Hot Work Procedure: A Step-by-Step Guide for UK Sites

Hot work — welding, cutting, angle grinding, brazing, and torch work — accounts for a disproportionate number of fires and insurance claims on UK construction and industrial sites. Most of these incidents share a common cause: a procedure that existed on paper but wasn't followed, or wasn't followed in full.

A hot work procedure sets out, in a step-by-step sequence, what must happen before anyone introduces a heat source on site. This guide sets out the procedure that robust UK site management systems follow, and explains how each step connects to your hot work permit and your legal obligations under the Regulatory Reform (Fire Safety) Order 2005.

This guide references the Regulatory Reform (Fire Safety) Order 2005 (SI 2005/1541), HSE guidance HSG250 (Permit-to-Work Systems), and industry practice from the Joint Code of Practice: Fire Prevention on Construction Sites (FPA / RISCAuthority). It is for general information and does not constitute legal advice.

What a hot work procedure is — and what it isn't

A hot work procedure is the site-level policy and protocol that governs all hot work activities. It is not the same as a method statement (which describes how a specific task will be done) or a risk assessment (which evaluates the hazards), though both of those feed into it.

The procedure answers: "On this site, what is the agreed sequence of events before any hot work starts?" That sequence — from planning and authorisation through to close-out and fire watch — is what a procedure codifies.

Without a procedure, each team makes its own judgment calls about fire watch periods, combustible material clearance, and permit requirements. With a procedure, the standard is set at site level, not by whoever happens to be nearest to the angle grinder.

Pre-work: what must happen before any hot work begins

1. Consider cold work alternatives

Before authorising hot work, the question that HSG250 and the RRO 2005 both build into their frameworks is whether the task can be done without introducing an ignition source. Mechanical cutting, cold-bolting, crimping, and hydraulic tools are all alternatives for some tasks. Where a cold work alternative exists, a hot work procedure should require it to be used — not just considered.

If hot work is the only practical method, proceed with the following steps.

2. Complete the risk assessment

A site-specific hot work risk assessment — not a generic template — is required before any hot work begins. The Regulatory Reform (Fire Safety) Order 2005 Article 9 requires the responsible person to conduct "a suitable and sufficient assessment of the risks to which relevant persons are exposed." For hot work, that means identifying the specific fire load in the work area, the hazards created by the specific welding or cutting task, and the people who could be affected.

The risk assessment feeds directly into the permit — it establishes what controls are needed, and the permit confirms those controls are in place.

3. Issue the hot work permit

The hot work permit is the gate that authorises work to begin. HSG250 describes permit-to-work as a formal, documented system for controlling work that carries significant risks. For hot work, that control function starts before anyone picks up a torch.

The permit should be issued by an authoriser — a person who is competent to assess whether the precautions on the permit are appropriate and in place. The permit holder (the person doing or directly supervising the hot work) should receive the permit, confirm they understand the conditions, and sign acceptance.

4. Clear combustibles or protect them

The required clearance distance for hot work is typically 10 metres in all directions — including above and below the work area, through floor voids, and into adjacent spaces. In practice:

• Combustible materials within the 10-metre radius should be removed where possible
• Where materials cannot be removed, they should be covered with fire-resistant blankets or welding curtains
• Flammable liquids, gases, and aerosols must be removed from the area entirely — not just covered
• Voids, ducts, and service penetrations should be identified and stuffed with fire-resistant plugs where sparks or heat could travel through them

If the work area cannot be cleared to the required standard, the work should not proceed.

5. Check and address fire detection systems

Most sites have fire detection systems. Hot work smoke and fumes can cause false alarms — and the standard response in many workplaces is to permanently disconnect detectors near hot work. This is a significant risk because:

• A temporarily isolated detector is a detector that won't catch a real fire
• Isolation should be coordinated with the site fire safety officer or the alarm monitoring company
• A compensatory fire watch arrangement should be in place to cover the period of isolation

The permit should record: which detectors have been isolated, who authorised the isolation, when they will be reactivated, and what compensatory monitoring is in place.

