A construction site is one of the most fire-prone workplaces in the UK. You've got combustible materials stacked everywhere, hot works throwing sparks, fuel and gas cylinders on site, temporary electrics, and escape routes that change by the week. Add a timber frame or a partly-built structure with no compartmentation, and a small fire becomes a total loss in minutes.
Winter makes it worse. Temporary heaters run in cabins and drying-out spaces, the days are short so more work happens under lights, and the temptation to leave a heater on overnight is real. That's exactly when a proper fire risk assessment earns its keep — so this is a good time to check yours is actually fit for the site you're on.
Do you legally need a fire risk assessment on site?
Yes. The Regulatory Reform (Fire Safety) Order 2005 applies to construction sites, and the CDM 2015 Regulations require the principal contractor (or the contractor on a single-contractor job) to plan, manage and monitor fire safety. There must be a responsible person who ensures a suitable and sufficient fire risk assessment is carried out and kept up to date.
Unlike a completed building, a construction site changes constantly. That means a fire risk assessment isn't a one-and-done document — it needs reviewing as the build progresses, as escape routes move, and as new high-risk activities (hot works, spraying, timber erection) start. If you're unsure whether a written assessment is required for your job, our guide on whether you legally need a risk assessment sets out the threshold in plain English.
What a construction site fire risk assessment must cover
A site fire risk assessment follows the same five-step logic as any fire assessment, but tailored to a live construction environment:
- Identify the fire hazards — sources of ignition (hot works, electrical equipment, smoking, heaters, plant), sources of fuel (timber, packaging, insulation, fuel/gas cylinders, waste), and sources of oxygen.
- Identify people at risk — operatives, visitors, neighbouring premises and the public. Consider lone workers and anyone working in enclosed or upper-level areas.
- Evaluate and reduce the risk — separate ignition from fuel, control hot works under permit, manage waste and storage, protect escape routes.
- Record your findings — the assessment, the significant hazards and the controls in place.
- Review and revise — as the site changes, and after any incident or near miss.
The controls that matter most on site tend to be the boring, disciplined ones: keeping combustible waste cleared daily, storing gas cylinders and fuel properly and away from the works, maintaining clear and signed escape routes, and never letting hot works run without a permit and a fire watch.
Hot works: the single biggest ignition source
Grinding, welding, cutting and burning cause a huge share of site fires — and the danger often isn't during the work, it's the smouldering that starts up an hour after the operative has walked away. That's why hot works should never happen on a nod. Every hot work task needs a permit, extinguisher checks, a fire watch during the work, and a monitoring period afterwards.
We've covered this in depth in our hot works permit guide, and you can pick up an editable hot work permit template that covers fire watch, extinguisher checks and sign-off. If hot works are a regular part of your job, treat the permit as non-negotiable.
Temporary buildings, cabins and heaters
Site cabins, welfare units and drying rooms carry their own fire risk — LPG heaters, portable electric heaters, overloaded extension leads and cooking equipment. Keep heaters clear of combustibles, never dry clothing over them, don't run them unattended overnight, and make sure cabins have working smoke detection and a clear exit. Test your fire alarm and emergency lighting arrangements as part of routine site monitoring.
Storage, waste and housekeeping
Most site fires grow because of what's lying around. Good housekeeping is genuinely one of the most effective fire controls you have:
- Clear combustible waste from work areas at the end of every shift.
- Store flammable liquids and gas cylinders in dedicated, secure, ventilated areas away from ignition sources and escape routes.
- Keep packaging, insulation and timber offcuts controlled — not piled next to hot works.
- Don't block fire points, exits or extinguisher positions with materials.
Escape routes, alarms and firefighting equipment
Because site layouts change, your means of escape must be reviewed regularly. Escape routes should be kept clear, adequately lit, signed, and lead to a defined muster point. Provide suitable, maintained firefighting equipment (the right extinguisher types for the risks present) and a means of raising the alarm that works across the whole site — a simple air horn or klaxon may be enough on a small job, but larger or noisy sites need something more robust.
Keep it live: monitoring and reviews
A fire risk assessment that reflects the site at ground-breaking is worthless six months in. Build fire into your regular site inspections — extinguisher checks, escape route walks, storage and housekeeping audits, and heater/cabin checks. Our Site Monitoring Bundle includes fire, welfare and plant checklists that make these walks quick and repeatable, so nothing slips.
Reinforce it with the people doing the work, too. A five-minute toolbox talk on fire prevention, hot works discipline or housekeeping keeps it front of mind — far more effective than a document filed in a folder.
FAQs
Who is responsible for the fire risk assessment on a construction site?
The responsible person — usually the principal contractor under CDM 2015, or the contractor on a single-contractor project. They must ensure a suitable and sufficient assessment is carried out by a competent person and kept up to date as the site changes.
How often should a site fire risk assessment be reviewed?
There's no fixed interval, but on a live construction site you should review it whenever the layout, escape routes or high-risk activities change significantly, and after any fire, near miss or significant incident. In practice that often means monthly or at each major project phase.
Is a fire risk assessment the same as a hot works permit?
No. The fire risk assessment is the overarching document covering all fire hazards on site. A hot works permit is a specific authorisation and control system for individual high-risk tasks like welding or grinding. You need both.
Do small jobs and sole traders need one?
If your work introduces fire hazards — and most construction and M&E work does — you should assess and control that risk. The scale of the paperwork matches the scale of the risk, but the duty doesn't disappear because you're a one-person outfit.
Can I use a template for a site fire risk assessment?
Yes — a good template gives you the structure and prompts so nothing is missed, but you must adapt it to your actual site, hazards and controls. Templates support a competent assessor; they don't replace the thinking.
Get your fire documents sorted
Fire safety on site comes down to a handful of documents done properly: your fire risk assessment, hot work permits, and regular monitoring. Grab an editable hot work permit template to control your high-risk tasks, add the Site Monitoring Bundle to keep your inspections tight, or go unlimited with SafetyPod Membership at £69/year for access to every template you'll need across the job. Instant download, fully editable, written by a NEBOSH-qualified team — so you can spend less time on paperwork and more time keeping the site safe.