The UK construction sector must take urgent action to address the growing threat of extreme heat on site, according to new research from the University of Reading.
As heatwaves become more frequent and intense, researchers warn that high temperatures are no longer an occasional challenge but an emerging occupational health issue that could have significant implications for project delivery, workforce wellbeing and site safety.
The study, which gathered responses from 307 site workers and managers across medium and large construction companies, found that many sites remain poorly prepared for extreme heat events.
Heat already affecting workers and projects
The findings reveal that 67% of site workers are concerned about the impact of heat on their health, while 44% have experienced a heat-related illness such as heat exhaustion, dehydration or heat stroke. Half of respondents said they know a colleague who has also been affected.
The impact extends beyond immediate health risks. Some 87% of workers reported feeling more fatigued in hot conditions, 61% said they struggled to concentrate and 58% said they became more irritable.
Researchers also found that discomfort and difficulties carrying out tasks begin at relatively modest temperatures. More than four in ten workers reported experiencing problems when temperatures reach between 20°C and 25°C – conditions that are becoming increasingly common during UK summers.
Training and protection gaps
The report highlights several shortcomings in how the industry is responding to heat-related risks.
More than half (57%) of workers said they had received no compulsory training on working safely in hot conditions. Confidence levels were also low, with only 37% of workers and 57% of managers saying they would know how to respond correctly if someone showed signs of heat stroke.
Protective measures were often viewed differently by workers and managers. While 67% of managers believed shaded rest areas were effective, only 47% of workers agreed, suggesting that site provisions may not always be reaching those who need them.
The suitability of PPE and workwear was another concern. Just 18% of site workers felt their summer protective clothing was appropriate for hot weather, while only 27% had access to effective personal cooling equipment such as cooling vests or cooling packs.
Cost and programme implications
Extreme heat is also creating challenges for project delivery.
Nearly half (48%) of managers reported that high temperatures had caused programme delays, while 55% said heat-related disruption had resulted in unplanned costs.
The research found that many workers and managers rely on personal experience rather than formal guidance when responding to heat risks, leading to inconsistent practices across sites.
Call for clearer guidance
Dr Alba Fuertes, Associate Professor at the University of Reading’s School of the Built Environment, said:
“Heat is already a danger for workers on construction sites and other outdoor workplaces on warm days, not a problem for some distant summer. Workers are experiencing heat-related illnesses, getting more tired, and losing focus, yet there is no legally defined maximum workplace temperature to protect workers from excessive heat in the UK.”
“The UK construction industry can no longer ignore heat. We need clearer guidance, better training and practical measures that protect workers before heat becomes a major cause of accidents, illness and delays.”
For self-builders and SME contractors, the findings highlight the need to consider heat resilience as part of site planning, workforce management and health and safety procedures. With hotter summers predicted, ensuring access to shade, hydration, cooling measures and heat-awareness training is likely to become an increasingly important part of delivering projects safely and efficiently.
