Managing heat on site: Why extreme weather is a duty holder’s responsibility

2026-08-13T11:12:17Z

Veriforce CHAS: Created page with "As UK summer temperatures rise, extreme heat can no longer be treated as an unexpected anomaly. On a construction site, a heatwave is not simply a weather event – it has an imp..."

As UK summer temperatures rise, extreme heat can no longer be treated as an unexpected anomaly. On a construction site, a heatwave is not simply a weather event – it has an impact on duty holder responsibilities.

Under the Construction (Design and Management) Regulations 2015 (CDM 2015), principal contractors must plan, manage, monitor and coordinate health and safety across the construction phase. That responsibility does not pause in peak summer during a heatwave. Instead, managing heat stress, dehydration and sun exposure becomes a critical component of your health & safety risk management on site.

Expectations are also evolving. Clients and principal contractors are placing greater emphasis on whether suppliers can demonstrate practical, site-specific health and safety capability - including how they identify, plan for and control foreseeable environmental risks such as extreme heat.

=== Heat as a foreseeable seasonal hazard ===

During a heatwave, a common pitfall on site is relying on reactive measures, such as arranging temporary shade only once temperatures have already spiked. However, under CDM 2015, heat must be treated as a foreseeable seasonal hazard within the construction phase plan (CPP) long before extreme temperatures peak.

This is particularly crucial on multi-contractor sites. During the hot summer months, workers from multiple trades often operate in direct sunlight while doing heavy physical labour. When high ambient temperatures are combined with physically demanding work and PPE that restricts heat loss or ventilation, the risk of heat exhaustion and heatstroke can escalate rapidly.

If heat risks are not considered within the CPP, principal contractors are likely to fail in establishing clear, site-wide protocols for how it should be managed once it becomes a live risk. A compliant CPP should set out triggers for action, establish clear lines of communication between subcontractors and detail how work will be adapted as environmental conditions change.

=== What should the construction phase plan say about heat risk? ===

When heat is identified as a foreseeable site risk, the construction phase plan should set out how it will be managed in practice. This includes how duty holders will provide suitable welfare, create safe rest areas, adapt work patterns, review PPE and check that controls remain effective as conditions change.

Hydration and welfare provision: Cool drinking water must be readily accessible across all areas of the site, not just restricted to a central main office or distant canteen. On large sites, temporary hydration points should be moved closer to active work zones.

Shaded and well-ventilated rest zones: Nobody wants to spend their break in a hot, airless temporary cabin. Without good airflow or cooling, they can quickly get very uncomfortable. Every site should have shaded spots outdoors or proper break rooms where people can cool off.

Work patterns and cooling breaks: Sometimes you have to change up the routine to keep people safe. That could mean moving the toughest, most physically demanding jobs to the cooler early morning, making sure everyone takes regular breaks in the shade and swapping out teams so no one is exposed to the sun for too long.

PPE adaptation and assessment: PPE should already be selected through the task-specific risk assessment, taking account of the physical demands of the work, the protection required and the conditions workers will face. During periods of extreme heat, duty holders should review whether existing PPE arrangements remain suitable and consider lighter, breathable alternatives where these provide the required protection and comply with site safety rules.

=== Documentation and evidence matter ===

Where heat controls are included in the construction phase plan, duty holders should also keep evidence of how those controls were communicated, implemented and reviewed. If a heat-related incident meets the threshold for reporting, or if the Health and Safety Executive visits following a concern or complaint, they may need to show that heat risks were considered and proportionate action was taken. This means keeping evidence of risk assessments, briefings and training, and, where appropriate, notes or logs showing how conditions were monitored and what actions were taken.

This evidence should be created as part of normal planning and site management, not after the event. Missing documentation cannot be recreated retrospectively and retrospective records are unlikely to provide credible evidence of effective risk management.

Principal contractors should be able to demonstrate that they identified heat risks, implemented practical control measures, communicated clearly with workers through daily briefings or toolbox talks, and monitored site conditions as they changed.

=== How clients and principal contractors can recognise effective heat risk management ===

Beyond having heat controls written into the construction phase plan, clients and principal contractors should be able to see whether those controls are being applied in practice. Effective heat risk management is usually reflected in clear planning, visible welfare provision, regular communication with workers and evidence that site conditions are being monitored as they change. This includes:

* Clear risk management processes: Evidence that heat has been identified as a foreseeable risk, assessed in relation to the work being carried out and addressed through practical site controls.

* Visible welfare and rest arrangements: Ready access to drinking water, shaded or well-ventilated rest areas, and arrangements that work across the whole site, including subcontractor work areas.

* Ongoing communication and review: Regular briefings, toolbox talks or site updates so workers understand the controls in place, alongside checks to confirm those controls remain suitable as temperatures and working conditions change.

As heat becomes a more frequent and foreseeable hazard on UK construction sites, principal contractors will increasingly be judged on how well they anticipate and manage it – not just by regulators, but by clients and supply chain partners too.

Veriforce CHAS supports organisations in demonstrating that their wider health and safety management systems are robust, consistent and subject to regular review. This can help give clients and supply chain partners confidence that foreseeable site risks, including environmental risks such as extreme heat, are being considered as part of effective risk management.

Ultimately, effective heat risk management should begin before temperatures rise and continue throughout the work. By combining clear site-wide controls with communication, monitoring and ongoing oversight, duty holders can help ensure that everyone on site understands the risks and knows how to work safely as conditions change.

=== For more information, visit: [https://www.chas.co.uk/ www.chas.co.uk]. ===

=== About Veriforce CHAS ===

Veriforce CHAS is the UK's leading provider of compliance and risk management solutions helping contractors (suppliers) and clients (buyers) demonstrate compliance with our award-winning supply chain and risk management solutions.

[[Category:Health_and_safety_/_CDM]] [[Category:Other_legislation]] [[Category:Construction_management]] [[Category:Building_safety]] [[Category:People]]

Designing Buildings - User contributions [en]

Managing heat on site: Why extreme weather is a duty holder’s responsibility