Most construction projects begin with a clear budget and programme. As works progress, however, costs can gradually move away from the original price. This is known as budget drift. Budget drift can be difficult to control, particularly when early warning signs are missed or when cost management is not carried consistently through the project team and wider supply chain.

One major issue is rarely the cause of budget drift. More often, it is the result of a series of smaller changes and decisions that build up over time. Rising material costs, labour shortages, programme delays, design development and supply chain challenges can all contribute. Individually, these may seem manageable, but together they can have a significant impact on the overall cost of a project.

The key to managing budget drift is to identify issues early, understand where they sit in the contractual chain, and make informed decisions before they develop into larger commercial problems.

Setting Projects Up for Success

The risk of cost issues can often be reduced before construction even begins. Choosing the right procurement route is an important starting point. Different procurement methods offer different levels of cost certainty, flexibility and risk allocation. The most suitable approach will depend on the project.

• Lump sum is a traditional procurement model that can provide greater cost certainty from the start of a project, particularly where the design is sufficiently developed before the contract is entered into. It offers clear separation between design and construction responsibility. However, changes made during construction can quickly lead to additional costs if they are not properly instructed, valued and recorded.
• Design and Build (D&B) provides a single point of responsibility, improving speed and cost certainty but potentially limiting design control.
• Management contracting offers flexibility and allows packages to be procured as the project develops. However, because the overall cost is not fixed at the start, there can be greater exposure to budget drift if costs are not carefully monitored. Construction management offers similar flexibility, but the trade contractors are contracted directly to the client. Both approaches can support early contractor involvement, but they require strong cost control, clear reporting and careful administration of each package.

Early contractor involvement can provide significant benefits. By engaging contractors during the design phase, projects can benefit from practical construction knowledge and a better understanding of likely costs before works commence on site.

Keeping Track of Costs During Construction

Even well-planned projects require regular monitoring. Budget drift often becomes a problem when issues are identified too late. By the time additional costs are recognised, delays may have increased and options for resolving the issue can be more limited.

• Key Performance Indicators (KPIs) play a crucial role in setting measurable goals for cost, quality, and time by defining clear milestones.
• Regular supplier audits and performance reviews help maintain accountability by checking whether consultants, contractors, sub-contractors and suppliers are complying with their contractual obligations, safety requirements, programme commitments and project reporting standards.
• A risk management strategy is essential for identifying vulnerabilities within the supply chain, including gaps between the main contract, consultant appointments, sub-contracts and supplier terms. Understanding where these risks sit can help you develop contingency plans and ensure they are managed before they affect cost, programme or quality.

Good contract administration should not stop at the main contract. The same discipline needs to flow through consultant appointments, sub-contracts, supply agreements and package orders. If obligations, notices, change procedures and reporting requirements are not properly aligned, issues can be missed or passed up the chain too late. This can leave parties exposed to avoidable cost increases, delay disputes and uncertainty over responsibility.

Regular project reviews, cost reporting and programme monitoring can help identify trends before they become major concerns. Understanding risks within the supply chain and reviewing contractor performance throughout the project can also help maintain control and reduce the likelihood of unexpected costs.

Managing Change Effectively

Change is inevitable on most construction projects. The challenge is ensuring that changes are recognised, assessed and managed properly. Even relatively minor design changes can affect both cost and programme. If decisions are delayed or changes are not properly recorded, additional costs can quickly accumulate.

Understanding how the contract deals with variations, extensions of time and additional costs is therefore essential. This understanding must also extend to the wider supply chain, so that notices, records, quotations, instructions and assessments are dealt with in a consistent way. Accurate records and clear communication between all parties can help ensure that changes are understood and addressed before they begin to affect project performance.

The Importance of Communication

One of the most effective ways to reduce budget drift is also one of the simplest. Open communication between clients, consultants, contractors and suppliers helps identify issues early and allows decisions to be made quickly. Problems rarely improve when left unaddressed. Discussing openly can often prevent relatively small issues from developing into larger commercial challenges.

Seeking Advice Early

Managing budget drift is not about eliminating every risk. Construction projects are complex and unexpected challenges will always arise. The goal is to identify issues early, understand their potential impact and take action before they escalate.

One of the most common mistakes is allowing issues to build up throughout a project and relying on the final account process to resolve them. Variations, delays, loss and expense claims, and changes to the scope of works are often easier to assess and agree when they arise. Left unresolved, they can become more difficult and time-consuming to negotiate, leading to prolonged final account discussions and uncertainty around the project’s true cost.

Seeking professional advice early can also make a significant difference, whether that involves reviewing procurement options before a project begins, monitoring costs during delivery or helping resolve issues as they arise. Early intervention often provides greater flexibility and more options for achieving a positive outcome.

If you would like to discuss cost management, procurement strategies, contract administration or project monitoring, the Overford team would be happy to help.