The JCT Design and Build Contract contains a series of optional “Supplemental Provisions” within Schedule 2. These provisions are often overlooked during contract negotiations, but they can significantly affect how a project is managed commercially and operationally.
Here’s a practical breakdown of what each one means.
Supplemental Provision 1 – Named Subcontractors
This provision allows the Employer to require the Contractor to use specific subcontractors for parts of the works.
This is often used for specialist packages such as M&E, roofing, façades, or lifts where the Employer has preferred suppliers.
Whilst this gives the Employer greater control, it can create risk for the Contractor, who may become responsible for delays, defects, or coordination issues caused by a subcontractor they did not freely choose.
For QSs, it’s important to review:
- Programme implications
- Design responsibility
- Warranty obligations
- Liability allocation
- Pricing assumptions
Supplemental Provision 2 – Valuation of Changes: Contractor’s Estimates
This provision encourages the Contractor to provide estimates for changes before the work is carried out.
Instead of valuing variations retrospectively months later, the parties attempt to agree the likely cost impact upfront.
This can improve:
- Cost certainty
- Forecasting
- Cashflow visibility
- Final account agreement
A typical estimate may include:
- Labour
- Plant
- Materials
- Design fees
- Preliminaries
- Programme impacts
The key for QSs is ensuring assumptions and exclusions are clearly stated to avoid disputes later.
Supplemental Provision 3 – Loss and Expense: Contractor’s Estimates
This provision works similarly to Provision 2 but relates specifically to loss and expense claims.
Rather than waiting until the end of the project to assess disruption costs, the Contractor is encouraged to provide estimated impacts as events arise.
Examples may include:
- Extended preliminaries
- Prolongation costs
- Additional supervision
- Disruption
- Inefficient working
This provision promotes proactive commercial management and gives the Employer better visibility of potential liabilities.
However, an estimate does not automatically create entitlement. The Contractor must still demonstrate that a Relevant Matter exists and that the costs are attributable to that event.
Supplemental Provision 4 – Acceleration Quotation
This provision creates a formal process for acceleration.
In simple terms, it allows the Employer to ask:
“What would it cost to finish earlier?”
The Contractor can then provide an acceleration quotation covering:
- Overtime
- Weekend working
- Additional labour
- Resequencing works
- Additional plant
Acceleration is often discussed informally on projects, which can lead to disputes later. This provision introduces structure by requiring costs and programme impacts to be reviewed before acceleration proceeds.
A good acceleration quotation should clearly identify assumptions, risks, and programme implications.
Supplemental Provision 5 – Health and Safety
This provision promotes collaborative health and safety management throughout the project.
Typical measures include:
- Site safety meetings
- Toolbox talks
- Audits
- Site inspections
- Near miss reporting
Performance is often monitored using:
- Accident rates
- Audit scores
- Training records
- Safety observations
This provision reinforces that health and safety is a shared project responsibility rather than simply a compliance exercise.
Supplemental Provision 6 – Cost Savings and Value Improvement
This is effectively a value engineering provision.
It encourages the Contractor to suggest ideas that:
- Reduce costs
- Improve efficiency
- Improve buildability
- Improve sustainability
Examples may include alternative materials, revised construction methods, or programme efficiencies.
However, QSs and Employers should carefully assess whether proposals negatively impact:
- Quality
- Warranties
- Compliance
- Lifecycle costs
- Long-term maintenance
Cheaper does not always mean better value.
Supplemental Provision 7 – Performance Indicators and Monitoring
This provision introduces formal performance monitoring through KPIs.
Typical KPIs may include:
- Programme performance
- Defects levels
- Health & safety performance
- Quality scores
- Client satisfaction
Performance is usually recorded through dashboards, reports, audits, and progress meetings.
Increasingly, Employers and frameworks use KPI performance to influence future work opportunities and contractor selection.
To Conclude
The Supplemental Provisions within the JCT Design and Build Contract are often treated as optional extras, but they can significantly affect project behaviour, commercial management, and risk allocation.
For Quantity Surveyors, understanding these provisions is essential for managing:
- Variations
- Loss and expense
- Risk
- Value engineering
- Contractor performance
They may be short clauses, but their practical impact on a live project can be substantial.
