Four workers installing an air source heat pump on a 14-storey roof in Staines-upon-Thames were, in the words of HSE, "lucky to escape" a fire that engulfed the entire roof space. According to the HSE Media Centre, the incident has now led to a prosecution — and it's a sobering read for anyone who sends people onto a roof with a welding torch.
What happened
On 26 July 2024, four subcontractors were working under the control of C Watkins Plumbing Limited, installing an air source heat pump on the roof of the Old Telephone Exchange development in Staines. Sparks from welding work ignited uncovered rigid foam insulation laid across the roof. The fire developed quickly, spreading across the whole roof space before burning itself out when it ran out of fuel.
The men escaped through a single opening in the floor and down a ladder to Level 14. There was no other way off the roof, no means of raising the alarm, and no fire extinguishers. An HSE inspector who happened to be nearby photographed the block ablaze.
The HSE investigation found the company had failed to plan, manage and monitor the hot works. Despite having policies that required them, there was no risk assessment or method statement in place, and no permit to work was issued for the welding. HSE inspector Stephanie Hickford-Smith said: "Watkins failed to follow its own procedures for hot works. It did not assess the risks and so had no control measures in place."
C Watkins Plumbing Limited pleaded guilty to breaching Regulation 15(2) of the Construction (Design and Management) Regulations 2015. The company was fined £20,000 and ordered to pay £8,270 in costs at Staines Magistrates' Court on 29 October 2026.
Why it matters to contractors
The detail that stings here is that the company already had the procedures — they just weren't followed on the day. Having a hot works policy sitting in a folder counts for nothing if the welding starts without a permit, without an assessment of what's nearby, and without someone checking the controls are actually in place on site.
Hot works near combustible materials is one of the highest-risk activities on any construction site. Rigid foam insulation, membranes, timber and packaging all burn fast. Put that on a roof with a single escape route and no alarm, and a stray spark becomes a life-or-death situation in seconds. HSE's HSG168 guidance makes the point that risk assessments must identify high-risk activities where fires can spread quickly and where evacuation is complex — a roof top is exactly that.
What to check on your site
- Is a hot work permit raised before any welding, grinding, cutting or burning? No permit, no spark. It should name the fire watch, confirm extinguishers are present, and set a cool-down period.
- Has the area been cleared of combustibles? Uncovered foam insulation, membranes and packaging should be removed or protected before work starts.
- Is there more than one way off the work area? A single ladder through a single opening is not an evacuation plan.
- Can workers raise the alarm? Means of alerting others and summoning help should be in place before work begins.
- Are extinguishers present and suitable? On the roof, at the task — not three floors down.
- Is someone monitoring? Procedures only work if site management checks they're followed, not just written.
Documents that help
If your hot works paperwork needs sharpening, a hot work permit template covers fire watch, extinguisher checks and sign-off, and our guide to permits to work explains when each type is needed. For the welding activity itself, the RAMS & Permits Bundle pulls together method statements and permit templates for high-risk work, and plumbing and heating contractors will find hot works and pipework covered in the Plumber & Heating Risk Assessment Pack.
These templates give you a professional, editable starting point to build your own site-specific assessments and permits — but documents don't do the job on their own. As this case shows, they only protect people when they're actually used, checked and followed on the day.
Take two minutes before the torch comes out
Browse the RAMS & Permits library and get your hot works paperwork in order before your next roof job — instant download, fully editable, from £3.99.