The importance of decking in fire safety for balconies
Whilst they are not yet enshrined in Building Regulations, fire safety measures for balconies are increasingly being stipulated by building warranty providers and regulatory bodies. Architects and developers should be mindful of these issues at the design stage of their projects.
Visit the centre of any major city and balconies will probably be visible in most directions. It’s estimated that there are over 45,000 high rise apartments in London alone, with flats comprising just over 50% of the capital’s residential accommodation. Balconies are now widely considered to be an important amenity in modern apartment living as the outdoor space for this type of property and they have become a widespread feature of residential development.
Given this proliferation, it is no surprise to read reports that highlight the frequency of associated risks such as fires. BRE Global carries out fire investigation on behalf of the Department for Communities and Local Government. According to their 2016 Document ‘Fire safety issues with balconies’, BRE Global reported 24 fires which have started on balconies since 2005. The most common causes were arson, careless disposal of smoking material and misuse of barbeques. Notably they reported six fire incidents in 2015 compared to just one in 2005. The document references case studies to highlight the potential of balconies as the fire’s starting point and the risk of it spreading up a building façade via combustible materials with mineral fibre or timber cladding, insulating panels, windows and other balconies above. Risks are compounded by the fact that wind speeds are stronger at a greater height and burning material can also fall to spread the fire to lower floors. BRE Global concludes that meeting Part B of the Building Regulations (covering fire safety matters) can be adversely affected by the requirements of Part L which states that ‘Reasonable provision shall be made for the conservation of fuel and power in buildings by limiting heat gains and losses through thermal elements in other parts of the building fabric.’
There are no fire safety requirements specifically relating to balconies in Part B (with the exception of balconies providing means of escape) but housebuilding warranty providers are increasingly aware of the potential risks and many are requesting balcony design modifications with reference to Part B4 which refers to the spread of fire on building exteriors. Architects, housebuilders and developers can pre-empt these concerns with careful choice of materials.
Timber decking is an obvious area of fire risk and BRE Global’s report includes case studies identifying discarded cigarettes on decking as the cause of fires. Neaco discuss detailed balcony specifications with architects across the UK and many are telling us that decking material is the primary safety concern for regulatory bodies (partitions between balconies are also a concern, but the issue is raised much less frequently). The design revision most commonly requested by warranty providers is the replacement of timber with fire resistant balcony decking. Similarly, wood-polymer composite decking, comprising a combination of plastics and timber fibres, is not considered to be sufficiently fire resistant balcony decking and is often rejected too.
Another alternative material, glass reinforced plastic (GRP), has properties which are problematic for fire resistance: in essence it is an oil-based product with a combination of materials and components which all react differently when exposed to fire. Polyester resins are made up of carbon, hydrogen and oxygen atoms and, like all organic compounds, they will burn. By altering their structure and/or by using additives, it is possible to modify their burning behaviour so that laminates made from such resins present a lower hazard under fire conditions. However, in practice this doesn’t represent a solution which is any safer than timber.
Realistically, this leaves steel and aluminium as the only viable alternatives. Quite apart from the practical advantages of being 1/3 of the weight of steel and the environmental benefits of being 100% recyclable, aluminium is a superior material for fire safety. Its thermal conductivity is four times faster: heat is conducted away faster and therefore a greater heat input is necessary to bring aluminium up to a given temperature than required for steel. Fire performance data for aluminium extrusion can be obtained from the results of BS 476 Fire Test Series. Aluminium achieves the highest possible rating for Part 4 (Non-Combustibility test), Part 5 (Ignitibility Test), Part 6 (Fire Propagation Test) and Part 7 (Surface Spread of Flame Test). These performance levels make aluminium the stand-out choice to satisfy fire safety requirements for balconies. It is important to note that painting its surface could reduce these performance levels.
In addition to its fire-resistant qualities, the working qualities of aluminium make for ease of fabrication, engineering and forming. Most alloy grades can be easily and economically machined (e.g. milling, turning) which means that bespoke sizes, profiles and features can be precision-engineered to serve the needs of balcony decking. For example, Neaco’s technical team has incorporated special performance requirements such as anti-slip surfaces into our Techdek aluminium grating, which is now widely specified for balcony flooring. This ability to provide slip resistance is another aspect which makes aluminium safer than timber, which over time becomes increasingly slippery underfoot.
Neaco have also developed designs which maximise drainage capability with a combination of open and closed construction – for example, our Neatdek metal grating system has a T-bar grille profile which has a 74% contact area yet disperses water quickly and efficiently. In balcony applications, this avoids the need for drainpipes and soffits, saving on cost whilst enabling a more minimalist aesthetic (we also provide a version of Neatdek with inserts within the gaps between bars – it doesn’t drain through the grille but still doesn’t require a soffit). Neatdek’s original design has also been adapted to form Neatdek 188, an innovative system with concealed drainage gaps below the surface. The profile provides total privacy by completely restricting the view from above and below whilst the absence of gaps on the foot contact area also makes it safe to walk in any type of footwear, including stiletto heels.
As a company which specialises in manufacturing architectural systems from aluminium, Neaco is a passionate advocate of its many benefits and especially its advantages in safeguarding against fire risk. The continuing increase in the numbers of apartments being built will in all probability lead to an increase in cases of balcony fires. By specifying aluminium for fire resistant balcony decking, architects can streamline the regulatory approval of their design schemes and, more importantly, improve the safety of their buildings.