Report on proposed fire curtain including calculation of radiation tenability and proposed alternative solution to the means of escape problem in Stanford Court, Cornwall Gardens, London, SW7.

fire curtain floor plan with red screen

Floor plan of flat showing proposed position of fire curtain (red line)

My client, the flat owner, was refurbishing a 4th floor flat. RBKC building control had provided a guidance document on the criteria that needed to be satisfied when fire curtains are to be deployed, and this required information on insulation against radiation so that flat occupants could pass by the hot curtain in a fire without suffering radiation burns

fire curtain bulge

Diagram of fire curtain showing bulge (green line) caused by expansion of fire gases which needs to be allowed for when assessing acceptable width of escape route

I was asked to make a calculation of tenability on the assumption that a 7m wide Coopers fire insulating curtain would be used to improve means of escape from bedrooms past sitting room and kitchen to the flat entrance door some 10m away through an unprotected area which could become smoke logged. I examined the floor plan and made the calculations according to BS7974 after obtaining from the curtain manufacturer the fire test radiation intensity (kW/m2 ) data at different times (0 to 20 minutes) for a BS 476 standard fire resistance exposure. I refreshed my memory on the guidance in BS 8524, and considered BS 9991 and BS 9999 which are recent guides on fire precautions in buildings.
My calculation result seemed acceptable to me but it did mean that if a curtain was used the layout of the sitting room would be severely restricted by the need to keep the curtain descent zone unobstructed by furniture. And this wold require the use of obstruction sensors.
I suggested alternative solutions including a very early acting (aspirating) FDA system with local fire suppression in the kitchen. It was later learnt that an external balcony could possibly give a secondary means of escape.
Client: private flat owner.