What is fire stopping in construction?

Fire-resisting walls and floors are a key part of a building’s fire strategy. They are designed to resist fire for a specified period and to limit the spread of fire and smoke between compartments, protecting escape routes and supporting evacuation.

These elements are penetrated not only during construction, but also during refurbishment, maintenance and later service installation. If those openings are not properly treated, the fire performance of the wall or floor can be reduced.

This is where fire stopping becomes critical. Sharpfibre delivers fire-stopping systems in line with recognised standards, tested details and the compliance requirements that apply throughout the building lifecycle.

What is fire stopping and why does it matter?

Fire stopping sits within the broader principle of compartmentation. UK buildings are designed in sections or “compartments”, each intended to resist fire for a set duration, often 30, 60 or 120 minutes. The purpose is to contain fire within one area, giving occupants time to evacuate and limiting structural damage.

Approved Document B of the Building Regulations states that openings where services pass through fire-resisting elements should be adequately sealed to maintain fire resistance. In practice, this means using systems tested to provide the required level of fire performance, typically integrity (E), which limits the passage of flames and hot gases, and, where required, insulation (I), which restricts heat transfer to the unexposed side.

Without appropriate fire stopping systems, fire and smoke can travel through concealed routes such as ceiling voids, risers or service shafts. Smoke spread in particular presents a serious life safety risk. This is reflected in the Home Office’s fire safety guidance for those with legal duties under the Regulatory Reform (Fire Safety) Order 2005, which explains that Responsible Persons must put in place and maintain general fire precautions.

How fire stopping became central to modern construction

Compartmentation has long been embedded in UK building design. Fire-resisting walls and floors were traditionally relied upon to limit the spread of fire between areas of a building. Earlier construction methods involved fewer service penetrations, and the integrity of compartments was generally easier to maintain.

As buildings became more complex, the volume of mechanical and electrical services increased significantly. Cable containment, ductwork and pipework now pass repeatedly through structural elements, and similar issues arise when existing buildings are refurbished, repurposed or upgraded. Each opening formed for services must be treated so that the fire resistance of the wall or floor is maintained.

This has made fire stopping a more defined part of compliance and fire safety design. BS 9999:2017, a British Standard for fire safety in the design, management and use of buildings, takes a risk-based approach and addresses the role of fire-resisting construction and compartmentation within the wider fire strategy. Products are also expected to carry third-party test evidence and classification under BS EN 13501-2, the European standard used to classify fire resistance performance, with installation following the assessed system detail.

Common fire stopping methods in buildings

Pipes and cables

For smaller cable penetrations, fire-rated sealants, mastics or putty-based systems may be used where they are tested for the relevant detail. Standards such as BS EN 1366-3 set out the fire resistance test method for penetration seals. Performance depends on the way the system is installed, including the size of the opening, the substrate and the arrangement of services.

Mixed service penetrations

In risers and plant areas, a single opening may contain several services grouped together. Fire-stopping boards or coated mineral fibre batts are often used here because they can close larger openings while allowing multiple services to pass through. Sealants are then applied around individual services to close smaller gaps. As with other systems, performance depends on the assessed arrangement.

Ductwork and fire dampers

Where ventilation ductwork passes through a fire-resisting wall or floor, fire dampers may be required to help maintain compartmentation. These are designed to close under fire conditions and limit the passage of fire through the duct. Their specification and installation should align with the relevant tested system and the wider fire strategy.

Floors, ceilings and movement joints

Fire stopping is not limited to service penetrations. Linear joints between floors and walls, and movement joints within slabs, also form part of the compartment line and require appropriate treatment.
Because these joints may be designed to accommodate movement over time, the system used must maintain fire performance while allowing for that movement. Linear joint seal systems are typically tested in accordance with BS EN 1366-4. Selection depends on joint width, expected movement and the surrounding construction, and the installed detail should match the arrangement that was fire tested.

Materials and products used in fire stopping

The proprietary fire stopping systems used will vary depending on the opening, substrate and required fire resistance period. Typical systems include:

• Intumescent sealants
• Fire-rated foams and mortars
• Pipe collars and wraps
• Mineral fibre boards with ablative coatings
• Linear joint seal systems

Fire resistance performance relates to the tested system detail. Ratings are based on testing to standards such as the BS EN 1366 series and classified under BS EN 13501-2. Installation guidance reflects the conditions under which the system was assessed, including substrate type, service layout and opening size.
This is where specialist oversight becomes significant. The selection and installation of fire stopping should align with the building’s fire strategy and the documented fire resistance requirements of each compartment.

How fire protection regulations shape fire stopping

Key regulatory framework

In England and Wales, the Building Regulations 2010 establish functional requirements for fire safety. Scotland and Northern Ireland operate under their own building standards, with similar principles of compartmentation and penetration sealing.
The Regulatory Reform (Fire Safety) Order 2005 applies once a building is in use. It requires that fire precautions, including passive systems, are maintained. In higher-risk residential buildings, the Building Safety Act 2022 has introduced additional accountability and documentation obligations.
Together, these frameworks influence how fire stopping is specified, installed and recorded in construction.

Responsibility for compliance

Designers are expected to incorporate appropriate fire stopping details into drawings and specifications, and contractors and specialists are responsible for installing systems in line with tested data and manufacturer guidance.
Once occupied, the Responsible Person must ensure that fire precautions remain effective. Alterations, additional services or refurbishment works should be assessed to confirm that compartmentation has not been compromised.

Signs of potential non-compliance

From an inspection perspective, common issues can include:

• Unsealed service penetrations
• Use of unsuitable materials in fire-resisting elements
• Damage following maintenance work

Addressing these concerns early helps to maintain alignment with the building’s original fire strategy.

A measured, system-led approach

When considered carefully, fire stopping is about preserving the compartmentation strategy on which the building’s fire performance depends. Each penetration, joint or interface is a point where the continuity of that fire-resisting construction must be maintained so that fire and smoke are contained as intended.

Effective fire stopping sits within a broader passive fire protection strategy, informed by regulation, supported by recognised standards and delivered through competent installation.
For organisations seeking clarity in this area, Sharpfibre brings technical understanding of tested systems, regulatory context and practical site application. In a discipline where small details can influence overall performance, that structured approach supports safer and more accountable outcomes.

To discuss your requirements or review existing fire-stopping arrangements, contact Sharpfibre for technical advice grounded in current standards and construction practice.