Limiting fire and smoke spread

Posted on 05/09/2014

Featured in Fire Risk Management Journal, September 2014

BM TRADA Senior Consultant Peter Barker highlights the importance of understanding fire and smoke control within buildings 

Very few people appreciate how quickly fire and smoke can spread through a building. Rapid fire spread with an extremely quick increase in temperature and the development of large volumes of smoke is possible within a matter of minutes of a fire starting. 

Left unchecked, a fire will continue to grow and exploit weaknesses in the building structure and, once a fire has engulfed a building, it has the potential to spread to adjacent buildings through radiated heat.

The need to limit fire and smoke spread, to protect the lives of people living and working in and around buildings, has been recognised for many years and is legislated for in Part B of Schedule 1 to the Building Regulations 2010 (as amended). Sections B2, B3 and B4 outline how the construction should limit fire growth (B2); contain fire growth to the room of origin and provide  structural stability (B3); and prevent fire spreading over the envelope of the building and travelling to adjacent buildings (B4).  A significant proportion of the materials, products and structures used for constructing buildings must therefore be considered in terms of fire performance in order to satisfy the requirements of the building regulations; this ‘built in’ fire performance is broadly defined as passive fire protection.

Understanding Buildings – Past, Present and Future

Most buildings in the UK are built using traditional methods of construction such as brick and block. It is these methods of construction that guidance documents such as Approved Document B have been based upon, drawing on decades of industry expertise. It is also traditional methods of construction that the controlling authorities, construction industry, insurers, fire and rescue service, property managers and homeowners are most familiar with. 

However, to meet increasing demands for sustainable buildings that can achieve higher standards of energy efficiency, coupled with faster completion times, more innovative construction products and techniques will need to be used, such as modular, panellised and site-based systems. This is reflected in the increasing number of construction projects using modern methods of construction (MMC), particularly in the education, healthcare and housing sectors. Occasionally, MMC are now integrated with traditional buildings that may pre-date our current building regulations in order to enhance environmental performance.

Irrespective of what materials or methods are used for a building, the building regulations require that the building must be constructed to secure reasonable levels of health or safety in case of fire. To achieve this goal, all systems must be constructed and installed in line with their tested and/or approved specification. For the same systems to continue to provide the required level of fire resistance throughout the design life of the building they must also be adequately repaired and maintained.

After the building has been completed it is the Regulatory Reform Fire Safety Order (RRFSO) that is the primary legislative instrument for fire safety. As a result of the increase in fire risk assessment, now a legal requirement for individuals responsible for the fire safety of their building, and inspection and enforcement activities by the Fire and Rescue Service, it is becoming clear that for a significant percentage of buildings there is not a sufficient flow of knowledge and information regarding passive fire protection within the construction sector. 

Problems are being identified in traditionally constructed buildings as well as MMC, some are a result of subsequent alterations since the building was constructed (e.g. additional services installed breaching compartment lines, change of layout), some because of poor building maintenance  e.g. defective fire doors, broken plasterboards, flaky paint on walls) and some because the building was not constructed to the original specification in the first place (e.g. missing fire breaks, poor fire stopping). In the majority of cases, the people that occupy these buildings would be under the assumption that they could make their way to a place of safety in reasonable time in the event of fire, when in reality that might not be the case. 

System based approach

Fire will always find the weakest link and the opportunity for weak links in the construction process is vast. For an individual item of passive fire protection to work as tested; it must be constructed with the correct components and be installed correctly. The products must then be correctly specified throughout the building in order to complement each other and work as an overall building system. There is little point in using linings that limit the growth of fire and smoke if other aspects of the building design allow the fire and smoke to travel freely. 

Although the Q1 2014 RICS Construction Market survey highlights a continuing improvement in activity, contractors are acutely aware that projects need to be delivered on time and to budget to maintain their profile within the industry and continue to win work. The pressure on time and money occasionally results in deviations from the original building design and corners being cut, which can have the potential to seriously undermine the assumed performance of the building in a real fire event. In some cases, cheaper alternatives are being used as construction materials that may not carry any fire resistance performance or have been tested for the application, thus reducing any safety margin of performance, or worse still completely undermining the fire resistance of the building. 

Furthermore competition on price within the building approvals sector means that it is becoming increasingly difficult for a Building Control Officer or Approved Inspector to quote for sufficient time to inspect all aspects of the building in sufficient detail to confirm whether all the materials or the whole installation is 100% compliant.

In addition to time and cost pressures there is a recognised shortage of skilled individuals working specifically within the field of passive fire protection within the construction sector. This has become more prevalent during the recession and now that we are beginning to see an upturn in construction, there is a concern that a lack of skills in the sector could affect the quality of installed passive fire protection measures.

For the MMC sector, there are some additional challenges posed by the shortage of skills in the construction sector. As for any new or innovative product, knowledge of the system and how it works is particularly important as there will be less industry experience of the product. Applying traditional building practices to MMC may be inappropriate and could compromise the structure of the building in a fire event. For any individual working on a project that uses MMC, demonstrable experience of working with the system should be required, which must include understanding how the passive fire protection features of the system work.

Knowledge and skills 

As discussed, increasing knowledge of passive fire protection within the construction industry is essential but really this should include building owners, occupants and trades people that are likely to have an impact on the structure of the building during its design life. There is no point in constructing buildings that are safe in the event of fire if there is a significant risk that this will be quickly diminished by the management and use of the building.

The solution is to close this knowledge gap through offering training and continuous professional development to all those involved in the construction process and throughout the life of a building. Manufacturers must offer training and guidance to those tasked with building these structures. Such courses should highlight the key features of MMC that may impact on the fire performance.

Third party certification schemes for products and personnel can go a long way to ensuring that the system-based approach required for passive fire protection is correct when the building is completed and throughout its design life. They not only demonstrate the quality that should be expected but allow traceability for future fire risk assessments and maintenance.  Such schemes require products to meet established test performance and require ongoing  production audits. Installer schemes require operatives to demonstrate their skills and knowledge with site installations regularly audited.

An example of such a scheme is BM TRADA’s Q-Mark Scheme for Fire Stopping Installation. This aims to ensure that that fire stopping solutions are being fitted correctly and to verify the competence of installation companies. Representatives of companies certified under the scheme will place a label next to each installation to confirm that it meets the requirements of the scheme and each will be registered with BM TRADA through their web-based database. 

Once this has been completed, BM TRADA will email a certificate to the responsible person, confirming details of what has been installed. For further information visit http://www.bmtrada.com/news/article/bm-trada-launches-q-mark-for-fire-stopping-installation

Building technology is continuing to develop to meet our needs for increasing energy efficiency with less reliance on finite resources and quicker build times. MMC are hoping to deliver on reducing the housing shortage within the UK and therefore we must have a skilled work force within the construction industry that understands the systems, how they differ from traditional methods of construction and the importance of detailing the passive fire protection systems correctly. 
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Featured in Fire Risk Management Journal, September 2014
 
BM TRADA Senior Consultant Peter Barker highlights the importance of understanding fire and smoke control within buildings.