System-Build Schools: Types, Common Issues, and Management
Introduction
In the post-World War II era, the UK adopted system-build construction methods to address urgent housing and infrastructure needs, including the rapid expansion and re-construction of schools. These innovative designs, which utilized prefabricated components, were a response to material shortages and the pressing need for educational facilities.
However, decades later, these schools often face significant structural and safety concerns and as reported recently in The Guardian there is now a calling for these buildings to have full structural surveys and safety checks.
This blog explores the various system-build types, delves into common defects and issues, examines the legislation for inspecting these buildings, and outlines best practices for management and maintenance.
Types of System-Build Schools in the UK
Some of the most common system-build methods include:
Laingspan: A concrete-based system utilizing precast concrete panels, often exhibiting structural weaknesses over time.
Integrid: A modular steel-framed system designed for adaptability but prone to thermal inefficiency.
Orlit: Prefabricated concrete panels with known issues of carbonation and reinforcement corrosion.
Vic Hallam: A popular timber-framed system with widespread use in temporary educational buildings.
CLASP: A modular steel-frame system widely used due to its scalability but facing concerns about long-term durability.
Later developments of CLASP are known as SCOLA (Second Consortium of Local Authorities) and MACE (Metropolitan Architectural Consortium for Education).
Common Defects and Issues
Structural Issues
Carbonation and Corrosion (Laingspan, Orlit):
Over time, carbon dioxide from the air penetrates the concrete, causing carbonation. This reduces the alkalinity of the concrete, leaving the steel reinforcement vulnerable to corrosion. Corroded reinforcement expands, leading to cracking and spalling of concrete, which can significantly weaken the structure.
Timber Decay (Vic Hallam):
Timber-framed systems are highly susceptible to rot, especially when exposed to moisture through leaking roofs or poor drainage. Untreated timber may also attract wood-boring insects, further compromising the structural integrity.
Settlement and Movement (Integrid, CLASP):
The lightweight construction of steel-frame systems can lead to differential settlement, where parts of the building shift unevenly, causing cracks and misalignments.
Deleterious Materials
High-Alumina Cement (HAC):
HAC was used in concrete production during the mid-20th century but was later found to lose strength over time due to a process known as "conversion," especially in damp conditions. This can result in the weakening of structural elements, necessitating remedial action.
Calcium Silicate Bricks:
These bricks are susceptible to freeze-thaw cycles, which can cause spalling (surface deterioration) and compromise structural integrity.
Reinforced Autoclaved Aerated Concrete (RAAC):
RAAC was widely used in the construction of schools from the 1950s to the 1980s due to its lightweight properties and ease of installation. However, it has proven to be a high-risk material as it lacks the durability of traditional concrete. Over time, RAAC panels can become brittle and prone to sudden failure, particularly when exposed to moisture or improper maintenance. This poses significant structural risks, especially in roofs and floors where RAAC panels are often located.
Asbestos in System-Built Schools:
Asbestos was widely used in insulation, ceiling tiles, wall panels, and other components due to its fire-resistant properties. In aging buildings, ACMs can become friable (easily crumbled), releasing harmful fibers into the air. Prolonged exposure to asbestos fibers is linked to severe health issues, including asbestosis, lung cancer, and mesothelioma.
Stramit Panels:
Stramit is a compressed strawboard material used in ceilings and partitions. While it was valued for its lightweight and insulating properties, Stramit lacks durability and is highly susceptible to water damage, which can lead to disintegration and loss of structural support.
Wood Wool Panels:
Wood wool is a composite material made from wood shavings bound with cement or other adhesives, often used in ceilings and walls for insulation and acoustic purposes. Over time, these panels can deteriorate, especially in damp conditions, leading to weakened structural integrity and the risk of collapse.
Thermal Inefficiency
One of the primary challenges of system-build schools is their poor thermal performance. When these buildings were constructed, energy efficiency standards were minimal or non-existent, with a focus on rapid assembly and cost-saving over long-term energy performance. As a result, many system-built schools are now considered thermally inefficient, leading to increased heating costs and difficulties in meeting modern energy performance regulations. This creates uncomfortable learning environments that may affect students' concentration and well-being.
