Fire performance of external thermal insulation for walls of multistorey buildings, third edition (BR 135)

BRE (Building Research Establishment) is an independent, research-based consultancy, testing and training organisation, operating in the built environment and associated industries.

In 2013, BRE published Fire performance of external thermal insulation for walls of multistorey buildings: Third edition (BR 135), written by Sarah Colwell and Tony Baker.

External cladding systems offer a potential route for the spread of fire through multistorey buildings. BR 135 sets out principles, design methodologies and fire spread performance characteristics for non-loadbearing cladding systems.

The first edition was published in 1988 in response to the increasing use of thermal insulation in the refurbishment of multistorey buildings. This third edition and has been revised to reflect the growing market for external cladding systems and the increasingly demanding requirements for thermal performance requirements. It also provides updated guidance on the performance of current materials and technologies.

It describes and illustrates scenarios based on typical examples of current practice, allowing designers to understand the parameters relating to fire safety design and the construction of external cladding. It also consolidates the fire performance classification systems for full-scale fire tests in BS 8414 Fire performance of external cladding systems.

The contents of BR 135 are:

• Executive summary.
• Introduction.
• Legislation.
• Mechanisms of fire spread.
• Cladding systems: Application and types.
• External finish construction types.
• Fire performance design principles for external cladding systems.
• Annex A: Performance criteria and classification method of BS 8414-1.
• Annex B: Performance criteria and classification for BS 8414-2.

BR 135 became the centre of attention in June 2017, when ACM cladding was the focus of investigations into the speed at which fire spread in the Grenfell Tower fire. See ACM cladding form more information.

--BRE Group

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