Syro Industry Co., Ltd.
Home / FAQs
Q: What is a fire rated door assembly?

A fire rated door assembly plays an essential role in the compartmentation of a building, acting as a barrier to the passage of flames and hot gases. It must delay the spread of fire for a designated period of time, protecting the escape routes for the building’s occupants. A fire rated door assembly is usually composed of a fire doorset, sealing systems, door hardwares and glazing systems.

Q: How doors burn?

Doors hardly ever burn through the middle – they always fail at the weakest point, which tends to be at the edges, where there is more oxygen available to promote combustion. Additional consideration is needed for ironmongery positions (hinges, locks, latches and concealed door closers) where there is a lot of metal to conduct extra heat into the fixings and the vulnerable surrounding timber. Doors also fail through the leaves distorting under exposure to very high temperatures, bending away from the frame. The intumescent seals help to hold the door leaf in place.

Q: What is the function of a sealing system?

Every door assembly will have a gap between the leaf and the frame, so it can operate. However, this same gap will allow fire, smoke, sound and draughts to pass through. Seals will normally be designed to prevent these unwanted elements moving from one side of the door to the other when the door is closed. If you look closely at a modern architectural door assembly, you’ll see that it relies on sealing systems for its performance.

A sealing system will:

● fill the gap to prevent or reduce the transfer of these unwanted elements;

● work with the door assembly to improve aspects of its performance;

● add minimal resistance to the opening and closing operation of the door;

● be serviceable in everyday use;

● be durable in the long term, so that performance is not diminished over time.

In some cases, the seal may be quite specific to a particular environment - but to avoid the need to fit multiple seals, many sealing systems are designed to fulfil a number of functions. For example, a fire seal may very often be combined with an integral smoke seal, and a smoke seal may sometimes function adequately as an acoustic seal.

Q: What are the minimum gaps and clearance for fire rated doors?

There are strict clearance limits on fire doors and if these gaps exceed the limits then the door is not compliant and should be replaced. For any fire rated doors to function properly, the clearances between the door leaf and the frame are extremely important. Smoke, acoustic and thermal seals will need to touch both the door and the frame to be effective; and most seals are designed to suit a 3mm gap between the door and frame. In the case of a seal mounted onto the door stop, the gap can be 2mm between the stop and the face of the door leaf. The threshold gap tends to be much larger than the perimeter gap. It’s also a ‘straight-through’gap, with no door stop – so it can be a difficult area to seal, particularly if a smooth transition is required from one side of the doorway to the other, say for wheelchair traffic.

Q: What is the required signage for the fire rated doors?

Many fire standards require that all doors the lead into a fire isolated stairwell or corridor must have approved signage permanently fitted to the door at eye level. In addition to this, doors that form a final exit for a fire isolated stairwell or corridor must have signage on BOTH sides of the door. Illuminated exit signs are only installed above the door on the inside of the door.

Q: How often must the fire doors be checked?

The frequency of the required inspections is determined by the building classification. In most cases for a commercial building the frequency is every 6 months and for the industrial / residential buildings the frequency is annually. You should check with your fire service provider to ensure that you are meeting your obligations in terms of your regular testing and maintenance of the fire doors.

Q: I have fire doors in my building. Do I have to have them replaced?

Many building owners are conducting routine replacement of the old fire doors as part of their commitment to workplace health and safety. You may not necessarily have to replace the fire doors, providing they are in good condition and are still functioning as required by the local authority standards. If the doors are in disrepair, have faulty hardware or do not have the required compliance tag on the door, the only option is to have the doors replaced and have new hardware installed.

Q: Are fire rated doors noncombustible?

Fire doors are not necessarily noncombustible. It is acceptable for portions of the door to be destroyed by combustion during exposure to a fire as long as the door assembly meets the fire test criteria of limiting temperature on the non-fire side of the assembly. This is in accordance with the overall performance goal of a fire rated door to slow fire propagation from one fire rated compartment to another for only a limited amount of time, during which automatic or manual fire fighting may be employed to limit fire spread, or occupants can exit the building.

Q: How can I install the fire rated doors?

As well as ensuring the door is hung properly and squarely, it is also very important that where a fire door is installed, any gaps left in the opening between the wall and the door frame must be properly filled with fire resisting material. Fire doors are normally installed by a certified carpenter. Please read more installation guidance.

Can a deadbolt be installed in a fire rated door?

Deadbolts are not permitted as hardware in firedoors because they negate the function of the door to be self latching. there are options, however, as some deadbolts can be removed and replaced with certain approved hardware. that said, in many cases the only way to ensure compliances is to have the door replaced and approved hardware installed.

