What Is Fire Stopping?

Fire stopping is a critical part of a building’s passive fire protection strategy. It refers to the process of sealing gaps, joints and penetrations in fire-resisting walls, floors and ceilings so that fire, heat, smoke and toxic gases cannot spread through them.

By containing fire and smoke within defined compartments, fire stopping helps protect escape routes, slows fire development and gives occupants and firefighters more time to respond.

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

Quick Answer: What Is Fire Stopping?

Fire stopping is the sealing and reinstatement of gaps, joints and service penetrations in fire-resisting walls and floors to prevent fire and smoke spreading between compartments. It ensures the wall or floor maintains its designed fire resistance.

Why Fire Stopping Matters

Fire stopping is vital because even small gaps can allow fire and smoke to spread quickly through a building. Smoke inhalation is one of the leading causes of fire-related deaths, and unchecked fire spread can make escape routes unusable.

Failed or missing fire stopping undermines fire compartmentation and can:

• Render escape routes unsafe
• Invalidate part of the fire strategy
• Lead to enforcement action or prosecution
• Increase the risk of injury, death and property loss

What Fire Stopping Actually Does

Fire stopping works by closing gaps and penetrations in fire-resisting elements so that the wall or floor retains its fire resistance. Examples include:

• Penetrations for pipes and ductwork
• Cable and data risers
• Conduits and flues
• Construction joints
• Voids around doors or transfer beams

Fire stopping systems generally fall into two main categories:

• Penetration seals – used around pipes, cables, ducts and other services passing through fire-resisting walls or floors.
• Linear joint seals – used between walls, floors and structural elements where movement or construction joints occur.

Both types are essential to maintain the integrity and insulation performance of fire-resisting construction.

Fire stopping maintains the integrity of compartment lines shown on fire strategy drawings.

Without proper fire stopping, fire and smoke can spread around the rated assembly even if the wall or floor itself remains intact.

Fire Stopping in Passive Fire Protection

Fire stopping is a component of passive fire protection (PFP) — systems that work continuously, without activation, to prevent fire spread. Passive fire protection includes fire-resisting walls, floors, fire doors, cavity barriers and fire stopping.

Together, these elements help:

• Maintain fire compartments
• Protect escape routes
• Provide time for evacuation
• Reduce structural damage

Unlike active fire protection systems such as alarms or sprinklers, passive fire protection works continuously without activation, forming part of the building’s structural fire resistance.

Common Fire Stopping Materials

The materials and systems used in fire stopping vary depending on the type and size of the penetration:

• Fire-resistant sealants and mortars
• Intumescent wraps and collars for pipes
• Fire-rated foam
• Fire-stop pillows or boards
• Fire-rated putty pads and wraps

These materials are tested and certified to specific fire resistance standards.

Fire stopping systems are typically tested to standards such as BS 476 and BS EN 1366, which assess integrity (E) and insulation (I) performance for defined fire resistance periods (e.g. EI30, EI60 or EI120).

Fire stopping systems must be installed in accordance with the specific tested system configuration; substituting products or altering installation details can invalidate fire test evidence.

Legal and Regulatory Context in the UK

Fire stopping is mandatory under UK building safety law and fire safety regulations:

Building Regulations & Approved Document B

Under the Building Regulations, fire stopping is required where penetration or gaps occur in fire-resisting structures. Approved Document B sets out guidance on how this must be achieved to maintain fire resistance.

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

Regulatory Reform (Fire Safety) Order 2005

The Responsible Person must ensure that fire precautions — including fire stopping — are maintained and remain effective over time.

Building Safety Act & Golden Thread Requirements

In higher-risk buildings, the Building Safety Act 2022 requires duty holders to maintain clear records (a golden thread) of fire stopping design, installation and maintenance from design through to occupation.

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

Common Fire Stopping Failures (and Why They Matter)

During inspections the most frequent issues include:

• Incorrect or missing fire-stop materials
• Gaps re-opened after maintenance or refurbishment
• Service penetrations not reinstated properly
• Poor workmanship or incorrect product selection
• Lack of documentation or evidence of compliance

Even a small unsealed gap can compromise a compartment’s fire resistance, defeating the purpose of passive fire protection.

When a Fire Stopping Survey Is Needed

Fire stopping surveys are typically required when:

• A fire risk assessment identifies potential breaches
• Building work, refurbishment or services installation has occurred
• Documentation is incomplete or missing
• Enforcement authorities request verification
• You manage a higher-risk residential or commercial building

A professional fire stopping survey identifies:

• Where fire stopping is required
• Where it is missing, defective or not compliant
• Remedial actions needed
• Documentation to support compliance

Where Fire Stopping Is Most Commonly Needed

Fire stopping is required wherever a fire-resisting element has been penetrated — for example:

• M&E services passing through walls or floors
• Door frames and structural connections
• Voids between compartments
• Stairwell enclosures
• Shaft walls and risers

Proper fire stopping restores the fire resistance of the element it penetrates.

Tips for Responsible Persons and Duty-Holders

• Use third-party tested fire stopping products
• Ensure installation by competent personnel
• Keep detailed records for compliance evidence
• Include fire stopping in risk assessments
• Inspect after maintenance, refurbishment or upgrades

Where possible, use third-party certified installers (such as FIRAS or BM TRADA approved contractors) and maintain documentation to support compliance and golden thread requirements.

Conclusion

Fire stopping is a vital part of building fire safety — a passive system that keeps fire and smoke where they start, protects escape routes, and provides essential time for occupants and emergency responders.

Failure to install or maintain effective fire stopping can compromise the entire fire safety strategy and expose occupants to serious risk.

If you’re unsure whether your fire stopping measures are adequate, a professional fire stopping survey will assess compliance and identify any remedial work needed.

Frequently Asked Questions

What is fire stopping in simple terms?

Fire stopping is the sealing of gaps, joints and service penetrations in fire-resisting walls and floors to prevent fire and smoke from spreading between compartments. It restores the fire resistance of a wall or floor where it has been breached.

Is fire stopping a legal requirement in the UK?

Yes. Fire stopping is required under Building Regulations (Approved Document B) wherever fire-resisting construction is penetrated. It must also be maintained under the Regulatory Reform (Fire Safety) Order 2005 as part of ongoing fire safety management.

What is the difference between fire stopping and fire compartmentation?

Fire compartmentation divides a building into fire-resisting sections. Fire stopping protects those compartments by sealing any gaps or penetrations that would otherwise allow fire and smoke to spread through walls or floors.

What materials are used for fire stopping?

Common fire stopping materials include fire-resistant sealants, intumescent collars, fire-rated mortars, fire boards, fire-stop pillows and wraps. The correct product depends on the type of service penetration and the required fire resistance period.

Can fire stopping fail over time?

Yes. Fire stopping can be compromised by building movement, refurbishment works, new service installations or poor workmanship. Even small gaps can significantly reduce the fire resistance of a compartment.

When is a fire stopping survey required?

A fire stopping survey may be required following refurbishment, where documentation is missing, if a fire risk assessment raises concerns, or when managing higher-risk residential or commercial buildings. Surveys identify missing or defective fire stopping and recommend remedial action.

What is the difference between fire stopping and cavity barriers?

Fire stopping seals penetrations and joints in fire-resisting elements. Cavity barriers close concealed voids within walls and floors to prevent hidden fire spread. Both are forms of passive fire protection and support effective compartmentation.