# Summer heat on site, heat stress, sun protection and your rights
There's no legal "too hot to work" number for site work, but your employer still has to stop you getting cooked or collapsing, heat and sun are health and safety issues, not just comfort.
Quick rule of thumb: no, there's no "32°C and we all go home" rule: but that doesn't mean you have to graft full tilt in blazing sun, no shade, no water and a loft that feels like a boiler room. HSE expect employers to adjust the job, provide water and shade, increase breaks and watch for heat illness when it gets hot.
1. No legal maximum, so what are your rights?
UK law doesn't set a maximum temperature for outdoor work, because conditions and jobs vary too much.
Instead, employers must assess the risk from heat and manage it, under the general duty of care and the Management Regs.
HSE's summer guidance says employers must act in hot weather, especially in physically demanding outdoor jobs like construction, by changing how and when work is done.
So you can't just quote a number and walk off, but you can absolutely expect a proper heat-stress risk assessment and real controls, not just "drink more water, crack on".
2. Heat stress, signs you're in the danger zone
HSE's heat-stress guidance (INDG451 and the temperature pages) say to watch for:
Early heat stress
- Heavy sweating, thirst, tiredness.
- Headache, dizziness, irritability, loss of concentration.
- Cramps, feeling weak or sick.
Heat exhaustion / heat stroke (medical emergency)
- Confusion, slurred speech, staggering.
- Hot, dry skin or sweating that suddenly stops.
- Fast pulse, collapse, possible loss of consciousness.
If you or a mate are into that second list, it's first aid and 999, not "sit in the shade and see how it goes".
3. What employers should be doing in hot weather
HSE's temperature guidance and hot-weather warnings spell out what "reasonable steps" look like on site:
Do a heat-stress risk assessment
Look at temperature, humidity, direct sun, physical workload, PPE, enclosed areas, and whether people are acclimatised. Use HSE's workplace temperature checklist as a basic risk-assessment tool.
Adjust the work
- Move the heaviest and dirtiest graft to early morning or later in the day where possible.
- Rotate tasks so one person isn't on the roof or in the plant room all day.
Provide water, shade and rest
- Make sure there is plenty of cool drinking water close to where people are working, topped up through the day.
- Provide shade or cool areas (tents, canopies, cabins) where people can take breaks out of direct sun.
- Increase and stagger rest breaks when it's really hot · especially for heavy work or when wearing lots of PPE.
Ventilation for enclosed spaces
For roof voids, plant rooms, confined spaces, employers need to consider extra ventilation (fans, air movement) and shorter time-limits inside, because temperatures climb faster and heat can't escape.
Training and emergency plan
- Train workers and supervisors on signs of heat illness and what to do if someone feels unwell.
- Have a clear plan for stopping work and getting help if someone overheats.
4. Sun, skin cancer and sunscreen
HSE and IOSH are very straight: long-term outdoor work, unprotected, significantly raises your skin-cancer risk.
IOSH's No Time to Lose campaign (solar radiation) says outdoor workers should get:
- Information on UV risk and skin-cancer signs.
- Protective clothing · long sleeves, hats with neck protection, sunglasses where safe.
- Access to sunscreen · ideally SPF 30+ broad-spectrum, applied regularly.
Is sunscreen PPE?
Under COSHH and PPE guidance, if sun exposure is a foreseeable workplace risk (for example, you're on roofs, scaffolds, civils), employers should treat protection the same way as other controls, shade, clothing, then sunscreen for bits you can't cover.
Many good employers now provide free sunscreen stations on outdoor sites as part of their duty of care.
You should still bring your own, but if you're working outside all day, it's reasonable to expect your employer to take UV seriously, not just the burns you complain about that night.
5. Hours, enclosed spaces and the lived reality
Hours and shifts
There's no legal right to shorter days or siestas in heat, but HSE's hot-weather alert to employers explicitly recommends:
- Rescheduling work to cooler parts of the day.
- Avoiding the most intensive tasks in mid-afternoon during heatwaves.
- Considering temporary changes to start/finish times to keep people safer.
Big, well-run jobs often do this informally, 6am starts, heavier work early, tidy-up and lighter tasks when it's roasting. Smaller sites may lag, but you're within your rights to ask for the heavy graft to be moved where it's clearly risky.
Roof spaces, plant rooms, voids
Confined-space and roof-void guidance warns that temperatures in enclosed or poorly ventilated areas can shoot up fast because heat can't escape.
Risks in those spaces:
- Temperature rising faster than outside, especially under dark roofs.
- Little airflow, so your body can't cool by sweating.
Good practice is short stints, good ventilation and close monitoring, not locking someone in a baking roof space all afternoon because "we need it done".
What to do next
- If it's hot on your site and there's no water, shade or adjusted schedule, raise it with your site manager · HSE explicitly expects these controls in hot weather.
- Buy SPF 30+ sunscreen and actually wear it · face, ears, neck, arms, every day you're outside. Non-melanoma skin cancer from UV is one of the most preventable occupational cancers.
- If someone shows signs of heat exhaustion (confusion, staggering, hot dry skin), get them into shade, cool them down with water, and call 999 · heat stroke can kill.
- If you work in roof voids or plant rooms, push for short stints, fans/ventilation and close monitoring · don't accept being left in a baking space for hours.
Sources
- Management of Health and Safety at Work Regulations 1999 · legislation.gov.uk/uksi/1999/3242/contents · employer duty to assess and control risks including heat.
- Workplace (Health, Safety and Welfare) Regulations 1992 · legislation.gov.uk/uksi/1992/3004/contents · temperature and welfare standards.
- HSE INDG451 · heat stress guidance for employers and workers.
- HSE workplace temperature checklist · basic heat-stress risk assessment tool.
- HSE hot-weather alert guidance · rescheduling work, water, shade, breaks, enclosed spaces.
- IOSH "No Time to Lose" campaign · solar UV as occupational carcinogen; employer duties on sunscreen and protective clothing.
- Health and Safety at Work etc. Act 1974 · legislation.gov.uk/ukpga/1974/37/contents · general employer duty of care.
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