How do we make modular buildings safer?

Will new regulations be enough to reduce the fire-safety risk posed by cavities in modular built structures? Ian Weinfass reports

More than eight months have passed since fire-service bosses published a five-page document outlining a litany of concerns about modular buildings.

Their warning came a year after structural safety-reporting body Cross-UK highlighted the potential for the concealed spread of fire and smoke inside extensive cavities within such structures.

Fire chiefs called for the government to implement a range of measures, such as amending regulations and defining competence requirements for people working on such buildings.

In January, the Department for Levelling Up, Housing and Communities (DLUHC) – which champions the use of modular construction – announced that it had commissioned a new standard for homes built using modern methods of construction (MMC).

This standard is being developed through the British Standards Institution (BSI) as a publicly available specification. It will include recommended voluntary technical standards for various MMC categories, as well as quality assurance and compliance processes.

But, despite sounds of encouragement in Whitehall, is enough being done in the post-Grenfell climate to ensure the safety of modular buildings? And what is the industry’s reaction to the concerns raised by firefighters?

Public sector backing

The oft-cited benefits of modular construction – where some or all of a building is manufactured in factories and then assembled on site – include cost, speed of build and the ability to operate in tight spaces. Supporters also hail the environmental advantages, including the reduction in waste.

Without an overhaul of the deregulated system, it’s just a matter of time until we see another major fire incident in a modular building

Mark Rowe, Fire Brigades Union

In 2017, Whitehall announced that it would favour offsite manufacturing on all publicly funded projects from 2019 onward.

Although the extent to which it has followed through on the commitment has been questioned, the modular method has been taken up enthusiastically by public sector bodies, such as the Department for Education, and by many private clients.

But, since then, some concerning incidents have occurred. In 2019, the Fair Isle Bird Observatory in the Shetland Islands – reported to have been built using volumetric modular methods – was destroyed by fire.

The following year, the Moorfield Hotel in Brae (pictured above), also in Shetland, had to be evacuated as it was devastated by flames.

A report from the Highlands and Islands Fire Rescue Service, seen by Construction News, confirms that the hotel building was constructed through modular methods and that the fire spread “through gaps or voids in construction”. Thankfully, nobody was hurt.

Later the same year, about 1,000 people were evacuated from six blocks at the Paragon development in Brentford, west London, owned by housing association Notting Hill Genesis and delivered by modular specialist Caledonian Modular in 2006 (the firm later went into administration in 2022 and was bought by JRL Group).

About 1,000 residents were evacuated from six blocks at the Paragon development in Brentford, west London, due to safety concerns. Credit: Alamy

The housing association cited safety concerns about both cladding and “building-performance issues”, and it said a review of the problems would take place. Remediation work on the blocks being carried out by Equans includes the installation of fire-rated cavity barriers and the replacement of combustible plywood sheathing with cementitious board.

Call for tighter rules

Cross-UK’s 2021 report warns: “The significance of the scenario of fire entering (potentially combustible) voids should not be downplayed, as it can complicate fire-service intervention for suppression.

That is why it should be explicit that a rigorous and robust system of supervision and inspection (fully or of an appropriate number of sample installations) be part of the contractor’s method statement for installation, [conducted] by a suitably qualified and experienced person at all times. This can ensure that any difficulties in physically accessing the space between the modules are overcome at the construction stage.”

Depending on the teams [you’re dealing with], they may have some experience, no experience or a lot of experience – it’s very variable. How the approach is followed should be more straightforward and set out in the regulations

Ben Paget, Volumetric Building Companies

Weeks after December’s policy statement from the National Fire Chiefs Council (NFCC), DLUHC announced it had commissioned the new BSI specification for homes built using MMC.

Now, a spokesperson for the NFCC tells CN: “We welcome the development of a publicly available specification for MMC but remain concerned that MMC buildings are being designed, approved and built without an understanding of their performance and safety.”

They say that the NFCC supports the aim of building faster and more sustainably, but warns that this cannot come “at the expense of safety”.

The spokesperson adds: “We are calling on the government to take further action to tighten the rules for the testing of MMC for the safety of both the public and firefighters. Government must address the need for an understanding of the materials, construction methodology and location of MMC buildings.

“Competency standards need to be embedded for practitioners working within MMC at all stages of the construction and occupation stages.”

As well as volumetric modular methods, the NFCC’s call for action covers other types of MMC. Examples include the use of engineered mass timber products such as cross-laminated and glued-laminated wood.

The Fire Brigades Union, which represents frontline firefighters, says problems in the residential sector stem from the government’s rush to increase housing numbers. “Modular construction is a new method of building, and many of the risks are untested,” says national officer Mark Rowe.

“But what is clear is that safety has been sidelined to maximise profitability and speed. This method of construction has been encouraged by the government and embraced by social-housing providers, despite serious questions about how fires spread in modular buildings.

