While fire safety professionals have found difficulty interpreting PAS 9980, as our previous article discussed, we have – as the standard's authors – seen particular problems with the preparation of fire risk appraisals of external walls (FRAEWs).
FRAEWs are critically important to understand the risk of external fire spread on existing buildings. Such buildings will necessarily fail to comply with current Building Regulations given that they were constructed to meet the requirements of previous versions.
They may even suffer from deficiencies, whether arising from their original design and construction or due to the passage of time.
However, existing buildings should still be perfectly safe to live and work in; FRAEWs carried out in accordance with PAS 9980 by competent professionals will differentiate buildings that are safe from those that are not.
By detailing some of the common mistakes we have encountered with appraisals, therefore, we can help ensure greater rigour when it comes to fire safety.
Some FRAEW reports include assessments that assume proper construction of fire protection in external walls where there has been no inspection.
Certain forms of external wall construction, as set out in PAS 9980, are inherently resilient to external fire spread and tolerant to construction defects, so their fire performance is unlikely to require an FRAEW.
However, in most cases FRAEWs are necessary for wall constructions that rely in some way on detailed aspects of construction.
External visual inspection is often not adequate to confirm the kind of wall construction; for example, rendered expanded polystyrene looks very similar to rendered blockwork, while brick slip closely resembles full brick.
It is therefore essential that these FRAEWs are supported by some form of intrusive inspection, even if only to confirm that the design information for the building is accurate.
Inspections do not need to have been conducted personally by FRAEW authors themselves; inspections by other appropriately competent persons could be relied on, provided the findings have been adequately recorded and communicated.
Nevertheless, some FRAEW reports are based on limited access to documentation.
There have been instances where appraisals are required, but where permission has not been granted for the appraiser to consider the building's current fire risk assessment because of concerns about the assessor's professional indemnity insurance; policies for fire risk assessors have been found to carry strict exclusions when it comes to external walls.
In such cases, the appraiser might have to make assumptions about the adequacy of provisions in the building, for example assuming that the compartmentation is adequate.
Such assumptions are acceptable, but must be clearly set out in the FRAEW report.
The report should also detail whether any assumptions are particularly significant in terms of risk outcome; that is, could a tolerable risk become intolerable in the event an assumption proves to be false?
Those factors should be clearly identified in the executive summary as well.
Where responsible persons are or become aware of these sorts of limitation about the work of any of professionals on their behalf, it is incumbent on them to coordinate the information they hold so that preventative and protective measures are properly implemented on the basis of facts, not just assumptions.
Some FRAEW reports attempt to deal with multiple different buildings as though they are identical. But any differences, however small, could result in a different risk outcome.
Given the complex manner in which different fire safety factors may interact with one another, it is thus imperative that changes to any one parameter are considered in the context of all others.
Even if the risk outcome for different buildings is the same, there may an opportunity for different remedial schemes that are more proportionate to each of the particular conditions.
Other reports simply state what fraction or percentage of a building facade is covered by an external wall construction, but fail to contextualise its location with reference to the potential hazards and the internal fire safety layout.
For instance, they may not make clear whether the construction presents an increased risk where it is close to openings into a protected common escape route.
As PAS 9980 sets out, an FRAEW needs to consider how external wall constructions interact with other parts of the building. But it is also important that report recipients – who may not see the building directly – can understand how the external wall constructions are arranged.
In situations where there are complex facades, for instance, it may be prudent to include photographs of all elevations to help them understand this and ensure nothing is missed.
Certain FRAEW reports treat compensatory features included in a fire-engineered solution as being automatically positive. Such approaches necessarily take different fire precautions to those in Approved Document B and other codes while aiming to provide the same overall level of safety.
For example, extended travel distances along means of escape might have been permitted in the approved design if mechanical ventilation were used on the basis of computational fluid dynamics analysis.
In such a scenario, the effect of the compensatory measure needs to be considered before making any conclusion about risk and whether this needs to be properly explained in the report.
Where the measure simply results in a building achieving the minimum standard required for health and safety then the overall effect on risk will be neutral.
It is only if the particular solution is beneficial in the context of an external wall fire that the outcome should be deemed positive.
This is the case where, for example, the appraiser can determine that the smoke extraction system would adequately protect common areas – even if fire did spread over the external walls and cause secondary fires – or establish that there are no drawbacks, such as inlet air vents, that may draw in smoke from an external wall construction fire.
