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Fire Prevention: the dangers of timber frame construction sites

UK Construction Online talk to Mike Burroughs, member of the Chief Fire Officers Association, on the dangers of timber frame construction sites.

Mike has been a member of the Chief Fire Officers Association (CFOA) Structural Timber Working Group since 2010. He left Devon and Somerset Fire and Rescue Service in 2015 having enjoyed a career of over 30 years.  He is now a forensic fire investigator with Fire Investigations (UK) LLP , and is fire consultant to the Structural Timber Association; he continues to sit on the CFOA Working Group.

 How common are construction site fires in the UK?

Recent statistics for England show that fires in dwellings under construction have declined from 27mike fire4 in the year 2009/2010 to 171 in 2014/2015 -a reduction of 38%. These figures are for all methods of construction. However, it is worth noting that it coincides with the recession which started in 2008 and subsequent increase/revival in construction projects in the last few years, as well as an increasing market share for timber frame in England.

Provisional figures show that housing starts in the UK have risen by 6% to 175,000 in the last 12 months and Timber Frame has a 27% share of that market.

What are the main causes of fire on construction sites?

I believe the biggest causes are deliberate fires and ‘hot works’.

What are the positives of timber frame building sites against their vulnerability to fire?

Advantages I am aware of include, sustainability, low carbon footprint, speed of build, and speed to making it weather tight. Various construction techniques are possible including prefabricated panels which are made in factory controlled conditions and assembled on site. Fires in cavities and voids are an issue in all construction types.

Are there any safety features on buildings to make them more resistant to the possibility of fire?

There are many different methods of construction that fall under the title ‘timber frame’. Standard Category A is vulnerable during construction but is appropriate in many circumstances. Once completed there is standard fire resistance within rooms.

Category B has increased fire resistance and Category C is clad with non-combustible boards.  Different features apply to other structural timber such as Cross Laminated Timber and GluLam.

How is safety maintained throughout the project?

Fire safety starts at the design stage and must be maintained throughout the project. In addition, as a condition of membership, members of the Structural Timber Association are required to adhere to the SiteSafe Policy as well as the 16 Steps to Fire Safety

The requirements of the Regulatory Reform (Fire Safety) Order 2005 apply to construction sites and are enforced by the Health and Safety Executive. Once the building is complete the Fire Safety Order is enforced by the local Fire and Rescue Authority.

What is done to promote a “fire safe” working environment to all workers / members of public?

Once the building is complete, the Fire Safety Order is enforced by the local Fire and Rescue Authority.  In addition, the Health and Safety Executive has published guidance HSG 168 Fire Safety in Construction. The Structural Timber Association has published guidance for members on ‘Design of Escape Routes During The Construction Process’.

What measures are in place for if a fire does occur on a timber frame construction site?

This very much depends on the size and complexity of the site as well as the construction method. As mentioned earlier, the Fire Safety Order applies to construction sites. This requires the ‘responsible person’ to take ‘general fire precautions’. This is defined as measures to reduce the risk of fire and spread of fire, providing sufficient means of escape and ensuring they can be effectively used, measures for fighting fire, measures for detecting and giving warning in case of fire and measures for training employees and mitigating the effects of fire.

In addition they are required to consider the ‘off site’ risk. This is where the Separating distance guidance published by the STA and recommended by HSE comes in

Finally, again as a condition of membership, members of the Structural Timber Association are required to register all sites over 600 square metres total floor area. This is via a database that is maintained by the Chief Fire Officers Association; entries are forwarded to the relevant fire and rescue service based on postcode. This makes the Fire and Rescue Service aware of the site and allows them to pre plan.

Timber Framers and contractors who are not Structural Timber Association members are encouraged, but not required, to notify the local fire service.

What is the 35 metre rule?

Referring to guidance from the Structural Timber Association (previously the UKTFA) , this recommends a maximum travel distance of 35 m (or 15 m if in a dead end) to a fire exit or protected route on structural timber construction sites, provided that enhanced fire warning systems have been installed, and they include strategically placed automatic fire detection to give the earliest warning of fire to occupants. The earlier warning gives slightly more time for escape and to cover the additional travel distance. If the enhanced fire protection is not in place then the standard distance of 25 m (12m in dead end) applies.

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