Taking control of envelope quality

24 June 2019

After the failings with the Edinburgh schools, and then the Grenfell Tower disaster, the envelope sector has come under close scrutiny for the quality of its work. Neil Gerrard examines how it has responded.

Dame Judith Hackitt was unequivocal in her assessment. Ignorance of regulations, a motivation to do things as quickly and cheaply as possible, a lack of clarity on roles and responsibility, and inadequate regulation – all of this had conspired to create a culture issue in construction that amounted to a “race to the bottom”, she asserted in her final report following her review of Building Regulations and fire safety.

“There is insufficient focus on delivering the best quality building possible, in order to ensure that residents are safe and feel safe,” she said.

It was a damning conclusion and another stain on the reputation of the construction sector, already reeling from the faults uncovered in 17 primary schools across Edinburgh after the collapse of a wall at Oxgangs Primary School in Edinburgh in January 2016, and growing disquiet about the high level of defects in the housebuilding sector.

It has also spurred the government into action. Not only did it last year announce a technical review of Approved Document B, which closed in March, it also opened a consultation on a “radical” new regulatory system for building and fire safety last month, which closes on 31 July.

But how well has the construction sector – and the envelope sector in particular – responded to quality concerns since Edinburgh and Grenfell?

Not well enough, if you ask CIOB past president Paul Nash, who is chair of the body’s Construction Quality Commission, whose work is shortly due to result in the publication of a new Construction Quality Code (see page 11).

“Do I think we could have another Edinburgh schools today? Yes. It is a shame to say it three years on,” says Nash. “What shocked me with Edinburgh schools is that we were talking about basic building technology. This was not a complex cladding system.

“Do I think we could have another Edinburgh schools today? Yes. It is a shame to say it three years on.”

Paul Nash, Construction Quality Commission, CIOB

“Grenfell is a much more complex problem because it was a refurbishment of an existing building and one of the wider issues is what happens when people go in and make alterations to existing buildings. The external envelope of a building has multiple functions that it has to perform, from aesthetics, to keeping the weather out, to keeping the heat in, acoustic performance and performance in fire.”

Mark Beard, chairman of Beard Construction and vice president of the CIOB, agrees that not enough progress has been made on the issue of quality but does see business leaders finally waking up to its importance. “Since Grenfell there has been a renewed focus, particularly when it comes to the external envelope, because of the public health issues around it. The issue of quality is rising up the agenda in boardrooms and in general dialogue within construction organisations,” he says.

Nash sees competence in the construction supply chain as key to delivering the required level of quality on building envelopes. Indeed, competence in two key areas – design and the workmanship involved during installation – is critical in his view.

While architects have traditionally had the competence on the design front, facades are now often such complex systems that the skills required to design it correctly are held in other disciplines, he argues.

Earlier involvement

In his eyes, that strengthens the case for earlier involvement of contractors and subcontractors. “There is a question mark over how we get the right skills around the table early enough in the process to ensure that what we design meets all the performance criteria. Very often those skills exist further down the supply chain with specialist subcontractors,” Nash says.

The issue of workmanship is a somewhat simpler issue, he contends, and it hinges on having a high standard of inspection and verification processes. “There is an issue in terms of whether the individual installers are competent, who is ensuring that what they are collectively doing meets the right standard?” he asks.

That’s a point echoed by Keith Laing, head of facades and cladding, at specialist envelope contractor Guildmore. “Legislation to improve construction quality has been welcome but there are still steps the private sector can take itself to ensure better practice,” he says.

“That can mean making sure that our quality inspection processes are constantly reviewed, having a clerk of works and making sure all managers and relevant people are trained to the highest level about which materials are the best in class.”

“Member companies should have confidence to report non-compliant or sub-standard work.”

James Talman, National Federation of Roofing Contractors

Meanwhile, National Federation of Roofing Contractors (NFRC) chief executive James Talman urges greater vigilance among construction firms, as his organisation focuses on not just keeping members safe, but also building occupants, in the post-Grenfell era. 

“Member companies should have confidence to report non-compliant or substandard work,” he says. “I said to one member, ‘if you install cladding, and you see that firestops are missing around the window for example, it might not be in your contract – but you know this is not compliant, so you should say that to your supervisor’. ”

Talman, who also sits on the Build UK board, warns that for his contractor members, making the right product choices in roofing or cladding construction is critical. 

