16/11/2022

Fire Doors in commercial premises

Passive fire protection for commercial premises

A fire door is a door that has been specifically designed to withstand fire damage for a set duration of time. They provide passive fire safety by allowing the building to compartmentalise, which delays the spread of fire into other areas of the building and prevents evacuation paths being blocked.

How fire doors work

The primary function of a fire door is to protect adjacent escape routes by preventing smoke and fire from escaping the affected room. Without a fire resistant door, evacuation may not be possible as corridors and stairwells can quickly become filled with toxic smoke or blocked completely by flames. Fire doors are engineered to close automatically, often with a metal hinge attached above the door, as they are not effective when left open.

Once room temperatures exceed 200 degrees celius, usually between 10 to 20 minutes after initial ignition, intumescent strips which surround the door begin to expand. This helps to suppress the fire by reducing the amount of oxygen which can be drawn into the room and also further prevents smoke escaping into other areas of the building.

Fire door codes

The duration of time that a fire door can withstand a fire will depend on the materials used and their density. The British Woodworking Federation (BWF) provides official certifications for the length of time that a door can withstand a fire in minutes. These are: FD30, FD60, FD90 and FD120. FD30 and FD60 are most commonly used to protect escape routes while FD90 and FD120 are recommended for containing a fire. Certificate information should be readily available to any building owner or tenant through the identification certificate, often located on the top of the door leaf.

During certification, doors are tested against a time-temperature curve, following test procedures specified in either BS 476-22:1987 or BS EN 1634-1:2014. It is important to note that even though a door may be rated for 30 or 60 minutes, the actual resistance time will vary depending on the nature of the fire, meaning doors may fail sooner or later than their certified rating.

Fire door components

Fire doors commonly consist of a solid timber frame while the door itself can be made from a composite material. Ironmongery – such as hinges, handles and door openers should be fire resistant and doors covered with a fire-resistant glass should be designed to withstand high temperatures for at least 60 minutes. The individual components which make a fire door are as follows:

Frame – supports the door in place. This should be built to the same standard as the door and installed at the same time.

Door closer – ensures that doors are automatically closed after use. Typically placed above the door itself.

Hinges – connects the door to the timber frame. Available in a range of sizes depending on the weight of the door.

Door handle – used to open the door. May also be in the form of a horizontal bar to improve accessibility during emergency scenarios.

Intumescent strips / smoke seal – seals fitted around the edges of the door which are designed to expand when temperatures reach 200 degrees celsius.

Vision panel – some doors may include a glass panel. This should use fire-resistant glazing.

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

Fire exits are located on external walls, designed to take people outside during evacuation. Fire doors can be both internal and external, with their main purpose being to prevent the spread of fire.

Fire exits require sufficient signage to direct people to them and can be left open when not in use. Fire doors, on the other hand, should never be left open and signage should be present to instruct people to keep them shut. Some fire doors may be installed with a device which holds the door open during normal use and automatically closes during an emergency scenario. These devices should be tested regularly to ensure functionality as they may fail after long periods of inactivity.

Installing and servicing fire doors

Fire doors are more advanced than a regular door and should therefore be installed by a competent person. During the FDIS 2019 annual inspection, 30% of doors were condemned due to poor installation, with the most common problem being excessive gaps and non-compatible foam. Regular servicing is a legal requirement and must also be carried out by a competent person. The following features should be checked during servicing.

Certification: New doors will have a label on the top or inside of the door however with some older doors this may be missing. A missing certification mark may mean the door is not adequate for fire protection and may fail during the event of a fire.

Gaps: The gaps between the door and frame should be no more than 4mm around the top and sides. The gap under the door can be up to 8mm. Large gaps can be repaired by adjusting the frame or leaf however if the frame is warped or bowed it may need to be replaced.

Seals: Should be fitted on all fire doors, undamaged and completely intact.

Hinges: At least 3 hinges should be securely attached to the frame with no missing screws.

Check the door can close unassisted: The door should close flush without assistance and without being caught on the frame.

UK fire door regulations

There are a number of UK regulations concerning fire doors which must be followed. In 2016 FDIS found that 76% of all fire doors were condemned as not fit for purpose. Whoever is deemed as the ‘responsible person’ are legally responsible to ensure correct installation and maintenance. Failure to do so can result in criminal prosecution.

Fire doors are legally required in public buildings, offices and factories. They are not required for private domestic use. Landlords have a responsibility to ensure the safety of their tenants under the Regulatory Reform (Fire Safety) Order 2005 (FSO) which means that fire doors must be installed in houses with multiple occupations (HMOs).

Fire doors are an essential part of any passive fire protection system and a legal requirement for all non-domestic environments. For further information and expert advice on fire doors, contact Sygma today.