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The jury's out on timber framed blocks

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Kurt Barling | 11:48 UK time, Thursday, 15 July 2010

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Another tower block fire in Kingston has reminded residents of the dangers of living in high rises. Residents have described the fire spreading rapidly, upwards.

This time there were no fatalities and the fire appears to have acted in a predictable way although questions will still need to be answered as to why the blaze spread rapidly.

The building had been fire risk assessed in November 2009.

Some residents described using the experience of the tragedy at Lakanal House in Camberwell.

They ignored Fire Service advice to stay put in the event of a tower block fire until firefighters arrive and got out. A number, probably inadvisably, used the lifts.

Residents continue to show anxiety about their vulnerability in the event of fire. Another fire is also a reminder to the London Assembly that its current investigation (due to report in September) into the safety of high rises in the capital is both timely and its recommendations urgent.

The question of whether to stay put is particularly important when it comes to timber framed buildings. Anecdotally it is reported that this type of structure is gaining favour with developers and constructors and more are being built across London.

This has worried some architects like Sam Webb who is concerned that these structures are not as safe as they are being made out to be.

In this month's Royal Institute of British Architects' journal, Webb highlights the ambiguity over a test on a timber framed block at the British Research Establishment Centre at Cardington in 1999.

The reason this deserves our attention is that the report of this test, TF2000, is often cited as a reassurance that timber framed buildings comply with the 60 minute compartmentalisation rule for blocks of flats. Each individual living unit must guarantee 60 minutes fire resistance for fire-fighters to rescue residents.

The compartment test was deemed a success in TF2000, but Webb reports that the testers failed to point out that in the very early hours of the following day the Fire Brigade was called out to the test centre because a fire in a cavity in the test block had reignited the block.

It took several hours to get the fire under control. Webb says this makes the test unreliable evidence on which to assume these types of structure are safe.

The UK Timber Frame Association have told us that the fire at the BRE test site was not relevant to passing judgement on the robustness of these structures because the test was specifically about compartmentation.

A subsequent report by Chiltern Fire into the causes of the cavity fire at the test centre, made it clear that a high standard of workmanship was critical in timber framed blocks to prevent the spread of fire. There should be adequate cavity stops and an open recognition that fire crews were not always familiar with detecting these types of fire, because they are often difficult to spot.

Back in December I reported on a similar cavity fire in an inhabited block in Croydon in 2007 which had destroyed the entire building. Webb cites this as strong evidence of how blocks behave in real life, as opposed to test, conditions. He concludes that we are far from understanding the dangers inherent in timber framed construction.

One way of being better prepared, acknowledged by the London Assembly in its preliminary investigations, would be an inventory of all such timber framed buildings in the capital.

Curiously enough I was in the process of trying to find out this information under the Freedom of Information Act. At BBC London we'd approached all 32 London boroughs to find out what they know.

The results are quite disturbing. Twenty-seven London boroughs are clueless. No idea how many timber-framed blocks have been built or are being built in their boroughs. Three claim they have a fair idea and Kingston and Newham refused to answer the question.

If we follow Webb's analysis in the RIBA journal, what this means in reality is that no-one has really got a handle on how safe these blocks are, and more importantly public authorities in London don't know how or where they are being built.

In the event of a fire in these blocks it is highly doubtful that the Fire Brigade will be warned about what they are dealing with until they get on site.
As the Chiltern Fire report said, specialist equipment is needed to search for cavity fires in timber-framed buildings.

The Chairman of the London Fire Authority, Brian Coleman, says this is evidence enough for him not to want to live in such a block. He also maintains that regulations need to be introduced so that the fire authority and local authority planners are provided with this information once a building is completed.

The new Head of Housing in Southwark, elected since the Lakanal debacle, says the fire in a timber framed block under construction in Peckham in November has convinced him that the law is deficient. Ian Wingfield believes that local authorities must once again have a statutory responsibility to be able to inspect buildings under construction.

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.

Comments

  • Comment number 1.

    It is disapointing to see yet another inaccurate 'report' on timber frame which links any fire issues of high rise building and timber frame in one sentence. Many of the recent fires in high rise blocks have in fact been in old concrete built buildings, where fire assesments have been hampered by design, and have nothing to do with timber frame. Also there cannot be a link between a building site fire and a completed building fire risk for obvious reasons to any who choose to think rationally.

  • Comment number 2.

    This article refers to "high rises" yet the examples given are only four storey buildings. By trying to link these to other fires which occurred in tower blocks built of concrete, you are scaremongering at best.
    If you have any example of genuine high rise timber frame buildings, that is over 75 feet high, please reference them.

  • Comment number 3.

