combustible cladding
Combustible Cladding
The term combustible cladding refers to external wall systems comprised of materials that are capable of catching fire and contributing to the rapid spread of flames across a building’s façade. In the UK, this issue gained significant attention following the Grenfell Tower tragedy, leading to stringent legislative changes and a nationwide effort to identify and remediate buildings at risk. These systems often contain cores made of polyethylene (PE) or other petroleum-based polymers that act as a fuel source when exposed to heat.
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Combustible Cladding
The term combustible cladding refers to external wall systems comprised of materials that are capable of catching fire and contributing to the rapid spread of flames across a building’s façade. In the UK, this issue gained significant attention following the Grenfell Tower tragedy, leading to stringent legislative changes and a nationwide effort to identify and remediate buildings at risk. These systems often contain cores made of polyethylene (PE) or other petroleum-based polymers that act as a fuel source when exposed to heat.
Managing the risks associated with unsafe combustible cladding involves a complex process of technical assessment, fire safety engineering, and physical remediation. For building owners and managing agents, the priority is to determine the composition of the existing materials, evaluate the presence of cavity barriers, and establish whether the system meets current Building Regulations. At CladdingTesting.com, we provide the technical clarity required to navigate these challenges, from initial intrusive inspections to full-scale recladding programmes.
- Regulatory Compliance: The UK government has implemented a combustible cladding ban on buildings over 11 metres, requiring non-combustible materials (typically Euroclass A1 or A2-s1, d0) for specific building types.
- Material Identification: Not all cladding that looks like metal is safe; flammable cladding often hides behind aluminium skins (ACM) or HPL panels.
- Risk Mitigation: If a building is found to have highly flammable cladding, interim measures like fire alarms or waking watches may be necessary until remediation is complete.
- Remediation Strategy: Solutions range from targeted repairs of cavity barriers to the complete flammable cladding replacement.
Key Takeaways
- Safety First: The primary risk of combustible cladding is the potential for vertical and horizontal fire spread, bypassing internal fire compartments.
- Legal Obligations: The Building Safety Act 2022 places clear responsibilities on "Accountable Persons" to manage building safety risks.
- Professional Assessment: Only intrusive surveys and laboratory testing can definitively confirm the safety of an external wall system.
- Financial Support: Various funds, such as the Building Safety Fund (BSF) and Cladding Safety Scheme (CSS), are available to help cover the costs of replacing combustible cladding.
- Holistic Approach: Remediation must look beyond the panels to include insulation, fire breaks, and fixing systems to ensure long-term integrity.
Understanding the Composition of Flammable Cladding
To understand why certain materials are classified as unsafe combustible cladding, one must look at the chemistry of the components. The most notorious material is Aluminium Composite Material (ACM) with a pure polyethylene core. Polyethylene is a thermoplastic that melts and drips when heated, providing a massive amount of energy to a fire. Even small amounts of this material can cause a fire to jump between floors in minutes.
High-Pressure Laminate (HPL) is another common material under scrutiny. These panels are made by layering paper or wood fibres with resin under high pressure. While some HPL panels have fire-retardant properties, many older versions are highly flammable cladding that does not meet modern safety standards. The way these panels interact with the insulation behind them—often combustible PIR or PUR foam—creates a "chimney effect" in the cavity.
The Role of Insulation and Cavity Barriers
The cladding panel is only the outer skin of the External Wall System (EWS). The materials behind the panel are equally critical. Many non-compliant cladding systems were installed over combustible plastic foam insulation. When the outer panel fails, this insulation fuels the fire further, shielded from the direct spray of fire service hoses.
Cavity barriers are designed to close the gap between the cladding and the building structure in the event of a fire. In many banned flammable cladding high rise buildings, these barriers were either missing, incorrectly installed, or made of inappropriate materials. Without functional cavity barriers, a fire can spread undetected behind the panels, making it nearly impossible to extinguish from the outside.
Common Types of Combustible Materials Found in UK Façades:
- ACM (PE): Aluminium Composite Material with a polyethylene core (Category 3).
- ACM (FR): Fire-resistant cores that may still be non-compliant depending on building height.
- HPL: High-Pressure Laminate panels, often used in rainscreen systems.
