Fire risk: preventing disproportionate fire damage
The occupants or owners of any apartment or flat within an institutional building are highly reliant upon the elements of construction that are present between their apartment and the neighbouring ones (above, below or adjacent) to separate them from the others in the event of a fire. By regulations/law, it is a requirement that these walls/floors are able to resist the actions of a fully developed fire for a period sufficient to allow the Fire and Rescue Service to either extinguish the fire in the adjacent enclosure or to provide protection to the escape routes to permit late evacuation if it has not been possible to control the fire.
Regrettably, there are two very vulnerable openings that may permit the fire to breach these fire resisting enclosures:
i) fire doors to gain access to the apartment
ii) risers, ducts and openings for the passage of services, water pipes, cables, soil pipes etc., from central supply
The first of these is a well documented subject and various guides to fire door technology will be found on websites such as www.ifsa.org.uk and www.intfire.com. The second set of apertures, those provided to accommodate the passage of services into the accommodation, is definitely the poor relation in respect of published guidance as to how fire can be prevented from exploiting these service penetrations. Regular guidance, as published in Approved Document ‘B’ 2006 in support of the England & Wales building regulations, just talks in general terms about the need to ‘firestop’ such apertures, but apart from a few vague references to proprietary materials, cementicious products and ‘mineral’ fibre there is little specific guidance. Unfortunately, the services entering modern apartments/suites are much more sophisticated and in greater number than even a few years ago. ‘Firestopping’ is just not the way to seal these penetrations. The insulation on cables must not be able to burn through the seal, expansion/bowing and buckling of the pipes and any cable supports must not be able to dislodge or negate the sealing system. The seals must be able to close-off any plastic pipes to prevent fire from exploiting them; including the 38mm pvc pipes that Approved Document ‘B’ appears to allow to pass through a wall or floorslab without bespoke sealing. Such pipes, even small ones, permit the passage of smoke in vast quantities and at the same time, adds to the smoke production unless sealed by a collar. It must be recognised that it is smoke that normally kills the occupants and ‘firestopping’ does not necessarily prevent the passage of smoke. In fact, the most commonly found form of firestopping is ‘pink-squirty-foam’ (comes in other colours), which is capable of producing significant volumes of toxic smoke itself when burning.
It is a fact that Approved Document ‘B’ pays‘lip service’ to the avowed objective to control the spread of fire and smoke. The ‘competent person’ who will now be employed by the ‘responsible person’ to carry out the Regulatory Reform (Fire Safety) Order mandated fire risk assessment may not feel at all willing to take such a liberal view, as does the guidance of the uncontrolled generation and passage of smoke. Consequently, proper bespoke systems may be the only way of obtaining a positive risk assessment.
Every form of service penetration seal, whether a gunnable sealant; a coated mineral wool batt; a pipe collar; intumescent pillows and, oh yes, even ‘pink-squirty foam’ should be sold with a field of application defining the size and number of services; the size of the aperture; the nature of the penetrated construction. Therefore, every specification/installation should call up sealing system that is proven/certificated for the actual application that you have.
Don’t take chances; only specify sealing systems that have evidence for your application. A failure to do so can have dire consequences on the resident and/or the building owner!