Fire risk assessment of duplex flat, Parkside, Wimbledon

I was asked to give advice on the splendid duplex apartment located on the fourth and fifth floors. There were doubts about the efficacy of an incorrectly installed cooker hood and extract, and on the lack of fire detection in the roof space, etc. I observed that the fifth floor is approximately 15 m from ground level and beyond the reach of normal fire appliance ladders for rescue so that fire detection needs to be rapid so that safe escape can be made down the staircase before it became smoke-logged. There was fire detection in the common parts hall but there was two-door separation between bedroom and sounder and it was doubtful if the sounder could be easily heard with the bedroom door closed; and I recommended that an acoustic test be carried out to confirm that 75 dBA criterion at the bed head position was met. I did not have access to the fire risk assessment for the common parts and did not know if a stay-in place or total evacuation policy was in place for an emergency.
I was shown a nominally 150 mm PVC plastic waste ventilation pipe (termed a stack pipe in ADB) believed to run continuously from ground level up to roof level. The stack had a decorative enclosure having no fire resisting properties and was considered a potential major fire hazard as fire could easily enter the boarded stack and travel several stories to emerge into a higher flat – an ideal geometry for rapid upward fires spread. If a fire reached the roof space it could cause considerable property damage by burning through the combustible roof with the potential to cause collapse of the roof construction into the accommodation below. It was not possible to establish if there were any intumescent collars fitted around the stack pipes within the concrete floor zone and further exploration was needed.
Down-lighters were installed in the ceiling of the uppermost floor and I pointed out that, while a roof did not require fire resistance under the building regulations, fire passing up through the down-lighters could ignite the roof and cause extensive property damage. However, the down lighters in the ceiling of the 4th floor would need to possess fire resistance if the floor was of timber construction. To accomplish this it is usual to instal a box- or cone-shaped fire resisting hood (usually made of intumescent coated/ impregnated fabric) above each downlighter. Alternatively modern down-lighters are on the market which include an intumescent built into the fitting.
There were also problems with a recent gas pipe alteration.

Client: flat occupier