In our two previous blogs, we covered fire tests currently being used for Building Regulations and those used to support Insurer Standards. This blog will discuss some of the key issues along with providing an overview of the most commonly used terminology in fire safety regulations and standards.
Currently, products or materials have classifications such as ‘combustible’, ‘low combustibility’, ‘limited combustibility’, and ‘non-combustible’. This terminology is used widely within current Building Regulations and Standards, including Approved Document B (AD-B), and there are numerous test routes that exist to determine the fire performance classification of a product, system or material. It is possible to achieve a ‘non-combustible’ or ‘limited combustibility’ classification with small-scale tests. However, as recent large-scale tests have demonstrated, these classifications can be misleading as an indication of how a full building envelope element may perform.
So, regardless of how a product behaves in a small-scale test, it is more important to know how it will perform and interact with other products as part of a system, and this should be the primary focus. It would be EPIC’s recommendation to use large-scale tested products and systems only. Ideally, BS 8414-1 or BS 8414-2 certified systems for buildings with a storey above 18 m, and LPCB or FM approved for below 18 m.
We have noticed in recent market communications and dialogue that the area most frequently causing confusion is the difference between metal-faced insulated panels and rainscreen systems so we covered this topic in more detail in the linked blog. Below you will find other commonly used terms along with a brief explanation.
Commonly used insulation in façade and cladding systems:
MW – mineral wool.
Phenolic foam – A rigid insulation foam product formed by polycondensation of phenol.
PIR – Polyisocyanurate. This is a rigid, closed cell foam insulation product.
PUR – Polyurethane. This was replaced by PIR in the UK in 2004 and has not been used by UK manufacturers of metal faced insulated panels since that time.
Visit the Insulation Manufacturers Association to learn more about how PIR and PUR is manufactured. http://insulationmanufacturers.org.uk/what-is-pirpur/
Each of these insulation materials has been shown to have proven fire performance when used appropriately. Check with individual manufacturers for relevant test standards and applications.
Commonly used metals in façade applications:
Aluminium – Naturally occurring metal, with a melting point of 660 Degrees C.
Copper – An orange-red metallic element, with a melting point of 1085 Degrees C.
Steel – An alloy of iron and other elements, with a melting point of 1510 Degrees C.
Zinc – A shiny, bluish-white metallic element, often used in alloys such as brass and bronze or as a coating for iron and steel. It is brittle at room temperature, with a melting point of 420 Degrees C.
Fire tests and standards:
BR 135; Fire Performance of External Thermal Insulation for Walls of Multi-storey Buildings – This is a guidance document that lays out the criteria for the large-scale testing of cladding systems using BS 8414 – Fire performance of external cladding systems.
BS EN ISO 1716 – ‘Reaction to fire tests for products – Determination of the gross heat of combustion (Calorific value)’ (ISO 1716: 2010). This is what’s referred to as the bomb calorimeter test and involves a test specimen in a device that includes a vessel containing only oxygen which is then placed in a water bath. The specimen is then burned under standardised conditions and monitored for heat release and loss of mass. The specimen size is 40 mm wide by 50 mm high.
BS 8414-1 and BS 8414-2 – Large-scale tests designed to represent a high-rise building, measuring fire spread and flame propagation. We have briefly covered this test in our blog on fire testing insulated panels to comply with current Building Regulations.
FM 4880 – Is a loss prevention standard developed by FM Approvals. It uses a variety of small and large-scale tests, which have been covered in our previous blog on fire testing to comply with insurer standards.
FM Approvals; Room Test or ISO 9705 – Full-Scale Room Test for Surface Products – Part of the FM 4880 suite of test standards. These are large-scale tests, designed to represent exposure to an internal fire, measuring fire spread and flame propagation. The products or systems tested must not contribute to the spread of fire, or compromise the structure, for the duration of the test.
LPS 1181 – Developed by the Loss Prevention Certification Board (LPCB) in consultation with the ABI, LPS 1181 examines and classifies the fire growth performance of insulated panels using the so called ‘Garage Test’. This has also been covered in a blog on fire testing to comply with insurer standards.
Accredited fire engineer – this is an individual with the appropriate level of training, experience, qualifications, and who is also registered with a professional body such as The Institute of Fire Engineers (IFE).
BRE – Building Research Establishment. BRE is part of BRE Trust and is an independent third party that offers advice, carries out research, and provides testing and certification services for the performance of products.
MHCLG – The Ministry of Housing, Communities and Local Government, formerly the Department for Communities and Local Government (DCLG).
Aluminium Composite Material (ACM) – Recently, the most commonly discussed composites are aluminium composite panels (ACP) where the skin is an aluminium sheet bonded to a PE core. Composites are lightweight and add no structural properties to a building. The core will not provide insulation properties. It is also important, when selecting building materials, that the product is certified as having adequate fire performance to suit the application.
Combustibility – is the measure of how easily a material burns when exposed to a flame source.
Desktop study – is an alternative route to compliance. It is important that, if this route is used, it should be carried out by a qualified fire engineer who will use existing fire test data from full scale tests to give a report on the expected performance of a specific construction.
Flammable – easily catches fire, e.g. Paper.
Insulated Panel or composite panel – These are panels with a low-density core sandwiched between a thin metal layer either side, normally steel. The core provides insulation properties, depending upon the type and thickness. It is also important, when selecting building materials, that the product is certified as having adequate fire performance to suit the application.
PE – Polyethylene. PE is included in some composite materials, such as ACM, to provide strength and rigidity and is not designed for, nor does it offer any, insulation properties.