Scorching success or summertime struggle?

As Britain faces increasingly hotter summers due to climate change, the construction industry finds itself grappling with a double-edged sword. Warm weather is often welcomed on-site, providing favourable working conditions and fewer delays caused by rain or frost. However, as temperatures rise beyond comfort levels, they bring with them a new set of challenges—from worker health risks to issues with materials and scheduling. In this article buildingspecifier.com editor Joe Bradbury explores the nuanced impact of warm summer weather on the construction industry, highlighting both the benefits and the drawbacks that contractors, developers and specifiers must consider.

The positive impacts of warm weather on construction

Improved working conditions (up to a point)

Warm, dry days offer a welcome respite from the inclement weather typically associated with British winters. When managed carefully, milder summer temperatures can improve morale and productivity. Ground conditions are more stable, reducing the complications involved in excavation, and outdoor tasks such as roofing, cladding and concrete pouring can proceed with fewer interruptions.

Additionally, longer daylight hours allow for extended shifts, increasing flexibility and potentially speeding up project timelines. Workers often feel more energised and positive during sunnier months, which can have a knock-on effect on efficiency and quality of work.

Fewer weather-related delays

One of the biggest causes of project delays in construction is poor weather—particularly rain, wind and freezing temperatures. Summer months, particularly in the south of the UK, tend to offer more predictable weather windows. This allows for better planning and scheduling, reducing costly downtime and helping to keep projects on track.

Dry weather also reduces the risk of flooding, which can cause serious disruptions to groundwork, utility installation and concrete setting. With fewer delays, contractors are better placed to meet deadlines and avoid penalties.

Enhanced site access and logistics

In winter months, muddy, frozen or waterlogged access routes can limit the ability of heavy vehicles to reach sites safely. In contrast, warm summer weather improves ground conditions and visibility, making deliveries and equipment transport more efficient and less hazardous. It also facilitates the movement of materials around the site, contributing to smoother operations.

Better conditions for concrete and paintwork (when controlled)

Concrete pouring and curing are temperature-sensitive processes. Warm, dry weather—if not excessively hot—creates optimal conditions for concrete to cure at a consistent rate, resulting in stronger, more reliable structures. Similarly, paint, render, and other finishes adhere and dry more effectively in dry, warm air than in damp, cold conditions.

For offsite manufacturers, controlled ambient temperatures can reduce energy costs associated with heating and dehumidifying production environments.

The negative effects of excessive heat

While moderate warmth can be a boon, extreme summer heat can quickly turn into a liability. The UK is experiencing an increasing number of heatwaves—events that pose significant challenges for construction sites in terms of health, safety, and quality control.

Worker health and safety

Perhaps the most immediate concern during hot weather is the health and safety of workers. Construction is already a physically demanding occupation, and working in high temperatures increases the risk of heat stress, dehydration, heat exhaustion, and even heat stroke.

Symptoms such as dizziness, fatigue, and confusion can impair judgement and reaction times, increasing the risk of accidents and injuries. The Health and Safety Executive (HSE) does not specify a maximum working temperature, but it does require employers to take action when workplace temperatures become uncomfortable or dangerous.

To mitigate these risks, employers must ensure access to shade, provide ample drinking water, schedule breaks, and where possible, adjust working hours to cooler parts of the day. However, such measures can reduce productivity and impact project timelines.

Material degradation and handling challenges

Certain construction materials do not fare well under extreme heat. Asphalt, for example, can become overly soft, affecting its integrity and making it more difficult to work with. Similarly, high temperatures can cause timber to expand or warp and increase the evaporation rate of water in concrete, leading to potential cracking or compromised strength if not managed properly.

Sealants, adhesives and paints can also become unstable or cure too quickly, compromising their performance. For this reason, quality control becomes more complex and may require additional testing or reworking.

Increased fire risk

Dry, hot conditions can increase the risk of fire, particularly in areas where combustible materials are stored or used. Sparks from equipment, electrical faults or carelessly discarded cigarette ends can ignite fires more easily when vegetation and materials are dry. This presents not only a health and safety hazard but also the potential for significant delays and insurance implications.

Disruption to workforce and scheduling

While longer daylight hours are an advantage, extreme heat may necessitate changes to working hours—such as earlier start times or split shifts—to avoid the hottest parts of the day. This can disrupt routines, require renegotiation of contracts or overtime payments, and may not be feasible for all trades or projects.

There is also the issue of workforce availability. If heatwaves coincide with peak holiday season, staffing levels may already be stretched. Combined with heat-related absences, this can lead to reduced site productivity and missed milestones.

A changing climate: long-term considerations

The frequency and intensity of heatwaves in the UK are increasing due to climate change. The summer of 2022 saw temperatures exceed 40°C for the first time on record, and similar extremes are predicted to become more common. The construction industry must prepare not just for seasonal warm spells but for a long-term shift in working conditions.

This requires a rethinking of how sites are planned and managed, with increased emphasis on heat mitigation strategies. These could include:

• Incorporating shade structures, canopies or cooling stations on site
• Using lighter-coloured or reflective materials for temporary surfaces to reduce heat absorption
• Designing building materials and systems that are more tolerant of temperature fluctuations
• Integrating sustainable urban drainage systems (SuDS) to combat dry ground and sudden summer downpours
• Exploring modular and offsite methods that reduce the time required for outdoor labour

Balancing the scales

The warm summer weather undeniably offers some important advantages to the construction industry—chief among them being improved site conditions, fewer delays, and enhanced worker morale. However, the risks associated with excessive heat are equally significant and must not be underestimated.

As the UK adapts to a changing climate, the construction sector will need to evolve its practices, technologies and site management approaches to continue operating safely, efficiently and sustainably through the height of summer.

Ultimately, whether warm weather becomes a friend or foe depends on how prepared the industry is to respond. By taking proactive steps now, construction professionals can turn up the heat on progress—without getting burned.