    I find it incredible that this blog has linked a concrete tower block fire with timbre frame. How are the two connected? I've read Sam Webb's article and at best it's an uneducated rant on a subject he clearly knows nothing about. I've lived in Sweden and the US where timber frame is used extensivly. Timber frame is without doubt the most sustainable method of construction, when someone can show me how to grow bricks then I'll sit up and listen.

  • Comment number 4.

    Another excellent example of poor journalism. As a good honest license payer I really expect more from the BBC.

    This ‘journalist’ here has taken the examples of two fires in masonry built tower blocks, and managed, somehow to make it in to a inflammatory and ridiculously inaccurate massacre of the timber frame industry. THAT is not news. Not even if this were a tabloid rag would it be news. Next you’ll be doing the big splash that we can’t have wooden floors or fixtures in our homes. Its utter nonsense and you should be ashamed of yourselves for broadcasting it to the rest of the world.

  • Comment number 5.

    I think it should be obvious to the reader that the first 5 paragraphs are referring to masonry built blocks. A key issue for tenants and residents in multi-storey blocks of flats (irrespective of the materials they are built from) is how safe are they and their families in the event of a fire. Can they get out and how can the fire be contained, long enough to get them out or to protect property. Fires are rare but do not discriminate depending on the materials used for construction as these comments quite rightly identify as does my initial blog. Fires in Colindale and Peckham made it absolutely clear security is an issue during construction when timber frame structures are most vulnerable. Croydon showed cavity fires are difficult to detect and this is a real danger where the timber frame structure effectively becomes fuel if the workmanship has not protected the building against rapid fire spread. No-one is arguing that timber frame multi-storey blocks are uniquely vulnerable to fire, that is self-evidently not the case. But here in London the London Assembly is conducting an investigation into both high-rise and timber frame buildings largely because public landlords have a duty to ensure their residents and tenants are safe. The London Fire Brigade are concerned that there is such poor record keeping in the capital and no inventory of timber-framed structures which would assist fire-fighting when it is needed. It is important that this gap is plugged and important we demonstrate why. Wooden floors and fixtures are not an issue, nor from what I can determine are timber framed houses. The issue here is when a fire breaks out the spread must be slowed down. In Croydon the fire spread after the Fire Brigade thought they had extinguished it and the building was lost. When public authorities cannot answer basic questions about the safety of timber frame structures, the public are entitled to press them. Furthermore the public is entitled to know who is checking that workmanship is up to scratch. This wasn't checked properly in Croydon after a refurbishment and at present we cannot be sure the work is done as there is no public register to identify it has been done. The Royal Institute of British Architect journal is a responsible peer reviewed publication and it carries a response from the BRE to Sam Webb's article which clarifies their differences with his analysis. Timber frame converts will of course argue they bring real benefits; all of this may be true but that does not prevent the duty to be clear about the risks involved in timber frame buildings when it comes to fires in them and fighting them. If the TF2000 test is the sole test to be relied upon then the enforcement of building regulations must surely be more rigourously applied. When we approached the UKTFA to comment on the Croydon fire they responded that they did not have enough detail to comment. The Fire Brigade report into the Croydon incident publised in March 2008 makes instructive and salutory reading and is available to anyone who cares to read it. I'm a little surprised the UKTFA seem to have overlooked it.

  • Comment number 6.

    The article and report by Mr Barling and the issues raised are easy to understand and I fail to see how the contributors cannot understand the observations. If any of you have read the article by Mr Webb, and I suggest that you do, you will realise the problems that we are now building.

    Having dealt with a large number of fires in various types of properties I would not live in a timber frame building. In fact the TF2000 report by BRE is flawed from the date it was published.

    BRE undertook a 60 minute fire test that was fully extinguished at 64 minutes. The Luton and Beds Fire Brigade checked and rechecked using thermal imaging cameras and left the site.

    Unknown to everyone at the test was the fact that the fire had in fact spread into the cavity and could not be seen with state of the art equipment because of the thermal insulation and plasterboard. Later that night the alarms went off and four of the six storeys were severely damaged.

    This was not the only major fire in the TF2000 building. Less than 2 years later after forensic tests were undertaken and extinguished by the fire brigade the same thing happened.

    The TF2000 timber frame building was built in a massive airship hanger with no weather problems by competent hand picked contractors and overseen by the interested parties including TRADA.

    The fires have never been publicly reported on by BRE to my knowledge and it was declared by BRE that the compartmentation lasted 60 minutes yet it is clear that the fire had already spread into the cavity within 64 minutes.

    These facts are well known and spoken about in the fire testing and fire protection industry and passed on by word of mouth. I have checked them by reading the fire reports from the fire brigade.

    I am also providing expert advice in regards to defective Fire Risk Assessments and defective fire protection specifications in high rise buildings of various types of structure. Some of the specifications are, in fact, making the properties more dangerous.

