How Do Fire Doors Work?
In the event of a fire, every second counts. Flames and smoke can spread quickly throughout a building, which is why measures designed to contain fire and protect escape routes are such an important part of an effective fire safety strategy.
Fire doors are specifically designed to resist the spread of fire and smoke for a defined period, helping to compartmentalise a building and give occupants more time to evacuate safely. However, a fire door is much more than just a heavier or thicker version of a standard door. Its performance relies on several specialist components working together correctly.
In this blog, we’ll explore the different parts of a fire door and how they work to provide vital protection for your people, property, and assets against the threat of fire.
What are the main parts of a fire door?
Understanding the different parts of a fire door helps explain what makes a fire door capable of resisting fire. Each feature has a specific role and should be appropriate for the particular doorset.
Some key fire door features include:
Fire resistant door leaf
The door leaf is the main moving part of the fire door and is manufactured to provide a specified level of fire resistance.
Fire doors can be manufactured from different materials and constructions depending on their intended use and certification. Common ratings provide 30 or 60 minutes of fire resistance, although higher performance doorsets are available where required by the building design or fire strategy.
The fire resistance rating applies to the tested doorset and its associated components, rather than simply to the appearance or thickness of the door leaf.
Fire door frame
The frame is an equally important fire door feature. A suitable fire resisting door leaf can’t perform as intended if it’s fitted into an inappropriate, damaged, or poorly installed frame.
The frame must be compatible with the doorset and correctly installed so the door fits within the permitted tolerances. Gaps that are too large, distortion, or damage around the frame can allow flames and smoke to move through the opening more easily.
The junction between the frame and the surrounding wall also needs to be installed and sealed appropriately so that the fire resisting construction around the door isn’t compromised.
Intumescent and smoke seals
Modern fire doors commonly incorporate intumescent seals around the edges of the door leaf or frame. When exposed to high temperatures, the intumescent material expands and helps seal the gaps around the door which restricts the passage of fire.
Smoke control is slightly different. Where smoke protection is required, separate smoke seals or combined intumescent and smoke seals can help restrict the movement of cold smoke before temperatures become high enough to activate the intumescent material.
Both features are important because smoke can travel through small gaps and present a serious risk to occupants even before flames reach an escape route.
Self closing mechanisms
Many fire doors are required to be fitted with an appropriate self closing device because a fire door can only provide effective protection when it’s properly closed within its frame.
The closer should allow the door to shut fully from any normal open position without being obstructed. A damaged, disconnected, or poorly adjusted closer can prevent the door from closing correctly and compromise the protection it’s intended to provide.
There are some situations where self closing devices aren’t required, so the correct arrangement should always be based on the type and location of the door and the relevant fire safety guidance.
Fire rated hinges and ironmongery
Hinges, locks, latches, handles, and other pieces of ironmongery can all influence how a fire door performs.
These components should be suitable for use with the particular doorset and installed in accordance with its supporting test evidence or manufacturer instructions. Using incompatible components or making unnecessary alterations can affect the integrity of the door.
Hinges must also remain secure and in good condition so that the door leaf remains properly aligned with the frame.
Fire resistant glazing
Some fire doors include glazed vision panels, particularly in corridors, schools, healthcare premises, and commercial buildings where visibility through the door may be useful.
Where glazing is included, the complete glazing system must provide the required fire performance. This includes not only the glass itself, but also the beads, seals, and method used to secure it within the door leaf.
Damage, inappropriate replacement glass, or alterations to the glazing arrangement could affect the performance of the complete doorset.
How do fire doors work?
Understanding the different parts of a fire door is just as important as knowing how all of these components work together to resist fire and smoke.
Fire doors work by forming part of a fire resistant barrier within a building. If a fire starts in one room or compartment, the closed fire door is designed to restrict the movement of flames, heat, and where appropriate, smoke into adjoining areas for a specified period.
This process is known as compartmentation. By containing the fire within a defined area, fire doors can help keep escape routes usable for longer and provide additional time for occupants to leave the building safely.
What makes a fire door effective isn’t the door leaf alone. A fire door should be considered as a complete assembly or doorset, with the leaf, frame, seals, hinges, closer, and other compatible components all contributing to its performance.
During everyday use, a fire door may look and operate much like a standard door. During a fire, however, the specialist materials and components are designed to respond to heat and help maintain the integrity of the opening.
If one of these fire door features are damaged, altered, poorly fitted, or incompatible with the rest of the doorset, the overall performance of the fire door can be compromised.
