Hot works cause fires — and a lot of them start hours after the tools are packed away. A dropped spark lodges in insulation, smoulders through the afternoon, and by the time the last person locks up, the seat of a fire is already building behind a wall. It's one of the most predictable causes of serious site and building fires in the UK, and it's almost entirely preventable with a proper permit system.
If you weld, cut, grind, braze, solder, use a blowtorch on felt roofing, or fire up any equipment that produces heat, sparks or open flame, this one's for you. Winter makes it worse: more work happens indoors, heaters and combustibles are stacked closer together, and daylight runs short so more hot work drifts into the last hour of the shift. This guide covers what a hot works permit actually is, when you need one, the controls that matter, and where to get an editable template.
What is a hot works permit?
A hot works permit is a formal, written control document that authorises a specific person to carry out a specific hot work task, in a specific location, for a limited period of time. It isn't a form you fill in once and forget. It's a live system: someone competent assesses the area, confirms the controls are in place, signs the work on, and — crucially — signs it off after a fire watch has confirmed nothing is smouldering.
A hot works permit sits within the wider family of permit-to-work systems. If you're new to permits generally, our permit to work guide explains how they work and the main types you'll meet on site, and our blog post on permit to work in UK construction walks through the practicalities.
When do you legally need one?
There's no single regulation that says "thou shalt issue a hot works permit". The requirement flows from your general duties. Under the Health and Safety at Work etc. Act 1974 and the Management of Health and Safety at Work Regulations 1999 you must assess risks and put suitable controls in place. Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person must manage fire risk. Where you're introducing an ignition source into a building or site, a permit is the recognised way to demonstrate you've done that.
In practice you should operate a hot works permit whenever:
- You're welding, cutting, grinding or brazing near anything combustible.
- You're using a blowtorch or hot-air gun — torch-on felt roofing is a classic high-risk task.
- You're working in an occupied or shared building, where a fire would spread to areas you don't control.
- The principal contractor or client requires one — many main contractors and insurers make hot works permits mandatory, and your insurance may be void without one.
- A risk assessment identifies significant fire risk — the permit is the mechanism that delivers the controls the assessment demands.
The permit doesn't replace your risk assessment; it delivers it. You still need a task risk assessment behind it. For roofing torch work, our Roofer Risk Assessment Pack covers the working-at-height and fire elements together, and for pipework and boiler brazing the Plumber & Heating Risk Assessment Pack covers hot works alongside pressure testing and gas work.
The fire risks that catch people out
Most hot works fires aren't caused by the flame itself — they're caused by heat travelling somewhere the operative couldn't see:
- Sparks and hot slag falling through gaps, into voids, or onto lower floors.
- Conducted heat through metal pipes and beams igniting combustibles on the far side of a wall.
- Smouldering materials — insulation, timber, dust and packaging that catch slowly and flare up long after work stops.
- Flammable atmospheres in confined or poorly ventilated spaces.
- Combustibles left too close — the single most common failing.
That last-hour drift is the killer. A spark that lands at 3:30pm has until 4:00pm to smoulder before everyone leaves — which is exactly why a fire watch after the work stops isn't optional.
Controls a hot works permit should enforce
A good permit forces the right conversation before work starts. As a minimum it should require:
1. Clear the area — remove combustibles within at least a 3-metre radius, or protect them with fire-resistant blankets.
2. Cover and seal gaps — protect floor openings, cavities and voids where sparks could fall.
3. Fire extinguishers to hand — the right type, checked in date, within reach of the operative.
4. Isolate what needs isolating — gas, flammable liquids, and any detection systems that must be managed (and reinstated afterwards).
5. Stop hot work at least one hour before the site closes — no exceptions.
6. A fire watch — someone monitors the area during the work and for at least 60 minutes after it stops.
7. Final sign-off — the area is checked and the permit is formally closed only when it's confirmed safe.
Combine this with a short toolbox talk before the task so the whole team knows the extinguisher locations, the fire watch arrangements and the stop time. It takes five minutes and it's exactly the kind of thing an inspector or insurer wants to see evidence of.
Who issues and who receives?
Keep the roles clear. A competent person — usually a supervisor or manager who hasn't got a hand on the torch — issues the permit and checks the area. The operative carrying out the work receives it, works within its conditions, and hands it back for closure. One person shouldn't mark their own homework. That separation is the whole point of a permit system.
FAQ
Is a hot works permit a legal requirement?
Not by name, but your duties under the Health and Safety at Work Act, the Management Regulations and the Fire Safety Order require you to control fire risk from hot work. A permit is the recognised way to do that, and it's frequently mandated by principal contractors and insurers.
How long does a hot works permit last?
It's issued for a single task, location and defined time window — typically one shift or less. If the work continues the next day, you issue a fresh permit and reassess the area.
Do I still need a risk assessment if I have a permit?
Yes. The risk assessment identifies the hazards and controls; the permit is the mechanism that puts those controls in place for a specific job. They work together.
How long should the fire watch last after work stops?
A minimum of 60 minutes of active monitoring after the last hot work ends, with a final check of the area before the permit is closed. Many insurers specify this.
Where can I get an editable hot works permit template?
Our RAMS & Permits library includes editable permit templates you can brand and reuse across your own jobs.
Get your permit system sorted
A hot works permit is cheap insurance against a fire that could close a client's building — or your business. Grab an editable permit from the RAMS & Permits Bundle, which gives you every method statement and permit template in one purchase, or if you want the risk assessments, monitoring forms and permits all in one place, SafetyPod Membership gives you unlimited access to all 113 templates for £69/year. Set the system up once, use it on every job, and never let hot work drift into the last hour again.