- MCM: Metal Composite Materials, including copper or zinc skins with combustible cores.
- Timber Cladding: Often found on balconies or as decorative features, which can ignite easily.
The Regulatory Framework and the Combustible Cladding Ban
The UK regulatory landscape changed fundamentally with the introduction of the combustible cladding ban in 2018, which was further refined in 2022. The ban applies to "relevant buildings"—including high-rise flats, hospitals, and student accommodation—over 18 metres, and has been extended in scope to buildings between 11 and 18 metres. For these structures, all materials becoming part of the external wall must reach Euroclass A2-s1, d0 or A1.
This shift from "functional" requirements to "prescriptive" material bans has left many building owners with non-compliant cladding. Even if a building was compliant at the time of construction, it may now fail current safety standards. This has created significant issues for leaseholders, particularly regarding the valuation and sale of properties, leading to the requirement for EWS1 (External Wall System) forms.
The Building Safety Act 2022
The Building Safety Act is the most significant piece of legislation affecting the industry in decades. It introduced the concept of the "Principal Accountable Person" and created a new Building Safety Regulator. Under this Act, developers are being held more accountable for unsafe combustible cladding, and there are new legal protections for leaseholders to prevent them from bearing the full cost of flammable cladding replacement.
Navigating these regulations requires a deep understanding of the law and construction technology. At CladdingTesting.com, we assist clients in interpreting these regulations and developing a roadmap for compliance that satisfies both the regulator and mortgage lenders.
Identifying Risks: The Inspection Process
Determining how many high rise flats with combustible cladding remain in a portfolio requires a systematic approach to inspection. A visual survey from ground level is rarely sufficient. A thorough investigation involves intrusive testing, where small sections of the façade are removed to inspect the internal build-up. This allows us to see exactly what lies behind the panels.
During these inspections, we look for:
- The type of core material in composite panels.
- The type and thickness of the insulation.
- The presence, spacing, and installation quality of fire cavity barriers.
- The condition of the sub-frame and fixings.
- Evidence of moisture ingress or structural deterioration.
Laboratory Testing and Sampling
Samples taken during an intrusive survey are often sent for laboratory analysis. This confirms the chemical composition of the materials and their reaction-to-fire classification. For instance, determining whether an ACM panel is PE or FR core is vital for risk assessment. These results form the basis of the EWS1 assessment and dictate the urgency of any flammable cladding replacement.
It is important to remember that not all cladding requires immediate removal. A qualified fire engineer can sometimes determine that the overall risk is low if other mitigation factors are in place. However, for highly flammable cladding, the path to safety usually involves physical intervention.
Remediation Options: Repair vs. Replacement
One of the most frequent questions we encounter is: "Does it all have to come off?" The answer depends entirely on the building's specific risk profile. Our approach at CladdingTesting.com is to evaluate every building individually. We avoid a "one size fits all" mentality, as full replacement is not always the only solution for non-compliant cladding.
Localised Remediation and Repair
In some cases, the cladding panels themselves may be acceptable, but the fire stopping is deficient. Remediation might involve stripping the panels, installing compliant cavity barriers, and then reinstating the original cladding. This is often more cost-effective and less disruptive for residents than a full reclad. Repair work might also address failed fixings or damaged panels that, while not a fire risk, pose a structural hazard.
Complete Flammable Cladding Replacement
When the materials are classified as unsafe combustible cladding (such as ACM Category 3), a full replacement is usually the only viable route to safety and compliance. This process involves:
1. Detailed design and specification of a new, non-combustible system.
2. Safe removal and disposal of existing hazardous materials.
3. Installation of new A1 or A2 rated insulation and panels.
4. Updating all cavity barriers and flashing details to meet modern standards.
Factors Influencing the Choice of Solution:
- Building Height: Taller buildings face stricter requirements.
- Material Type: The specific fire rating of the existing panels.
- Building Use: Residential buildings are prioritised over commercial ones.
- Funding Requirements: Schemes like the BSF have specific criteria for what they will fund.
- Structural Capacity: Ensuring the building can support the weight of a new cladding system.
