Avoiding Work Fires

The Heat is on – Hot Work Fires on the Rise

Hot work fires on construction sites are on the rise. CHAS, the supply chain risk management experts, explain what you need to remember when undertaking this type of work.

More than a quarter of all accidental fires on construction sites are sparked by ‘hot work’, according to Freedom of Information data obtained by insurer Zurich.

Combustible materials can be easily ignited by a stray spark and cause serious harm to buildings and people. It also leads to millions of pounds worth of damage each year, not to mention reputational damage.

It is therefore vital that your workplace establishes a suitable safe working system for hot work before people carry it out.

What is hot work? 

The term ‘hot work’ refers to tasks involving the use of open flames, the application of heat or in some cases friction, which may potentially lead to the generation of sparks or heat.

The British Standards Institute (BSI) defines ‘hot work’ in BS 999 (1) as “any procedure that might involve or have the potential to generate sufficient heat, sparks or flame to cause a fire”.

It includes welding, flame-cutting, soldering, brazing, grinding and the use of other equipment incorporating a flame, such as tar boilers.


Hot work can harm people by causing burns, illness due to fumes, eye damage from debris, or hearing loss due to noise. However, the most common and significant risk of hot work is fire.

Home Office data obtained by Zurich under Freedom of Information shows that between January 2015 and March 2019, fire crews in England attended 1,587 construction fires – of which 28% (2) were caused by hot work, or other sources of heat.

The insurer’s own claims data shows that 15% of the total cost of all UK fires in commercial and industrial properties involve hot work.

Fire hazards posed by hot work include flying sparks; heat conduction when working on pipes; flammable swarf, molten metals, slag, cinder and filings; hot surfaces; and explosive atmospheres.

Areas of particularly high risk include torch-applied roofing, where there are roof voids present and work such as angle grinding close to combustible materials.

BS 9999 states that “hot work should only be undertaken if no satisfactory alternative method is feasible”. Every possible alternative for completing a task should therefore be considered before deciding to proceed with hot work.

Hot work permits

If hot work on a construction site is unavoidable, a hot work permit is required for any temporary operation involving open flames or producing heat and/or sparks.

Issued for a maximum of one day by a competent and authorised person before work begins, the permit will detail who will be carrying out the work (staff or contractors); what the work will involve; hazards identified and actions taken to remove them (e.g. flammable liquids, combustible materials); fire watch procedures; site inspection procedures; and emergency procedures.

The use of a permit system provides a formal means of recording the findings and authorisations required to undertake hot work. It is an extension of the safe system of work – it does not, by itself, make the job safe. Organisations must therefore have robust procedures for ensuring that contractors adhere to the hot work permit.

According to Zurich, an organisation can only have oversight of the hot work permit system if it has somebody physically on site. It’s also vital to identify the right person within an organisation to monitor the performance of the hot works permit system (3).

Carefully vetting contractors from the outset is important too. For one thing, it’s important to use a contractor experienced in hot works. For true peace of mind, though, the contractor should be accredited by a recognised health and safety scheme such as CHAS, The Contractors’ Health and Safety Assessment Scheme, to demonstrate that their workers are trained to safely use hot work equipment.

Best practice

Guidance from the Health & Safety Executive (HSE) details many of the areas seen on checklists for hot work permits – from the importance of good housekeeping to fire watch procedures.

For example, on the importance of good housekeeping with regards to welding (4), the HSE states: “Clear away wood, fabric, cardboard and other flammable material before starting a welding job. Heat, sparks and drips of metal and slag can travel a considerable distance and start fires in adjacent rooms.”

On fire watches, it advises: “Where hot work cannot be carried out in a safe area, or where combustible material cannot be removed from the work area, a fire watch should be maintained during and after the hot work. This watch should be maintained for at least 30 minutes after the completion of the hot work, but where an unintended ignition may be difficult to detect or slow to develop, this may need to be extended to 60 minutes.”

Beyond compliance

Organisations looking to go above and beyond compliance may want to consider using thermal imaging cameras.

Zurich is urging contractors to adopt them as standard to help reduce the number of fires caused by welding, grinding and torch-applied roofing.

The cameras, which cost as little as £400, could detect more hot spots before they ignite. The devices can also be used to take time-stamped photos to demonstrate fire watches have been carried out.

The insurer is also pressing for a voluntary licensing system to encourage best practice and provide peace of mind to businesses when choosing contractors. Before carrying out or supervising hot work, contractors would complete a one-day training course, giving them a licence valid for five years.

Scandinavian countries have had a similar ‘passporting’ approach in place since the 1980s, which is said to have significantly reduced hot work fires to less than 5% of fire losses over the last decade.

The Fire Protection Association (FPA) is one body that offers a hot work passport scheme in the UK. It is designed for supervisors and operatives who carry out risk assessments to complete hot work permits. Over 2,850 hot work passports have been issued to date and it is valid for five years from the date of completion.



In many instances, the use of hot work equipment is the most efficient way to achieve certain tasks during construction, renovation and maintenance.

However, all activities classed as hot work inherently carry a degree of risk, with the dangers often exacerbated by poor practices and processes.

Whether hot work is being undertaken by your own staff or external contractors, it should always be authorised, monitored and documented.

Better training and awareness around pre-work assessments combined with the use of new technology such as thermal cameras could go a long way to dramatically reducing the frequency of fires caused by hot work.

For more information about any of CHAS’s products or services, contact 020 8545 3838 or visit www.chas.co.uk



(1) BS 9999: Code of practice for fire safety in the design, management and use of buildings.

(2) A result of either combustible articles too close to heat source, negligent use of equipment or appliance; other intentional burning; or overheating.

(3) https://newsandviews.zurich.co.uk/wp-content/uploads/2017/05/An-in-depth-guide-to-hot-works-safety_.pdf

(4) Welding: Safety risks from welding – HSE


For editorial enquiries: georgina@blackthorn-media.co.uk

About Dylan Garton

Dylan Garton is a cofounder of Skill Builder and freelance video producer, camera operator and video editor.

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