By Shruti Verman | CertIOSH
5 Min read

Fire on a construction site is not a theoretical risk. It is one of the most destructive and fast-moving hazards in the industry — and one of the most preventable. Yet fire safety is often treated as a box-ticking exercise: a few extinguishers positioned near the site entrance, a fire point sign, and a muster point marked on the site plan.

That is not a fire safety strategy. Here is what one actually looks like.

Why construction sites are particularly vulnerable

A permanent building has fixed escape routes, installed fire detection, and suppression systems. A construction site has none of these by default. The environment changes daily — new materials arrive, trades overlap, hot works move around the site, and temporary structures go up and come down. The risk profile shifts constantly, and the controls need to shift with it.

Common fire causes on construction sites include hot works (cutting, welding, grinding), careless disposal of smoking materials, arson, electrical faults in temporary supplies, and the accumulation of combustible waste. Any one of these, combined with the large quantities of flammable materials typically on site — timber, insulation, solvents, fuel — can result in a fire that takes hold within minutes.

Hot works — the highest risk activity

More construction site fires are started by hot works than any other single cause. Cutting and grinding produce sparks that travel several metres and can smoulder in combustible material for hours before igniting. A hot works permit to work system is non-negotiable on any site where these activities take place.

The permit should require:
– Removal or protection of combustible materials within a minimum radius (typically 5 metres, more depending on the activity).
– A designated fire watcher present throughout the work and for at least 30–60 minutes afterwards
– Fire extinguishers immediately available at the point of work
– Supervisor sign-off before work begins and after the fire watch period ends

The fire watch period after hot works is the one most commonly skipped. It is also the one that matters most — a significant number of construction site fires start from smouldering material that was not visible at the time the work finished.

Combustible waste — the overlooked hazard

Waste accumulation is one of the most common fire risks on site, and one of the most avoidable. Timber offcuts, packaging, insulation off-cuts, and paper products build up quickly when housekeeping is not actively managed.

Good fire safety practice requires waste to be removed from work areas at the end of each shift, stored in designated skips away from the main structure, and not allowed to accumulate against buildings or within enclosed spaces. Skips should be positioned away from site entrances and the main structure — a burning skip pushed against a building facade can cause significant structural damage within minutes.

Temporary electrical supplies

Temporary electrical installations on construction sites are a significant ignition source. Overloaded distribution boards, damaged cables run across floors and doorways, and non-weatherproof equipment used in wet conditions all create real risk.

Temporary electrical installations should be inspected regularly by a competent person, with records maintained. Extension leads should not be used as a substitute for properly installed temporary supplies, and all electrical equipment brought onto site should be PAT tested before use.

Means of escape — think ahead

On a working construction site, the means of escape changes as the build progresses. What was an open escape route last week may be blocked by new materials, temporary structures, or ongoing works this week.

Escape routes need to be reviewed and communicated as the site develops — not just set at the start of the project and forgotten. This includes making sure that all workers on site, including subcontractor operatives who may only be present for a day or two, are briefed on current escape routes and the muster point as part of their site induction.

Fire alarm systems on construction sites are often temporary and basic. Make sure all workers know what the alarm sounds like and what to do when they hear it. A fire drill at least once during the project is good practice and reveals gaps you will not find any other way.

Fire risk assessment — not a one-off

The Regulatory Reform (Fire Safety) Order 2005 requires a fire risk assessment for any workplace, and a construction site is no exception. The assessment should be reviewed regularly — at least every time there is a significant change to the site layout, the works being carried out, or the materials present.

In practice, the fire risk assessment should be a living document, reviewed in site manager meetings and updated as the project progresses. A risk assessment completed at the start of a project and never revisited is of limited value on a site that looks completely different six months later.

A practical fire safety checklist

At minimum, every construction site should be able to answer yes to all of the following:

– Is there a current, reviewed fire risk assessment for this site?
– Are fire points clearly marked, accessible, and stocked with appropriate extinguishers?
– Is a hot works permit to work system in operation?
– Are combustible materials and waste managed and removed daily?
– Is the temporary electrical installation inspected and in good condition?
– Do all workers know the current escape routes and muster point?
– Is the muster point recorded and accounted for in the event of an alarm?
– Are fire extinguishers inspected monthly and serviced annually?

If the answer to any of these is no, that is the gap to close first — before the next hot works permit is signed off, not after.

Fire safety on construction sites is not complicated. It requires consistent attention, a willingness to stop work when controls are not in place, and a site culture where people feel able to raise concerns when they see something wrong. The technical measures matter, but the behaviour matters more.

Shruti Verman is an HSE consultant and NVQ assessor with four years of UK construction site experience.
Evoris Global Consulting provides HSE advisory, auditing, and training services to organisations in the UK and India.
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