Heatwaves and contract terms

For the past week or so, the UK has been gripped by a heatwave that has sent temperatures soaring to record levels, bringing an unprecedented red weather warning from the Met Office. Such weather causes adverse heath effects, travel problems, and more. Year on year we see periods of extreme heat across the UK – the mercury creeps higher, and temperatures stay higher for longer.

What does this mean for construction contracts?

During construction, “exceptionally adverse” weather may entitle contractors to additional time and/or money. In the JCT standard forms, exceptionally adverse weather counts as a “relevant event”, giving rise to an extension of time (EOT) entitlement. Similarly, the FIDIC Red Book entitles the contractor to an EOT if works will be delayed by exceptionally adverse climatic conditions. Both JCT and FIDIC are silent as to what constitutes exceptionally adverse weather or climate.

Under the NEC ECC, extreme weather may be a compensation event, but only if the measurement in question is shown to occur on average less frequently than once in 10 years. With extreme weather events becoming more commonplace, this may prove a difficult hurdle to overcome. It is also interesting that in the NEC, the pre-printed weather measurements in the contract data which could potentially give rise to a compensation event only include rainfall, freezing temperatures and lying snow – no mention of high temperatures.

>>Also read: Flood defences: a challenge and opportunity for civil engineers

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At design stage, the impact – or potential impact – of high temperatures may be more fundamental, as buildings and infrastructure are required to withstand increasingly significant temperature extremes.

For example, in direct sunshine railway tracks can be as much as 20˚C hotter than air temperature. Because the rails are made of steel, they expand as they get hotter, and become susceptible to buckling. Network Rail reports that most of its network can operate until track temperatures reach 46˚C, which is roughly equivalent to an air temperature of 30˚C. Problems can arise, however, when air temperatures creep above 30˚C.

On the roads, several local authorites, including Hampshire and Lincolnshire county councils, said last week that they planned to send out gritters to spread sand in an effort to stop roads melting. If you thought melting tarmac in the UK was bad, spare a thought for motorists in China, where state TV recently showed a section of heat damaged road in Jiangxi province which had arched up by 14cm.

Measures are available to mitigate the effects of extreme temperatures: rails can be painted white to absorb less heat, weaknesses can be repaired, roads can be gritted, and Hammersmith Bridge can be wrapped in giant pieces of foil and propped up by a £420,000 temperature control system.

The question is: who pays?

Who pays?

Where contracts are subject to fitness-for-purpose obligations, contractors should carefully analyse employers’ requirements to ensure any stipulations regarding ability to withstand weather extremes can be met. Similarly, those procuring works need to consider the long-term resilience of assets. This will involve a cost-benefit analysis of whether it is preferable to adopt more heavily engineered (and expensive) solutions now, which are capable of withstanding extreme climatic conditions in the future – whether that be heat, cold, flooding or storms.

Ability to withstand climatic extremes may also be a concern where, although the contract does not require fitness for purpose, it does stipulate a design life

Ability to withstand climatic extremes may also be a concern where, although the contract does not require fitness for purpose, it does stipulate a design life. This issue arose in the 2020 Technology and Construction Court case Blackpool Borough Council vs VolkerFitzpatrick Ltd. In that case, His Honour Judge Stephen Davies explained design life with reference to two British Standards.

BS ISO 15686-1:2000: Buildings and constructed assets – service life planning contains a definition of design life as being the service life of the asset intended by the designer. Service life is the period of time after installation, during which a building or its parts meets or exceeds performance requirements. Performance requirements are defined in the standard as a minimum acceptable level of a critical property.

BS EN 1990:2002: Basis of structural design refers to “design working life”, being the assumed period for which a structure or part of it is to be used for its intended purpose “with anticipated maintenance but without major repair being necessary”. Maintenance is defined in the same standard as the set of activities performed during the working life of the structure in order to enable it to fulfil the requirements of reliability.

In Blackpool vs VolkerFitz, therefore, it was found that a structure cannot realistically be intended to be maintenance-free for its design life, whereas it can reasonably be assumed that it ought not to need major repairs. The distinction between maintenance and major repairs is a question of fact and degree. Painting railway tracks white each summer might well be considered maintenance. Repairing gaping holes in Jiangxi roads is probably major repair.

All the above considerations apply equally to other types of weather events, with flood defences, dams and railway embankments being obvious examples of at-risk critical infrastructure.

Katherine Doran is a director in the construction and infrastructure team at DWF