Fire Stopping and Penetration Seals

What This Requirement Covers

Fire stopping seals the gaps created when services (pipes, cables, ducts, and trays) pass through fire-resisting elements such as compartment walls, compartment floors, and protected corridors. Without effective fire stopping, fire and smoke can spread through the building via these concealed routes, bypassing compartmentation.

Approved Document B requires that all openings in fire-resisting elements are sealed to maintain the fire resistance of the element.

Key Requirements

Service Penetrations

1. Every pipe, cable, duct, or conduit passing through a fire-resisting wall or floor must be fire-stopped to maintain the fire resistance period of the element
2. Fire stopping must be tested to BS EN 1366-3 (penetration seals) and classified to BS EN 13501-2
3. The fire-stopping product must be compatible with the service type, size, and the construction through which it passes
4. Proprietary fire-stopping products (intumescent collars, wraps, pillows, sealants, mortar, and batts) must be installed in accordance with the manufacturer's tested details

Linear Joint Seals

1. Joints between fire-resisting elements (e.g., the junction of a compartment wall and a concrete floor) must be sealed with fire-resistant sealant or board
2. Linear joint seals must be tested to BS EN 1366-4 and achieve the same fire resistance as the elements being joined

Cavity Barriers

1. Cavities within or between fire-resisting elements must be closed with cavity barriers at:

- The junction of compartment walls with external wall cavities - At intervals not exceeding 20 metres in concealed roof spaces (or 8 metres in specific situations) - At the edges of all cavities, around window and door openings in cavity walls

1. Cavity barriers must achieve at least 30 minutes fire resistance or be constructed of non-combustible material at least 38 mm thick

Ductwork

1. Ducts passing through fire-resisting elements require either:

- A fire damper compliant with BS EN 15650 at each penetration, or - The duct itself constructed to achieve the fire resistance of the element it penetrates

1. Fire dampers must be accessible for testing and maintenance

Third-Party Certification

1. Approved Document B recommends that fire stopping is installed by operatives certificated under a third-party scheme
2. Recognised schemes include FIRAS (Warrington Fire), IFC Certification, and BRE Global
3. Third-party certification provides evidence of competence for Building Control and for the building's fire safety file

Practical Compliance Tips

1. Specify fire-stopping products at design stage and include them in the project specification; do not leave selection to the installing subcontractor
2. Photograph all fire stopping before it is concealed by finishes; date-stamped photographs provide evidence for Building Control and the building safety case
3. Use a single fire-stopping system throughout the project where possible to simplify quality assurance
4. Ensure fire-stopping operatives have the correct training and third-party certification for the products they are installing
5. Programme fire-stopping inspections into the construction schedule; inspect before plasterboard or ceiling installation
6. Fire stopping around plastic pipes requires intumescent products that will close the void when the pipe melts in a fire
7. Keep a fire-stopping register recording the location, product used, operative, and date of installation for every seal