Fire Safety on Construction Sites UK 2026 — A Compliance Guide for Trades

Why Construction Sites Carry Such a High Fire Risk

A live site combines hazards that you would never tolerate in a finished building. Understanding why the risk is so concentrated is the first step to controlling it.

• Hot works everywhere: welding, grinding, soldering, paint stripping with heat guns, bitumen boilers and disc cutting all produce sparks, flames or hot surfaces that can ignite nearby materials hours after the work stops.
• Large quantities of flammable materials: timber, insulation, packaging, adhesives, solvents, fuels and LPG are often present in volumes far beyond a normal workplace.
• Temporary services: jury-rigged power, trailing leads, site generators, temporary heaters and overloaded extension boards are a recurring ignition source.
• Combustible insulation and cladding: some insulation products and temporary weatherproofing sheeting spread fire alarmingly fast once alight.
• Partially built escape routes: stairs may be incomplete, corridors blocked with materials, fire doors not yet hung and exits not signed — so a small fire can trap people quickly.

Put simply, a construction site has more ways to start a fire, more fuel to feed it, and fewer ways to put it out or get people away from it than almost any other environment a trade business operates in.

The Legal Framework You Are Working Under

Fire safety on sites is governed by overlapping legislation. You do not get to pick one — they apply together, and ignoring any of them can lead to enforcement notices, prosecution or, after a serious incident, manslaughter charges.

The Regulatory Reform (Fire Safety) Order 2005

The Fire Safety Order is the cornerstone of fire law in England and Wales (Scotland and Northern Ireland have equivalent regimes). It applies to construction sites and places a duty on the "responsible person" — usually the principal contractor or the employer in control of the premises — to carry out a fire risk assessment, put in place general fire precautions, and keep them under review. It is risk-based: you must identify the hazards, decide who could be harmed, and act to reduce the risk so far as is reasonably practicable.

CDM 2015

The Construction (Design and Management) Regulations 2015 sit alongside the Fire Safety Order and deal specifically with construction work. CDM 2015 requires that sites are organised so that fire risks are managed, that there are suitable means of escape and firefighting equipment, and that emergency procedures are prepared and communicated. Duties fall on clients, principal designers, principal contractors and contractors — so even if you are a subcontractor, you carry CDM responsibilities for the work you control.

HSG168 — Fire Safety in Construction

HSG168, the HSE guidance titled "Fire safety in construction," is the document the industry and inspectors look to for what good practice actually looks like. It is not law itself, but it sets out how to meet the legal duties: how to assess fire risk on a site, how to plan escape routes, how to manage hot works and storage, and how to put together a site fire plan. If you follow HSG168, you are a long way toward demonstrating compliance with both the Fire Safety Order and CDM 2015.

The Site Fire Risk Assessment and Fire Plan

Everything starts with a written site-specific fire risk assessment. A generic template pulled off the internet is not enough — the assessment must reflect the actual site, the stage of construction and the materials present, and it must be reviewed as the build progresses because the risk changes week to week.

A workable assessment identifies the ignition sources, the combustible materials, the people at risk, and the controls in place, then drives a site fire plan. The fire plan is the practical document the whole site works to. It should cover:

• Where escape routes run and where the assembly point is
• The location of fire points, extinguishers and the means of raising the alarm
• Hot-works controls and where flammable materials are stored
• Who is responsible for fire safety and who calls the fire service
• How the plan is communicated at induction and updated as the build changes

On larger projects the fire plan is often a standalone document with a marked-up site plan; on smaller jobs it can be a section of the construction phase plan. Either way, it must be communicated to everyone on site, including subcontractors and visitors.

Controlling Ignition Sources and Hot Works

Most construction fires start from an ignition source meeting a combustible material. The two big categories are hot works and electrical or heating faults. Cut the ignition sources and you cut the fire risk dramatically.

Hot works — welding, grinding, cutting, soldering, blow-torch and bitumen work — are the single biggest cause of serious site fires. The standard control is a hot-works permit system backed by a fire watch kept for at least an hour after the work finishes, because smouldering can take time to flare up. We cover hot-works permits and fire watch procedures in detail elsewhere, so here it is enough to say: no hot works should ever happen on your sites without a permit, a cleared area, the right extinguisher to hand, and a post-work watch.

Beyond hot works, manage the other common ignition sources: keep temporary electrics inspected and avoid overloading boards, position site heaters well clear of combustibles and never leave them running unattended overnight, and switch off and isolate plant and battery chargers at the end of the day.

Safe Storage of Flammable Liquids and Gas Cylinders

Fuels, solvents, adhesives and LPG are the fuel load that turns a small ignition into a major incident. They need to be stored properly, not stacked wherever there is space.

