Passive Fire Protection
What is it?
Buildings only catch fire if the requirements of the fire triangle are fulfilled: heat, a fuel and oxygen. Once the fire is established, it will move, and spread potentially very quickly, and easily faster than a person can run, particularly if it is dark and smoky as well.
Also known as “Fire Stopping”, passive fire protection is there to encapsulate any fire that breaks out and prevent it spreading to other places, or surfaces, which fire can damage to the point of failure. This gives occupants a chance to escape, and fire services time to arrive and control the outbreak.
Passive fire protection is a very important part of fire protection and mitigation and should not be ignored. A fire will pass through a hole in a wall the size of a pencil in 4 minutes. Fires will spread under floors and through roof voids, and beat retreating people, appearing in front of them as they think they are escaping.
It is a common myth that stuffing rockwool or glassfibre into a hole will stop a fire. Not so. Fire in the form of incandescent gases, will pass through as if it were not there. Similarly people often use so-called fire resistant foams, but these too will eventually ignite and fail. It is vital to utilise the correct materials to block the progress of a fire., and equally vital to fit them correctly.
Who needs it?
Any building where fire can break out (which is more or less any building), needs to be assessed for fire spread mitigation measures. In your own home, we say “Close the door on a fire”. Fire resistant doors offer the first line of protection, in conjunction with smoke alarms to alert your family in time to escape. Similarly, plasterboard walls and ceilings will help to slow the fire while you get out.
In large buildings, it is vital to control where the fire can spread because occupants may not be mobile, such as care homes, or hospitals and so must be encapsulated in a fireproof segment, requiring only the movement of the occupants in the affected section or zone. It only needs a plastic pipe passing through a floor, with a larger hole around it, to allow the fire to jump floors. Such pipes should be passed through fire “collars” that are intumescent and melt to block the hole, including crushing the pipe and preventing the passage of hot gases.
If you feel your premises are not adequately “fire stopped” you need to get a professional survey, by an organisation, like Fal Fire, which is experienced in both the spread of fire, and the materials available to prevent this.
Unprotected holes passing between floors in large multi-storey buildings, and inadequate provision of fire doors (or defective fire doors) are incredibly common and can be the weak link in your fire protection.