6. Position extinguishing equipment

Extinguishing equipment — a fire extinguisher of the correct type for the fire load in the area — must be immediately available at the work location. "At the end of the corridor" is not immediately available.

The correct extinguisher type depends on the fire load: CO2 for electrical equipment, dry powder or CO2 for general hot work, water mist for areas with combustibles. The permit should confirm the correct type is in position.

During the work

7. Deploy and brief the fire watch person

A fire watch person's sole role during hot work is fire vigilance — they do not assist with the work or take on other tasks. The fire watch person should:

• Remain in sight of the work area throughout the hot work activity
• Have the fire extinguisher immediately to hand
• Know the emergency alarm points and evacuation procedure
• Have the authority to stop work immediately if they identify a hazard

A fire watch arrangement where the welder's mate also watches for fires while helping to position steelwork is not a fire watch. It is a role that has been assigned but cannot be fulfilled.

8. Monitor conditions during the work

Conditions can change during a hot work session. The fire watch person — and the permit holder — should watch for:

• Smoke from adjacent areas that could indicate the fire has spread beyond the immediate work zone
• Changes in conditions that trigger the need to stop work — unexpected discovery of flammable materials, deterioration in weather conditions affecting fume dispersal, loss of the fire watch person
• Approach of the permit time limit — permits should have a specific end time, and if work is still in progress when the permit expires, it should be closed and a new one issued

9. Control the work area

The permit should define the boundaries of the hot work area. No personnel other than those on the permit should be within the cordoned zone during active hot work. This applies particularly where hot work is happening on a level above other trades — sparks are not contained by floor level.

After the work: close-out and fire watch

10. Stop hot work at the permitted time

When hot work finishes — or when the permit time limit is reached — the work stops. Any continuation requires a new permit.

11. Complete the fire watch period

The fire watch continues after hot work has stopped. Materials can smoulder and ignite long after the torch or angle grinder has been put down. A 60-minute fire watch period after hot work ceases is common UK site practice and a frequent minimum in insurer and principal contractor requirements. Individual sites may require longer periods — particularly where the fire load is significant or materials have been exposed to sustained heat.

The fire watch person should inspect all surfaces and void spaces that sparks or heat may have reached. The permit should record that the fire watch was completed, who completed it, at what time, and with what result.

12. Reactivate fire detection systems

Once the fire watch is completed and the work area is confirmed clear, fire detection systems that were isolated should be reactivated. The monitoring company or building management should be notified. The permit close-out section should capture: who reactivated the systems, when, and confirmation that the systems are functioning.

13. Close the permit

The permit should be formally closed by both the permit holder and the authoriser — signed with the time the work was completed and the fire watch was finished. The closed permit goes into the permit register.

HSG250 is explicit that permits must be formally closed — a permit that is never officially closed represents a control system that has lost track of whether the risk has been fully addressed.

Building your hot work procedure into the permit

The value of a hot work procedure increases when it is explicitly connected to the permit template. A permit that references the site hot work procedure — and requires the permit holder to confirm they have followed each step — turns the procedure from a paper document into an operational checklist.

The permit to work checklist covers the structure of pre-start, during-work, and close-out checks for all permit types including hot work. For a hot-work-specific template that captures all 13 steps above in a structured form, the hot work permit template provides the complete structure.

Key references

• Regulatory Reform (Fire Safety) Order 2005 (SI 2005/1541) — Articles 9 and 12 on fire risk assessment and dangerous substance duty
• HSG250: Permit-to-Work Systems — HSE guidance on formal permit systems for high-risk work
• Dangerous Substances and Explosive Atmospheres Regulations 2002 (SI 2002/2776) — DSEAR duties where flammable substances are present

Disclaimer

This guide is for general information only. Hot work procedures and legal requirements depend on the specific work, site conditions, and insurance requirements involved. Always consult a competent fire safety or H&S professional and the primary legislation for your specific circumstances.