Fire doors must be checked regularly as they are crucial in protecting escape routes and maintaining compartmentation. They are usually made from timber or steel and are designed to provide 30 to 60 minutes of protection. But before you think of installing one, it’s important to understand how they work and how to identify the right door for you. Identifying Fire-Rated DoorsTimber fire-rated doors normally require a gap of around 3 to 4 millimeters, between the door leaf and the frame. To maintain fire resistance, the gap is normally protected by an intumescent seal that’s installed in either the door or the frame. The intumescent seal expands to seal gaps in the early stages of a fire. If the door contains a glazed panel it will also normally be fitted with an intumescent material.To restrict the spread of smoke at ambient temperatures, smoke seals may also be fitted. Occasionally metal fire doors may be more appropriate than timber, for example where fire resistance of more than one hour is required. To identify a door and its rating you should look for a label or plug from a third party certification scheme.LabelsLabels or plugs from certified providers, are a reliable indicator that a door meets the designated fire resistance. Labels usually indicate the period of time that a door will resist fire. Each label is generally numbered. This is useful in tracing the door manufacturer if a replacement is required or there are problems. Old doors are unlikely to have labels. But if they are solid heavy construction and similar to other fire doors in a building, they probably are fire-rated doors. If there is any doubt, a professional opinion on a doors performance must be obtained or a proven replacement fitted.GapsGaps around fire-rated doors should be three to four millimeters. Gaps larger than this are unlikely to hold back fire and smoke. In older buildings, doors may not have intumescent strips, so only a nominal 20 minute fire resistance can be expected. Current recommendation are that a door with an intermittent strip affording a minimum of 30 minutes of fire resistance is fitted. Metal doors are not usually fitted with intumescent strips.Smoke SealsMany fire-rated doors are now fitted with smoke seals that prevent smoke spreading at normal temperatures. These seals are usually polymer blades or brushes. An Assessor should check that smoke seals are present and in good condition. They should completely fill the gap between doors and frame.IronmongeryFire door ironmongery is complex. The combinations of hinges, latches and push plates are almost infinite and many are not compatible with each other or particular types of door leaf and frame. Most fire-rated doors will be hung on three or more hinges. If the door has dropped due to failure of hinges or fixings or if the door does not close properly, remedial work should be undertaken as soon as possible. Fire risk Assessors should also check for the presence and the condition of intumescent seals. They should be fitted at the top and both side edges of the door. Intumescent protection for ironmongery should also be used to prevent early door failure. This is especially important for one hour fire resisting timber doors.Self-Closing DevicesIt is very important that self closing devices, close fire doors completely. Failure to close correctly or overcome the resistance of the latch, can usually be rectified by correct adjustment of the door closer and/or strike a plate. Many fire-rated doors are held open by automatic door releases. When the fire alarm is activated, these devices must release the door and it should then, fully shut. Correct operation should be checked and records kept.Emergency Escape DoorsDoors use for means of escape which may not be fire doors, for example final exit doors out of a building must open easily. Only one hand movement such as turning a lever or pressing a push pad or bar should be needed to open an emergency escape door. All fire doors must be adequately signed. Extra security locks should not be fitted to fire exit doors. If additional security is required, there are a variety electronic devices that unlock with the fire alarm.If a fire or protecting a means of escape is fitted with an air transfer grill, it needs to be a type that is linked to a suitable fire detection alarm system. The fire risk Assessor should check that the operation of any air transfer grills has been regularly checked and recorded.