Are your timber projects as safe as they can possibly be while they are onsite? That’s when they are at their most vulnerable, as many fire protection measures aren’t necessarily in place yet.
The new Timber Fire Safety webite – timberfiresafety.org – contains a wealth of essential information about ensuring that timber buildings are constructed to be as safe from fire as possible. Here is an edited excerpt of some of its guidance concerning the construction phase.
In a completed building, timber components are shielded from the effects of fire in a number of ways. Those might include protective layers (internally and externally) or methods of active fire protection. But during construction, timber members are often exposed when active protection measures are not yet fully functional.
The Joint Fire Code
The Joint Fire Code (or, to give its full title, the Joint Code Of Practice on the Prevention of Fire on Construction Sites and Buildings Undergoing Renovation) is currently in its 9th edition. This was published in 1992 and introduced specific measures to ensure adequate detection and prevention of construction fires.
It was also the first to prescribe not only the methods of mitigating risks but also how to limit the impact of fires. The insurance sector has expected all contractors to comply with the Code as a prerequisite for obtaining insurance since its publication.
Fire safety – the fundamental concepts
The fire safety concepts for buildings during construction, developed in the 1990s, remain largely unchanged and can be summarised by the Joint Fire Code’s 16 Steps.
There are two main priorities in the mitigation of fire threat during construction:
1. Preventing ignition
This includes preventing and/or controlling heat sources – for example, by banning smoking onsite and implementing a regime of hot working permits. It also includes controlling the interaction of heat sources and potential fuels, and the storage and handling of fuels. One typical example of these mitigating measures might be, say, the recommendation for highly flammable liquids to be stored in special containers.
There are over 300 fires on construction sites every year. About 60% of fires on construction sites are accidental, while deliberate acts account for about 40%.
2. Managing the impact of fire (if prevention is not successful)
This takes two forms: the management of the fire itself and management of exposure to the fire. The fire size is managed by, for example, limiting the amount of oxygen available. This can be achieved by installing the windows as early as possible in the construction process.
In some projects the early installation of active fire protection systems allows these to be functional at a reasonably early stage in the period of construction. This is generally only feasible if active fire protection forms part of the completed building’s fire safety strategy.
The final measure is to compartmentalize the building to limit the fire’s rate of spread, thus limiting the size of the fire itself.
Fire risk assessments
A fire risk assessment can help identify solutions, which might be a combination of actions or a bespoke solution. Whilst fire is a risk for all forms of construction, large amounts of unprotected timber onsite means additional information is likely to be required for timber projects, as outlined by the Health and Safety Executive (HSE) in the UK.
Regulatory Reform (Fire Safety) Order 2005 (FSO) sets out the law on general fire safety for construction sites. The FSO requires that a ‘responsible person’ must carry out, and keep up to date, a risk assessment and implement appropriate measures to minimise the risk to life and property from fire.
Who is ‘the responsible person’?
The responsible person will usually be the main or principal contractor in control of the site. The Principal Designer and Principal Contractor are required to manage the risk of fires during the construction phase. At tender stage, the Principal Designer must ensure there is sufficient design information for the Principal Contractor to undertake fire risk assessments, including a fire safety plan for the site.
The Principal Designer is obliged to consider fire risk and request action from the Principal Contractor (or executing entity) of the works. The Principal Contractor’s role is to manage the on-site risks and the off-the-site risks during the construction phase.
The need for frequent review
Fire safety considerations need to be included at the outset, the initial design phase, ensuring that information is shared with the contractor as soon as possible. The fire safety plans will almost certainly need to change during the construction phase to reflect the changing site conditions.
The on-site risk assessment that drives the fire safety plan will require reviews that will continue throughout the construction phase. This only stops when the building is completed and handed over.
Visit timberfiresafety.org for comprehensive guidance on fire safety strategy for timber buildings.