What Is Passive Fire Protection?

Passive fire protection (PFP) refers to the fire-resisting elements and systems built into a building’s structure that are designed to contain fire and smoke within defined compartments without requiring activation.

Unlike active systems such as fire alarms or sprinklers, passive fire protection works continuously and automatically. It is part of the physical construction of a building and plays a fundamental role in protecting escape routes, maintaining structural integrity and slowing the spread of fire.

If you are a Responsible Person, landlord, managing agent, facilities manager or building owner, understanding passive fire protection — and ensuring it remains effective — is essential for compliance and life safety.

Quick Answer: What Is Passive Fire Protection?

Passive fire protection is the system of fire-resisting walls, floors, doors, cavity barriers and fire-stopping measures built into a building to prevent the spread of fire and smoke. It works automatically, without activation, to maintain fire compartments and protect escape routes for a specified period of fire resistance (such as 30, 60 or 120 minutes).

How Passive Fire Protection Works

Passive fire protection works by dividing a building into fire-resisting compartments. These compartments are designed to contain a fire within a defined area for a specified duration.

This is achieved through:

• Fire-resisting walls and floors
• Protected stairwells
• Fire doors
• Cavity barriers
• Fire-stopping around service penetrations
• Fire dampers within ductwork

Together, these elements:

• Limit horizontal and vertical fire spread
• Reduce smoke migration
• Protect escape routes
• Support stay-put strategies in residential buildings
• Maintain structural stability during a fire

Passive fire protection forms the backbone of a building’s fire strategy.

Passive vs Active Fire Protection

It is important to distinguish between passive and active fire protection systems.

Active fire protection systems require activation in order to operate. These include:

• Fire alarms
• Smoke detectors
• Sprinkler systems
• Smoke control systems

Passive fire protection systems, by contrast, are built into the structure of the building and function automatically. They do not rely on power, detection or mechanical operation to work.

Both systems are essential — but passive fire protection provides the structural containment that allows active systems to operate effectively.

Effective passive fire protection ensures that active systems such as alarms and sprinklers can operate within a controlled and compartmented environment.

Common Examples of Passive Fire Protection

Passive fire protection includes a range of structural measures designed to contain fire and smoke.

Fire-Resisting Walls and Floors

Compartment walls and floors are constructed to achieve specific fire resistance periods, commonly:

• 30 minutes (EI30)
• 60 minutes (EI60)
• 90 or 120 minutes in larger or higher-risk buildings

In fire resistance classifications, “E” refers to integrity (resistance to flame and hot gases passing through), and “I” refers to insulation (resistance to heat transfer).

These elements form the boundaries of fire compartments.

These elements are tested to recognised standards such as BS 476 and BS EN 1364 to demonstrate integrity (E) and insulation (I) performance for defined fire resistance periods.

Passive fire protection products must be installed as part of tested system configurations; substituting materials or altering installation details can invalidate fire test evidence.

These compartment boundaries are typically shown on fire strategy drawings and define the intended limits of fire-resisting construction within the building.

Compartment lines define the maximum size and configuration of fire compartments permitted under the building’s fire strategy.

Fire Doors

Fire doors protect openings within compartment walls and help prevent fire and smoke from spreading into escape routes.

They must:

• Be correctly installed
• Include intumescent strips and smoke seals
• Be self-closing
• Be properly maintained

(See also: Fire Door Inspections)

Fire Stopping

Fire stopping seals service penetrations and joints in fire-resisting walls and floors.

This includes:

• Penetration seals around pipes and cables
• Linear joint seals between structural elements

Without fire stopping, even small gaps can compromise an entire compartment.

(See also: What Is Fire Stopping?)

Cavity Barriers

Cavity barriers prevent concealed fire spread within:

• External wall cavities
• Roof voids
• Ceiling voids

They are particularly important in multi-storey and residential buildings.

(See also: What Are Cavity Barriers?)

Fire Dampers

Fire dampers are installed within ventilation ducts to prevent fire and smoke spreading through mechanical ventilation systems.

Why Passive Fire Protection Is Critical

Passive fire protection:

• Slows fire growth
• Contains smoke spread
• Protects escape routes
• Provides evacuation time
• Reduces structural damage
• Supports firefighter intervention

It also helps maintain the structural stability of a building during a fire, reducing the risk of premature collapse and enabling safe evacuation and firefighting operations.

Without effective passive fire protection, fire can spread rapidly through concealed voids and service routes, rendering escape routes unusable.

