The Health and Safety Executive (HSE) is warning construction firms to check the safety of gas flues, following roofing work, after the occupants of 11 bungalows in Birmingham were put at risk of carbon monoxide entering their loft spaces.

This warning comes after Surrey firm Wates Construction Ltd was fined £7,000 with £2,491 costs by Birmingham Magistrates' Court.

Prosecution followed roofing work carried out by sub-contractors working for Wates, the principal contractors for the works, on a number of bungalows in Rednal Road, Birmingham, between June and September 2006. The integrity of warm air flues, which vent through roof ridge terminals, was discovered to have been disrupted in 11 of the properties, potentially causing a build-up of lethal carbon monoxide in the loft space.

Every year, approximately 25 people die from carbon monoxide poisoning caused by appliances and flues that have not been properly installed or maintained.

Another CORGI registered subcontractor had warned Wates about the need to check the flues after the roofing work had been completed. Wates failed to do this.

Speaking after the case, HSE investigating inspector Mike Ford said:  "The dangers of damaging flues are well known in the building and refurbishment trade. Such dangerous work, as that seen in Rednal Road, puts lives at risk from carbon monoxide poisoning."

Wates Construction Ltd pleaded guilty to contravening section 3(1) of the Health and Safety at Work Act 1974.