What can stop a fire door from working properly?
Even a correctly specified fire door can become ineffective if it’s damaged, altered, or poorly maintained.
Some of most common issues that could stop a fire door from working as intended include:
- Doors being wedged open, preventing them from containing fire and smoke.
- Faulty self closing devices, meaning the door doesn’t close fully into the frame.
- Damaged or missing seals, reducing the ability of the doorset to restrict fire or smoke.
- Excessive gaps around the door, which can compromise its performance.
- Loose or damaged hinges, causing the door leaf to drop or become misaligned.
- Damage to the door leaf or frame, including holes, splits, or impact damage.
- Inappropriate alterations, such as fitting unsuitable locks, handles, glazing, or other hardware.
- Poor installation, which may prevent even a correctly manufactured fire doorset from achieving its intended performance.
Fire doors are frequently used as part of everyday building circulation, which means wear and damage can develop gradually. Regular inspection and maintenance are therefore essential to identify defects before they affect the door’s ability to provide protection.
We can keep your fire doors working effectively
Understanding how fire doors work is only part of maintaining effective passive fire protection. The door leaf, frame, seals, closer, hinges, glazing, and other components all need to remain in suitable condition throughout the life of the door.
At Pyrotec, we provide a range of professional fire door services for commercial properties across Brighton, Eastbourne, Crawley, and the wider UK thanks to the backing of the LS Fire Group. From fire door surveys and installation, to maintenance, repairs, and replacement, we can help ensure your fire doors are compliant and working effectively.
Whether you’re responsible for a commercial premises, residential building, or wider property portfolio, our experienced team can help identify defects, recommend appropriate remedial work, and ensure your fire doors continue to support the wider fire safety strategy of your building.
Don’t hesitate to contact our expert team today to discuss your fire door requirements in more detail or to arrange a professional fire door survey.
FAQs around how fire doors work
- What is a fire door set?
- A fire door set is a complete assembly made up of the fire resistant door leaf, frame, seals, hinges, closing device, and any other compatible hardware or glazing. These components are designed to work together to provide a specific level of fire resistance.
- Do fire doors prevent the spread of smoke and flames?
- Fire doors are designed to slow the spread of fire and smoke between different areas of a building, helping to maintain compartmentation and protect escape routes. Intumescent seals expand when exposed to heat to help restrict the passage of flames, while smoke seals can help reduce the movement of cold smoke around the door.
- Are fire doors required by law?
- Fire doors are required in many residential and non-residential buildings where they form part of the building’s fire safety strategy. Under the Regulatory Reform (Fire Safety) Order 2005, responsible persons must ensure appropriate fire precautions are in place and properly maintained. The exact number, location, and fire rating of doors will depend on your building type, layout, occupancy, and fire strategy, so requirements should always be assessed on a site specific basis.
- Where should fire doors be located?
- Fire doors are typically positioned where they’re needed to protect escape routes, separate fire compartments, and isolate higher risk areas. Common locations include corridors, stairwells, kitchens, plant rooms, electrical cupboards, entrances to flats, and areas separating different uses within a building. The correct location will vary depending on the premises, so a fire risk assessment or fire strategy should be used to determine where fire resisting doors are required.
- What happens if a fire door is left open?
- A fire door that’s left open can’t effectively separate one fire compartment from another. This can allow fire and smoke to move more quickly into corridors, stairways, or adjoining rooms and may compromise protected escape routes.
- Can you replace fire door hinges or handles with standard ones?
- Hardware fitted to a fire door should be compatible with the particular doorset and its supporting evidence. Replacing hinges, locks, latches, or other components with unsuitable alternatives can affect the fire performance of the assembly. Where hardware needs replacing, the specification for the fire door should be checked and suitable components fitted by a competent and qualified person.
- What should I do if a fire door seal is damaged?
- Damaged, missing, or loose fire door seals should be investigated and repaired where necessary. The replacement seal must be appropriate for the particular door and provide the required fire and, where applicable, smoke performance. If in any doubt, seeking professional advice is strongly recommended.
- Can a damaged fire door be repaired?
- Some fire door defects can be repaired, depending on the type and extent of the damage and the evidence supporting the doorset. Problems such as damaged seals, some hardware defects, or issues with closing mechanisms may be suitable for remedial work. More extensive damage to the leaf, frame, or glazing may require specialist assessment or replacement. A fire door survey can help determine the most appropriate course of action.