Legal Requirements in the UK

Passive fire protection is not optional — it is a legal and regulatory requirement.

Building Regulations & Approved Document B

Under the Building Regulations, fire-resisting construction must be maintained wherever penetrations or joints occur.

Approved Document B provides guidance on:

• Compartment sizes
• Required fire resistance periods
• Fire-stopping and cavity barrier requirements
• Protection of escape routes

Approved Document B requires that fire resistance is maintained where services pass through compartment walls and floors.

Regulatory Reform (Fire Safety) Order 2005

Under the Regulatory Reform (Fire Safety) Order 2005, the Responsible Person must ensure that fire protection measures — including passive systems — are maintained in efficient working order.

Building Safety Act 2022

For higher-risk buildings, the Building Safety Act requires duty holders to maintain clear documentation (the “golden thread”) of fire protection systems, including passive fire protection measures.

Failure to maintain effective passive fire protection can result in enforcement notices, prosecution and significant fines.

Installation and inspection of passive fire protection systems should be carried out by competent, appropriately trained personnel, and third-party certification schemes such as FIRAS or BM TRADA can provide additional assurance of compliance.

Common Passive Fire Protection Failures

During inspections, common issues include:

• Missing or defective fire stopping
• Compromised cavity barriers
• Non-compliant fire doors
• Structural alterations breaching compartments
• Poorly documented installations
• Inadequate reinstatement following refurbishment

Even minor defects can significantly reduce fire resistance performance.

When Is a Passive Fire Protection Survey Required?

A passive fire protection survey may be required when:

• A fire risk assessment identifies potential concerns
• Building works or refurbishment have occurred
• Fire strategy documentation is incomplete
• You manage a higher-risk residential building
• Enforcement authorities require verification
• You require due diligence evidence for compliance
• You require independent verification of compartmentation integrity

A professional survey typically includes:

• Inspection of compartment walls and floors
• Fire door assessment
• Fire-stopping inspection
• Cavity barrier verification
• Photographic evidence and reporting
• Remedial action recommendations

In some cases, intrusive inspection may be required to verify concealed voids and cavity barrier installation.

Why Passive Fire Protection Surveys Matter

Passive fire protection can be compromised over time due to:

• Maintenance works
• Service installations
• Structural alterations
• Poor workmanship
• Building movement

A passive fire protection survey provides defensible evidence that:

• Compartments remain intact
• Fire resistance is maintained
• Defects are identified and prioritised
• Compliance obligations are met

For landlords, managing agents and housing providers, this is critical risk management.

Conclusion

Passive fire protection is one of the most important — and often least visible — components of building fire safety.

By containing fire and smoke within defined compartments, it protects escape routes, maintains structural integrity and provides vital time for evacuation.

However, passive fire protection is only effective if it remains intact and properly maintained.

If you are unsure whether your building’s passive fire protection systems remain compliant, a professional survey provides clarity, assurance and defensible evidence of due diligence.

Frequently Asked Questions

What is passive fire protection in simple terms?

Passive fire protection is the built-in structural protection that slows the spread of fire and smoke within a building. It includes fire-resisting walls, floors, fire doors, cavity barriers and fire-stopping systems that work automatically without activation.

Is passive fire protection a legal requirement in the UK?

Yes. Passive fire protection is required under Building Regulations, including Approved Document B, and must be maintained under the Regulatory Reform (Fire Safety) Order 2005. Responsible Persons have a legal duty to ensure fire protection measures remain effective.

What is the difference between active and passive fire protection?

Active fire protection systems require activation to operate, such as fire alarms, sprinklers or smoke control systems. Passive fire protection is built into the structure of a building and works continuously without activation to contain fire and smoke.

What are examples of passive fire protection systems?

Examples include fire-resisting compartment walls and floors, fire doors, cavity barriers, fire-stopping seals around service penetrations, and fire dampers within ventilation systems.

How long does passive fire protection last?

Passive fire protection systems are designed to provide specific fire resistance periods, commonly 30, 60 or 120 minutes. Their effectiveness depends on correct installation, compatible materials and ongoing maintenance.

Does passive fire protection need inspection?

Yes. Passive fire protection can be compromised by refurbishment works, service installations or building alterations. Regular inspection and surveys help ensure compartments remain intact and compliant with fire safety legislation.

What happens if passive fire protection fails?

If passive fire protection is breached or defective, fire and smoke can spread rapidly between compartments, compromising escape routes, undermining the fire strategy and increasing life safety risks.