE – can be relied on.

Designed to test the compartmentation performance of such timber frame buildings to stop the spread of fire internally, the structure passed the fire resistance criterion set for it (the fire brigade put out the fire after 64 minutes). However, Mr Webb points out that several hours later, firefighters were called back to the site to extinguish a fire that had developed from the original test in a cavity, and spread rapidly through cavities on several floors.

Questioning the claim that timber frame buildings are only more vulnerable to fire in the construction phase, Mr Webb also referred to two fires – one on Christmas Day 2007 in Croydon and another in March this year in Austria – in which respectively a four-storey and a three-storey occupied blocks of flats were destroyed in fires.

Responding to Mr Webb’s assertions that complete reliance cannot be placed on the findings of the TF2000 test report, a spokesperson for BRE told RIBA Journal that while the compartment fire test “met the stated objectives of the programme”, the test report should be read in conjunction with the guidance in Multi-Storey Timber-Frame Buildings – A Design Guide (BR 454).

“[The design guide] points out that quality of workmanship is vital in relation to the success of fire safety provisions. It also makes clear that the correct location and installation of cavity barriers and fire stopping is important in maintaining the integrity of the structure wherever the material within the cavity provides a medium for fire spread.”

The post-test fire ultimately led to a further collaborative research project with Chiltern International Fire called Understanding Fire Risks in Combustible Cavities. The results of this project also informed the guidance in BR454, say BRE.

Mr Webb concludes his article by referring to the UK Timber Frame Association’s assertion that cavity wall fires in general are extremely rare in the UK, representing about 0.07% of all fires attended by fire and rescue services. “That does not appear to be borne out by what happened and is certainly not what happened in Croydon,” he says. “Is there anything else we have not been told?”

Lack of knowledge
The controversy surrounding timber frame buildings has also been taken up by the BBC's special London correspondent, Kurt Barling. In his latest blog he says that out of the 32 London boroughs the BBC had approached, 27 of them had no idea how many timber frame residential blocks have been or are being built.

Referring to the London Assembly's inquiry into high rise and timber frame buildings, Mr Barling says: "We should know what the London Assembly makes of all this by the beginning of September. They may only be able to recommend a change in the law, but they could certainly make it clear there needs to be an urgent change in the culture which seems to have relegated fire safety priorities in high rise London.
 
Background to TF2000 project