Temporary Works Design
Temporary works are an essential part of almost every construction project. While they are not part of the finished structure, they often carry significant loads and are critical to maintaining safety and structural stability during construction.
Many structural failures occur during construction rather than after completion. For this reason, temporary works design requires the same level of engineering rigour as permanent structures.
What Are Temporary Works?
Temporary works are structures or systems used to support loads during construction, alteration, or demolition. Common examples include:
Propping and shoring systems
Temporary beams and supports
Excavation support and shoring
Formwork and falsework
Temporary bracing and stability systems
Although these elements are removed once construction is complete, they often carry loads equal to or greater than the permanent structure at critical stages.
Why Temporary Works Design Is Critical
Temporary works frequently experience:
Incomplete load paths
Unbalanced or eccentric loading
Construction-stage loads not present in the final design
At early stages of construction, permanent structural elements may not yet be able to resist design loads. Temporary systems must therefore bridge this gap safely. Failures in temporary works can result in:
Sudden structural collapse
Serious injury or fatality
Project delays and cost overruns
Legal and insurance consequences
For these reasons, temporary works should always be engineered, documented, and controlled.
Key Engineering Considerations in Temporary Works Design
1. Construction Sequencing
Temporary works design is closely linked to the construction sequence. As such, engineers will typically assess:
Which elements are installed first
When loads are applied or removed
How stability is maintained at each stage
A structure that is stable in its final form may be unstable during intermediate stages without temporary support.
2. Load Assessment During Construction
Temporary works are designed for:
Self-weight of partially completed structures
Construction loads (materials, equipment, workers)
Accidental and impact loads
Wind loads acting on incomplete structures
These loads can differ significantly from permanent design loads and must be assessed independently.
3. Stability and Load Paths
Temporary structures must provide clear and continuous load paths.
Vertical load transfer to suitable foundations or bearing points
Lateral stability against wind and accidental loads
Restraint against buckling and overturning
Loss of stability is one of the most common causes of temporary works failure.
4. Support Conditions and Bearing Capacity
Temporary supports are often placed on existing slabs, soil, pavements and partially completed structures. As such, engineers check that:
Bearing pressures are acceptable
Local punching or settlement will not occur
Existing elements are not overstressed
Assuming existing structures can support temporary loads without verification is a common and dangerous mistake.
5. Temporary Works for Alterations and Demolition
Temporary works are especially critical when:
Removing load bearing walls
Altering structural framing
Creating large openings
Demolishing structural elements
In these cases, temporary systems must safely support loads until permanent works are installed and capable of resisting design actions.
Common Temporary Works Failures
Based on site investigations and industry experience, frequent causes of failure include:
Removal of props before permanent works are complete
Unapproved changes to temporary systems on site
Inadequate load assessment
Insufficient bracing or restraint
Lack of engineering documentation
Many failures occur because temporary works are treated as site matters rather than engineered systems.
The Engineer’s Role in Temporary Works
Structural engineers provide:
Temporary works design calculations
Drawings and layout plans
Construction sequencing notes
Load limits and restrictions
Certification where required
When Is Temporary Works Design Required?
Temporary works design is typically required when:
Modifying load bearing elements
Supporting large spans during construction
Excavating near existing structures
Constructing multi-storey or staged structures
Required by building surveyors, councils, or insurers
Even for short-duration works, engineering design significantly reduces risk.
Final Thoughts
Temporary works are often the most vulnerable phase of a project’s structural life.
Although they are removed once construction is complete, they carry real loads and real risks. Treating temporary works with the same engineering discipline as permanent structures is essential to maintaining safety, preventing failures, and ensuring successful project delivery.
Engaging a structural engineer for temporary works design protects workers, projects, and long-term outcomes.
