In this exclusive interview, Global HSE Group’s Managing Director Andrew Cooper, Façade Team Manager Andreas Marais and Fire Safety Consultant Keith Plowman discuss misconceptions around PAS 9980
Where is the industry still getting façade risk wrong post-PAS 9980?
Keith Plowman: Buildings tend to fall into two main categories. You have pre-2000 era buildings, which are generally built quite well. Then you get buildings from around 2000 until the Grenfell era. Some are good but we do come across some shockers.
Andrew Cooper: Another issue is the misconception that risk is binary: combustible equals replace, non-combustible equals safe. It isn’t that simple. The understanding of PAS 9980 is also an issue. It is a risk methodology, not a materials checklist.
You can have all the right materials, but workmanship is often the key issue that undermines the integrity of the structure.
What misconceptions do clients commonly have when instructing a façade fire risk assessment?
Andreas Marais: A lot of people see PAS 9980 as a compliance document, which it’s not. People have a Fire Risk Appraisal of External Walls (FRAEW) done to identify faults in their building, but that’s not what the document is there for. The methodology behind it is well adaptable into a different process which would then give you the outcome that they are looking for.
AC: Clients also often assume that a desktop review will suffice and height alone determines risk, which isn’t true. They often think that an EWS1 form is the same as an FRAEW and the outcome is simple and is a pass-fail result.
An FRAEW is a robust risk assessment of the existing state of the building and its underlying issues. It’s showing what was built, and then it should identify proportionate deliverable solutions.
Why is a desktop review rarely enough for complex buildings?
KP: We have a relatively new building. The documentation is fantastic and managed through a system that will feed into the future ‘golden thread’ of information.
What we don’t have is robust photographic evidence of how those materials were installed. The drawings can show they’ve got cavity barriers in the right place, and they are the right materials, but that doesn’t take into account how it was fitted.
So sometimes you do need to have that intrusive investigation, even if it’s a much smaller scope than you would do without the documentation just to prove that what you find is on the site.
AC: It’s like having the “Rolls-Royce” of document management systems and detailed records from the original build, but if you’ve not backed it up with photographic evidence, you’ve always got that uncertainty.
What does a robust intrusive FRAEW involve?
KP: If you’re instructed to undertake an FRAEW on a building that had little or no documentation, you need to strike a balance between not stripping every single façade off the building to see exactly what’s there. You would need to target key locations but make sure you target enough areas to obtain a representative sample.
In terms of putting a number on that, the bigger and more complex the building the more openings you would look to make on that façade system to understand what’s going on behind the surface.
AC: Whatever we do has to be defensible and hypothesis led. It means that clients and third parties can have confidence in the approach.
Typical inspection locations might include slab edges, window heads, and sills. The inspection strategy must reflect the actual construction type. The aim is to get the maximum value for the client while causing the least disruption or damage to the building.
Crucially, we’ve got to identify the insulation, membranes, sheathing boards and other concealed components so that the façade can be properly assessed against the PAS 9980 risk criteria.
What façade defects are you consistently uncovering?
AM: The lack of a sheathing board, especially in steel framing system (SFS). In a typical SFS build up from any supplier, you’ll have plasterboard on the inside, the SFS insulation and then a sheathing board. From that sheathing you would build up to your external wall.
But, because PIR insulation is foam-based, some installers omit the sheathing board. They’ll have plasterboard, SFS with the PIR on that and cavity barriers stuck onto the face of the PIR.
The problem is that if those cavity barriers aren’t fixed back to a tested substrate with a fire rating, they’re effectively doing nothing.
How should PAS 9980 be applied as a risk-based methodology rather than a tick-box exercise?
AC: One of the common failures we see is they don’t start with credible fire scenarios and reinforces a conversation Keith and I had regarding a building that is non-combustible that had non-compliance issues in relation to missing cavity barriers.
However, if you look at the credibility of fire scenarios you would actually apply a different outcome to the one that was given. One of the other problems is that it is being applied across all building types. The originally standing was aimed at for high-rise residential buildings, but it’s now being used for hotels and offices where internal fire strategies can be very different. That is causing quite a bit of confusion in the industry.
KP: The other side of it is the fact that you have multiple companies doing these external wall assessments. Some are purely fire engineering, while some are façade engineering.
The balance that we’ve struck is that we have very experienced façade engineers doing the intrusive investigations who are experienced enough in terms of understanding the fire strategy of the building that they can make informed decisions.
Following that, we have the ISO 9001 peer review process, where a senior fire engineer reviews the assessment.
Once unsuitable cladding or cavity barriers are identified, what engineering options are available?
KP: It depends entirely on the building. Several factors come into play, including the construction type. Remediation strategies will be very different for a concrete frame building compared with a timber frame structure, for example. There’s always a trade-off between safety and cost, as blunt as it may sound.
AC: Now we have a black and white approach — maximum intervention, replace everything or make it non-combustible. Instead, it should be maximum risk reduction against a practical background. The other thing is that it is very rarely a single solution. It’s typically a combination of measures, tailored to the building and the specific risks involved.
Another important consideration is that it’s not only about life safety. It’s also about asset value. How do we maintain value in the asset? How do we maximise that? How do we help the client realise that value further down the line and protect the building and their investment?
Where does façade remediation intersect with fire strategy, compartmentation, structural constraints and building performance?
AC: The fundamental thing is that a façade solution can’t be done in isolation without the fire strategy. The fire strategy must be a fundamental driver of the outcomes FRAEW as well as findings.
The FRAEW and solutions proposed in relation to any façade remediation should align with the strategy assumptions, as well as with structural constraints, MEP systems and the long-term durability of the building.
But it also needs to tie into what we’re going to use the building for in the future. What we don’t want is a poorly integrated approach that creates further problems down the line, and we’ve come across that quite a bit.
How do you manage façade remediation on occupied buildings while minimising disruption?
AM: That would be a building specific case in each instance, but you could sequence your work to different levels or areas. It’s always going to be disruptive in a way, but everyone will endure the same level of disruption. There will be the obvious things of noise and things like that, but there are some things that you can mitigate.
AC: It’s all about the planning, pre-engagement, strong communication with the client and residents or tenants about how we’re going to approach and minimise guest disruption.
Without the client we can’t achieve a clear plan, and where we’ve got it right that’s been the case generally. Where we’ve got it wrong, it’s been the breakdown of communications, lack of planning and not having clear expectations or being very clear about what we’re actually going to do.
Where is façade risk assessment heading over the next three to five years?
AM: Something that is lacking is where an FRA will be done on a building. They might identify some cladding there that they say ‘I’m not sure so let’s prompt an FRAEW’ which is the usual route to an FRAEW but then it’s never really fed back.
Essentially, you’ll have two documents living alongside each other. What the Single Building Assessment (SBA) in Scotland has done is combined them to become a single source of key information on that building.
AC: I think there’ll be a great scrutiny of assessor competence and lower tolerance for uncertainty, stronger audit expectations, more digital traceability and increased emphasis on proportionality. We can see that with the confusion now in relation to buildings that fall either tolerable or medium.