Fires may sweep rapidly through buildings via their dry-lining systems, a study by drywall specialist Hammerton Associates has found.
Under the pressure of a fire, said the company, smoke can be forced through the dry-lining system. This was highlighted in a building it recently inspected where soot had travelled in from outside, through the dry-lining system and dropped onto the managing director's plate in the directors' dining room. There turned out to be 50mm of soot lining the beams and columns. If soot can get in then so can smoke, says Hammerton.
The solution, it argues, is to firestop column/ beam junctions and also places where beams pass through the external walls. 'Nobody has ever brought this to light,' said Roy Hammerton. 'There isn't a manufacturer which says you should firestop the connections.' The problem is not picked up, he said, by fire-testing to BS476, because this is done at a very low pressure of only 19 Pa. In contrast, said Hammerton, real fires can generate a pressure of more than 2000 Pa, 'which will blow the firestopping out of pipes'.
Hammerton says this is newly discovered but not the only risk in building. 'There isn't a building in London I would classify as firesafe,' he said.