'The effect of compensatory measures needs to be considered before making any conclusion about risk'
Some FRAEW reports are excessively reliant on, or have unrealistic expectations of, the fire and rescue service (FRS).
As emergency responders, their role is to respond in the event that something unexpected or unforeseen occurs. Their attendance and intervention should not be presented by an FRAEW report as a measure for reducing a risk that the appraiser foresees.
For example, timber cladding across the external walls of a single escape stairway does not become tolerable just because it would be within reach of firefighting appliances.
Where an FRAEW report does rely on such intervention it needs to consider whether the FRS has sufficient time and access to deal with the anticipated fire spread.
For example, the predicted rate and extent of fire spread must be slower than firefighters' arrival and set-up time, and they must be physically able to intervene: just because a particular elevation is not more than 18m high does not mean that they can access it.
Neither is it reasonable to expect that FRS will be able to conduct external firefighting at height.
While an individual service may possess aerial ladder platforms or similar appliances, these generally take much longer to deploy than ordinary fire appliances, are invariably fewer in number, and are likely to be more remote geographically.
Where an FRAEW considers the provision of facilities for the FRS that accord with Part B5 of the Building Regulations, the report should regard this as neutral in terms of risk rather than a positive risk factor that can offset negative ones, as it is only the regulatory minimum that has been met.
Risk tables are used in some FRAEW reports simply to tick off positive, neutral or negative factors, with the overall outcome decided according to the number of ticks in each category.
This is at variance with the recommendations of clauses 13.5 and 13.6 of PAS 9980, which call for risk factors to be weighted depending on the particular circumstances.
For example, polystyrene insulation in a BR135-classified rendered cladding system will carry a much less negative weighting – if it is negatively weighted at all – than a system without such a classification or exposed polystyrene insulation in the cavity of a ventilated rainscreen.
The relative importance of each component in the fire performance and facade configuration and the building's fire strategy factors should be considered.
For example, the combustibility of the cladding in a rainscreen is likely to have a greater impact on overall performance than that of the insulation, while the protection afforded to common escape routes is likely to be more important than the potential for falling debris around the building curtilage.
The relative importance can be considered qualitatively, or by quantified or semi-quantified weighting. Any weighting must be evidenced and justifiable, and a failure to consider relative importance in effect applies a weighting of 1.0 to everything.
Therefore, the rationale for any weighting or absence of weighting needs to be clearly explained. Information relating to risk factors must be gathered to inform the expert judgement of the appraiser.
Overreliance on fixed scoring systems in an attempt to avoid the need for such judgement may result in flawed conclusions.
There are also FRAEW reports that rely on analytical chemical techniques rather than fire testing to make conclusions about fire resistance.
For example, two composite panels may contain identical amounts of a polymer such as polyethylene or cellulose, but the fire retardant in one may have a dramatic effect on its fire performance compared to the other's.
Analytical chemical techniques may miss that fire retardant entirely, and, even if they identify it, will be unlikely to quantify its impact on fire performance adequately.
Another consideration is that FRAEW reports are being provided for buildings other than blocks of flats, such as hotels. Although there is in principle no reason why they should not, this is still currently outside the scope of the standard.
The methodology in PAS 9980 can readily be adopted for hotels, but it is important that any FRAEW report acknowledges this is outside its scope.
The fact that there is a fire detection and alarm system and a simultaneous evacuation strategy – and that most hotels have more than one stairway – can often offset many negative risk factors relating to the fire performance of the materials, products and systems in the external wall build-ups, especially for low-rise hotels.
However, we have seen one FRAEW report that justified removing combustible insulation from behind brick and solid metal cladding on a four-storey hotel; such work should have been considered as disproportionate to the risk.
'Although there is no reason why FRAEWs should not be provided for hotels, this is outside the scope of PAS 9980'
Complex facade-related jargon or poorly defined or explained abbreviations are found in some FRAEW reports.
As PAS 9980 sets out, the target readership for reports is broad; but as it specifically includes general fire risk assessors who need to incorporate the findings into their assessments, it is important to write in a way that they can understand.
Some FRAEW reports do not feature executive summaries, for instance. Clause 15.7 of PAS 9980 recommends that these are included to present the key findings and an overall assessment of the risk rating.
Such summaries are important for various reasons.
