Construction Site Fire Statistics UK: 2026 Facts, Data & Key Insights

Construction Site Fire Risk: Dynamic, Dangerous, and Demanding

Construction sites carry a fire risk profile unlike any other workplace environment. They are dynamic — the building changes shape every day, escape routes that were clear yesterday may be blocked today, and the fire compartmentation that will eventually protect the finished building does not yet exist. They are diverse — multiple employers, contractors, and self-employed workers share a site, each bringing their own equipment, practices, and understanding of site procedures. And they involve fire-intensive activities — hot work, temporary electrical installations, flammable materials, and construction processes that generate heat, sparks, and ignition sources in close proximity to large quantities of combustible material.

For the broader context see our Fire Statistics UK: The Definitive Guide and Workplace Fire Statistics UK.

Key Facts & Figures (Overview)

Construction Site Fire Causes

Arson is consistently the leading cause of fires on vacant or partially occupied construction sites. Partially completed buildings — with no occupants, incomplete security measures, and large quantities of combustible materials — are attractive arson targets. Timber frameworks, packaging materials, temporary boarding, and insulation products all burn readily. Site security during out-of-hours periods is a primary fire prevention measure.

Hot work is the leading cause of fires on occupied and active construction sites. Welding, cutting, grinding, and brazing generate sparks that can travel considerable distances and remain active long after the worker has moved on. Hot work fires often start hours after the work is completed, when smouldering materials eventually ignite fully — a pattern that makes them particularly dangerous because the site may be unoccupied by the time the fire develops.

Temporary electrical installations: Construction sites rely on temporary power supplies — generators, temporary distribution boards, and site cabins — that are not part of a permanent building. These temporary systems degrade rapidly in the demanding site environment and require frequent inspection. Overloaded circuits and damaged cabling are persistent ignition sources.

Flammable materials storage: Construction sites store large quantities of flammable and combustible materials — timber, solvents, adhesives, insulation, fuel — that must be managed to prevent accumulation of dangerous volumes near ignition sources.

Smoking: Despite site smoking restrictions, smoking remains a persistent cause of construction site fires — particularly in partially complete enclosed areas where smouldering materials can develop undetected.

Legal Requirements for Construction Site Fire Safety

The Regulatory Reform (Fire Safety) Order 2005: Applies to construction sites. The Responsible Person — typically the principal contractor — must conduct a suitable and sufficient fire risk assessment and implement appropriate fire precautions. On multi-employer sites, each employer also has fire safety obligations for their own workers.

The Construction (Design and Management) Regulations 2015 (CDM): Require the principal contractor to prepare and maintain a Construction Phase Plan that addresses health and safety — including fire safety — for the duration of the construction phase. The plan must identify fire risks, specify control measures, and include emergency procedures.

The Electricity at Work Regulations 1989: Apply to temporary electrical installations on construction sites, requiring them to be maintained to prevent danger. The IET's guidance on temporary installations (BS 7671 Part 7) sets the specific requirements for construction site electrical systems.

Hot Work Permit Systems: Not legally mandated by name, but considered a necessary control measure for hot work activities. A hot work permit system requires formal authorisation before any heat-generating work begins, specifies the precautions to be taken (clearance of combustibles, fire extinguisher at the work location, fire watch during and after), and documents the activity.

The CDM Fire Safety Obligation

The Construction Phase Plan required under CDM 2015 must address fire safety in sufficient detail for the scale and risk of the project. For large or complex projects, this typically includes:

On multi-employer sites, the principal contractor must ensure that all contractors understand and comply with the site fire safety arrangements — not just their own employer's procedures.

Arson on Construction Sites

Construction sites are among the most targeted property types for deliberate fire-setting. The factors that make them attractive to arsonists include: vacancy (particularly at nights and weekends), incomplete security, limited surveillance, and high quantities of combustible materials.

Preventive measures recognised by insurers and fire safety practitioners as most effective include:

For full arson statistics see our Arson Statistics UK guide.

Written by Fire Safety Experts

This guide was produced by the team at Fire Marshal Training, a UK provider of RoSPA and CPD-accredited fire safety training. Construction sites represent one of the most demanding and dynamic fire safety environments — requiring fire marshals with specific knowledge of site-specific risks, temporary installation hazards, and multi-employer emergency coordination. Our training equips construction fire marshals and CDM-responsible managers with that knowledge. For related data see our Fire Statistics UK: The Definitive Guide, Workplace Fire Statistics UK, Arson Statistics UK, and Cost of Fire to UK Businesses.

Sources & References