“Without an overhaul of the deregulated system, it’s just a matter of time until we see another major fire incident in a modular building.”

He urges the government to invest more in fire-safety inspectors to hold firms to account, and calls for the establishment of a UK-wide statutory advisory body on fire safety that would include the participation of his union.

No compromise

Make UK Modular, a trade body that represents six specialists in the sector including Laing O’Rourke, defends the standards to which modular buildings are delivered. “Make UK Modular and its members completely agree that fire safety is of critical importance to all housing providers,” a spokesperson says.

“There is no compromise on fire safety, and indeed our standards and testing routinely go above and beyond what is required.”

They add that modular specialists are spending heavily on research and development to improve homebuilding, especially in areas of safety.

But others in the sector support the NFCC’s call for more regulation. “We have a lot of experience of what we do, but as soon as we take that to a wider design team, there’s not always the same level of competence and experience,” says Ben Paget, senior engineering associate at Volumetric Building Companies.

He adds that the modular specialist often spends a lot of time educating a client’s wider team on how volumetric modular construction works, and then sometimes has to repeat this with local authorities and fire departments.

“Depending on the teams you get, they may have some experience, no experience or a lot of experience – it’s very variable,” Paget explains. “How the approach is followed should be more straightforward and set out in the regulations.”

More clarity in regulation or law about where responsibilities lie between manufacturers of modules and their installers would also be helpful, he says.

Tony Wells, managing director of Merit, which acts as both contractor and supplier on all of its jobs, says the fragmented nature of the industry is responsible for many of its most serious safety issues.

He adds that there is no question of where responsibility lies if the company designs, manufactures and builds everything itself.

“If you want to transition to manufacture, you have to design every nut and bolt, and through that process you will [also] gain productivity,” Wells says.

“We are doing our absolute utmost to engineer out operational, ESG [environmental, social and governance] and fire risk.”

Building Safety Act

A DLUHC spokesperson says the government has “taken significant steps to regulate the building industry” through the Building Safety Act 2022 and the creation of the Building Safety Regulator.

They add: “We are making buildings better and safer by ensuring that anyone involved in design or building work can do their job properly and in compliance with Building Regulations.

“That is why we are introducing a new framework for registration and regulatory oversight of the building-control profession. All homes, including modular, must meet building regulations and fire-safety standards – no one should have to live in an unsafe home.”

Hywel Davies is chief technical officer at the Chartered Institution of Building Services Engineers and an ex-chair of the former Building Regulations Advisory Committee, which previously gave advice to ministers on technical issues (the committee was disbanded earlier this year under the Building Safety Act). He believes the new building-safety laws, in conjunction with existing Building Regulations, could go a long way towards alleviating concerns.

Davies points out that B3(4) in Schedule 1 of the 2010 Building Regulations means a building must be designed and constructed so that, in the event of fire, it will be “maintained for a reasonable period”.

He says: “We’re promised a new regime in which people are going to need to demonstrate their competence to the regulator.

“If a designer says ‘I don’t know how to comply with B3 paragraph 4’, under the new regime the answer will be ‘then you’re not competent and you shouldn’t have taken this job’, or ‘if you didn’t realise you had to do this until after you took the job, you need to go back to the client and say that we’re not competent to do this’.”

Davies adds that it can take years to introduce new building regulations or amend existing ones, adding: “My feeling is, why don’t we get the new regime and the [BSI publicly available standard], and see what they look like and how that settles down before we call for anything more?”

Ultimately, though, he says: “I think the NFCC is quite right to flag the concern about unseen cavities in volumetric MMC, as, at the end of the day, it’s firefighters who are risking their lives. We owe it to them to get this right.”

The insurance question

It is not only firefighters who have raised concerns about modern methods of construction (MMC) – questions have also been posed by insurers.

“We recognise the benefits of MMC, and its potential benefits for boosting the housing supply and meeting net-zero commitments,” says Lucie Hart, policy advisor, general insurance at the Association of British Insurers (ABI).

“More information is needed to understand the potential impacts of MMC and the durability, resilience and repairability of the products, especially around how the products would react to perils such as a fire, flood or subsidence,” she adds. “It is fundamentally important that MMC does not negatively impact fire safety, and building regulations must be able to adapt to innovation in the development industry.”

Echoing some of the NFCC’s calls, the ABI is calling for the creation of a publicly available database of information about MMC buildings. It also urges certification of products and steps to ensure that
the labour force is skilled in the use of MMC development and products. An ABI spokesperson says: “It’s about an increase in training and making sure there is an experienced workforce, competent in the materials and assembly, maintenance and/or repair techniques required.”

They add: “We would like to work with government, the construction industry and other relevant stakeholders to ensure that properties built using MMC are resilient to a wide range of perils, and are built and maintained in a way which enables them to access affordable insurance for the lifetime of the property.”

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