Are construction contracts ready for a hotter future?

The UK construction industry has traditionally treated weather-related risk as a winter issue. Programmes, risk registers and contracts often account for storms, flooding and freezing temperatures. Extreme heat, by contrast, rarely receives the same level of attention. That position is becoming increasingly difficult to sustain given recent events.

Heatwaves are occurring more frequently and with greater intensity. Alongside broader climate-related pressures and requirements, they are influencing how projects are procured, designed, delivered and operated. Yet many of the industry’s assumptions, from productivity allowances and programme contingencies to applicable standards and contractual risk allocation, typically remain rooted in historical approaches and weather patterns. The question for the industry is no longer whether temperatures are rising. Instead, it is whether the UK is building for a climate that no longer exists.

The immediate effects of high temperatures are most visible on site. Heat can reduce productivity, prompt revised working patterns and increase requirements for rest or hydration breaks. Heat can complicate temperature-sensitive activities, including concrete works, asphalt laying and the application of adhesives. Fire risk, plant performance, storage requirements and logistics may also be impacted.

Conditions once deemed extraordinary may become part of the environment in which a competent contractor is expected to plan and price its work, creating a potential risk gap

A few unusually hot days can have consequences lasting far longer than the weather itself. Activities are re-sequenced, resources become unavailable and delays impact supply chains. For an industry operating on carefully considered budgets and finely balanced programmes, heat is not simply a health and safety or environmental concern. It is a wider cost and delivery risk.

So, who carries the risk? Standard industry contract forms, such as JCT, NEC and FIDIC, contain mechanisms through which weather events may entitle a contractor to additional time, money or both. However, parties should not assume that a heatwave automatically qualifies: it is a high threshold. Whether relief is available depends on the agreed wording and applicable requirements, the supporting project records and sometimes historical weather data.

More fundamentally, increasing temperatures may alter the distinction between “exceptional” and “foreseeable” adverse weather. Conditions once deemed extraordinary may become part of the environment in which a competent contractor is expected to plan and price its work, creating a potential risk gap. Employers may believe contractors have allowed for hotter conditions, while contractors may assume contractual relief if temperatures exceed historic norms. If neither the contract nor the programme addresses the issue clearly, that gap may develop into a dispute.

Clearly, the context is important, and the answer is not necessarily another heavily amended clause or policy. Better risk management starts earlier. Tender documentation should identify assumptions upon which the project is based. Programmes should identify heat-sensitive activities and realistic mitigation measures. 

Contracts should then clearly allocate responsibility for foreseeable weather conditions and define how exceptional events will be assessed and managed. We may – indeed, perhaps should – start to see bespoke weather-related provisions in contracts. 

The challenge does not end at practical completion. Developers, investors and asset owners are procuring buildings and infrastructure expected to remain operational for decades. The relevant question is not simply whether an asset complies with today’s requirements, but whether it will remain safe, usable and commercially attractive throughout its operational life.

Overheating can affect occupant comfort, energy demand and operational performance. Heat-related risks may also manifest through other property damage or health and safety incidents. Prolonged dry conditions can contribute to ground movement, with implications for foundations and buried infrastructure in susceptible locations. 

Clients will seek to make informed decisions where greater resilience options require additional capital expenditure. Suppliers could therefore face closer scrutiny or challenge on the climate scenarios used, the advice given and the extent to which future performance was considered. Retrofitted measures to address thermal performance or other issues may prove costly and carbon intensive.

Heat is no longer simply a health and safety issue or an environmental concern. The industry’s response cannot be confined to temporary site measures and working practices during a heatwave. 

Climate considerations will continue to influence procurement strategy, design, contractual drafting and project governance. Future disputes may concern not only what the contract said about the weather, but whether design and project teams planned appropriately for conditions they could no longer credibly ignore in the circumstances. 

I feel there are three core questions:

1. What climate conditions is the asset likely to encounter throughout its lifecycle?

2. Where do those conditions create delivery, performance or commercial risk?

3. Which party is best placed to manage that risk, and does the contract allocate it accordingly?

Today’s exception is becoming tomorrow’s baseline. 

Sheena Sood is a senior partner at Beale & Co