Passive Fire Protection UK — What Builders and Contractors Need to Know (2026)

1. What is Passive Fire Protection?

Passive fire protection is the set of building components designed to prevent or slow the spread of fire and smoke without active intervention. Where active systems (sprinklers, fire alarms, smoke extract) require mechanical or electrical operation to work, PFP works through the building's construction itself — it is always "on".

Key PFP components include:

• Fire-resistant compartmentation — fire walls, floors, and ceilings constructed to contain fire within a defined zone for a specified period
• Fire doors — self-closing doors rated to resist fire and smoke passage for 30 or 60 minutes
• Intumescent products — seals, wraps, and strips that expand when heated to close gaps around pipes, cables, and door edges
• Fire-resistant glazing — glass assemblies tested to resist fire spread in partitions and doors

PFP is a legal requirement. Every new and refurbished building must incorporate it in accordance with the Building Regulations, and every tradesperson on site plays a role in maintaining it.

2. The Building Regulations Context

Part B (Fire Safety) of the Approved Documents to the Building Regulations sets out the requirements for fire safety in England and Wales. Scotland (Technical Handbook) and Northern Ireland (Technical Booklets) have equivalent standards. Part B covers means of escape, internal spread of flame, access for fire services, and external fire spread — all of which involve PFP.

The most practical requirement for contractors is this: every penetration through a fire-rated wall or floor must be fire-stopped to maintain the compartment's rating. Every time a pipe, cable tray, duct, or conduit passes through a fire-rated element, a hole is created. That hole, if left unsealed, will allow fire and smoke to pass through in minutes — destroying the protection the compartment was designed to provide.

This obligation applies to all first- and second-fix trades: electricians, plumbers, mechanical contractors, gas engineers, and anyone else who drills, chases, or cuts into fire-rated construction. It is not the responsibility of the main contractor alone.

3. Compartmentation: What It Means in Practice

A building is divided into fire compartments — rooms, floors, or sections — that should prevent fire from spreading for a defined period. Common ratings are 30 minutes (REI 30), 60 minutes (REI 60), and 120 minutes (REI 120). Residential buildings typically require 60-minute compartmentation between floors. Stairwells and protected routes may require higher ratings.

When a tradesperson drills through a compartment wall or floor — to run a soil pipe, a cable tray, or a heating flow — they break that compartment. The compartment now fails to meet its rated period. The tradesperson who makes the penetration is responsible for restoring it.

In practice, this means:

• Fitting a fire-rated sleeve or intumescent collar around plastic pipes passing through the wall or floor
• Using a certified cable transit system or intumescent sealant around cables
• Applying fire-stopping compound or pillows around larger service openings with multiple penetrants
• Recording the penetration, the product used, and the installer — and keeping that record available for inspection

This is not an optional extra. Leaving penetrations unsealed is a Building Regulations breach, a potential health and safety offence, and a significant liability exposure if fire occurs.

4. Common Passive Fire Protection Products

The market for PFP products is well-developed, with a range of certified solutions for different penetration types. Key products include:

• Intumescent pipe collars and wraps — fitted around plastic pipes (soil pipes, waste pipes, MDPE) where they pass through a rated element. As the pipe melts in a fire, the intumescent material expands to seal the void and restore the compartment's integrity.
• Fire-rated cable transit systems — modular frames fitted into wall or floor openings, accepting multiple cable bundles and providing a tested fire rating around the whole assembly.
• Intumescent sealants — applied around small gaps, service entries, and junctions between walls and ceilings. Available as acrylic or silicone-based products for different substrates.
• Fire-stopping pillows — compressed mineral fibre pillows used in larger openings where multiple pipes and cables run together. Removable and re-usable, which suits ongoing service access.
• Fire-resistant duct insulation and wrap — applied around ductwork passing through rated elements, maintaining the duct's integrity and preventing fire spread through HVAC systems.

All products used must be tested and certified to the relevant standard — typically EN 1366 (testing of service installations) for penetration seals. Major manufacturers include Hilti, Rockwool, Intumex, Nullifire, and Pyroguard. Substituting a cheaper, uncertified alternative is not acceptable and will not satisfy a Building Control inspection.

5. Fire Doors: The Most Common PFP Item on Site

Fire doors are the single most visible PFP element on any construction site. They are also the most commonly failed item in fire safety inspections.

FD30 (30-minute fire door) is the standard for most residential and commercial applications — required between habitable rooms and escape routes in flats, between integral garages and dwellings, and in many commercial settings. FD60 (60-minute) is used in higher-risk or higher-duration areas such as stairwells, plant rooms, and lift lobbies.