Combustible Cladding
Logistics of High-Rise Recladding Projects
Working on banned flammable cladding high rise projects presents unique logistical challenges. These buildings are often in dense urban environments and, crucially, remain occupied throughout the works. Managing the safety of residents, pedestrians, and workers while maintaining the building’s weather-tightness is a significant undertaking.
Access is a primary consideration. Depending on the building's height and footprint, we may use mast climbers, cradle systems, or traditional scaffolding. Each has its pros and cons regarding speed, cost, and resident privacy. Mast climbers are often preferred for high-rise work as they offer a stable platform and can be moved efficiently, reducing the "caged" feeling for residents.
Minimising Resident Disruption
We understand that a flammable cladding replacement project is stressful for leaseholders. Open communication and structured sequencing are essential. By working on one elevation at a time, we can limit the period during which specific flats are impacted. Dust suppression, noise management, and strict working hours are standard practice to ensure the environment remains habitable.
Furthermore, the removal of cladding can temporarily reduce the thermal performance of the building. We plan our removal and installation phases to minimise the time the building is "exposed," ensuring that residents do not face excessive heating costs or damp issues during the transition to the new system.
The Financial Impact and Funding for Remediation
The cost of replacing combustible cladding can be astronomical, often reaching millions of pounds for a single block. This has led to a major crisis in the UK property market. Fortunately, several mechanisms are now in place to help building owners and leaseholders manage these costs.
Government Funding Schemes
The UK government has committed billions of pounds to address the cladding crisis. The Building Safety Fund (BSF) targets residential buildings over 18 metres, while the Cladding Safety Scheme (CSS) covers buildings between 11 and 18 metres. These funds are designed to cover the "eligible" costs of remediating unsafe combustible cladding, though the application process is rigorous and requires detailed technical evidence.
At CladdingTesting.com, we work alongside consultants to provide the technical surveys and costings necessary for these fund applications. Having an accurate, evidence-based assessment of the works required is the first step in securing financial support.
Developer Pledges and Legal Redress
Many of the UK's largest developers have signed a pledge to remediate buildings they constructed, regardless of whether they qualify for government funds. For buildings where the developer is no longer in business or refuses to act, the Building Safety Act provides new avenues for legal action, including Building Liability Orders. This ensures that the burden of highly flammable cladding does not fall solely on the individuals living in the flats.
Technical Considerations for New Façade Systems
When we replace combustible cladding, we aren't just looking for fire safety; we are also looking for long-term performance. The new system must be durable, weather-tight, and thermally efficient. Modern non-combustible systems often use solid aluminium, pre-coated metal, or fibre cement panels.
Material Selection
Solid aluminium panels (typically 3mm thick) are a popular choice for flammable cladding replacement. They are non-combustible (Euroclass A1), lightweight, and recyclable. Another option is mineral-wool-cored sandwich panels, which provide excellent thermal insulation while meeting strict fire safety criteria. The choice of material often depends on the original design intent and the structural capacity of the existing sub-frame.
Interface Details and Weathering
A common mistake in remediation is focusing only on the panels and ignoring the "interfaces"—where the cladding meets windows, balconies, and roofs. If these details are not handled correctly, the building may suffer from water ingress or air leakage. Our technical team ensures that every interface is redesigned to be both fire-safe and weather-proof, often improving the building's overall energy rating in the process.
Environmental and Sustainability Factors
Remediating combustible cladding is also an opportunity to improve a building’s carbon footprint. By installing modern, high-performance insulation during the recladding process, building owners can significantly reduce energy consumption. Furthermore, many of the non-compliant cladding materials we remove, such as aluminium skins, can be recycled rather than sent to landfill.
Sustainable procurement is also becoming more important. We look at the "embodied carbon" of replacement materials, helping clients choose systems that are both safe and environmentally responsible. This holistic view ensures the building is fit for the future in every sense.
Future-Proofing Your Building Assets
The landscape of building safety will continue to evolve. Managing agents and owners must move away from reactive maintenance and toward proactive asset management. Keeping a detailed "Golden Thread" of information—digital records of materials, fire safety assessments, and maintenance logs—is now a legal requirement for high-risk buildings.
