Online CPD Article – Fire Safety in Flat Roofing

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CPD ARTICLE ON FIRE SAFETY

Fire safety has been in the spotlight since the Grenfell tragedy in 2017. New regulations and changes to guidance has seen areas in the construction industry, including flat roofing and waterproofing, to change their way of working.

In 2018, Dame Judith Hackitt’s report outlined the first major steps towards raising standards even higher by outlining recommendations relating to all areas of construction – and roofing was no exception.

Here, we explain the most up-to-date fire safety regulations, what fire testing consists of and how to ensure safe performance on site.

Building Regulation Changes: Ban on Combustible Materials

In response to the recommendations in Dame Judith Hackitt’s report, the Government’s first action was to ban the use of combustible materials on high-rise residential buildings, which came into force in England on 21 December 2018.

It prohibits the use of combustible materials anywhere in the external walls of high-rise residential building over 18m above ground level and containing one or more dwelling.  Scotland followed suit in October 2019, but went one step further by reducing the threshold for compliance to buildings over 11m.

In September 2019, Building Regulations in England covering fire safety – Approved Document B – was amended and updated. This stated that any products forming part of external walls on high-rise residential buildings need to meet the BS EN 13501-1 fire class requirements and achieve a result that deems them non-combustible.

The new rules apply to anything considered to be a ‘specified attachment, which is defined as a balcony attached to an external wall, so only non-combustible materials can be used for these structures.’

However, the ban does not apply to the following:

  • Any part of a roof – except part a roof pitched at an angle of more than 70 degrees to the horizontal, if that part adjoins a space within the building to which people have access, and access is not solely for repairs or maintenance work, and if that part is connected to an external wall.
  • Membranes
  • Thermal break materials where it is necessary to include these materials to meet the requirements of Part L of Schedule 1.

Currently, it is a little unclear in the regulations as to what the definition of a balcony is. The documentation is currently undergoing consultation, which closes on 25 May 2020, and should offer more clarity.

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Fire Testing

National Building Regulations in the UK regulate fire safety. Guidance on complying with the regulations is set out in accompanying documents, published by the Government of each country. The aim of each country’s regulations are all broadly the same, but solutions presented in the guidance documents may vary.

England and Wales each have their own version of Approved Document B, Volumes 1 and 2, which came into force in August 2019. In Scotland the guidance is found in Section 2 of the Technical Handbooks, while in Northern Ireland it is Technical Booklet E.

Previously, the determining factor of external fire performance for roofs was set out in the national classification, BS 476-3:2004. Now, the European Classification system set out in BS EN 13501-5 – which has run alongside the British Standard for many years – is the main reference for external fire performance of roofs in the UK.

This classification still covers external fire penetration and spread of flame of roof systems in their response to fire from outside the building. However, this is different and should not be confused with individual components and materials tested for reaction to fire.

A roof’s resistance to external fire exposure, in terms of fire spread across the surface and penetration through the construction, is classified separately in accordance with EN 13501-5. A roof can be rated one of the following, from best to worst: BROOF(t4), CROOF(t4), DROOF(t4), EROOF(t4), or FROOF(t4).

EN 13501-5 refers to four separate roof tests, detailed in ENV 1187. The (t4) refers to the use of test 4, which is the only one sufficiently rigorous to demonstrate compliance with UK fire safety requirements. The performance rating of a roof typically dictates how far from a boundary or another building the particular construction may be used.

The more complex the building, the more specific the requirements in terms of fire safety and performance. Applying general principles to buildings where specific provisions are required risks compromising fire safety.

In flat roofing, BS 6229:2018 (Code of practice for flat roofs with continuously supported coverings), provides useful guidance, and depending on the level of complexity, advice may also be sought from a fire engineer or other specialist during specification or design stages. Some projects, meanwhile, require consultation directly with the local fire service.

