2. How long can fire doors withhold fire and smoke?
There are various components which make up a fire door; you will typically be able to identify the following:
Door leaf – this is the door itself which must be manufactured and certified with a suitable fire rating to the building it will be contained in.
Door frame – this must be compatible with its counterpart, the door leaf, and fitted correctly to ensure the gaps are appropriate and meet the size needed to fulfill its function.
Smoke/Fire seals – these should fill all of the gaps around the door leaf when closed.
Intumescent strips – unlike smoke seals which retain their current form at all times around the frames of fire doors to block fire and smoke, intumescent strips expand when exposed to extreme heat, further sealing the gap around the door frame.
Hinges – these must have the correct fixings in the right locations, as well have appropriate hinge pads, to ensure the door opens and closes efficiently.
Door closer – this is another facilitator to ensure the door closes automatically; you’ll usually see a metal box attached to an arm behind the fire door at the top (which often goes unnoticed!), although not all fire doors have a door closing mechanism.
Latch/lock (to ensure that the fire door remains closed) – this is also fitted within intumescent protection for fire/smoke resistance.
Threshold seals – this closes the gap underneath the door leaf when closed.
Signage (clearly indicating that it is a fire door so they should be kept shut) – you will usually see a blue circular sign on a fire door indicating that it is a fire door and must be kept shut.
Some fire doors also have glazed panels and must be suitably fire resistant, as well as fitted with intumescent glazing seals. Air grilles are also used where extra ventilation is required, which are then designed to close if the fire alarm is activated. You may also see on some fire doors additional ironmongery such as push bars and push pads to provide easy escape in an emergency.