Building Design’s regs columnist Andrew Mellor looks at what PAS 9980 says about assessing fire risk, external wall construction and cladding on blocks of flats
Last week the British Standards Institute (BSI) published a draft form of PAS (publicly available specification) 9980: Fire risk appraisal and assessment of external wall construction and cladding of existing blocks of flats.
The length of the title alone suggests that this is not going to be concise and, at 182 pages, you will need a free weekend to be able to read it all for the first time.
Of course, this is a very serious matter and the document’s length and detailed content are warranted. Credit should be given to all those who have worked on it for producing the draft in such a short period of time. Included are fire incident case studies, a history of fire safety regulations and standards and a glossary of definitions which will be of interest and use to many in the industry.
The draft standard has been eagerly awaited by some owners of multi-occupancy residential buildings so that they can begin to understand if the external walls of their buildings may pose a low or tolerable risk and will or will not require remediation.
The standard is not meant to help demonstrate compliance of the external walls with the Building Regulations or any other legislation or standards. Nor is it to replace the EWS1 form, which some may have understood was to be one of the intentions when the standard is formally published. Perhaps, therefore, it is hoped that mortgage providers will not request an EWS1 form for buildings with external walls that are deemed to pose low or acceptable risks using the assessment process in PAS 9980.
Those commissioning external wall assessments must insist on the use of PAS 9980 – and those they commission as assessors must be suitably qualified and not not just claim to be
The objectives of the PAS include providing a standard methodology which can be used consistently to assess the risk of fire spread across all external wall assessments and to enable those receiving the assessments to better understand the findings and related risks.
The standard introduces a fire risk appraisal and assessment of external walls (the “FRAA”) which will feed into the fire risk assessment required by the Fire Safety Order and presumably the future safety case required for taller buildings. It is important to note that the standard applies to multi-occupancy residential buildings of all heights and not just those over 18m, and it can be applied to other similar building types such as student accommodation and specialised housing.
Risk is defined in the draft standard as a combination of the likelihood of external fire spread, consequential secondary fires and tenable escape conditions, and effective fire service intervention. Risk categories will be low, medium and high. Medium risk will be deemed to be tolerable risk although may require some level of remediation or additional fire safety measures to get the building to this risk level. High risk will mean that further analysis is required, likely fire engineering analysis, which may well lead to the need to remediate the external walls to some extent.
The FRAA considerations will include the full external wall construction, spandrel panels, any attachments including balconies, other fire hazards and risks, the surroundings to the building, the escape routes from the building and fire service access. It is a very holistic assessment process which is required to be to be undertaken by highly competent assessors. The draft PAS sets out the competency expectations and provides a detailed methodology for undertaking the assessments.
It must be remembered that the current standard is a draft and that it may change before its intended full publication in late summer this year.
What we can be sure of is that external wall assessments will be more thorough and accurate where the PAS is followed, despite the process being subjective. More must be done to ensure that those commissioning external wall assessments will insist on the use of PAS 9980 when it is published and that those they commission as assessors are suitably qualified and do not just claim they are.
Andrew Mellor leads the development consultancy team at PRP. The practice has been advising MHCLG and conducting research around policy and building regulations.