Fire doors are much more than just thicker doors. They are purpose-built doors engineered to resist fire and smoke for a set period. Understanding what fire doors are made of, what fire door core materials are used and how they’re constructed will help you choose the right one for your home or workplace.
What Materials Are Fire Doors Made From?
Internal Doors offers a wide variety of fire doors by material and finish. Core materials commonly used in fire doors are:
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Calcium silicate core: A non-combustible, dense material used in many Internal Doors fire-rated engineered doors. It’s particularly resistant to fire damage.
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Engineered solid core / laminated cores: These are timber-based constructions using layers of timber and engineered wood bonded together for strength and stability under heat. Some fire doors have solid oak lippings or thick veneers over these cores.
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Fire-resistant composite or chipboard cores: These cores combine wood fibres or particles with fire retardants. They’re less expensive but still capable of meeting FD ratings if properly manufactured and certified.
In addition to the core, other materials play a critical role:
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Intumescent strips/seals: Around the edges of the door frame. These expand under heat to seal gaps and stop fire/smoke spread.
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Fire-rated metal hardware: Hinges, locks and handles must all be certified to work under fire conditions. If you install non-rated hardware, the overall fire door performance can be compromised.
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Fire-rated glazing: When glazed panels are included, the glass must be fire-rated. The framing around the glass must also be compatible with the fire rating test.
What Are FD30 Fire Doors Made Of?
The specification “FD30” means the door is tested to resist fire (both flames and smoke) for at least 30 minutes. To achieve that:
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Doors typically have a minimum thickness requirement; many FD30 internal fire doors are 44 mm thick.
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The core is often of the types mentioned above: engineered wood, calcium silicate or a fire-resistant composite.
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Intumescent seals are fitted along the edges. These are essential for the integrity of the rated door under fire.
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All hardware (hinges, handles etc.) must also be tested for FD30 performance.
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If glazed, fire-rated glazing is used and sealed properly within the framing.
Why Does Fire Door Material Matter?
Understanding fire door materials and construction matters because:
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It determines how long a door will resist fire (the FD rating), which is crucial in giving people time to escape and delaying fire spread.
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Using the wrong core, or non-rated hardware or poorly glazed panels can invalidate the certification.
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Material choice also affects durability, finish, maintenance and how the door complements your interiors: e.g., oak veneer looks very different from primed or painted finishes. At Internal Doors we offer multiple finishes (oak, walnut, veneer etc.) so you don’t have to compromise style.