Ensuring Fire Compartmentation Compliance
Fire does not respect design intent, budgets, or assumptions. It only respects barriers that work.
That is the fundamental reason why fire compartmentation sits at the heart of UK fire safety legislation. When done correctly, it buys time - time for occupants to escape, time for fire and rescue services to intervene, and time to prevent a localised incident from becoming a catastrophic failure.
Yet, despite clear guidance in Approved Document B, failures in passive fire protection remain one of the most common and dangerous compliance issues found on UK construction projects.
This article explains what fire compartmentation is, why it matters, and how to achieve compliance through proven passive fire protection measures, including fire dampers, fire doors, and fire-stopping systems.
What Is Fire Compartmentation?
Fire compartmentation is the practice of dividing a building into fire-resistant compartments using walls, floors, and protected shafts. Each compartment is designed to contain fire and smoke for a specified period, typically 30, 60, 90, or 120 minutes.
Approved Document B makes this intent clear under Requirement B3, which requires buildings to be constructed so that, in the event of fire:
- The premature collapse of the building is avoided
- Fire and smoke spread within the building is restricted
- Fire spread between adjoining buildings is limited
In simple terms: fire compartmentation turns one big problem into a series of smaller, manageable ones.
Without it, smoke and flame travel rapidly through voids, service penetrations, and ventilation systems—often unseen until escape routes are compromised.
Passive Fire Protection: The Silent System That Must Never Fail
Passive fire protection (PFP) differs fundamentally from active systems like sprinklers or alarms.
It does not rely on activation, power, or human intervention. It must work automatically, every time, under extreme conditions.
Key passive fire protection measures include:
- Fire-resisting compartment walls and floors
- Fire doors and door sets
- Fire-stopping around service penetrations
- Cavity barriers
- Fire dampers within ventilation and ductwork systems
Approved Document B is explicit that openings in compartmentation must not compromise fire resistance, particularly where mechanical services pass through fire-separating elements.
This is where many buildings fail—not in design drawings, but in execution.
Fire Dampers: A Critical Line of Defence in Ventilation Systems
Ventilation systems are essential for modern buildings. They are also one of the most common pathways for fire and smoke spread.
Where ductwork passes through compartment walls or floors, fire dampers are required to maintain the integrity of the fire-resisting barrier.
Approved Document B clearly states that mechanical ventilation and air-conditioning systems must not allow fire or smoke to bypass compartmentation.
What Does a Fire Damper Actually Do?
A fire damper is designed to:
- Remain open during normal operation
- Automatically close when exposed to heat, typically via a fusible link
- Seal the duct opening to prevent the passage of fire and hot gases
When specified, installed, and maintained correctly, fire dampers restore the fire resistance of the wall or floor they penetrate.
FD Series Fire Dampers: Designed for Compartment Integrity
The FD Series Fire Damper, supplied by Inbuild and developed by BSB Engineering is engineered specifically to meet these requirements.
The FD Series features the following specifications:
- Is tested to BS EN 1366-2 (fire resistance testing for fire dampers)
- Is classified to BS EN 13501-3 with an E (Integrity) rating
- Complies with BS EN 15650, the fire damper product standard
- Is tested in both vertical and horizontal orientations
- Is suitable for installation in masonry walls, drywall partitions, and concrete floors
Crucially, the FD Series is installed as tested, a requirement that Approved Document B and Building Control bodies consistently emphasise.
A compliant product installed incorrectly is not compliant.
Installation: Where Compliance Is Won or Lost
One of the most common misconceptions in passive fire protection is that product certification alone guarantees compliance. It does not. Approved Document B repeatedly stresses that openings, penetrations, and service installations must be detailed and constructed so they do not reduce fire resistance.
For fire dampers, this means:
- Installing only in tested supporting constructions
- Following manufacturer-approved installation methods
- Maintaining correct clearances, fixings, and fire-stopping details
- Avoiding unauthorised site modifications
The FD Series supports a wide range of tested installation variants, including angle frame, HEVAC frame, and cleat and drop-rod methods, helping contractors achieve compliance without improvisation.
Fire Doors, Fire-Stopping, and the Weakest-Link Problem
Fire compartmentation is only as strong as its weakest detail. Approved Document B includes extensive guidance on:
- Fire door sets (Appendix C)
- Protection of openings and fire-stopping
- Service penetrations and shafts
Common failures include:
- Missing or incorrectly fitted fire-stopping
- Fire doors wedged open or poorly maintained
- Unsealed service upgrades carried out post-completion
Fire dampers are often installed correctly during construction, only to be compromised later by undocumented alterations.
This is why fire safety information under Regulation 38 is critical. Building owners must be provided with accurate records of installed fire protection systems so they can be inspected, maintained, and preserved throughout the building’s life.
Compliance Is Not Optional, It Is a Legal Duty
Approved Document B is statutory guidance supporting the Building Regulations 2010. While alternative solutions may be acceptable, the burden of proof lies with those responsible for the building work. Designers, contractors, installers, and building owners all carry responsibility.
Failure to comply can result in:
- Building Control refusal or enforcement action
- Costly remedial works
- Invalidated insurance
- Prosecution under the Regulatory Reform (Fire Safety) Order
Passive fire protection is not an area for shortcuts. It is an area for discipline, documentation, and tested systems.
Best Practice Checklist for Fire Compartmentation Compliance
To achieve robust, defensible compliance:
- Design compartmentation early, do not treat it as a coordination afterthought
- Specify tested passive fire protection products, including fire dampers
- Install products exactly as tested and approved
- Maintain clear records for Regulation 38 handover
- Inspect and maintain fire dampers, doors, and fire-stopping throughout the building lifecycle
Products like the FD Series Fire Damper support this approach by combining certified performance, installation flexibility, and standards compliance helping ensure that compartment lines remain intact when they matter most.
At Inbuild, the focus is not simply on supplying products but on supporting compliant, reliable passive fire protection systems that align with Approved Document B and the realities of modern construction.