Critically, a fire door is the whole assembly — not just the door leaf. The tested assembly includes:

• The door leaf (including core material and facing)
• The door frame and fixings
• Hinges (typically a minimum of three certified hinges)
• Intumescent and smoke seal strips (fitted to the door leaf or frame rebate)
• A self-closing device (mandatory on all fire doors)
• All ironmongery (locks, handles, letterplates) — all must be compatible with the tested assembly

Third-party certification schemes — BM Trada Q-Mark and Certifire — provide assurance that fire door assemblies have been tested and independently verified. Specifying or fitting Q-Mark or Certifire certified doors is best practice and increasingly expected by building control.

Common site failures that invalidate a fire door's rating:

• Incorrect ironmongery not compatible with the tested assembly
• Missing or incorrectly fitted intumescent strips
• Door leaf not fitting the frame correctly — gaps exceeding 3mm around the leaf
• Self-closer removed or disabled
• Door wedged open (a fire safety offence in its own right)
• Hinges not rated or incorrectly positioned

Fitting a fire door is not the same as fitting a standard door. If you are installing fire doors, you should hold relevant competency evidence — FIRAS accreditation is the industry benchmark.

6. Responsibilities on Site

The principle is clear: the tradesperson who makes the penetration is responsible for fire-stopping it. If you drill the hole, you seal the hole. This is not delegable to someone else unless it has been formally agreed as part of the contract.

On managed contracts, there will typically be a Method Statement for fire-stopping that must be followed. This sets out the approved products, the installation method, and the documentation requirements. Deviating from the Method Statement — using a different product, skipping a step — is a contract breach as well as a regulatory one.

The principal contractor should maintain a passive fire protection schedule — a record of all penetrations made, the fire-stopping product used, the installation date, and the installer's identity. This document is increasingly required for Building Safety Act compliance and must be available for inspection by Building Control.

Third-party accreditation for installers of fire-stopping and fire doors is provided by FIRAS (Fire Industry Association scheme). FIRAS-accredited companies and individuals have demonstrated competence through assessment and are subject to ongoing audit. FIRAS accreditation is not yet mandatory in most circumstances, but it is strongly preferred by specifiers and required on some contracts.

7. The Building Safety Act 2022

The Building Safety Act 2022 is the most significant piece of building safety legislation since the Construction (Design and Management) Regulations. Introduced in the wake of the Grenfell Tower fire, it has fundamentally changed the regulatory environment for higher-risk buildings — defined as residential buildings of 7 or more storeys or 18 metres or more in height.

The Act introduces the concept of the golden thread of information — a complete, accurate, and accessible record of all information relevant to the building's safety, maintained throughout design, construction, and occupation. For contractors, this means that fire-stopping records are no longer a nice-to-have. They are a legal obligation that must be demonstrable to the Building Safety Regulator (BSR), a new body with powers to investigate, prosecute, and require remediation.

For in-scope higher-risk buildings, the requirement is explicit: you must be able to show where every fire-stopping penetration was made, what product was used, who installed it, and when. Photographic evidence is expected. Records must be handed over as part of the building's safety case at completion.

Even for lower-risk buildings outside the Act's higher-risk regime, the culture is changing. Building Control bodies are requesting more documentation, clients are requiring photographic evidence of fire-stopping, and contractors who cannot demonstrate their compliance are increasingly at a commercial disadvantage. The direction of travel is clear: document everything.

8. Liability and Insurance

The liability position for contractors who fail to fire-stop correctly is serious. If a fire spreads through a building because of an unsealed penetration or a defective fire door assembly, and that failure can be traced to a specific contractor's work, liability falls on that contractor. This can include civil claims from building owners, occupiers, and insurers, as well as criminal prosecution under the Building Safety Act or the Health and Safety at Work Act 1974.

Professional indemnity and public liability insurance for contractors specifying or installing PFP is increasingly important — and increasingly scrutinised by underwriters. Some insurers now require evidence of third-party accreditation (FIRAS, BM Trada Q-Mark) before they will provide cover for fire-stopping or fire door installation work. Premiums and indemnity limits can be materially affected by whether a contractor holds accreditation.

FIRAS accreditation provides a documented record of competence. In the event of a claim or investigation, being able to demonstrate that your operatives were assessed as competent and that your installations were carried out in accordance with a tested system specification significantly strengthens your position. It is not a guarantee, but it is the best available evidence.