Fire Stopping: Why You Need It and Why It Matters
Fire stopping is the unsung hero of building safety. Hidden inside walls and floors, it silently prevents fire and toxic smoke from spreading through a building — protecting lives and buying critical time for evacuation. Here is everything building owners and managers need to know.
In short: Fire stopping is the system of tested materials used to seal openings where services — pipes, cables, ducts and conduits — pass through fire-rated walls, floors and ceilings. Every penetration is a hole in the building's fire resistance, and without a correct seal it becomes a direct route for fire, smoke and toxic gases to bypass compartmentation entirely. It is a legal requirement under the Regulatory Reform (Fire Safety) Order 2005, Approved Document B of the Building Regulations, the Fire Safety Act 2021 and the Building Safety Act 2022. Because the defects sit inside walls and floors, they are usually only found by survey.
What Is Fire Stopping?
Fire stopping is a system of materials used to seal openings and penetrations in fire-rated building elements — walls, floors and ceilings — through which services such as pipes, cables, ducts and conduits pass.
Every time a service passes through a fire-rated element, it creates a penetration: a hole in the fire-resistant structure of the building. Without appropriate fire stopping, that penetration becomes a direct route for fire, smoke and toxic gases to travel between fire compartments — bypassing all of the fire resistance built into the walls and floors.
A correctly installed fire stop restores the fire resistance of the element at the point of penetration. When exposed to fire, fire stopping materials expand, harden or otherwise activate to seal the gap and prevent fire spread.
What Is Fire Compartmentation?
To understand why fire stopping matters, you first need to understand fire compartmentation. Buildings are divided into fire compartments — self-contained sections bounded by fire-rated walls, floors and ceilings. The purpose of compartmentation is to contain a fire within the compartment where it starts.
Effective compartmentation means:
- Fire and smoke are contained, limiting damage to the affected area
- Occupants in other parts of the building have more time to evacuate safely
- Fire services have more time to respond and control the fire
- The structural integrity of the building is better preserved
Fire stopping is what maintains that compartmentation at every service penetration. A building can have perfect fire-rated walls and floors, but if the penetrations are not properly sealed, the compartmentation is compromised.
Where Is Fire Stopping Required?
Fire stopping is required wherever a service passes through a fire-rated element. Common locations include:
Does Your Building Have Compliant Fire Stopping?
Fyrup carries out fire stopping surveys and remediation across London and the South East.
The Legal Requirement
Fire stopping is a legal requirement under several pieces of UK legislation and guidance:
Regulatory Reform (Fire Safety) Order 2005
The responsible person for any non-domestic building must carry out a fire risk assessment and implement appropriate fire safety measures, including maintaining the integrity of fire compartmentation and all penetration seals.
Building Regulations 2010, Approved Document B
Sets the fire performance requirements for buildings, including compartmentation and the sealing of service penetrations. New buildings and those undergoing relevant building work must comply.
Building Safety Act 2022
Introduced significantly strengthened duties for higher-risk residential buildings, with the Building Safety Regulator overseeing compliance. Fire stopping quality and documentation are explicitly within scope.
Fire Safety Act 2021
Extended fire safety duties for multi-occupied residential buildings to include the structure, external walls and all flat entrance doors — with implications for compartmentation and fire stopping throughout.
Common Fire Stopping Failures
Fire stopping defects are found in a significant proportion of buildings during surveys. The most common failures include:
The Hidden Nature of Fire Stopping Defects
Unlike a missing fire door or a blocked exit, fire stopping defects are usually invisible without an intrusive survey. They exist inside walls and floors, often concealed by decoration or finishes. A building can look perfectly maintained and still have significant fire stopping deficiencies that would allow fire to spread freely between floors and compartments.
What Does a Fire Stopping Survey Involve?