Q: What is Acoustic Door?

A door assembly needs to be separately designed and evaluated for its acoustic performance. Many doors that need to provide acoustic containment will almost certainly have to provide fire and smoke resistance too.

Door assemblies respond to airborne sound (such as conversation or music), rather than structureborne sound (such as footsteps or hammering). To reduce the amount of sound which passes from one side of the door to the other, we need to consider two things – the door leaf construction and the sealing system. Both of these have an effect on performance and Syro Industry offers a perfect solution up to 42dB. Read more.

Q: What is the largest size of visible glazing that can be put into a fire rated door?

Glazed panels are often required in fire rated doors. In door assemblies, especially those on circulation routes, glazed apertures allow people to see others approaching from the opposite direction: they also allow fire and smoke to be seen without opening the door thereby making a real contributionto safety. In Syro Industry, a fire rated door can bear a maximum glazing coverage of 0.5 square meters in a single door panel.

Q: What are my primary options in fire-rated glass?

The glass product most often associated with fire rating is polished wired glass (Pyroshield). It has provided fire protection for more than 100 years, and is frequently seen in schools, hospitals, and other high occupancy facilities. The biggest advantage of wired glass has been its low cost. However, its relatively low impact safety resistance and institutional look of the wire are sometimes considered drawbacks and with new building codes being adopted such as IBC 2006/2009, traditional wired glass usage will be severely limited. 

A second type of fire-rated glazing is glass ceramic. Once installed, this wireless product looks similar to window glass. Glass ceramic products, such as those in the FireLite family, provide fire ratings from 20 minutes to 3 hours. Like wired glass, the glass ceramics are able to withstand the thermal shock of water thrown by sprinklers or fire hose. It can also have beveled edges and be sandblasted for artistic effect. 

Glass ceramic is also available as Insulated Glass Units (HBE90). The IGU are made of two layers of glass with an air space in between. They can incorporate many types of float glass - clear, tinted, Low-E, mirrored, etc. Depending on which components are used, they provide not only fire protection but can comply with energy and safety codes as well. The IGU’s are sometimes used for interior applications where sound reduction is desired. 

A final category of fire-rated glazing is specially tempered glass. Products such as Pran-S, Pyrawhite only carry ratings such as 30 or 60 minutes and -- extremely important -- they cannot withstand the thermal shock of water thrown from sprinklers or fire hose.

Q: What kind of hardwares can be used on fire rated doors?

To understand fire door hardware, you must remember that fire doors serve four main purposes: 1) To serve as a regular door at all times; 2) toprovide ready egress during a fire; 3) to keep fire from spreading throughout the building; and 4) to protect life and property.

To adequately perform these functions, a fire door must be equipped with fire listed hardware

for dependable operation. Proper hardware selections can be verified by consulting the current editions of “Building Materials Directory” published by Underwriters Laboratories Inc., “Directory of Listed Products” published by Intertek Testing Services and “Hardware for Labeled Fire Doors” published by the Door and Hardware Institute. These manuals identify hardware and other products that may be used in fire-rated assemblies.

The National Fire Protection Association’s publication, NFPA 80, entitled, “Standard for

Fire Doors and Fire Windows” provides guidance for installing fire doors and frames and

hardware in the openings of a building.


A labeled fire door must be hung on steel bearing-type hinges. The use of steel is necessary

since non-ferrous metals become “elastic” at much lower temperatures, which could allow serious dislocation of the door during a fire. There are certain hinge designs made of non-ferrous metals which may be used on fire doors in accordance with the listing information for the particular hinge. These hinges are usually used on doors of lesser fire rating.

The bearing type knuckles on hinges are required in order to provide smooth operation and to minimize wear throughout the lifetime of the opening. Remember, a fire door must close in the event of a fire. Worn hinges will cause the door to sag, effectively preventing the door from closing. Exception: Some manufacturers may provide doors with hinges which are non-bearing type when they are part of a listing assembly.

NFPA 80 allows the use of standard weight (1.34 inches leaf thickness) 4-1/2" hinges on

1-3/4-hour doors up to 4'0" in width and 8'0" in height. Doors over 8' in height shall have heavy weight (.180 inches leaf thickness) 4-1/2" hinges. Some manufacturers have the capability of providing lighter weight hinges on doors over 8' in height as part of a listed assembly. (Consideration should be given to larger hinge sizes for heavy or frequent use doors.)

2. Latching devices

EVERY SWINGING FIRE DOOR MUST HAVE A LABELED AUTOMATIC LATCHING DEVICE TO ENGAGE THE STRIKE. Deadlocks may be provided in addition to the latch bolt, except on doors used as a means of egress, where interconnected locks may be used which retract the dead bolt with the latch bolt. Dead bolts may not be used in place of latch bolts.

