Government action follows exposé of "potentially risky" chimney flue liners in Building Homes.
The government has launched an urgent inquiry into the safety of real fire chimneys made of "potentially risky concrete components" built into thousands of new homes.

Last Wednesday, construction minister Nick Raynsford announced an "expert risk assessment" after being told of concerns about the safety of the UK's best-selling concrete flue liner, made by Dunbrik (Yorks) of Wakefield.

Results of tests carried out by several building control authorities showed that samples of Dunbrik's "real fire" product contained high proportions of silica sand, which is specifically rejected in the relevant British Standard (BS 6461).

One test ordered by Staffordshire Moorlands District Council found that samples of flue liners manufactured by Dunbrik in July 1998 contained more than 50% sand. Raynsford said the test results were "inconclusive" but that they did show that building control authorities and warranty providers might have grounds for concern.

Local authority investigations were prompted by Building Homes' publication in November of the results of tests conducted for it by the Building Services Research and Information Association in July 1998, which found that two product samples manufactured in April 1996 and June 1998 contained more that 40% sand.

Silica sand expands at 500 °C and, when used as the aggregate in concrete, risks damage from chimney fires. Raynsford stressed to the Commons that products "solely comprising kiln-burned aggregate, pumice and cement are not known to give rise to any problems".

The DETR was prompted to review the problem when local authorities withheld build completion notices on new houses fitted with concrete flues.

Dunbrik is believed to have up to three-quarters market share of the 35 000 houses built every year with the "real fire" flues that are the subject of the DETR review.

Raynsford said the DETR inquiry will assess how many houses have been built with the potentially risky flues and the nature of the risks to householders.

The minister will ask an independent contractor to evaluate all available data and to advise on drawing up new performance standards to minimise risks to householders.

He said: "There appears to be insufficient evidence at present to warrant advising householders to take any additional care in the ways that they use their fireplaces." The British Standards Institution last week apologised for a fax that more than a year ago ended a criminal investigation into Dunbrik.

In a statement, the BSI said: "BSI wishes to make it clear that it cannot state whether any concrete flue manufacturers' products comply with Building Regulations. BSI accepts any statements made in various correspondence may have created a misleading impression regarding this point, and apologises for any confusion caused. An internal investigation on this matter is presently under way within BSI." Essex Trading Standards officers, who had spent eight months compiling a case for prosecuting Dunbrik under the Trade Descriptions Act, dropped their investigation after being sent a copy of a BSI fax dated 12 January that rejected claims that its products did not comply with Building Regulations.

The apology comes within days of the BSI quality service managing director Mike Gilbert leaving the BSI "to pursue other interests".