Fire Safety in blocks of flats - Unsatisfactory Smoke Control and Fire Resisting doors Â– Pt 13
Our series of blogs on fire safety in blocks of flats has looked quite often at how, in many cases, fire safe construction which adhered to legislative standards at the time of building remain acceptable, even though current fire safety guidance has changed. In one area, however, previous guidance is so far removed from current standards that it must be addressed.
Smoke dispersal methods used in the past have now been proven to be unreliable and unsatisfactory and so no longer provide an acceptable method of smoke control. Blocks with unsatisfactory smoke control methods are therefore forced to address the issue in two ways: Smoke control arrangements and travel distances.
For example, benchmarks for existing flats with unsatisfactory smoke control follow:
In blocks of flats with a single stairway, where flats open directly onto the stairway:
Up to six storeys in height – manually opening vents or windows would be acceptable.
Exceeding six storeys in height – automatically opening vents should be provided.
In blocks of flats with a single stairway, with a corridor or lobby approach separating the flats from the stairway and in which there is a travel distance of 7.5 to 10m:
Up to six storeys in height – openable vents are acceptable.
Over six storeys in height or greater than 10m travel distance, or where ventilation is only provided in the stairway – automatically opening vents or powered ventilation is required.
In blocks where corridor smoke dispersal systems are in place, cross-corridor doors may be necessary to implement a smoke containment approach. The openable vents or powered ventilation should be maintained to ventilate those sections.
Advice from a fire engineering or fire safety specialist should always be sought if smoke dispersal is present in single stairway buildings.
The subject of fire-resisting doors is one which will take us through the next blog issue too. Fire-resisting doors are an essential part of fire containment and control within a block of flats and are generally found at the entrance to each flat, along the protected escape route which would include at any entry to a staircase and in cross-corridor doors. The aim is to limit fire spread for a period of time to facilitate safer egress from the building and avoid fire spread between the flat of fire origin and other flats and the common areas.
Current benchmark guidance for the protected escape route within individual flats calls for FD20 fire resisting doors which means that it is a fire door which will resist the passage of fire for a minimum of 20 minutes. Fire-resisting doors which form part of the protected escape route from the flat entrance to the final exit should be FD30S doors, which means that the door will resist fire for 30 minutes and will have smoke seals to prevent smoke spread between areas. These doors will also have intumescent strips and cold smoke seals fitted along the top and sides and would be self-closing.
Next week’s blog will continue on the subject of fire-resisting doors and will look at those blocks of flats where the fire-resistant doors do not meet current benchmark standards. In the meantime, if you have any queries about a project or wish to discuss this blog series, please contact Peter Gyere in the first instance on 0208 668 8663.
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