What Are Fire-Rated Doors Made Of?

With so many variable parts, fire-rated doors need to be properly installed and regularly tested to ensure every component is working as it should.

Double glass door inside a building is separating a room from the hallway.

Modern doors are made up of multiple components and use a range of materials to satisfy both design aesthetics and functionality. However, it is also important that the various parts work together to keep the building and its occupants safe — specifically by preventing a fire from spreading and creating safe routes to designated emergency exits.

With this being said, just having a fire-rated door isn’t necessarily enough. With so many variable parts, fire-rated doors need to be properly installed and regularly tested to ensure every component is working as it should.


Fire-rated doors are made using a combination of various materials and components. Different materials play different roles, but it’s important to have a winning combination to ensure success.

Core Materials

Steel fire doors are a popular and sturdy material choice. Steel is a non-combustible material and will not feed a fire. Steel and other metal doors are typically more cost-effective than wood doors and come with a higher rating.

Most people probably wouldn’t consider wood as a desirable material for fire resistance, but many fire-rated doors are made using timber. These doors are typically filled with more resistant filler material like gypsum. Hollow steel doors can be filled with gypsum, as well.

Vermiculite and other aluminum or metal panels can be added to wood doors for further fire resistance and to meet hygiene requirements where applicable. Having protective panels also makes a fire-rated door more weather resistant when used as an exterior door.

If a more natural look is desired but you don’t want to use a timber door, wood veneer may be the best solution. Wood veneer is a thin wood panel that can be added to the outside of the doors. It is as versatile as timber and can be sanded, stained and treated in a variety of ways to fit any design.


It is becoming more common to see glass panels and windows in fire-rated doors. Glass that isn’t fire resistant could potentially explode and create an even bigger threat during a fire. But more and more options have become available that provide the aesthetic benefits of glass while still meeting strict safety regulations.

Wire mesh glass was one of the first fire-resistant options available. Wired glass has a visible steel mesh placed into the glass during the manufacturing process. The wire mesh is designed to reinforce the glass and hold any glass pieces should they break during a fire. It has high fire resistance, but other options have become available with better clarity and benefits.

Ceramic glass is replacing wire mesh glass as the most common glazing option. It is glass that has been heat-treated and crystalized into a stronger piece of glass that has high thermal stability. Ceramic glass can be clear, tinted or mirrored for a range of design choices, and its insulation abilities make it an energy-efficient option.

Another way to make fireproof glass is by using liquid sodium silicate. The sodium silicate fills and seals the glass, making it resistant to fire. Another benefit is that it absorbs extreme heat from a fire and turns opaque as it expands, making the glass less transparent to help prevent people from panicking.

Borosilicate glass is one of the newest fireproof glass options, and possibly one of the strongest. It can stand extreme temperatures for an extended period of time and will not explode. It is more lightweight than other options but sturdier and will remain transparent so people can see if it is safe on the other side of the door.

Glass in fire-rated doors needs to stand up to extreme heat for a substantial amount of time. They are also required to pass hose stream tests and sometimes need to be smoke and air leakage proof.


Close up on the open red door with gold crash bar. The large, industrial room in the distance is blurred.

A fire-rated door assembly is not just about the door and the frame, but every little piece involved including hardware, seals and the frame. These also all must be properly installed and tested to ensure the fire-rated door is effective.

Door Hardware

The door hardware includes hinges, latching mechanisms and closing devices.

A minimum of three hinges is required for every fire-rated door assembly to prevent warping. The hinges need all the screws, clear markings and certification to pass.

All fire-rated doors must be equipped with positive latching hardware. This latching system must also stand up to pressure caused by fire so that the door remains closed and secure. Fire exit hardware is also required, and panic hardware is typically seen on fire-rated doors. Panic hardware is exit hardware that is easy to operate in case of an emergency.

Fire-rated door closures must be designed to automatically close the door in case of a fire. Some closures come with the ability to keep the door open legally when it is safe to do so, but automatically close when a fire is detected. Fire-rated doors should never be propped open, as this prevents them from working properly.


Fire-rated doors are designed to be kept closed and sealed. Sealants and fire-rated expanding foam fill the gaps between the door and its frame to further seal the door and prevent the spread of smoke and toxic gasses.


Windows are not required but may be beneficial. Being able to see clearly through a door can help a person decide if that is a safe exit path or if they should find an alternative route.

Windows can also assist firefighters and emergency personnel in quickly locating the source of a fire or vulnerable people who need assistance.

These glass panels still need to be fire-rated and meet the strict regulations discussed above.


Elevator lobby across from a community kitchen space. The walls are white brick and the kitchen is white and modern. There are three elevators each with a yellow, see-through smoke curtain deployed in front of them.

Fire-rated doors may be regular doors with smoke or fire curtains installed as well. These curtains create a “fire-rated door” by making up for what the regular door lacks to meet regulations.

Fire curtains are discreet and virtually invisible when not deployed, making them an increasingly desirable option for their design versatility. They are also more reliable than traditional fire-rated doors because they can not be tampered with, propped open or obstructed.

In cases where a fire-rated door is not rated for smoke and air leakage, smoke curtains can be added to create a safer environment and keep exit routes clear of disorienting smoke.

Most injuries and deaths during a fire are not due to exposure to flames but rather smoke inhalation. Property and assets can also be irreparably damaged by smoke and toxic gases, so installing extra safety measures like smoke curtains is worth the investment.

Importance of Proper Installation

White door with black handle in white wall. Black and white exit signs are above and to the right of the door.

Even if a fire-rated door fulfills all the standards in terms of materials and components, a wrong installation can have some serious negative consequences — an improperly installed fire-rated door is an ineffective fire-rated door.

Without the proper measures in place to resist fire, the flames can spread freely and easily, damaging property and destroying emergency exit routes. Smoke and toxic gases can also seep through and cause serious injuries or even death.

Therefore, fire-rated doors need to be properly installed with the utmost care and attention to detail by those certified to do so. One quick way to check whether a fire-rated door has been installed properly is by checking the required label.

Fire-rated doors must also be tested annually to ensure all materials and components are working efficiently and effectively as designed. If even one component is not working, the entire fire-rated door is compromised.

Choose Fire-Rated Doors From SG Architectural Specialties

The SG Architectural Specialties team is well versed in all Smoke Guard products as well as a variety of partner life safety products.

Not only can we provide in-person maintenance and consultations, but we are also happy to provide documentation and maintenance manuals when needed and answer any questions you may have.