Effective compartmentation for fire safety in blocks of flats
Last week’s blog touched upon fire resistance of walls and floors in blocks of flats. Fire resistant construction and fire doors between flats and the common areas is an essential part of a fire safe design and is known as compartmentation.
Compartmentation will restrict fire spread to the flat of origin most commonly, for a specified amount of time. The idea of such a design is that fire cannot spread causing escape routes to become inaccessible and that occupants of other flats are not in danger of fire spreading. This allows for the ‘stay put’ policy of evacuation most commonly used in blocks of flats. Only the occupants of the fire of origin flat would evacuate the building and the fire service would then be able to subdue the fire in a controlled manner.
Compartmentation does not stop fire spread for an indefinite period of time, but the benchmark level for blocks up to five storeys is 30 minutes and 60 minutes for blocks with six or more levels.
In new builds, this standard of construction is expected and a lesser standard considered unacceptable. However, in some older buildings, it is not possible to raise the standard of construction to the required levels of fire resistance and compensatory methods are then employed to ensure the safety of the building occupants.
These compensatory methods may be improvements that are made to existing fire escape routes or by providing additional escape routes. It may be that a fire alarm system or fire suppression system such as sprinkler installation is necessary.
When considering the condition of existing floors and walls within a block, particular attention should be paid to openings through which fire can spread. Fire can utilise service ducts, ventilation ducts and shafts, risers and refuse chutes. Equally, the condition of the construction around openings for gas, water, electricity etc. should be examined.
Shared ventilation and shared heating, in older blocks, can all present a serious threat to fire containment within the flat of origin and can lead to fire spreading to other flats within the block.
During an intrusive inspection, a type 2 or type 4 fire risk assessment, it is necessary to open up the construction to ascertain the level of fire stopping material present in such areas as kitchens and bathrooms where service pipes enter the flat.
Smaller pipes, less than 4cm in diameter are not usually considered a concern. Larger pipes could provide an avenue for fire and smoke spread. Fire seals are often used in new builds to avoid the pipes being used in this manner and it is possible to retrofit seals in older blocks, however the upheaval would be such that the flat in question would need to be unoccupied.
Next week’s blog will continue to look at Effective compartmentation in blocks of flats and will discuss shared ventilation ducts and what can be done to mitigate the risk of fire spread. We will also begin to touch upon means of escape.
In the meantime, if you have any queries about this blog, about your own project or wish to know more about fire risk assessment, please contact Peter Gyere in the first instance on 0208 668 8663.
The Complete Fire Safety Management Platform is the only fully comprehensive online fire risk assessment and fire risk management platform. Our aim, at CFSM, is to make the process of becoming fire safe, straightforward and, to use our expertise in fire risk assessment and fire safety management to guide you through each step, resulting in your premises meeting all legal, insurance and ethical fire safety considerations.