The Hidden Dangers of Poor Fire Compartmentation

Written by Peter Thompson

Introduction

In fire safety, compartmentation often works behind the scenes – out of sight, rarely considered – until disaster strikes. But when fire and smoke spread unchecked through weak Compartment lines and voids, the consequences can be devastating leading to greater damage, higher risk to life, and failure to meet regulations. 

Let us explore why compartmentation matters, what common failures to look for, and how to carry out basic checks on your building’s compartmentation.

Why Compartmentation Matters

Fire compartmentation is the practice of dividing a building into self-contained sections (compartments) using fire-resistant walls, floors, ceilings, doors, (and penetrations removed). Its main purposes are:

  • Delay the Spread of Fire and Smoke
    By isolating each area, compartmentation helps contain a fire long enough for occupants to escape and for emergency services to respond.
  • Protect Escape Routes
    Corridors, stairwells, lift shafts and other escape paths must be protected from fire intrusion. Proper compartmentation ensures these are not compromised.
  • Reduce Property Damage and Business Interruption
    Limiting fire spread confines damage to a smaller area, reducing repair cost and downtime.
  • Meet Regulatory Requirements
    Building codes and fire safety regulations require certain levels of compartmentation depending on building use, height and occupancy.

In short: good compartmentation is a critical layer of passive fire protection that buys time: time to evacuate, to fight the fire, and to prevent a catastrophe.

Common Failures in Compartmentation

Even when buildings are designed with compartmentation in mind, execution and maintenance issues can undermine it. Some of the most frequent failures are:

  • Holes, gaps and breaches
    Every service penetration — pipes, cables, ducts, conduits — is a potential weak point. If not properly sealed with fire-rated collars, wraps or firestop systems, holes let fire and smoke pass quickly from one compartment to another.
  • Poorly sealed joints and movement gaps
    Junctions between walls and floors, junctions around service risers, and control joints may not be sealed correctly. Over time, materials settle, joints move, or sealants degrade, creating gaps.
  • Inadequate fire doors or frames
    A fire door that doesn’t fully close, or a frame that’s not properly sealed, undermines a compartment boundary. Vision panels, ironmongery and gaps around doors are common weak spots.
  • Improper or unqualified repairs
    After renovations or maintenance, penetrations may be patched without using fire-rated materials or following approved firestop systems. “Temporary” fixes become long-term vulnerabilities.
  • Deterioration, corrosion or damage
    Materials age. Firestopping coatings may degrade, collars corrode, sealants shrink or crack. Damage from accidental knocks, drilling, or repurposing can also introduce weaknesses.
  • Misuse of non-fire rated products
    Using standard plasterboard, non-rated sealants, or regular insulation in a fire compartment boundary rather than materials rated for fire resistance is a serious error.

Each of these failures can turn a supposedly protected compartment into an open pathway, enabling smoke and fire to spread faster than anticipated.

How to Check Your Building’s Compartmentation

You don’t need to be a specialist to perform a preliminary check of compartmentation, though for full compliance you should engage fire engineers or certified inspectors. Here’s a guide to basic checks you (or your facilities team) can carry out:

  • Study the building’s fire strategy or compartmentation drawing
    If available, compare the as-built plan to actual walls, floors and penetrations to see where compartments are supposed to exist.
  • Walk the escape routes and compartment boundaries
    Carry a flashlight and spend time in corridors, stairwells and service risers. Look out for:
    • Pipes, cables, ducts passing through walls or floors
    • Gaps around services or between structural elements
    • Open or damaged fire doors
    • Beams or soffits that reduce fire rating and are not protected
  • Check all penetrations and service routes
    Every pipe, cable tray, junction box, conduit, ducts that cross a compartment boundary should have proper firestopping. Look for patches, collars, wraps, intumescent seals, fire-rated caulk, etc. If you see penetrations sealed with non-fire rated materials (e.g. standard mastic, filler, cardboard) that’s a red flag.
  • Inspect fire doors and door frames
    Check whether fire doors close fully and latch. Inspect the edges for gaps, sealing strips, intumescent strips. Look at the hinges, closers, thresholds — all should be undamaged and appropriate for fire doors.
  • Look for signs of wear, damage or ad hoc repairs
    Cracks in walls, gaps at joints, chipping of sealants, damage from maintenance work, or patches with mismatched materials can indicate poor compartment integrity.
  • Test smoke passage (if safe)
    Under controlled, small-scale conditions (or with a smoke pen) you can check whether smoke passes through a joint or gap. This is illustrative, not conclusive.
  • Engage professional fire stopping / compartmentation surveys
    A qualified inspector can carry out integrity testing (e.g. pressure tests, smoke tests, thermography) and verify compliance to standards (e.g. EN 1366 / ISO firestop standards, local building/fire Legislation).

Conclusion & Key Takeaways

Poor fire compartmentation is a silent but serious threat. While you may never see smoke or flames in your walls, the risks are real: failure to contain fire, danger to life, increased damage and regulatory liability.

To guard against these risks:

• Recognise that compartmentation is as important as active fire systems (sprinklers, alarms)
• Be vigilant for holes, gaps, degraded seals, and improper repairs
• Carry out regular inspections (internally or via professionals)
• Ensure all modifications or refurbishments maintain fire integrity
• Document inspections and remedial works for compliance and accountability
Contact us to discuss your Fire Compartmentation requirements or concerns.

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