Regular inspections of the building envelope, even after remediation, are vital. Checking for blocked drainage, damaged seals, or bird nesting in the cavity can prevent small issues from becoming major repairs. Combustible cladding was a hard lesson for the industry, but it has led to a new standard of rigour that will ultimately make our cities safer.
How Many High Rise Flats with Combustible Cladding Remain?
Data from the Department for Levelling Up, Housing and Communities (DLUHC) suggests that while hundreds of buildings have been completed, thousands more are still in the process of investigation or remediation. As of late 2023, there were still a significant number of buildings where highly flammable cladding had not yet been fully replaced. The pace of work is increasing, but the complexity of high-rise construction means this remains a multi-year project for the UK.
The challenge is not just the unsafe combustible cladding itself, but the capacity of the industry to deliver these complex works. There is a high demand for specialist contractors, fire engineers, and qualified surveyors. This is why early engagement with specialists like CladdingTesting.com is crucial for ensuring your project is programmed and delivered efficiently.
Frequently Asked Questions
What exactly makes cladding "combustible"?
Cladding is considered combustible if it contains materials that contribute to a fire. This is measured by the Euroclass rating system. Materials rated Class B to F are combustible. In the UK, combustible cladding typically refers to anything that fails to meet the A1 or A2-s1, d0 standard required for high-rise buildings. The most common culprits are polyethylene cores and certain types of plastic foam insulation.
How do I know if my building has unsafe combustible cladding?
You cannot tell just by looking. You need an EWS1 survey or a Fire Risk Appraisal of External Walls (FRAEW) conducted by a qualified professional. This involves reviewing original building plans, taking samples of the materials, and conducting intrusive inspections to check for cavity barriers and insulation types. If you are a leaseholder, your managing agent should be able to provide the status of these assessments.
Is a building with combustible cladding "unmortgageable"?
Not necessarily, but it is much more difficult to secure a mortgage. Most lenders require an EWS1 form with a rating of A1, A2, or B1 to approve a loan. If a building is rated B2, it means remediation is required, and lenders will often refuse to lend until a funded plan for flammable cladding replacement is in place. Recent agreements between major lenders have eased this slightly, provided there is a clear path to remediation.
What is the difference between remediation and replacement?
Remediation is a broad term that means "fixing the problem." This could include replacing the cladding, but it could also mean adding missing fire breaks or upgrading the fire alarm system. Flammable cladding replacement is a specific type of remediation where the outer panels and potentially the insulation are completely removed and replaced with new, non-combustible materials.
Who pays for the removal of non-compliant cladding?
Under the Building Safety Act 2022, leaseholders in buildings over 11 metres are protected from most costs associated with unsafe combustible cladding. The costs should be covered by the developer (if they are still active), the government's Building Safety Fund or Cladding Safety Scheme, or, in some cases, the freeholder. Managing agents are responsible for identifying the appropriate funding route.
How long does a recladding project usually take?
A typical high-rise project can take anywhere from 6 to 24 months, depending on the building's size and the complexity of the work. This includes the design phase, procurement of materials, and the physical installation. Planning for logistics, such as scaffolding and resident access, is often the most time-consuming part of the pre-construction phase.
What are interim fire safety measures?
If a building is identified as having highly flammable cladding, the Fire and Rescue Service may require interim measures to ensure resident safety until remediation is finished. This might include changing the building's evacuation strategy from "Stay Put" to "Simultaneous Evacuation," installing a common fire alarm system, or employing a "Waking Watch" to patrol the building 24/7.
Can I stay in my flat during the recladding process?
Yes, in the vast majority of cases, residents remain in their homes while the work is carried out. The work is external, so there is usually no need for internal access to the flats. However, there will be noise, some loss of natural light due to scaffolding, and residents may need to keep their windows closed during certain phases of the flammable cladding replacement.
What is an EWS1 form?
The EWS1 (External Wall System) form is a document created by the Royal Institution of Chartered Surveyors (RICS) to help lenders assess the risk of a building's cladding. It is not a legal safety certificate but a valuation tool. A rating of A1 or A2 means the wall is unlikely to support combustion, while a B2 rating means that unsafe combustible cladding has been found and remediation is needed.
Combustible Cladding