Analysis of the criteria developed to approve the use of combustible materials on tall buildings uncovers inadequate processes
New research, led by academics at the University of Central Lancashire (UCLan), has found that the test regime which allowed combustible materials to be used in the external walls of thousands of tall buildings across the UK omits key details that are critical in evaluating the fire safety of materials used.
The multidisciplinary team of designers, fire safety experts, regulators and researchers undertook a detailed review of the façade fire tests and classification criteria used in the UK to demonstrate the compliance of combustible façades with Building Regulations; specifically, the BS 8414 test methodology and the BR 135 criteria.
It was found that key details were omitted from the large-scale façade fire tests. This included details which directly impacted the risk of vertical fire and smoke spread over the external wall, such as windows and their surrounds arranged above each other, along with other openings, such as vents and flues.
Another issue noted by the research team is that the classification rules allow the temperature to rise by up to 600°C within the first 15 minutes, three metres above the fire, where an apartment two floors above would typically be found.
However, there is no maximum threshold temperature after that 15 minute assessment window, even though some cladding types with a ‘pass’ reach temperatures well in excess of 600°C and up to 900°C after 25-30 minutes, as recent Ministry for Housing, Communities and Local Government tests with HPL cladding have shown.
Although other temperatures are recorded in the test protocols, they are not part of the pass/fail criteria. As well as this, failure criteria are not set for factors such as falling debris, delamination, building collapse or pool fires.
The publication of this paper coincides with the release of the latest version of the BS 8414 test methods for external cladding systems. The revised test standards include clarifications that aim to improve the consistency of test results and new requirements for the formal reporting of tests, but do not address some of the inadequacies highlighted by the team’s research – for example, it states that windows, doors, balconies or ancillary penetrations such as vents, are not tested.
Published in Fire Technology – a Springer Nature journal – the research calls for a review of the current standards for testing external walls. This includes the need for a thorough revision of the BS 135 criteria to align with specific fire safety objectives.
Professor Richard Hull, professor of chemistry and fire science at UCLan, commented: “Despite a number of measures being implemented since Grenfell Tower, including the combustibles ban for residential buildings constructed after February 2019, the process by which combustible façades are permitted on tall buildings in England still does not ensure adequate fire safety.
“With over 500,000 people across the UK still estimated to be living in buildings with combustible cladding, it is imperative that the BS 8414 test, and the BR 135 criteria, are reviewed further. We are calling on the government to instigate an independent review of the current tests and criteria to ensure that they are robust and representative of actual buildings.”
Jim Glocking, technical director at the Fire Protection Association added: “This research has shown that the fire safety of occupants in buildings with combustible, vented facades cannot be assured without additional, non-compulsory testing, even following the revised standard. An extension of scope to include assessment of the fire toxicity of combustible products would also seem prudent for some higher risk building types and occupant categories.”
This research has been published in the Springer Nature journal, Fire Technology. The full paper can be accessed at: https://doi.org/10.1007/s10694-020-00993-z
The research was carried out by Professor Richard Hull, Professor of Chemistry and Fire Science at the University of Central Lancashire (UCLan), Jim Glocking, Technical Director at the Fire Protection Association, Judith Schulz, Associate Director (Fire Safety Engineering) and Darren Kent Associate Director (Facades) at Arup, and Tony Crimi, President, A.C. Consulting Solutions Inc.
The University of Central Lancashire (UCLan) is a leading modern university with thriving campuses in Preston, Burnley, Westlakes (Cumbria) and Cyprus.
Founded in 1828 as the Institution for the Diffusion of Knowledge, UCLan now has a staff and student community approaching 38,000 and an employment-focused course portfolio containing over 350 undergraduate programmes and nearly 250 postgraduate courses.
As well as being a national leader in the number of student and graduate start-up businesses it supports, UCLan is also Lancashire’s largest provider of graduate level qualifications, supplying highly skilled graduates into the workforce. The University also has established links with global businesses, police constabularies, NHS trusts and more than 1,000 regional enterprises across a variety of sectors.
Internationally the University now enrols students from more than 100 countries and has partnerships with 125 institutions from across the globe.
The University has an established research reputation with world-leading or internationally excellent work taking place within the areas of Business, Health, Humanities and Science. UCLan is also ranked in the top 6 percent of universities worldwide in the 2019-20 Centre for World University Rankings, as well as holding the maximum 5 QS stars for the quality of its teaching.
With a strong focus on continually improving the student experience, UCLan is currently undertaking a £200 million project to redevelop its Preston Campus. The vision is to create an attractive and inviting, world-class environment helping to create jobs, kick-start regeneration and attract inward investment into the city and North West region.
UCLan’s Centre for Fire and Hazard Science is the UK’s leading centre of excellence on the fire safety of materials.
The centre specialises in fire science, fire retardants, fire toxicity and the harmful components of fire effluents and residues. It has been represented on the Hackitt Review of Building Regulations, the Grenfell Tower Inquiry, the House of Commons’ Environmental Audit Committee, and Sir Patrick Vallance’s Scientific Advisory Group on Grenfell Tower fire contamination. It has produced over 100 peer-reviewed publications on various aspects of fire safety.