Hot work is any job that produces heat, sparks or flames – welding, cutting, grinding, brazing, soldering, or using a blowtorch for roofing or paint stripping. It's one of the most common causes of fires in buildings during maintenance and construction.

Is a Hot Work Permit a Legal Requirement?

No law specifically says "you must have a hot work permit". But the law does require you to assess and control fire risks – through general health and safety law, the fire safety law in each nation and, on construction sites, the Construction (Design and Management) Regulations. A permit is the recognised way to do that for hot work.

The Health and Safety Executive (HSE) lists hot work as higher-risk work that may need a permit, and many insurers make permits a condition of cover. As the HSE points out, a permit doesn't make a job safe by itself – it's the precautions it records that do.

First, Can You Avoid It?

The safest hot work is none at all. Consider cold alternatives first – for example, bolting instead of welding, cold cutting, or push-fit or crimped pipe fittings instead of soldering.

What a Permit Should Include

  • Exactly where the work is and what it involves.
  • Who's doing it, and who issued the permit.
  • When it starts and when it expires – a permit should cover one job, in one place, for one shift. No blanket permits.
  • A checklist of precautions, signed off before work starts.
  • Fire watch and final check sign-off at the end.

Typical Precautions

  • Clear the area – remove anything that can burn within about 10 m, including on the other side of walls, floors and ceilings. Sparks can travel through gaps into the next room.
  • Protect what can't be moved – cover it with fire-resistant blankets or welding curtains.
  • Extinguishers at hand – at least two suitable extinguishers, including a water-based one. See Which Fire Extinguisher Do I Need?.
  • Gas cylinders – secured upright and kept well away from the work.
  • Fire detection – only isolate detectors in the immediate area if needed, and reinstate them when the work finishes.

Fire Watch – How Long?

Smouldering material can burst into flames long after the work has stopped. Guidance varies:

  • The HSE advises watching for at least 30 minutes after the work finishes, and up to 60 minutes where a fire could develop slowly.
  • The construction industry's Joint Code of Practice and many insurers ask for a continuous watch of at least 1 hour, followed by further checks.
  • Many permits require hot work to stop at least 1 hour before the end of the working day, so no one leaves the site straight after.

Follow whichever is longest – especially your insurer's requirements.

Training

Anyone doing hot work, or acting as fire watcher, should be trained. The Fire Protection Association's Hot Work Passport is a widely recognised course, valid for 5 years.

More information: HSE – welding fire risks, HSE – permits to work and Scottish Fire and Rescue Service – hot works. See also Fire Safety on Construction Sites.

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Worth remembering… your fire risk assessment is what decides what your premises need. This guide is general advice, not a substitute for it.

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