Fire Doors have two important functions in a fire; when closed they form a barrier to stop the spread of fire and when opened they provide a means of escape.
A well designed timber fire door will delay the spread of fire and smoke without causing too much hindrance to the movement of people and goods.
Every fire door is therefore required to act as a barrier to the passage of smoke and/or fire to varying degrees depending upon its location in a building and the fire hazards associated with that building.
The main categories of fire doors are FD30 and FD60 fire doors which offer 30 and 60 minutes fire protection.
The most commonly specified integrity levels are:
- FD30 – 30 minutes
- FD60 – 60 minutes
- FD90 – 90 minutes
- FD120 – 120 minutes
Fire doors are usually 44mm or 45mm thick and are available in a large range of designs and colours, to look at the door you wouldn’t even know it’s a fire door.
Is your door a fire door?
Older panel doors, especially if less then 44mm thick, are unlikely to be FD30.
Hollow flush doors using egg box or similar construction will not be FD30. This can be detected by the weight of the door, because fire doors are much heavier than a hollow door.
Fire Door Seals or Fire and Smoke Seals
Intumescent fire door seals should be fitted to the stiles and head of a fire-resisting doorset.
These seals are fitted into grooves cut into the door or the frame, or alternatively, can be surface mounted. As soon as the temperature in the vicinity of the strips exceeds 200°C, usually about 10-15 minutes after the start of a fire, the seal swells and seals the gaps between door and frame.
As smoke spread is an even greater threat to life and property than flames, particularly in the early stages of a fire, fire doors might also have to be fitted with a ‘cold smoke’ seal to prevent the ingress of smoke around the door edges
Combined smoke and intumescent seals are available.
Fire Resisting Glazing
Glazing may range from a small vision panel in a door to a glazed screen for maximum light transmission and safety. Ordinary glass cracks when exposed to heat and is liable to fall out fairly early in a fire. Fire resisting glass can withstand exposure to the heat condition in a fire test for at least 60 minutes before it reaches a temperature high enough to soften it. This is mainly because, with clear FR glazing, nearly 50 per cent of the incident heat is transmitted through the glass by radiation.
How big should gaps around fire doors be?
Best practice guidance states that the gaps at the sides and top of a timber fire door should be between 2 and 4mm. You can measure the gap with a simple gap gauge.
** information from www.firesafe.org.uk