Temporary works failures on UK construction projects are rarely caused by a single technical error. In London, where projects involve complex sequencing, constrained environments and multiple subcontractors, incidents are more often the result of breakdowns in coordination, communication and control across the temporary works system.
This article explains why temporary works failures occur on UK construction sites, the most common causes identified in practice, and what BS 5975 requires to prevent incidents.
Why Temporary Works Fail on Site
While temporary works are designed to support construction safely, they often operate under conditions that are more complex and less predictable than permanent works.
Temporary works must support partially completed structures, manage changing load paths and adapt to evolving site conditions. These dynamic conditions increase the risk of failure, particularly where control systems are weak.
Evidence from industry investigations shows that failures are rarely due to a single design error. Instead, they typically involve multiple contributing factors, including incomplete information, poor communication and lack of verification.
Understanding Temporary Works Failure in Practice
Temporary works failures can take many forms, including collapse of formwork, failure of excavation support, instability of propping systems or movement of scaffolding and access systems.
These failures often occur at key stages such as loading, alteration or removal, where systems are subjected to changing forces or conditions.
In many cases, the design itself is technically correct, but the system fails because it is not implemented, checked or maintained in accordance with the design intent.
Design-Related Failures
Design is a critical part of temporary works, but failures are often linked to incorrect assumptions rather than calculation errors.
Where design briefs are incomplete or unclear, designers may not fully understand loading conditions, sequencing or site constraints. This can lead to designs that are unsuitable for actual site conditions.
The importance of design verification is addressed in Temporary Works Design Check Categories Explained (BS 5975): Category 0, 1, 2 and 3, which outlines how designs must be checked according to their complexity and risk level. Without appropriate design checks, errors or omissions may not be identified before construction.
Coordination Failures
A common cause of temporary works incidents is breakdown in coordination between different parties.
Temporary works involve designers, coordinators, supervisors and site operatives. If communication between these roles is weak, critical information may not be shared, leading to unsafe conditions.
As explained in Temporary Works Coordinator (TWC) Duties Explained: Roles, Responsibilities and BS 5975 Compliance, the TWC plays a central role in managing the temporary works process, ensuring that designs are approved, risks are identified and systems are controlled. Where this coordination function is weak or unclear, gaps in control can develop.
Site Implementation Failures
Even where design and coordination are correct, failures can occur during installation and use.
Temporary works may be incorrectly installed, modified without approval, or used outside their design limits. In some cases, materials may be unsuitable or damaged, or connections may not be constructed as specified.
The role of site supervision is critical in preventing these issues. As outlined in Temporary Works Supervisor (TWS) Duties Explained: Site Responsibilities and BS 5975 Compliance, the TWS is responsible for ensuring that temporary works are implemented in accordance with approved designs and that any issues are identified and addressed.
Risk Assessment Failures
Temporary works operate in environments where conditions can change rapidly. Without proper risk assessment, hazards may not be identified or controlled.
For example, changes in ground conditions, weather or loading may affect the performance of temporary works. If these risks are not assessed and managed, the likelihood of failure increases.
Temporary Works Risk Assessment (BS 5975): How to Identify and Control Risks explains how hazards must be identified and controlled throughout the temporary works lifecycle. Where risk assessments are incomplete or not updated, critical risks may be overlooked.
Permit and Control Failures
Many temporary works failures occur when systems are loaded or used without proper verification.
Permit systems are designed to prevent this by ensuring that temporary works are not put into service until they have been designed, checked, installed and inspected.
As explained in Temporary Works Permits Explained (BS 5975): Permit to Load, Proceed and Dismantle, permits act as formal control points within the process. Where permits are bypassed, issued without inspection or ignored, temporary works may be used in an unsafe condition.
Inspection Failures
Inspection is a critical control stage, but failures often occur where inspections are inadequate or not carried out.
Temporary works may be subject to damage, movement or changes in loading conditions during use. Without regular inspection, these issues may go unnoticed.
Temporary Works Inspections (BS 5975): When, Who and What Must Be Checked highlights the importance of inspecting temporary works before use, during operation and after any changes. Without effective inspection, there is no assurance that temporary works remain safe.
Common Patterns in Temporary Works Failures
Across different types of projects, several common patterns can be identified:
These factors often combine, creating a situation where risks are not identified or controlled.
What This Means on Site
In practical terms, preventing temporary works failures requires a structured approach that integrates all elements of the BS 5975 system.
This includes:
Temporary works should never be treated as secondary or informal. They must be managed with the same level of control as permanent works.
Evidence-Based Summary
Temporary works failures are not typically caused by a single design error but by a combination of breakdowns across the control system, including design, coordination, risk assessment, inspection and permit management. Evidence shows that incidents often occur where temporary works are used without proper verification, where design assumptions do not match site conditions, or where communication between roles is weak.
In practical terms, this means that safe temporary works delivery depends on the integrity of the entire BS 5975 system, with each control point functioning effectively to ensure that temporary works are properly designed, implemented and managed throughout the construction process.
This article explains why temporary works failures occur on UK construction sites, the most common causes identified in practice, and what BS 5975 requires to prevent incidents.
Why Temporary Works Fail on Site
While temporary works are designed to support construction safely, they often operate under conditions that are more complex and less predictable than permanent works.