    Please remember TF2000 was carried out on a brand new building before tenants have had years of occupation to damage the plasterboard walls by hitting them, allowing leaks to occur over months damaging the plasterboard and rotting the timbers and before well meaning Housing Officers have had extractor fans fitted through the walls removing any fire protection etc etc

    One timber frame block in Croydon was completely burnt down because the windows were replaced and fire got into the cavity, one block only 2 years old burnt down in Manchester because a contractor soldered a length of duct on to an existing duct. I have also seen photographs of a block that burnt down because a cigarette end was dropped outside the flat on bark chippings next to a missing airbrick. If they had been traditional brick and block these losses would never have occurred.



  • Comment number 7.

    I do not agree with the blogger's comments regarding it being clear between high rise concrete building fires and timber frame buildings. What is clear is that the headline is sentational and the first two paragraphs introduce fires that have little to do with timber frame. If the blogger had wished the distinction to be clear he would have done so but chose not to. It is simply sentionalistic journalism. This is further supported by asking Brian Coleman, whose anti-timber frame stance is well know, to comment when other more qualified people could have been offered the opportunity given ample notice.

    From the Chiltern Fire report which followed the TF2000 test, unlike the previous commentator I am confident in saying that a heat camera was not used to check whether the fire had penetrated the cavity during the initial test. The Chiltern Fire report tests which followed on from the compartment test show that each time a heat camera was used various fire brigades that took part in the tests found the test fire in a relatively short time. The issue is then, regardless of construction type, fires should be fully extinguished before anyone can return to a building. Surely this is logical.

    It should also be noted that new block built houses are no longer simple masonry structures. Cavities need insulating to conform to new levels of regulations. Buildings are more complex today as a result and fire fighting techniques altered to deal with these. I know there is much good work being done by the Chief Fire Officers Assoication and other agencies to improve techniques.

    It was also clear that since the Croydon building was constructed in the '70s, passive fire protection has improved and when 'upgrading' the windows to uPVC in the block, the structure should have also been upgraded at the time with the latest fire protection. It clearly wasn't.

    Unlike other methods of construction, timber frame structures are built from the most sustainable building materials available to man - wood. When built and constructed correctly they can last for 100's of years. Witness the many timber frame homes that are still standing in many parts of the country. Unlike some comments made, they are not the lowest cost option but offer a secure way of building high performance building fabrics that minimise fuel bills and provide comfortable living. As a technology it cannot be dismissed by such negative journalism and one man's opinion which at best mixes many issues which are cobbled together to try and make a point.

  • Comment number 8.

    This comment was removed because the moderators found it broke the house rules. Explain.

  • Comment number 9.

    It is good to see that you have read the available reports Geoff.

    The Croydon Fire was in a block built in the late 60's. Over the years it had had three changes of windows. The detailed Fire Brigade report shows that they used thermal imaging at the Croydon Fire found nothing, left site and were called back a few hours later to fight a fire in the cavity. Result of an initial small fire we are agreed was total loss.

    We are agreed re TF2000 that the fire had breached the fire compartment within 64 minutes. So why does the BRE TF2000 report make it clear that compartmentation in a brand new unlived in, undamaged, unaltered property give the green light to TF buildings up to 9 storeys in height - all on the basis that the compartmentation worked!

    Even where compartmentation prevents fire spread it does not prevent smoke spread. I have had a number of instances where all the adjoining houses and flats rapidly filled with smoke that passes through the cavites and out of the power sockets, pipe ducts and at floor level at the junction of the plasterboard and concrete slab and at the timber floor junction with plasterboard.

    Whilst smoke can pass through lime sand mortar in brickwork wall where it is unplastered it takes a long time to get through.

    The rapid total building loss scenario both during and after construction in TF building is well known. The recent Salzburg total loss fire in brand new residential block was caused by a cigarette dropped into a bucket on a balcony roof. How many brick, block or concrete buildings would have suffered total loss in such a scenario?

    To say TF lasts hundreds of years - it certainly does with Oak Frame - a wood which is slow burning and hard to ignite as it does not start to smoulder easily. With modern building we are dealing with fast grown softwood which ignites easily and burns away rapidly.

    And think of this - why in the blitz didn't London become a fireball like other cities in the UK and Germany? The reason is clear - the London Building Acts and Wren had banned timber frame buildings. All the fires were contained in solid brick, stone and concrete structures behind walls that do not collapse easily due to their thickness.

  • Comment number 10.


    I thought that the debate needed a contribution from someone who spent forty one years tackling fires as an operational firefighter.
    They are usually the people who have to face the consequences when things go wrong.

    Modern methods of construction and materials are now developing fast, faster than the Fire Service's understanding of how they will react in fires. The Fire Sevice's knowledge gap needs to be addressed by government research.