A fire stopping survey involves a systematic inspection of the building to identify all service penetrations through fire-rated elements and assess the adequacy of the fire stopping installed. This will typically involve:
- Review of available as-built drawings and service layouts
- Physical inspection of accessible wall and floor penetrations
- Where necessary, minor intrusive investigation to access concealed penetrations
- Assessment of installed fire stopping against the manufacturer's tested system data
- Photographic recording of all penetrations — compliant and defective
- A written report identifying all defects with priority classifications
- Recommendations for remediation with specification for appropriate products and systems
Who Needs a Fire Stopping Survey?
Residential Buildings
Blocks of flats and houses in multiple occupation (HMOs) — particularly following the Fire Safety Act 2021 and Building Safety Act 2022.
Commercial Properties
Offices, retail units and mixed-use buildings where significant services pass through compartment walls and floors.
Healthcare Facilities
Hospitals and care homes with complex service distributions and high-risk occupancies.
Post-Refurbishment
Any building where services have been altered, extended or added since original construction.
Fire Incidents
Following any fire, however minor — to assess whether compartmentation has been compromised.
Pre-Purchase Due Diligence
Buyers and lenders increasingly require evidence of fire stopping compliance as part of property transactions.
Frequently Asked Questions
What is fire stopping?
Fire stopping is a system of tested materials used to seal openings and penetrations in fire-rated walls, floors and ceilings, wherever services such as pipes, cables, ducts and conduits pass through them. When exposed to fire, the materials expand, harden or otherwise activate to seal the gap and restore the fire resistance of the element at that point.
Why does fire stopping matter?
Buildings are divided into fire compartments so that a fire is contained where it starts. Every service penetration is a hole through that boundary. Without correct fire stopping, fire, smoke and toxic gases travel straight between compartments and bypass all the fire resistance designed into the walls and floors — which means less time for occupants to evacuate and for the fire service to respond.
Is fire stopping a legal requirement in the UK?
Yes, under several pieces of legislation. The Regulatory Reform (Fire Safety) Order 2005 requires the responsible person to maintain the integrity of compartmentation and penetration seals. Approved Document B of the Building Regulations 2010 sets the fire performance requirements for new work. The Fire Safety Act 2021 extended duties in multi-occupied residential buildings, and the Building Safety Act 2022 brought fire stopping quality and documentation explicitly within the Building Safety Regulator’s scope for higher-risk buildings.
Where is fire stopping required?
Wherever a service passes through a fire-rated element. Common locations include pipes through fire-rated floors between flats, cables and cable trays through fire walls, ventilation and HVAC ductwork, electrical conduits through compartment walls, soil and drainage pipes, data cabling, structural beam and column penetrations, and gaps around window and door frames in fire-rated walls.
What is the difference between fire stopping and compartmentation?
Compartmentation is the division of a building into self-contained sections bounded by fire-rated walls, floors and ceilings. Fire stopping is what maintains that compartmentation at every point where a service penetrates it. A building can have perfectly specified fire-rated walls and floors and still have compromised compartmentation if the penetrations through them are not properly sealed.
Can you use expanding foam for fire stopping?
Not standard expanding foam. Using it in place of a tested fire stopping product is one of the most common defects found during surveys. Fire stopping has to be a product tested for the specific application and installed within the manufacturer’s tested system parameters — the right product for the service type, correctly sized, and correctly fitted.
What are the most common fire stopping failures?
Standard expanding foam used instead of a tested product; penetrations left entirely unsealed after services were installed; the wrong product for the service type, such as an incorrect collar size for the pipe diameter; installation outside the manufacturer’s tested parameters; historic penetrations never sealed in the first place; new services run through existing seals without reinstatement; and seals damaged by later construction, maintenance or redecoration.
How are fire stopping defects found?
Usually only by survey. Unlike a missing fire door or a blocked escape route, fire stopping defects are concealed inside walls and floors and behind finishes, so a building can look perfectly maintained while having deficiencies that would let fire spread freely between floors and compartments.
Is Your Building's Fire Stopping Up to Standard?
Fyrup's passive fire protection specialists carry out fire stopping surveys, produce detailed written reports and carry out remediation work to restore compartmentation compliance across London and the South East.