A BBC News London investigation has concluded that hundreds of thousands of council homes are at a greater risk from the consequences of a fire because their traditional wooden window frames have been replaced with PVC-U windows. The revelation comes days ahead of the inquest into the deaths of six people who died when fire ripped through Lakanal House in Camberwell, last July.
https://news.bbc.co.uk/1/hi/england/london/8401597.stm
https://www.croydonguardian.co.uk/news/4783450.Croydon_probe_finds_PVC_windows
BBC London has been pursuing the investigation following the Lakanal House fire in Camberwell in July. Concerns were raised shortly after the blaze that the rapid spread of the fire had been helped by the PVC window frames. Southwark Council told the British Plastics Federation that the windows in Lakanal House were aluminium, but residents have subsequently claimed that the windows were definitely plastic.
Across London vast numbers of buildings have seen traditional wooden window frames replaced with PVC plastic, including a block in Croydon which burned to the ground in 2007.
The BBC has seen the results of a test conducted by BRE that compared PVC windows to those with wooden frames. (The BBC London report also refers to ‘the striking similarities’ of another fire which destroyed a block in Croydon on Christmas Day 2007. The official report into that fire blamed incorrect installation of PVC windows. PVC was used to fill gaps around the window – when the fire began it melted, causing the block to burn down.
Some facts about wood and PVC
– There is no requirement in Building Regulations for fire performance to be a consideration in specifying external windows unless they are within 2m of a fire escape.
– The melting point of PVC is 100 to 260 o C
– Ignition temperature of unplasticised PVC
o Flash ignition = 391 o C
o Self ignition = 454 o C
*(Source : PVC handbook : Charles E. Wilkes, James W. Summers, Charles Anthony Daniels, Mark T. Berard)
– Wood does not melt.
– Wood burns at a constant rate depending on the density of the timber
o Softwood 1mm / minute
o Hardwood 0.6mm / minute
– In a fire, wood chars. The char acts as an insulator – in effect, it protects the wood below the char surface and so preserves its original properties.
– To give an example, a 30 minute softwood fire door frame has a minimum thickness of 33mm, most fire doors are made from wood and are usually 40mm thick.
