Fire Doors — The Unsung Heroes of Building Safety (And Why Yours Are Probably Wrong)

Fire doors are possibly the most important fire safety feature in any building, and simultaneously the most abused. They get propped open with wedges, held back with bins, had their closers removed because they're "annoying," and painted so many times the intumescent strips have been sealed shut.

If you've never given your fire doors a second thought, this is the article that might change your mind.

What Fire Doors Actually Do

A fire door has one job: to contain fire and smoke for a specified period of time. A standard FD30 fire door provides 30 minutes of fire resistance. An FD60 provides 60 minutes. During that time, the door holds back flames, heat and toxic smoke, keeping escape routes clear and giving occupants time to get out.

Without fire doors, a fire that starts in one room can spread through an entire building in minutes. Smoke — which kills more people than flames — can fill corridors and stairwells almost instantly. Fire doors buy the single most valuable commodity in a fire: time.

But here's the crucial point: a fire door only works if it's correctly installed, properly maintained and kept closed.

The Legal Requirements

The Regulatory Reform (Fire Safety) Order 2005 requires the responsible person (typically the employer, building owner or landlord) to ensure that fire safety measures — including fire doors — are maintained in good working order.

This means fire doors must close fully into their frames, the self-closing device must function correctly, intumescent strips and smoke seals must be intact and unobstructed, glazing must be fire-rated (not standard glass that's been swapped in during refurbishment), gaps around the door must not exceed 3mm (when closed), hinges must be adequate (three hinges for FD30 doors), and signage must be in place where required.

The Fire Safety (England) Regulations 2022 added further requirements for residential buildings, including quarterly checks of fire doors in communal areas and annual checks of flat entrance doors.

The Most Common Problems

Having inspected thousands of fire doors across hundreds of buildings, these faults appear with depressing regularity:

Doors propped open. The number one problem. A fire door propped open is not a fire door — it's a hole in your fire compartmentation. If people need doors held open for operational reasons, fit hold-open devices linked to the fire alarm that release automatically when the alarm activates.

Missing or damaged intumescent strips. These are the strips fitted into the edges of the door or frame that expand when exposed to heat, sealing the gap between door and frame. If they're painted over, missing, or the wrong type, the door won't perform as rated.

Failed self-closing devices. The closer must pull the door fully shut into the frame every time, from any angle. If the door sticks, bounces back, or only closes to within a few inches of the frame, the closer needs adjusting or replacing.

Excessive gaps. The gap between the door and frame should not exceed 3mm when the door is closed. Gaps larger than this allow smoke to pass through, defeating the purpose of the door. Threshold gaps up to 8mm are generally acceptable with appropriate smoke seals.

Unauthorised modifications. Cat flaps, letter boxes, additional locks, non-fire-rated glazing panels, ventilation grilles — any modification to a fire door that hasn't been done in accordance with the door manufacturer's specifications compromises its fire rating.

Wrong furniture. Standard hinges instead of fire-rated hinges. Plastic handles instead of fire-rated ironmongery. Every component on a fire door needs to be compatible with the door's fire rating.

How to Check Your Fire Doors

You don't need specialist equipment for a basic fire door check. Walk up to each fire door in your building and check the following:

Does it close fully into the frame under its own power? Is the self-closing device working? Are the intumescent strips and smoke seals present and intact? Are the gaps around the door within acceptable limits? Are there three hinges (for a standard-height FD30 door)? Is the door free from damage, warping or unauthorised modification? Is the door labelled or marked as a fire door?

If any fire door fails these basic checks, it needs attention. Some issues (adjusting a closer, replacing a missing smoke seal) are quick fixes. Others (replacing a damaged door, fitting correct glazing) require a fire door specialist.

The Bigger Picture

Fire doors are part of a broader fire compartmentation strategy. Walls, floors, ceilings and doors work together to divide a building into fire-resistant compartments. If any element fails, the whole strategy is compromised.

This is why fire doors appear in virtually every fire risk assessment. And it's why "propped open fire doors" is consistently one of the most common findings — because it's consistently one of the most dangerous practices in building fire safety.

Need your fire doors assessed? Book a Fire Risk Assessment →

York Green Safety Partners includes comprehensive fire door inspection as part of every fire risk assessment. Based in Cheshire, covering the whole of the UK.