What FD30 means
FD30 is a British fire door classification. The number 30 refers to the minimum time in minutes that the door assembly can hold back a fire on one side while the other side remains below critical temperature thresholds. An FD30 door is tested as a complete assembly: the leaf, the frame, the intumescent seals, the glazing, the hinges, and the lock all function together as a fire barrier. Swap one component for a non-listed equivalent and the rating no longer applies.
The testing standard in the UK is BS 476-22 for fire resistance and BS EN 1634-1 under the European harmonised system. Both expose the door to a furnace temperature curve that reaches approximately 945 degrees Celsius at the 30-minute mark. The door must prevent flames from passing through, limit the temperature rise on the unexposed face, and maintain structural integrity for the full rating period. An FD30 door that passes both integrity and insulation criteria is marked FD30, while one that passes only integrity is marked FD30S (integrity only, with smoke control).
Where FD30 doors are required
UK Building Regulations Approved Document B specifies where FD30 doors go:
Between a garage and a house: The door connecting an integral garage to the dwelling must be FD30 rated. This is the residential equivalent of the 20-minute fire separation required under the International Building Code.
Flats and apartments: The front entrance door to each flat opening onto a communal corridor or stairwell must be FD30. The door is the first line of compartmentation between the dwelling and the escape route.
Escape routes: Doors on protected stairways and protected corridors in buildings with floors above 4.5 metres need FD30 ratings to keep the escape route tenable during a fire.
Commercial compartmentation: Walls separating different occupancies or fire compartments require FD30 or FD60 doors at every opening, depending on the wall rating.
Storage and service rooms: Boiler rooms, electrical cupboards, and storage rooms with combustible contents typically require FD30 doors to contain a potential fire at its source.
The local building control officer confirms which doors need FD30 and which need FD60. Requirements differ for new build versus renovation, and listed buildings have separate considerations under the fire safety order.
FD30 construction
An FD30 door is built differently from a standard internal door. The core determines the fire resistance:
Mineral core is the most common for FD30 timber doors. A compressed mineral board sits between timber stiles and rails. The core provides the fire resistance, while the timber gives structural support and a face for veneer or laminate finishing. A typical FD30 mineral-core door is 44 to 54 millimetres thick.
Particleboard with fire additives is an alternative core for lower-cost FD30 doors. It meets the rating but weighs more than mineral board and can degrade faster in humid environments.
Steel construction is used for FD30 doors in industrial settings, plant rooms, and service areas. A steel door with mineral wool insulation inside a pressed steel shell achieves FD30 or higher ratings. Steel FD30 doors are heavier and need heavier-duty frames and hinges.
Every FD30 door carries a label or plug from a third-party certification body. The two main UK schemes are BWF-CERTIFIRE and BM TRADA Q-Mark. The label identifies the door model, the fire rating, the maximum size, and the approved hardware configuration. A door without third-party certification will not satisfy building control.
Intumescent seals and smoke seals
The gap between the door leaf and the frame is where fire and smoke break through first. FD30 doors use two types of seal in this gap:
Intumescent strips are fitted into a groove machined into the door edge or the frame rebate. At around 150 degrees Celsius, the strip expands to seal the gap, blocking flame and hot gas passage. FD30 doors typically use a 10mm by 4mm strip, while FD60 uses 20mm by 4mm. The strip must run continuously along the head and both jambs, with no breaks at hinge positions.
Cold smoke seals use a brush or blade seal to block cold smoke infiltration before the intumescent activates. An FD30S door has both intumescent and smoke seals. Building regulations require smoke-sealed doors on escape routes in common areas of multi-occupancy buildings.
The seals are part of the tested assembly. Replacing them with a generic product from a hardware store voids the certification. Always replace seals with the exact product specified by the door manufacturer.
Glazing in FD30 doors
Where vision panels are needed, the glazing must be fire-rated. FD30 doors accept three types of fire glass:
Georgian wired glass is the cheapest option. A steel wire mesh embedded in the glass holds broken pieces in place during a fire. It meets FD30 integrity requirements but does not limit heat radiation to the unexposed face.
Borosilicate glass has low thermal expansion and resists thermal shock. It meets both integrity and insulation criteria for FD30, making it suitable where the door faces occupied space on both sides.
Ceramic glass withstands higher temperatures than borosilicate and is used where longer ratings or larger pane sizes are needed. It costs more but offers better optical clarity.
The maximum glazed area in an FD30 door is defined by the test report. A larger pane than tested will void the rating. The glazing beads and intumescent glazing tape are also part of the tested assembly.
Hardware for FD30 doors
Every piece of hardware on an FD30 door must be CE or UKCA marked and listed for use with that door model. The key hardware requirements:
Hinges: Three hinges minimum for FD30. Self-closing hinges or separate overhead closers are required on all fire doors. The closer must meet BS EN 1154 and be adjustable for closing speed and latching action.
Locks and latches: Must be CE/UKCA marked to BS EN 12209. A fire door must latch in the closed position. A rim lock or tubular latch that fails to engage under fire conditions compromises the integrity of the assembly.
Door closers: Every FD30 fire door in a building must self-close and self-latch from any angle of opening. If the door does not close fully, it is not a fire door. Closers need periodic adjustment to maintain the closing force as the door settles.
Signage: Fire doors must display a blue mandatory sign reading “Fire Door Keep Closed” or “Fire Door Keep Locked” on both faces. This is a legal requirement under the Regulatory Reform (Fire Safety) Order 2005.
FD30 versus UL ratings
FD30 and the 20-minute UL rating serve similar purposes but come from different test traditions. FD30 is tested under BS 476-22 or BS EN 1634-1, which use a furnace curve that reaches about 945C at 30 minutes. UL 10B uses a similar temperature curve but with a neutral pressure furnace. UL 10C adds positive pressure, which is more demanding because it pushes hot gases through gaps in the door assembly.
In practice, an FD30 door and a 20-minute UL-rated door both hold fire back for their rated period. They are not interchangeable because the test standards differ, and building inspectors look for the specific rating called out in the local code. A building designed to UK Building Regulations needs FD30. A building designed to the International Building Code needs the UL rating.
Manufacturers who sell into both markets carry dual certification. If your project is in the UK, Commonwealth, Middle East, or a jurisdiction that follows British standards, specify FD30. If your project follows IBC or NFPA, specify the UL rating.
Maintenance and inspection
An FD30 door is a legal fire safety device. The Fire Safety Order 2005 places responsibility on the building owner or responsible person to maintain fire doors in working order. Regular checks include:
- Door closes fully from any open angle without binding
- Latch engages securely in the strike plate
- Intumescent and smoke seals are present, continuous, and not painted over
- Hinges are tight, with no visible wear on the knuckles
- Gaps around the door leaf do not exceed 4mm at the head and jambs, 8mm at the threshold
- Vision panel glazing is intact with no cracks
- Certification label is present and legible
Any defect found during inspection must be fixed with listed spare parts from the door manufacturer. Substituting a hinge or seal with a generic equivalent voids the fire rating. Document each inspection and keep records for the fire authority.
Related guides
UL Rated Fire Doors: What the Rating Actually Covers
Steel vs Wood Fire Doors: Which Is Right for Your Building
Fire Rated Rolling Shutter Doors: What to Specify Before You Order
How to Choose Fire Rated Doors for Hotels, Apartments, and Commercial Buildings
