Why Fire Compartmentation Matters (and What Happens When It Goes Wrong)
- Apr 9
- 3 min read
Fire compartmentation is one of the most important parts of a building’s fire safety - but it’s also one of the most commonly overlooked.
In simple terms, compartmentation is what stops fire and smoke from spreading throughout a building. When it’s working properly, it protects escape routes, limits damage, and gives people time to get out safely.
The problem is, in many buildings, it’s either not installed correctly or it’s been compromised over time.
What is compartmentation actually doing?
Buildings are designed to be divided into fire-resisting sections, known as compartments. These are made up of walls, floors, and doors that are built to hold back fire for a set period - usually 30, 60, or 120 minutes.
When this works as intended:
Fire is contained to the area where it starts
Corridors and stairwells remain usable for escape
Firefighters can operate more safely
Damage is limited
This all relies on one thing - everything being properly sealed and maintained.
What we commonly find on site
In reality, compartmentation is often compromised without anyone realising. Some of the most common issues we come across include:
Missing or poorly installed fire stopping - Openings for pipes, cables, and ductwork are left unsealed - or filled with the wrong materials. This creates hidden routes for fire and smoke to spread.
Fire doors not performing as they should - Fire doors are a key part of the system, but we often see gaps around frames, missing seals, or doors not closing properly.
Hidden breaches in voids and risers - Ceiling voids and service risers are areas where problems often go unnoticed. These spaces can allow fire to travel quickly through a building if they’re not properly protected.
Image 1 (L) - Ceiling void containing multiple services with little or no effective fire stopping. These hidden spaces can allow fire to travel unseen through a building.
Image 2 (R) - Larger view of a ceiling void showing the complexity of services and the difficulty in maintaining compartmentation without proper inspection and control.
Poor workmanship or incorrect products - We regularly see fire stopping that looks fine on the surface but hasn’t been installed correctly—or isn’t suitable for the required fire rating.
Follow-on works damaging compartmentation - One of the biggest causes of problems is work carried out after the original installation. New services get added, holes are drilled, and fire stopping is removed - but not properly reinstated.
Over time, this can seriously weaken the building’s fire protection.
Why this is a problem
When compartmentation isn’t working properly, fire and smoke can spread much faster than the building was designed for.
That can mean:
Less time for people to escape
Smoke spreading into protected routes
Increased damage to the building
Greater risk for firefighting crews
Potential compliance issues
And in many cases, these issues aren’t visible without a proper inspection.
What can be done
The only way to be sure is through inspection.
A compartmentation survey helps to:
Identify defects and breaches
Highlight higher-risk areas
Provide clear recommendations
Support compliance with fire safety requirements
Depending on the building, this may involve non-intrusive checks or more detailed intrusive inspections.
Final thoughts
Compartmentation isn’t something that can be installed and forgotten about.
It needs to be:
Done properly in the first place
Checked regularly
Maintained over time
When it’s right, it does exactly what it’s meant to - contain fire, protect escape routes, and ultimately save lives.
If you’re unsure about the condition of your building, it’s always worth getting it checked.
If you require a compartmentation survey in London or would like advice on your building’s fire safety, our team is here to help. We will advise on the appropriate level of inspection and support you from survey through to remedial works.
Contact us today to arrange a survey or discuss your requirements.
