The Building Safety Act requires owners to evidence that higher-risk buildings are safe for their occupants, and manage the risks. But it’s not just a case of deciding whether to strengthen them or deconstruct them: Steve Cross and James McCulloch at Ridge explain the options.

Under the Building Safety Act 2022, landlords (as the “Principal Accountable Person”) are required to have correctly registered all higher-risk buildings with the Building Safety Regulator, part of the Health and Safety Executive. This includes any buildings over 18m or seven storeys. But one category that will be prioritised for scrutiny are those constructed using large panel systems (LPS), where precast panels were stacked on top of one another without structural ties to prevent collapse. LPS was used for tower blocks on a massive scale between the 1950s and the 1970s, and many of these buildings are still occupied today.

Here are five questions to help landlords to meet their obligations.

1. Do you know if your buildings are LPS?

As of 1 October 2023, every LPS tower should be registered with the regulator as a higher-risk building. They must also evidence that each building is safe, and that any fire and structural risks have been managed or mitigated.

One stumbling block to compliance is that many owners are not aware that their buildings were part of a system build – for example, where a local authority’s housing stock was transferred to a housing association without full records. Neither can a building’s underlying structure be determined from its appearance, as many have since been rendered or reclad. If an owner has not correctly identified a building’s construction, they will not have understood how to assess the risks it poses, and their safety strategy will be based on false assumptions.

However, identifying LPS buildings doesn’t have to be a daunting task. One housing association asked us to identify which of their 30,000 buildings were constructed using LPS: with desktop research, we were able to narrow down the search to 150 buildings, and then to just 10 or 15 which required site visits for confirmation.

2. Do you have a detailed understanding of their condition?

Once it’s been established that a building was constructed using LPS, it is essential to carry out intrusive investigations to determine that it is structurally sound. This will depend on aspects such as the amount of reinforcement, whether it is properly installed and the level of concrete cover, the quality of the concrete, and if the structure is properly tied.

A standard visual survey is not sufficient to evidence this. Even where the original drawings are available, they may not reflect how a building was actually constructed – we have examined supposedly identical buildings where one has passed the tests and the other has failed.

This is why intrusive investigations are essential: a structural engineer who has been unable to do this will be forced to caveat their conclusions, rendering their report of little value. It is also helpful if the engineer has experience of LPS buildings from the 1950s or earlier through to the early 1970s, because different construction methods were used, bringing different risks.

Due to a deficiency in the early structural codes, it’s common to find that a building constructed pre-1968 wasn’t tied properly, that the detailing or installation of reinforcement is poor. Even though it may have been in use for many decades, it may not have been put under stress, for example in a fire or gas explosion. Under these conditions, if a building is not correctly detailed, it won’t necessarily stand up.

3. Are you managing the risks effectively?

The Building Safety Regulator has already given notice to some landlords of the need to submit Safety Case Reports for higher-risk buildings, with the supporting “Golden Thread” of evidence, demonstrating that they have identified the fire and structural risks, and are managing them effectively.

For example, a concrete frame building may not have insufficient cover to the reinforcement to provide the required two-hour stay-put fire resistance window – there might be only enough for an hour, which means that the fire service has half as much time to work safely in that building. In these cases, the fire service would need to be involved straight away so that they can advise on the strategy. Additional measures would need to be put in place, such as sprinklers and a full building alarm system – many buildings don’t have these basics. The fire service will need to know if there are any mobility-impaired residents and where they are, so that they can focus on getting them out.

A building safety case is a new kind of submission, but it does not necessarily require a completely new set of documents. In April, the government clarified that landlords could use existing fire and building surveys, pointing out that “it would be extremely unusual to have none of this information to hand already”. However, it is important to ensure that any historic information needs to be to the correct level, current and reviewed by an appropriate professional. This is where a gap analysis can be a useful process to establish what information is in place, compared with what is expected.

4. Do you really have to knock them down?

A building that is found to be structurally unsound is not an automatic candidate for demolition, and it may not be necessary to immediately evacuate the occupants. But it does have to go through a risk assessment process with effective risk reduction measures put in place.

A costed options appraisal will consider everything from interim measures to make it safe, to risk management strategies such as removing gas cooking and heating, to structural strengthening and additional building systems, to demolition and full replacement. The owner can then decide whether it is economically feasible to make the building safe, or whether deconstruction and replacement would be the better course of action.

5. Is this an opportunity to build back better?

Where the decision is made to retain a building, remediation works can be a chance to carry out other essential compliance or upgrade works.

On one London estate, over a six-month period we replaced 800 gas boilers with heating interface units fed by an enhanced district heating system. While we were reproviding the hot water to each flat, our client decided to upgrade the kitchens, bathrooms and fire compliance at the same time. Similarly, strengthening works can be combined with retrofitting to improve a building’s thermal performance, and help meet Net Zero targets.

Even where demolition isn’t necessary, some of our clients have taken the opportunity for wider regeneration. A building may be defective or poorly performing in other ways, or simply no longer meet the community’s needs. Replacing it can modernise, diversify or expand an area’s housing stock, and create a better living environment overall.

Whatever approach a social landlord decides to take, this is a decision with significant implications, so it’s important to have confidence that it’s the right one. There are only a handful of companies that have a forensic understanding of how LPS buildings work and how they fail. We peer review each other’s work, and we are in constant dialogue with the BRE to develop industry best practice.

It’s important to remember that an LPS building may be perfectly safe for its occupants – but only by asking the right questions can landlords have this comfort.

For more information regarding this topic contact the experts. 

James McCulloch is a Chartered Engineer with over 20 years’ experience in structural and civil design. He has worked on many LPS projects throughout the UK. Contact him at jmcculloch@ridge.co.uk

Steve Cross is a Project and Programme Manager and Building Surveying Partner. He has project managed work on many LPS blocks. Contact him at scross@ridge.co.uk

Both Steve and James will be representing Ridge at this year’s CIH conference in Brighton on 8 and 9 May 2024.