Flat Roofing & Hot Works

One area in flat roofing which often comes under a lot of scrutiny is the use of hot works on site. In a country where wet, rainy days are considered the norm, contractors are often faced with standing rainwater on a roof before being able to start on a project.

Having a clean, dry substrate is vital prior to the installation of many flat roofing systems. There are a number of effective methods of drying a roof that can be used by the roofing contractor, but one of the most common is to use a gas torch or naked flame. However, if not used correctly and safely, this can present health and safety issues both to contractors and the general public.

Safe2Torch Campaign

The National Federation of Roofing Contractors (NFRC) has issued guidelines for safe practice when using gas torches in roofing. The Safe2Torch campaign has been developed in partnership with contractor and manufacturer members of the NFRC.

Martin Fisher, BSc Hons FIoR IKO Technical Manager at IKO PLC, had been closely involved in the consultations to design the new guidelines, working with the NFRC and other manufacturers in a two-year process to deliver a simple series of steps to follow when approaching a roofing project.

To control this, undertake risk assessments and method statements, and use competent operatives that have undertaken detailed manufacturer training on product installation. Also adhere to health and safety guidelines such as those outlined in the NFRC’s Safe2Torch.

According to the National Federation of Roofing Contractors (NFRC) Safe2Torch campaign, the majority of all the flat roofs installed in the UK will see a gas torch being used and there are circumstances whereby the use of a naked flame is unavoidable. In light of this, it is important all operatives that do have to use a gas torch should be familiar with and understand the principles of the Safe2Torch conditions.  Yet, in contrast, there are options whereby gas torches and the like do not have to be used.

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Products with Graphite Technology

It is advisable to use products from a well-known, reputable manufacturer with an in-house technical team that can offer advice, guidance and sometimes site visits to ensure any potential risks can be minimised.

At IKO, we have developed a range of products with Graphite Firewall Technology. When exposed to heat, the graphite expands through coating forming a heat shield. The base carrier is also coated with expandable graphite crystals, prior to the application of SBS coating bitumen.

Some of the benefits of this technology include;

  • No toxic gas release and reduced heat release
  • Very low degree of smoke production
  • Maintained primary waterproofing function
  • Halogen-free technology
  • Reduced dripping of the burning coating
  • Highest UK and European testing standards
  • Full BBA (British Board of Agrément) approval

Products within the IKO range with Graphite Firewall Technology, include;

IKO UPXL – a high performance bitumen membrane flat roofing system.These membranes have been engineered to incorporate thicker coatings with enhanced polymer content and high-strength reinforcements for outstanding durability. Click here to find more.

IKO Ultra Prevent – a high content SBS polymer modified bitumen coating, offering an outstanding low-temperature flexibility of -25°C. Click here to find more.

IKO Goldseal – durable elastomeric built-up roofing system which provides an advanced flat roofing remedy for new build and refurbishment projects. Click here to find more.

IKO Mach Two – a bituminous single-ply waterproofing membrane for use as either a partially bonded system using a specified IKO polyurethane adhesive, or as a mechanically-fastened system. Click here to find more.

IKO Safestick Prevent – a revolutionary self-adhesive system with the latest tackifier chemistry for outstanding all-round performance, made up of high-tensile polyester base and SBS elastomeric bitumen coating. Click here to find more.

IKO Protorch – a high performance polyester-based torch-on cap sheet, incorporating a specially blended SBS modified bitumen coating with fast flow properties. Click here to find more.

IKO Easyseal Pro Cap Sheet – a high performance self-adhesive bituminous roofing cap sheet, developed specifically for the professional installer, as well as the discerning DIYer and for use where traditional torch-on techniques are inappropriate or prohibited.  Click here to find out more.

CONTACT US

If you have a roofing project concerning fire safety or want to get technical advise in general, contact us to discuss your project needs.

IKO offers various RIBA Approved CPDs on different subjects which are all available as webinars due to Covid-19. Get in touch with us to arrange a webinar presented to you at your preferred date and time.