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Fire Doors Explained


What is a fire door?

Fire doors create a barrier to slow the spread of flames and smoke during a building fire. They’re an important part of a passive fire protection system, enabling buildings to be separated into fire cells to delay the spread of fire from one area to another.


What does a fire door do?

Most of the time they act just like any other door. But in the event of a fire, put simply: when closed they form a barrier to stop the spread of fire and limit the spread of smoke and harmful gases, and when opened they provide a means of escape.


Do fire doors need to be closed at all times?

Fire doors must be self-closing and self-latching. In the event of a fire, they need to create a barrier to limit the spread of the fire. And for that reason, they must not be wedged open or have any other obstruction keeping them open. A fire door can be left open if it’s fitted with an approved fire door retainer. These are hold-open devices designed to keep a fire door open until a fire alarm is triggered, which will then close the door.


What’s the difference between a fire door and a normal door?

The most important distinction is that fire doors are a technical doorset with legal requirements under the Building Code and Safety Standards. A fire door is not just the door leaf, but a complete doorset, so as well as the leaf it also includes the frame, glazing, seals, and hardware - the complete assembly. And even then, it’s not a certified fire door until it’s been correctly installed. Only once it’s correctly installed, with fire door declarations completed, can it be certified.


What do fire ratings mean?

Fire Resistance Ratings are written in a specific format based on four factors: structural, integrity, insulation, and smoke rating. The first three are measured in minutes.

Structural: This is the structural adequacy or stability rating that determines how long something will maintain its load-bearing capacity. As fire doors are not structural elements, or non-load-bearing, a fire door’s structural rating will be recorded as a dash.

Integrity: The integrity rating is how long the doorset will protect from flame and hot gasses passing through. This is the time the door will protect people and property from a fire, before the doorset begins to breakdown.

Insulation: This is the time it takes for the heat to pass through the doorset including vision panels to the maximum permissible level. Note, under AS2 there are different requirements for sprinklered versus unsprinklered buildings.

Smoke rating: This is not time-related. A door is either smoke rated or it isn’t. A smoke rated doorset will stop smoke transferring between two spaces and is identified by the ‘sm’.


Where must a fire door be used?

A fire door must be used when the fire engineering report dictates it. Generally, this is due to numerous tenancies within a building (ie, apartments or hotels), or to meet an escape strategy (ie, convention centres). In most cases, a door within a fire wall will need to be a fire door. Refer to your project’s fire engineer for details specific to your project.


What are the features of a fire door?

The most important feature is that the door leaf itself – has a specialty core designed to slow down the effects of fire. That core along with the facings and the framing & hardware have been developed and tested to comply with the safety standard. Specific facings, jamb types (ie, timber or steel), leaf edges, meeting stile types, vision panel size and beading, and ventilation grilles all have an impact on the required fire rating of the doorset.


Ten essential features of a fire door:

1. GLAZING. Appropriate glazing systems must be supplied and installed by the manufacturer. The size of the vision panel and beading type is constrained by the fire rating of the door.

2. SIGNAGE. The door needs to be correctly marked with the appropriate Fire Door signage adjacent to the handle or push plate.

3. LOCKS & LATCHES. A fire door must be self-latching using approved latches. Anything, such as deadbolts, which could inhibit the doors ability to be self-latching must not be fitted. The latch needs to hold the door firmly in place without rattling.

4. DOOR HANDLES. All hardware, including handles, must be approved and comply with safety standards. Once fitted, handles need to operate smoothly and return to position correctly. Hardware approvals are specific to each door manufacturer's doors so hardware must be from the manufacturer's approved hardware list.

5. GAPS. There must be an even gap all around between the door and frame targeting a mean of 3mm. The gap underneath the door leaves (the floor clearance), must be within a minimum of 3mm, and no greater than 10mm between the bottom of the door leaf and the top of any floor covering. This allows for maximum of 25mm to your non-combustible flooring or slab, then allows for fitting of your combustible flooring such as 15mm carpet & underlay, if a maximum of 10mm clearance is not exceeded.

6. MECHANICAL CLOSER. As mentioned earlier, all fire doors must be self-closing. The self-closing device needs to be adjustable to meet frictional force requirements as per safety standards. It must be an approved closer, fitted securely and operating correctly.

7. ELECTRO-MECHANICAL HARDWARE. In addition to basic mechanical closers, a range of door hardware is available for specific door functions (magnetic latches, hold-open devices, electronic openers, etc).

8. FIRE TAGS. Fire tags identify a doorset and its certification. They provide details specific to that doorset – its fire rating, date of manufacture and an ID number that relates to the Fire Door Register. There must be a tag on both door leaf and door frame. An Installer Declaration must be completed by the Door Installer and Hardware Installer prior to the Manufacturer issuing the fire tags. All fire doors require these documents to be completed and the doorset recorded on a Manufacturers Fire Door Register. 

9. HINGES. Fire doors must have at least three certified hinges. They need to be fitted firmly with no missing screws.

10. INTUMESCENT FIRE & SMOKE SEALS. Intumescent seals are designed to expand when a certain level of heat is sensed. They close off the gaps around the door in case of a fire. Seals must be fitted at the head and all vertical edges between the door leaf and the frame, and between leaves in multi-leaf doorsets.


Fire doors need to be maintained and regularly checked. Modifications to a certified fire door after it has been installed will void its certification, and that includes replacing handles, hinges or other hardware.


The above video explains Fire Doors for the New Zealand market. Regulations differ from country to country so if you are not in NZ then please refer to the regulations pertaining to your country.

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