“A lot of our smaller members are potentially exposed during their work because design responsibility is often passed down the supply chain, and they think the manufacturers’ products cover them,” he says.

“But sometimes, companies will choose a pick and mix system, with different components from different manufacturers and different origins, which are not fully tested when used together. So, we tell members to stick to tried and trusted systems.”

Nigel Blacklock is technical director for flat roof manufacturer Bauder, and well aware of the problems that can occur with “mixing and matching” products.

“Someone will always try and change one component of it, usually for a small financial gain. You are actually putting everything at risk,” he says.

“If you present a fire test certificate and building control comes back and says, ‘yes but this has Bauder insulation on it and you have used something different’, don’t come sobbing to me.

“They are different products. It may not necessarily matter if you changed them but the point is you don’t know.”

Digital uptake

Could improved data management provide part of the answer? Following the Hackitt report, many focused on her “golden thread” of information: the idea that improved digital records would transform quality of design, construction and asset management.

Talman sees a role for better use of digital technology, although he says its adoption in the roofing sector has been slower than he would have hoped.

“There has been less push on digital from manufacturers than we expected. They have struggled getting to grips with data standards. However, our member contractors mainly at the top end, such as Prater, are pushing forward with it,” he adds.

Blacklock agrees: “Five years ago, I had the first BIM object in the industry for flat roofing but few people were asking for them and from the manufacturers’ point of view it seems to have stalled.

“But in principle, if BIM is fully embedded and you have a unified model, it becomes more difficult for people to make last-minute changes for value‑engineering reasons.”

Nash wants to see a regulatory system that is less open to interpretation but feels that better inspection and site supervision is also required. While he acknowledges that main contractors are already making inroads, he also wants to see a reassessment of the drivers for construction projects – placing a greater emphasis on quality, ahead of time and cost.

“It’s about how you drive the right culture and behaviours – and that has to come from the top down,” he asserts.

The quality challenge — and what needs to change

Views from across the envelope sector on changing the quality culture

“While we take care to specify the appropriate roof systems for each individual project, we often see last-minute substitutions to reduce costs.

“There have been some recent amendments to Building Regulations, but more needs to be done to bring clarity and to reflect modern construction methods.”

Dean Grady, product manager for single-ply membrane, Sika Sarnafil

“One widespread issue is the competency of installers. Better training is key, as are inspections and evidence of checks being carried out.

“There needs to be more emphasis on making sure you can do a job to the right technical specification, with an emphasis on quality rather than just on cost.”

Carlton Jones, director, MCRMA

“The government can set certain policies but if it is not seen to police, then the danger is we go back to the way we were. We also need to be careful of unintended consequences.

“The changes to Approved Document B have caused grey areas that are very difficult in terms of interpretation.”

Nigel Blacklock, technical director, Bauder

NFRC raises quality bar with RoofCert

After research conducted with the Construction Industry Training Board (CITB) highlighted that reputation among contractors is a concern, the NFRC has introduced its RoofCert accreditation scheme for individual roofers.

Positioned as “roofing’s answer to Gas Safe”, it aims to raise the level of professionalism in the sector. This year, it began piloting the RoofCert Technical Knowledge Test for slating and tiling, the first of nine roofing disciplines that will be UKAS accredited.

“This reputation issue dates back to before Grenfell. It was prompted by behavioural and quality issues, particularly in housing work,” explains Talman. “Defect examples are typically in the details, such as hip flashing, chimney dressing

“The first pilot of the test was in Yorkshire and 70% passed. So that shows the test is rigorous. Some 1,500 individual names have put themselves forward for RoofCert. They want to say to main contractors and clients up the supply chain, ‘we’re aware of quality concerns, this is what we’re doing about it’,” he says. “We will also add a rainscreen cladding test on to the RoofCert scheme and are lobbying government for support.”

Talman argues that RoofCert can also help with retentions. “We would ask main contractors: are retentions held because of concerns about quality issues?” he says. “Because we are addressing these quality issues through RoofCert. We will measure the quality and productivity improvements and produce an output score.”

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