FIRE SPREAD between the floors of unsprinklered curtain walled buildings is likely to be much quicker than assumed, according to the latest research carried out by the Loss Prevention Council.
Fire tests at the LPC's Borehamwood research centre showed that fire can break through standard curtain walling within minutes, especially if furniture is placed close to windows. Glazing failure occurred in less than five minutes in the LPC test with real office furniture, and within seven minutes the curtain walling was completely destroyed.
This implied 'considerable fire growth and damage' before fire-fighters could arrive, the LPC states in the research report it published this week.
The research also cast doubts on the use of ordinary float glass in double glazing systems. 'Where float glass is used in curtain walling, means must be found to delay failure, as this appears to be the weakest link in the system,' the report states.
Aluminium-framed curtain walling systems escaped major criticism, despite softening and distorting as temperatures reached 200degreesC. LPC's tests showed that even with fire resistant glazing, the aluminium frame would disintegrate within 30 minutes and allow the flames to spread upwards.
The LPC, however, believed this would be long enough for the original fire to have largely burned itself out. It was glazing rather than frame failure that contributed to the rapid upward spread of fire, which caused more than £15M of damage to the Mercantile Credit building in Basingstoke, Hampshire, in 1991, the LPC concluded (NCE 25 April 1991).
A further series of tests confirmed the benefits of sprinkler systems. When water was sprayed directly onto float glass glazing it prevented failure until the main fire threat had passed, while sprinklers were generally successful in preventing both glazing and firestop failure.
'Fire spread in multistorey buildings with glazed curtain wall facades' is available from the LPC, Melrose Avenue, Borehamwood, Herts, WD6 2BJ, price £49.50.