The detail that stands out in this case is not simply that welding sparks started a fire. It is that the company already had hot works procedures, but they were not followed on site.
On 30 October 2026, the Health and Safety Executive (HSE) reported that C Watkins Plumbing Limited had been fined £20,000 and ordered to pay £8,270 in costs after a prosecution at Staines Magistrates’ Court the previous day. The company pleaded guilty to breaching Regulation 15(2) of the Construction (Design and Management) Regulations 2015.
The fire happened on 26 July 2024 at the Old Telephone Exchange development in Staines-upon-Thames, a 14-storey apartment block under construction. Four subcontractors, working under C Watkins Plumbing’s control while installing an air source heat pump, were welding on the roof. Sparks ignited uncovered rigid foam insulation, and the self-sustaining fire spread across the roof space.
The men escaped through a single opening in the floor and down one ladder to Level 14. There was no other way off the roof, no means of raising the alarm and no fire extinguishers. According to the HSE, the company had not put in place a risk assessment, method statement or hot-work permit for the welding, despite having procedures that required them.
That gap between the procedure written down and the work actually carried out matters to safety. It matters to enforcement. And it can matter when insurers investigate a loss.
1. A policy is not the same as a safe working practice
A health and safety document may show that a business knows what it expects workers to do. It does not show that the controls were actually used.
After an incident, the practical questions are likely to include: Was the task assessed? Was a permit issued? Were combustible materials identified and protected or removed? Were workers briefed? Was anyone monitoring the work?
Those questions matter to regulators and can be part of an insurer’s investigation into a claim. If the business has declared certain procedures or risk controls, but its records and site practice do not match, that could lead to difficult questions about what happened and how the loss developed. Depending on the policy wording and circumstances, a claim may be disputed. That is not the same as saying that any breach automatically removes insurance cover: the facts and the specific policy terms matter.
But a procedure left in a folder is weak evidence of risk management. I think this is one of the more frustrating, avoidable gaps in construction: systems can look adequate on paper while the job is being done without them.
2. Hot-work permits are a practical trigger for prevention
Welding, cutting and grinding can put sparks and heat close to combustible materials. Rigid foam insulation is an obvious concern if it is uncovered and near hot works. A permit process creates a pause before work begins: someone checks the area, decides what needs to be removed or protected, confirms suitable precautions and authorises the task.
A permit is not a substitute for a proper assessment or competent supervision. It is one way of making sure that the assessment is translated into action at the workface.
The HSE’s HSG168 Fire Safety in Construction guidance says fire safety should be considered at design and procurement stages, and managed throughout construction. It also highlights the need to identify work where fire could spread quickly or evacuation may be complex, and to review assessments and controls as site conditions change.
On a live project, those conditions do change. Materials arrive, work areas move and trades overlap. A hot-work assessment that was relevant last week may not reflect what is now stored or installed nearby.
3. Escape, alarm and firefighting arrangements can limit the loss
The four workers had one route off the roof: through a floor opening and down a ladder. There was no means of raising the alarm and no extinguisher. They escaped, but a small change in where the fire started or how quickly it spread could have made the outcome very different.
These provisions are about protecting people first. They can also affect how far a fire develops before it is detected or tackled. In this case, the fire spread across the roof space. On construction projects, damage to work in progress, materials and neighbouring property can create substantial claims. Public liability and contract works losses can reach six or seven figures when a serious fire affects a whole roof or wider parts of a development.
Insurance cannot make an unsafe escape route safe, nor can it guarantee payment for every loss. Cover depends on the risks insured, policy limits, exclusions, conditions and facts of the claim. It is still sensible to understand what protection is in place for third-party property damage and the contract works themselves. Moyak’s pages on General Contractor Liability Insurance and Commercial Combined Insurance explain some of the cover areas businesses may want to discuss with a broker.
4. Subcontractors do not remove the duty to manage work
The four workers were subcontractors, but the HSE said they were working under C Watkins Plumbing’s control. The prosecution was brought against the company that controlled the work, not against the workers.
That distinction is important. Hiring a subcontractor does not, by itself, settle who is responsible for planning and managing a particular activity. The roles, agreements, actual control of the work and applicable duties all need to be considered. In practical terms, businesses should know who is arranging the assessment, issuing permits, coordinating trades and checking that controls remain in place.
We have discussed the liability split in another case where two firms were fined after a dumper overturned. The details differ, but the same practical point applies: having another firm on site does not make it safe to assume that someone else has taken care of every risk.
Whether your work takes you to Kent, Essex or London, the practical point is the same: site controls and insurance arrangements need to reflect the real work being undertaken on the day, not the version of it described in a policy folder.
5. What contractors should check now
A short review of how hot works are managed can help expose the gap between policy and practice. Ask:
- Do our hot-work procedures exist only on paper, or are they followed on site?
- Are permits issued before welding, cutting or grinding begins, and who is authorised to sign them?
- Are workers and supervisors clear on the controls and the conditions that would stop work?
- Is combustible material, including foam insulation, removed or protected before hot works start?
- Are suitable escape routes, alarm arrangements and firefighting equipment available and usable?
- Would our records, site practice and account of events align if our liability insurer asked about them after a fire?
Keep records that reflect what actually happened, not simply what the system was supposed to do. Revisit controls when the work area or site conditions change. And make sure insurance discussions reflect the actual trades, activities, subcontracting arrangements and project risks. Our guide to choosing construction contractor insurance sets out some of the cover considerations contractors should discuss.
The HSE inspector, Stephanie Hickford-Smith, said the company failed to follow its own hot-work procedures and had not assessed the risks, leaving no control measures in place. The four men were lucky to escape.
The practical lesson is straightforward: procedures only help if they are put into use. Check the work on site, confirm who is responsible for each control, and speak with your broker if the cover does not clearly reflect the work your business undertakes.