Large Panel System (LPS) buildings are a legacy of post-war Britain’s push to deliver housing at pace and scale. Built primarily in the 1950s to 1970s using prefabricated concrete panels, LPS blocks enabled the rapid construction of high-rise homes across the UK, many of which remain occupied and in use today. However, structural safety concerns, especially following high-profile incidents such as the partial collapse of Ronan Point in 1968, have led to a renewed focus on the integrity of these buildings.

This renewed focus is now embedded in law. As a consequence of the Building Safety Act 2022, every stakeholder in the maintenance and improvement of all high rise buildings has an increased focus on the long term stability and safety of the structures within their control. This includes fire and any structural concerns, as well as a responsibility to register every structure with Building Safety Regulator. For LPS buildings, concerns over stability and safety has been in the background for decades, and inevitably the need to remediate where necessary has taken on new urgency.

Under the requirements of the Building Safety Act, local authorities and housing associations must carry out thorough structural assessments of higher-risk residential buildings (HRBs), including those constructed using LPS. These buildings are particularly vulnerable to progressive collapse caused by accidental loads such as internal explosions or fire. This is due to the reliance on panel joints rather than overall structural redundancy. In cases where reinforcement work may have been assumed but never completed, as seen at Southwark Council’s Ledbury Estate, these vulnerabilities are even more critical.

Social landlords managing ageing LPS stock face a complex challenge. The question isn’t simply “are they safe?”,  it’s how best to assess them, reassure residents, and determine whether strengthening, refurbishment or demolition is the most appropriate path forward. While some providers may ultimately choose demolition and new build, there are many cases where practical, cost effective strengthening options can safely extend the life of these buildings.

Steel anchor solution

The Helifix SockFix system is one such solution. SockFix functions as an integral component of consulting engineers’ safety critical strengthening upgrade measures.  Helifix SockFix is a fully grouted stainless-steel anchor installed into predrilled holes. Once inserted, a woven sock around the anchor expands as it’s filled with SockFix Grout, forming a secure load-bearing bond within the hollow precast concrete units. Crucially, this method enables strengthening of joints between floor slabs and wall panels which is the key structural weakness in many LPS designs. Carried out externally from scaffold or mast climbers, this solution can be carried out minimising major disruption to residents.

Helifix SockFix is specifically engineered to overcome one of the most common challenges encountered in LPS buildings: anchoring into hollow or lightweight precast units. Standard fixings are ineffective in these applications due to the risk of grout loss and insufficient contact with the host material. SockFix addresses this by actively controlling the grout within the cavity, ensuring a consistent bond without requiring the void to be fully filled with cementitious material. This not only improves reliability and installation speed, but also reduces the volume of material used and associated embodied carbon.

Remediation process

Anchoring solutions are often queried by clients in relation to how they fit into the wider LPS assessment and remediation process. The answer is that they are typically deployed once a structural investigation has identified vulnerabilities but they can also play a role in interim risk mitigation. For example, in buildings where piped gas has been removed but reinforcement hasn’t yet been completed, SockFix anchors can provide additional mechanical restraint and peace of mind during occupancy.

The starting point for any project is correctly identifying the LPS design type and its known risk profile. Many landlords have only partial records of how their blocks were built or strengthened post-Ronan Point. LPS blocks may well have received structural intervention in the 1970s or 1980s, but the quality and verification of those measures can vary significantly. It’s not uncommon to find that assumed strengthening wasn’t actually carried out or that undocumented changes make new assessments more complex.

Where such uncertainty exists, clients often appoint a consulting structural engineer to investigate the construction type and current condition. Common defects uncovered at this stage include misalignment of panels, sloping floors, cracking, movement between structural components, and spalling of concrete or masonry.

Tailoring the solution to the building is critical. No two LPS blocks are identical, and many were constructed with inconsistent jointing or incomplete documentation. The best practice approach involves on-site investigation, anchor pull testing, and technical design bespoke to each project. This will ensure the systems utilised reflect the real condition of the building, not just what’s shown on historical plans.

While demolition is sometimes the preferred or necessary option, particularly in cases of widespread deterioration or resident-led regeneration programmes, strengthening is often the more cost-effective and less disruptive solution in the short to medium term. In fact, housing providers are increasingly adopting a phased approach: reinforcing first to address immediate safety obligations, then reviewing options for long-term redevelopment in consultation with residents.

Ledbury lessons

The Southwark Council case offers important lessons. Its investigation into the Ledbury Estate revealed that previous strengthening work, assumed to have been carried out in line with historical BRE guidance, had not in fact been completed. The council’s decision to commission a detailed structural investigation, engage residents early, and present a range of options was exemplary. It’s also a reminder that visual inspections alone are not enough. Invasive testing, supported by structural engineering expertise, is essential to fully understand the condition of LPS buildings.

From a technical perspective, anchoring systems are well suited to reinforce the mechanical connections in LPS blocks. For housing managers, they offer a route to maintaining building safety and legal compliance with minimal tenant disruption. Financially they can significantly reduce the need for decanting and the capital costs associated with full rebuilds.

Ultimately, managing LPS risks is not about finding one universal answer, it’s about taking a building-by-building approach, informed by thorough investigation and supported by proven, adaptable solutions. 

With over 575 LPS tower blocks still standing across the UK, the need for practical, scalable and sensitive remediation strategies has never been greater. Leviat is  committed to working with housing providers to ensure these buildings can continue to serve communities safely and securely for years to co