    I would like to quote extracts from the Chief Fire Officers' Associations official website in a report on Timber Framed Buildings, when in 2007 a Task & Finish Group was established to examine emerging concerns over rapid fire spread in timber-framed buildings. The Group, which included Fire & Rescue Service staff and trade union representatives as well as officials from CLG, HSE and the Building Research Establishment, reported in early 2009.

    Some of the main findings in the report are as follows:

    “We have seen a number of serious fires, including major incidents in London and Edinburgh where the evidence suggests strongly that the volume of timber in the construction contributes to the fire hazards and the risks to constructions workers and firefighters alike. Fire development is extremely rapid and generates very large amounts of
    heat flux.

    A number of significant concerns exist based upon the experience of the fires we have seen
    to date. These include:

    a) Unlike traditionally-built property, a timber framed building is very likely to be at the greatest risk of fire during the early stages of construction due to the amount of exposed and unprotected combustible elements and where there is minimal active or passive form of fire protection;
    b) Fires in timber framed buildings under construction have all seen very rapid fire spread and early structural collapse, and the severity of heat generated has caused spread to neighbouring buildings;
    c) Within completed timber frame buildings the risk of fire spread in the event of a fire occurring can increase dramatically should there be any aspects of poor workmanship in areas such as cavity barriers, fire stopping or finish quality;
    d) There is concern that, in the longer term, wear and tear as well as professional and DIY alterations will increase the risk of fire spread in completed buildings even if workmanship on the original construction is good.

    The Group also reviewed existing guidance available from the UK Timber Frame Association and it is unclear how well publicised this is. Concerns also exist about the degree to which it works alongside other guidance from the HSE and joint Codes of Practice. It is also obvious that once these buildings are completed, the facades will often
    be of a different construction and often it will be almost impossible to distinguish the premises from one built in a more traditional fashion. The resultant difficulty in assessing the method of construction could lead to firefighters making an inappropriate risk assessment.

    There are two other matters which, amongst all the rest, are perhaps the most concerning of all from a public safety point of view. First, at least one example is known where partial occupation was planned whilst construction was continuing elsewhere. Fire broke out before this planned occupation took place which, since the fire spread extremely rapidly and to all parts of the building, can be construed as a narrow escape.

    Second, it is apparent that a significant proportion of new large-scale timber framed developments will be in the social housing market. Given the risks identified in the future resilience of this type of construction, it is of concern that buildings most vulnerable to rapid fire spread will potentially contain some of the more vulnerable members of our communities. This problem has additional and very serious implications for anyone with mobility difficulties as the traditional “defend in place” arrangements, whereby people can remain in a place of relative safety whilst awaiting rescue, will be redundant in the face of such rapid fire spread.”

    The report made some ten recommendations, which can be found on the CFOA website, including consideration being given to further research into the concerns relating to the resilience of TF buildings and in particular the possibility for passive fire protection measures being compromised. In addition it was recommended that the recommendations within the report should be cross-referenced with those in the recently produced document from CLG entitled “Innovative Construction Products and Techniques” (January 2008).
    It was further recommended that:
    i) Research should be carried out into the suitability of the ‘defend in place’ strategy for large TF buildings.
    ii) Research should explore alternative (practical) strategies if appropriate.
    iii) The potential risks associated with the ‘defend in place’ strategy for large TF buildings should be included in guidance for the fire service.

    There appears to be a problem here for the fire & rescue service, which needs to be resolved.

    One final point, which puzzles me:

    If the TF2000 fire test was to test compartmentation yet the fire got into the cavity, how can it be considered a success? Why was this never mentioned in the main report?

  • Comment number 11.

    The jury is out on timber framed blocks accurately reflects concerns expressed to me by a number of stakeholders in the business of construction and maintenance of multi-storey buildings, including the fire authorities. It would be unfair to say they have a clean bill of health as it would be to say they present a disproportionately high risk. It is important that these questions are openly debated though, when it is becoming a popular Modern Method of Construction, lest we be lulled into a false sense of security on the fire risks involved, and the challenges in elimintating these risks.
    As the blog suggests we did approach the UKTFA which represents the interests of over 200 companies in the UK operating in the timber frame industry. They also work with many organisations, including the Chief Fire Officers Association and HSE. As well as asking them about the BRE test we asked them to comment on the Croydon fire which led to a total loss. A spokesman told us: "In relation to the Croydon Fire, they (UKFTA) have chosen not to make official comment as not enough is known by the UKFTA about the incident for them to make an informed and cohesive statement." Much is known about the fire in Croydon in December 2007 from the Fire Investigation report (a public document), so anyone whith an interest in fire safety should read it. Its a little bit surprising that a leading body like the UKFTA might not have digested its conclusions.

 

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