When selecting latching devices, it is important to use the correct length of latch bolt, a requirement that can vary with the door construction and the manufacturer’s fire testing program. It is common for a pair of doors to require a longer latch bolt throw than a single door. The minimum latch bolt length that must be used for any given door is indicated on the fire door label.

Some state and city building code authorities allow the use of a “push” and “pull” function on certain fire rated openings. This push/pull function does not include a self-latching device and does not allow a fire door to perform its vital function. Without a latching device the door will not remain closed during a fire. A manufacturer cannot fire label a door prepared only for a push/pull function.

3. Fire exit hardware

Exit devices may be used on labeled doors provided the door labeling specifically states

“Fire Door To Be Used With Fire Exit Hardware.” This label indicates that the door has been properly reinforced for fire exit devices. Doors that bear this label must pass a panic loading test in addition to the standard fire test. The panic load test measures the structural capability of the door to allow the hardware to operate in a panic situation. Care must be taken when selecting exit devices for use on fire rated doors, as some devices have been tested for panic loading only, and not fire tested. In addition, exit devices have size and hourly rating restrictions, and must be properly labeled and identified as fire exit hardware.

4. Closing devices

A properly sized closing device is the last of the “basic” fire door hardware requirements. A fire door must be in a closed and latched position to serve as a protective barrier in the event of a fire. For this reason, either spring hinges or a listed door closer is required. When the door is closed, the closer has served its role as a protective device.

5. Hold open devices

Mechanical hold-open devices and hold-open arms on door closers should be avoided. Fusible link equipped closers with a hold-open feature are available, but the fusible linkages

will not function quickly enough to allow the door to act as a protective barrier to save human lives. Tests and investigations have proven that smoke and toxic gases are the main cause of death in tragic fires. Doors held open by electromagnetic release devices are the only ones which will close quickly enough to prevent the passage of the toxic gases and smoke. These devices are activated by electronic detectors that sense smoke and/or the products of combustion.

6. Flush bolts

Where pairs of doors are being used as an entrance to an equipment room or similar situation, manual flush or surface mounted bolts may be used to secure the inactive leaf. Under these circumstances, the NFPA recommends that the inactive leaf have no knob or other visible hardware. Labeled fire exit devices are mandatory for exits unless local authorities give specific approval for the use of labeled self-unlatching and latching devices, such as automatic flush bolts on the inactive leaf. The self-unlatching feature must work only when the active leaf is opened.

7. Floor springs.

Double action pairs of doors should only be provided with vertical rod fire-exit device hardware on both leaves. The vertical rod devices may be either surface mounted or concealed.

Double action doors and frames are part of a listed assembly and only those door designs that are named in a frame manufacturer’s published listing may be used.

8. Astragals

Astragals may or may not be required on pairs of doors depending upon the individual door manufacturer’s labeling capabilities. Pairs of doors that do require an astragal shall have at least one that projects a minimum of 3/4-inch beyond the edge of the door to which the astragal is attached. Pairs of doors that are in a required means of egress may not be equipped with an astragal that inhibits the free use of either leaf. An astragal may not be used on pairs of doors with vertical rod exit devices on both leaves of the pair. Pairs of three hour doors always require an astragal per NFPA 80. Other combinations of fire exit hardware on the active leaf and a vertical rod device on the inactive leaf are acceptable. In some situations a coordinator may be needed to allow the inactive leaf to close ahead of the active leaf. This ensures proper latching of pairs of doors. Some manufacturers are able to supply labeled pairs of doors with an open-back strike without an astragal, which eliminates the need for a coordinator.

Q: What is the Primary Goal of Fire-Exit Hardware?

The primary goal of fire-exit hardware — managers should avoid using such terms as panic hardware because of its negative connotation — is to provide free egress for occupants, even children and people with disabilities, and even in the dark.

Facilities also must have clear exit marking and door hardware that allows a door to swing in an unrestricted manner from any direction of egress. Evacuation signals also must be visible and audible.

In many regulations and guidelines, doors must comply with to qualify as accessible. Besides minimum door clearances and threshold-height limits above the floor. Handles, pulls, latches, locks, and other operating devices must allow easy grasping with one hand. The hardware cannot require tight pinching or grasping or the twisting of the wrist. Operation should require no more than 5 pounds of force, and thumb-operated mechanisms are prohibited. Lever, push/pull, and U-shaped handles generally comply, but some cylindrical knob handles might not.