• Flammable liquids: keep only the minimum quantity needed for the day's work in the work area. Bulk stock belongs in a designated, ventilated, fire-resisting store away from the building, ignition sources and escape routes, with spill containment underneath.
• LPG and gas cylinders: store cylinders upright, secured against falling, in a ventilated external cage or compound — never in basements, voids or enclosed spaces where leaking gas can pool. Keep full and empty cylinders separated and clearly marked, and keep oxygen cylinders apart from fuel gases.
• Valves and fittings: turn cylinders off at the valve when not in use, check hoses and regulators for damage, and remove cylinders from the building at the end of the working day wherever practical.
• Signage: mark stores clearly with the relevant hazard warning signs so everyone — including the fire service — knows what is inside.

Combustible Waste and Good Housekeeping

Housekeeping is the cheapest and most overlooked fire control on any site. Offcuts, packaging, shrink-wrap, sawdust and empty containers are an enormous fuel source, and a tidy site simply has less to burn.

• Clear combustible waste regularly throughout the day — do not let it build up against the building or near escape routes.
• Store waste in designated skips or bins kept a safe distance (typically several metres) from the structure and from any ignition source.
• Never burn waste on site. Site bonfires are a frequent cause of fires that spread to the works.
• Keep escape routes, corridors and stairwells completely clear of stored materials and waste at all times.
• Deal with oily rags and solvent-soaked materials carefully — some can self-heat and ignite, so store them in lidded metal containers.

Means of Escape, Signage and Assembly Points

On a finished building, escape routes are designed in. On a live site, you have to create and maintain them deliberately as the structure changes. People must always be able to get out quickly, even from the upper floors of a partially built structure.

Make sure there are enough escape routes for the number of people on site and the size of the building, that they lead to a place of safety, and that travel distances are not excessive. Routes must be kept clear, adequately lit (temporary emergency lighting may be needed in enclosed areas), and clearly signed with photoluminescent or illuminated fire-exit signage that works even if the temporary power fails. Designate a clear assembly point well away from the building and from site access roads the fire service will use, and make sure everyone knows where it is from their induction onward.

Fire Points, Extinguishers and Raising the Alarm

Even a well-controlled site needs the means to tackle a small fire and, crucially, to warn everyone and get them out fast. Provide fire points — clearly signed stations with an extinguisher and a means of raising the alarm — at accessible locations across the site, especially near higher-risk areas such as hot-works zones and flammable stores.

The means of raising the alarm must be reliable and audible across the whole site. On small sites this might be a manually operated klaxon, air horn or rotary gong at each fire point; on larger or multi-storey sites a temporary site-wide alarm system is needed. Everyone must know the alarm signal and the action to take.

Choosing the right extinguisher matters — using the wrong type can make a fire worse or put the operator in danger. The table below summarises the common types and the fire classes they are suited to.

For most construction work you will rely on water, foam, dry powder and CO² units, sited to suit the risk in each area. Make sure they are in date, that people know how to use them, and that tackling a fire never takes priority over getting out and calling 999.

Smoking Controls

Discarded cigarettes remain a stubborn cause of site fires, particularly in waste areas and timber stores. Construction sites are workplaces and so are subject to smoking-at-work law, but the fire risk justifies going further. Operate a strict no-smoking policy across the working areas of the site, and provide a designated smoking area well away from the building, materials storage and waste, with proper metal bins for safe disposal. The same rules apply to vaping where the device or battery could be an ignition source. Make the policy part of the site induction so there is no ambiguity.

Timber-Frame and Temporary Construction

Timber-frame construction and lightweight temporary structures deserve special attention because, before the fire-resisting linings and compartmentation are installed, fire can spread through the exposed frame with frightening speed. There have been several high-profile fires on large timber-frame sites that destroyed entire blocks within minutes.

On these projects the controls tighten considerably. The construction sequence should aim to install fire-resisting plasterboard linings and compartment walls as early as possible so that exposed-frame periods are kept short. Hot works on or near the frame should be heavily restricted or avoided entirely while it is exposed. Separation distances between the building, site accommodation and storage become more important, because a fire in an exposed frame can radiate enough heat to ignite neighbouring structures. The industry has developed specific guidance for large timber-frame projects, including measures around early warning, site security to deter arson, and limiting the size of exposed-frame areas — and on any sizeable timber-frame job those measures should feed directly into your fire risk assessment and fire plan.

Arson and out-of-hours fires are a real threat on all sites but especially on timber frame. Good perimeter security, removing the fuel that vandals can ignite, and keeping waste away from the structure overnight all reduce the chance of a deliberately set fire taking hold when no one is there to catch it early.

Fire Risk Sources and Their Controls — Quick Reference

Pulling It Together

Fire safety on site is not a one-off form — it is a continuous discipline that runs through induction, daily housekeeping, hot-works control and the way you store and handle materials. The legal duties under the Fire Safety Order and CDM 2015, with HSG168 showing what good practice looks like, all point in the same direction: assess the risk for your specific site, write a fire plan everyone understands, control the ignition sources, keep the fuel load down, and make sure people can always get out and raise the alarm. Do that consistently and you protect your crew, your client's project and your own business from an incident that could otherwise end all three.