As those involved in carrying out FRAEWs are generally responding to a very high level of demand for their work, this also increases the chance of simple errors or reports that contain contradictory information.
Given the importance of – and potential consequences arising from – the contents of an FRAEW report, it is therefore important that they are subjected to careful quality control to try to avoid such errors.
We have also seen FRAEW reports that include extensive text from PAS 9980 itself.
While it may be necessary to excerpt or quote discrete portions to make or support a point in a report, authors should not be presenting wholesale sections of the code as their own work when the reader could just be referred to the document itself, which is freely available online.
There are cases of clients insisting on having a PAS 9980-compliant FRAEW carried out on completion of a recladding project that involved removing combustible elements, and replacing them with non-combustible materials and products.
This is problematic, however, as it is evidence not only of PAS 9980 FRAEWs being conflated with external wall system 1 (EWS1) forms, but also of a fundamental misunderstanding of the purpose of an appraisal and what it involves.
As set out in clause 1 of the code, FRAEWs are not needed for buildings whose external walls do not contain any combustible materials, such as those covered by and complying with Building Regulation 7(2).
Where a client insists on an updated EWS1 form after remediation, the original signatory should be instructed to update it based on full evidence of the remediation that can be proved rather than having to carry out another FRAEW.
If an FRAEW report recommends that remedial works are required, the client may want evidence that these are carried out to a standard such that the fire risk is now tolerable.
However, an FRAEW is not a means of evidencing the work carried out or recording the design and installation of the replacement cladding.
Such evidence would normally take the form of design documentation and as-built records, including photographs to prove the work was undertaken, and building control sign-off.
If a client also considers it necessary to update the FRAEW so there is independent confirmation of tolerable risk, one option would be for them to employ the appraiser who produced the original report to review the design and installation of those works.
They can then either update the FRAEW or provide other appropriate documentation.
In any case, it should not be necessary to conduct a fresh FRAEW from scratch where one has previously been carried out, and doing so for wall constructions that have recently been remediated is unlikely to be a judicious use of expertise and resources.
An FRAEW may also recommend that works subject to Building Regulations are carried out.
Where this is required, the design team may need to submit the report to the local authority's planning and building control departments, so the rationale for works that are needed and those that are not can be properly communicated.
This may be particularly important if work is expected to lead to a tolerable risk outcome, despite not complying with guidance such as Approved Document B.
However, no FRAEW can in any way negate the need to comply with prescriptive legal requirements, such as Building Regulation 7(2).
'It should not be necessary to conduct a fresh FRAEW from scratch where one has previously been carried out'
There have been various instances of clients commissioning multiple FRAEWs on individual buildings. Generally, this appears to have been done for the purpose of scrutiny and providing assurance that the conclusions of any one FRAEW are sound.
However, it also poses a risk that clients will choose to adopt the findings of whichever FRAEW is most beneficial to their commercial position.
For instance, a stakeholder having to fund remedial works themselves may select the report that recommends the least onerous remedial work to achieve a tolerable risk.
Even if this is not the case – for example, if the stakeholder simply wants a second opinion on any issues that the first FRAEW identified – commissioning an entirely separate survey means they run the risk of having two reports with different conclusions.
Where responsible persons commission multiple professionals to help them in carrying out their duties, it is for them to decide which is the most appropriate advice to follow.
As set out in our first article, the industry is continuing to familiarise itself with PAS 9980, but it is worth noting that, based on the FRAEWs we have seen, the quality of reports being produced is on the whole improving.
We also hope that our discussion of the issues in these articles will help to accelerate this trend.
This article has been prepared in consultation with the National Fire Chiefs Council (NFCC). We gratefully acknowledge NFCC input in collating and summarising issues that its members have faced when reviewing FRAEWs that purport to comply with PAS 9980 as part of their work to enforce the Regulatory Reform (Fire Safety) Order 2005.
Dr David Crowder is a partner at DCCH Experts
Contact David: Email
Neal Butterworth is a director at Design Fire Consultants
Contact Neal: Email
Colin Todd is managing director at C.S. Todd & Associates
Contact Colin: Email
Steven Daws is a senior consultant and quality manager at C.S. Todd & Associates
Contact Steven: Email
Bart Kavanagh is a partner at Expert Architect Studio
Contact Bart: Email
Related competencies include: Fire safety, Legal/regulatory compliance, Risk management
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