What fire ratings do spandrel panels need to achieve?

Spandrel panels are an important element of multi-storey curtain walled buildings, concealing their structure and services, and adding visual interest or continuity to the facade. However, as part of the external wall finish, they also have a key part to play in ensuring fire safety and compliance with the building regulations.

An image signifying fire safety.

Understanding the risk of external fire spread

It is easy to picture how a fire originating from inside a building can catch and spread throughout the interior spaces and into the construction through gaps in the structure and fabric. However, as we sadly saw in the case of the Grenfell Tower fire in 2017, it is possible for internal fires to break out of windows or doors and begin to spread up the face of the building. External walls close to boundaries may also be at risk of being exposed to direct flames from fires in adjoining buildings or other sources, such as vehicle fires.

This risk is particularly pronounced in taller properties— where you will commonly see curtain wall systems being applied— as a fire high up on a building facade may be out of the reach of fire-fighting hoses on the ground. Therefore, it is vital to ensure the external wall system on taller buildings will not contribute to the development of the fire, or promote vertical fire spread up the facade.

Spandrel panels and the U.K. fire safety regulations

Whilst all the nations of the UK have their own set of regulations, each recognises the importance of ensuring all external wall systems are made from materials which do not aid fire spread and, in reaction to the Grenfell Tower fire, have introduced new legislation on the performance of facade materials on high rise buildings:

England

Approved Document B: Fire Safety (ADB) under B4 External fire spread Regulation 7 requires external walls of ‘relevant buildings’ over 18 metres to be constructed with materials achieving a European Class A1 or A2-s1, d0 rating (i.e. be non-combustible or of limited combustibility) in accordance with BS EN 13501-1.

This includes non-vision window spandrel panels.

‘Relevant buildings’ are defined as those with a storey at least 18m above ground level (not including roof-top plant areas or any storey consisting exclusively of plant rooms), which contain one or more dwellings, an institution, or a room for residential purposes, and include sheltered housing, student accommodation, care homes, hospitals, boarding school dormitories, hotels, hostels, and boarding houses.

The government has also announced new statutory guidance to restrict the combustibility of materials used in and on the external walls of residential buildings between 11-18m in height. To be deemed compliant, the materials should be class A2-s1, d0 or better or meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS8414-1 or BS 8414-2. This gives designers the options to use more environmentally positive, but perhaps lower performing, materials on lower risk buildings.

Wales

The Welsh Approved Document B: Fire Safety (ADB) B4 External fire spread Regulation 7 (England and Wales) also requires external walls of ‘relevant buildings’ over 18 metres to be constructed with materials achieving a European Class A1 or A2-s1, d0 rating (i.e. be non-combustible or of limited combustibility) in accordance with BS EN 13501-1. However, it does not include hotels, hostels and boarding houses in its definition. There are also currently no extra provisions for building 11-18m.

Scotland

Whilst there is also a requirement for non-combustible materials under the Scottish regulations, the limitations are slightly different. Under Technical Handbook Section 2: Fire for domestic and non-domestic buildings states that the external walls on all buildings with a storey at a height of more than 11m, and certain assembly, entertainment, hospital, and residential care buildings below 11m (Clause 2.7.1) must be constructed using Euroclass A1 or A2 rated materials (no “s” or “d” rating mentioned – see section below for what these letters denote). It also asks that external wall systems that sit less than 1m from a boundary should achieve this performance.

What is EN 13501-1 reaction to fire?

Referred to in the building regulations above, ‘EN 13501-1 Fire classification of construction products and building elements – Classification using data from reaction to fire tests’ is the European standard for determining and classifying the reaction to fire of construction products. It is a small-scale test that categorises products into Euroclasses A1, A2, B, C, D, E and F. A1 products are considered non-combustible, A2 products to be of limited combustibility, with B to F classed as combustible in ascending order.

Class A2 and lower are also rated for how much smoke and flaming droplets are produced when exposed to fire. Smoke production, categorized as “s”, is rated from 1 to 3 (1 = low to no smoke); Flaming droplets, categorized as “d”, is rated from 0 to 2 (0 producing no droplets).

It is important to note that spandrel panels as full systems, including internal and external facings, core material, tray, and other components, cannot currently achieve an A1 rating due to the adhesives used to connect all the elements and potentially the powder coating applied to the external face. A2 is the highest performance rating available, meeting the requirements of limited combustibility under the regulations.

How does Speedpanel test its spandrel panels?

Traditional spandrel panels that are built up on site often derive their overall fire rating from testing each of the elements individually. However, this approach only really tells us how the components act in isolation, whereas a real fire situation requires the whole system to work together to prevent a fire spreading. This is why we manufacture and test Speedpanel A2® panels as a single component. Both our Glass- and Aluminium-faced panels achieve an A2-s1, d0 rating. Helping projects achieve compliance with building regulations across the U.K., Speedpanel A2® offers a clear and honest picture of the performance of the product as a complete system, helping specifiers to ensure safe, compliant, and beautiful curtain wall buildings.

Explore our A2 rated insulated spandrel panels.

This information is correct at time of writing, but the regulations are subject to amendments. For the latest version of the regulations, please refer to the government websites in the individual regions.

Speedpanel

3 May 2022