Fire Safety Risks
Timber systems like the Vic Hallam, as well as older steel-frame buildings, may lack adequate fireproofing. System builds with their timber or light weight frames and lightweight cladding materials, present inherent fire risks. Timber is naturally combustible, and untreated or aging fire retardants further exacerbate this issue. Many of these buildings were constructed before modern fire safety standards, lacking adequate compartmentalization, fire-stopping measures, and fire-resistant materials.
Common vulnerabilities include gaps and voids in prefabricated joints, which can allow fire and smoke to spread rapidly, as well as the use of combustible insulation and cladding materials. Additionally, outdated fire alarms and degraded fire safety features increase the risk of undetected or uncontrolled fires.
Mitigation strategies include upgrading fire safety systems, replacing flammable materials with non-combustible alternatives, and applying modern fire-retardant treatments. Regular fire risk assessments and compliance with regulations, such as the Regulatory Reform (Fire Safety) Order 2005, are essential to ensure these buildings remain safe for occupants.
Aesthetic and Functional Limitations
System-built schools are often considered outdated, with limited adaptability to modern teaching methods. Narrow corridors, small classrooms, and poor lighting are common complaints which is why they are a priority under the Priority School Building Programme
Legislation and Guidance for Inspections of System-Built Schools
UK Legislation
Control of Asbestos Regulations 2012:
Requires duty holders to identify and manage asbestos in buildings. Schools must have an asbestos management plan and conduct regular surveys to monitor the condition of ACMs.
Building Regulations (England and Wales):
Updated regulations set standards for the safety, health, and welfare of building occupants. While older buildings are not required to meet all modern standards, upgrades must comply with regulations during renovations.
Health and Safety at Work Act 1974:
Places a general duty on employers (including schools) to ensure the health and safety of occupants. This includes addressing structural and material risks.
Professional Standards
British Standards (BS 8415):
Provides guidance on inspecting and assessing prefabricated buildings, including structural components.
Department for Education Guidance:
Publications like Managing Older School Buildings offer practical advice for maintaining system-built schools safely.
Estate & site teams as well as responsible persons can also refer to The Good Estate Management for Schools guidance.
Local Authority Inspections:
Local councils may require periodic inspections for system-built schools to assess structural and material safety. Many have frameworks to address issues specific to schools built during the mid-20th century.
Managing System-Build Schools
We’ve identified six key steps responsible bodies and estates teams can take to effectively manage older and system built properties:
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Engage a qualified surveyors and/ or structural engineer to conduct regular condition surveys. Focus areas include:
Structural integrity of concrete and steel components.
Presence and condition of ACMs.
Timber decay or infestation.
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Implement a maintenance schedule to address minor issues before they escalate.
Regularly inspect and clean roofs, gutters, and windows to prevent water ingress.
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Replace or reinforce deteriorated concrete and steel components.
Improve thermal performance through external cladding, new glazing, and insulation upgrades.
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Install modern fire alarm and suppression systems.
Retrofit fireproofing materials to enhance the resistance of structural components.
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Employ a competent and qualified asbestos surveyor to regularly inspect ACMs to ensure they remain undisturbed.
Safely remove ACMs during renovations or if they pose a health risk.
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There will inevitably come a time where remediation is no longer cost-effective, and phased replacement of the building may be necessary.
This can be put into effect at an early stage and planned efficiently if a structural survey is undertaken as soon as possible.
Conclusion
System-build schools are a crucial part of the UK’s educational history but face significant challenges due to their age and construction methods. Addressing structural, material, and safety issues is vital for ensuring the safety and functionality of these buildings.
To date, as the DfE see to prioritise these schools, they are being replaced with new modular structures built using modern methods of construction (MMC), promoted through government initiatives. However at least seven such schools built or partially built since 2020 are now earmarked for demolition because they are structurally unsafe. As such it appears that we still have the inability to learn from history. The DfE need to employ a long term replacement strategy which ensures minimal disruption to educational activities.
By adhering to legislative requirements and employing professional inspections and maintenance plans, schools can manage these buildings effectively. At Spicer Surveys, we provide expert building surveys and tailored management strategies to help schools navigate these challenges.
Contact us today for professional advice and support.