A fire door is not just a normal door—it’s a specially designed barrier that protects people and property by slowing the spread of fire and smoke. Understanding what a fire door is made of is essential for homeowners, building managers, and anyone responsible for fire safety compliance.
Fire doors are built from carefully selected materials and components that work together to provide fire resistance, durability, and legal compliance. In this article, we’ll break down every element that makes up a fire door and explain why it’s critical for safety.
Core Materials of Fire Doors
The core of a fire door determines how long it can resist fire. Different fire door grades (FD30, FD60, FD90, FD120) use different core materials:
Solid Timber Core: Often used in residential and office fire doors, solid timber cores are dense and provide natural fire resistance.
Composite Timber Core: Made from layers of engineered timber, offering strength and stability while resisting warping.
Mineral Core (Gypsum or Calcium Silicate): Provides superior fire resistance and is commonly used in commercial buildings or high-risk areas.
Steel Core: Found in industrial or high-security settings, steel cores offer both fire resistance and structural strength.
The thickness and type of core directly influence the door’s fire rating.
Fire-Resistant Surfaces
The door’s surface layers protect the core from heat and mechanical damage while giving the door a finished look. Common surface materials include:
- Timber Veneer: Provides a natural wood appearance while allowing the core to function effectively.
- Laminate or MDF: Durable surfaces for internal doors in offices or commercial spaces.
- Steel or Metal Facing: Used for industrial doors or where high-security and fire protection are both required.
The surface layer must also withstand high temperatures without compromising the core.
Fire-Resistant Glass
Some fire doors include windows for visibility or aesthetics. These are made from specialized fire-resistant glass:
- Borosilicate Glass: Highly heat-resistant and unlikely to crack under high temperatures.
- Ceramic Glass: Offers excellent fire resistance and can withstand extreme heat for longer periods.
- Anti-Shattering Mesh: Often added to prevent glass fragments from spreading smoke or flames.
Only certified fire-rated glass may be installed in a fire door to maintain the door’s rating.
Seals and Intumescent Strips
Fire doors rely on seals to prevent smoke and fire from passing through gaps:
- Intumescent Strips: Expand when exposed to heat to seal gaps between the door and frame.
- Smoke Seals: Specifically designed to contain smoke during a fire, often combined with intumescent strips.
- Silicone or Fire-Resistant Sealant: Fills gaps and improves airtightness while resisting fire.
These components are essential for the door to function effectively as a fire barrier.
Hardware and Mechanisms
Proper hardware ensures the fire door closes and locks correctly, which is critical for safety:
- Hinges: Must be fire-rated and support the door’s weight and movement.
- Locks and Handles: Fire-rated to maintain integrity during a fire.
- Self-Closing Mechanisms: Spring-loaded or hydraulic devices that ensure doors close automatically in case of fire.
Without certified hardware, the fire door cannot perform as designed.
Certification
A fire door is only considered a true fire door if it has been tested and certified by an approved laboratory. Certified doors include:
Manufacturer label
Fire rating (FD30, FD60, FD90, or FD120)
Date of manufacture and test information
Certification guarantees the door meets the required fire resistance standards.
Common Fire Door Materials by Use
Fire doors use different materials depending on the type of building and the level of fire protection required. For residential flats and offices, fire doors typically have a timber or MDF core with a veneer or laminate surface and usually carry a fire rating of FD30 to FD60.
In commercial buildings, doors often feature a mineral or composite core with laminate or steel surfaces, providing a higher fire rating of FD60 to FD90. For industrial or high-risk areas, fire doors are built with a steel or reinforced core and steel surfaces, offering the highest protection with ratings from FD90 to FD120.
Maintenance Tips for Fire Door Materials
To maintain fire resistance:
- Avoid cutting or drilling into the door
- Keep intumescent strips and seals intact
- Inspect glass panels for cracks or damage
- Ensure hardware functions correctly
Regular inspections are essential to maintain certification and safety.
Conclusion
Fire doors are carefully engineered assemblies, not just regular doors. Their core materials, surfaces, glass panels, seals, and hardware all work together to provide fire resistance. Understanding what a fire door is made of is key to selecting the right door, ensuring compliance, and protecting lives.
Always use certified fire doors with proper installation and maintenance to maximize safety.