Temporary works must support partially completed structures, manage changing load paths and adapt to evolving site conditions. These dynamic conditions increase the risk of failure, particularly where control systems are weak.
Evidence from industry investigations shows that failures are rarely due to a single design error. Instead, they typically involve multiple contributing factors, including incomplete information, poor communication and lack of verification.
Understanding Temporary Works Failure in Practice
Temporary works failures can take many forms, including collapse of formwork, failure of excavation support, instability of propping systems or movement of scaffolding and access systems.
These failures often occur at key stages such as loading, alteration or removal, where systems are subjected to changing forces or conditions.
In many cases, the design itself is technically correct, but the system fails because it is not implemented, checked or maintained in accordance with the design intent.
Design-Related Failures
Design is a critical part of temporary works, but failures are often linked to incorrect assumptions rather than calculation errors.
Where design briefs are incomplete or unclear, designers may not fully understand loading conditions, sequencing or site constraints. This can lead to designs that are unsuitable for actual site conditions.
The importance of design verification is addressed in Temporary Works Design Check Categories Explained (BS 5975): Category 0, 1, 2 and 3, which outlines how designs must be checked according to their complexity and risk level. Without appropriate design checks, errors or omissions may not be identified before construction.
Coordination Failures
A common cause of temporary works incidents is breakdown in coordination between different parties.
Temporary works involve designers, coordinators, supervisors and site operatives. If communication between these roles is weak, critical information may not be shared, leading to unsafe conditions.
As explained in Temporary Works Coordinator (TWC) Duties Explained: Roles, Responsibilities and BS 5975 Compliance, the TWC plays a central role in managing the temporary works process, ensuring that designs are approved, risks are identified and systems are controlled. Where this coordination function is weak or unclear, gaps in control can develop.
Site Implementation Failures
Even where design and coordination are correct, failures can occur during installation and use.
Temporary works may be incorrectly installed, modified without approval, or used outside their design limits. In some cases, materials may be unsuitable or damaged, or connections may not be constructed as specified.
The role of site supervision is critical in preventing these issues. As outlined in Temporary Works Supervisor (TWS) Duties Explained: Site Responsibilities and BS 5975 Compliance, the TWS is responsible for ensuring that temporary works are implemented in accordance with approved designs and that any issues are identified and addressed.
Risk Assessment Failures
Temporary works operate in environments where conditions can change rapidly. Without proper risk assessment, hazards may not be identified or controlled.
For example, changes in ground conditions, weather or loading may affect the performance of temporary works. If these risks are not assessed and managed, the likelihood of failure increases.
Temporary Works Risk Assessment (BS 5975): How to Identify and Control Risks explains how hazards must be identified and controlled throughout the temporary works lifecycle. Where risk assessments are incomplete or not updated, critical risks may be overlooked.
Permit and Control Failures
Many temporary works failures occur when systems are loaded or used without proper verification.
Permit systems are designed to prevent this by ensuring that temporary works are not put into service until they have been designed, checked, installed and inspected.
As explained in Temporary Works Permits Explained (BS 5975): Permit to Load, Proceed and Dismantle, permits act as formal control points within the process. Where permits are bypassed, issued without inspection or ignored, temporary works may be used in an unsafe condition.
Inspection Failures
Inspection is a critical control stage, but failures often occur where inspections are inadequate or not carried out.
Temporary works may be subject to damage, movement or changes in loading conditions during use. Without regular inspection, these issues may go unnoticed.
Temporary Works Inspections (BS 5975): When, Who and What Must Be Checked highlights the importance of inspecting temporary works before use, during operation and after any changes. Without effective inspection, there is no assurance that temporary works remain safe.
Common Patterns in Temporary Works Failures
Across different types of projects, several common patterns can be identified:
- Temporary works used before completion or approval
- Design assumptions not matching site conditions
- Unauthorised modifications on site
- Inadequate communication between teams
- Failure to carry out inspections
- Weak or unclear coordination
- Inadequate competence or training
These factors often combine, creating a situation where risks are not identified or controlled.
What This Means on Site
In practical terms, preventing temporary works failures requires a structured approach that integrates all elements of the BS 5975 system.
This includes:
- Preparing clear and accurate design briefs
- Carrying out appropriate design checks
- Maintaining a live Temporary Works Register
- Implementing formal permit systems
- Carrying out regular inspections
- Ensuring effective coordination and communication
- Appointing competent personnel
Temporary works should never be treated as secondary or informal. They must be managed with the same level of control as permanent works.
Evidence-Based Summary
Temporary works failures are not typically caused by a single design error but by a combination of breakdowns across the control system, including design, coordination, risk assessment, inspection and permit management. Evidence shows that incidents often occur where temporary works are used without proper verification, where design assumptions do not match site conditions, or where communication between roles is weak.
In practical terms, this means that safe temporary works delivery depends on the integrity of the entire BS 5975 system, with each control point functioning effectively to ensure that temporary works are properly designed, implemented and managed throughout the construction process.
For a structured overview of how temporary works should be managed in UK
construction, including roles, design checks and compliance
requirements, see this Temporary Works UK: BS 5975 Compliance Guidance.
|
Expert Verification & Authorship: Mihai Chelmus
Founder, London Construction Magazine | Construction Testing & Investigation Specialist |
