An investigation by the Health and Safety Executive found the chimneys were used to flue working gas boilers and fires at the properties in Devon and Cornwall, meaning the gases had no means to escape and could build up inside.
Prosecuted by HSE, Cornwall Housing, pleaded guilty to a breach of the Health and Safety at Work etc Act 1974 and was fined £6,660 and ordered to pay £697 in costs.
Its contractor, Barry Shipton, Tavistock, pleaded guilty to a breach of the Gas Safety (Installation and Use) Regulations 1998 was fined a total of £2,664 and ordered to pay £692 in costs.
Bodmin magistrates heard the work was undertaken at a property in Bodmin, and a property in Callington.
After the work was completed, Cornwall Housing own gas engineers had inspected the properties and classed the situation at both properties as ‘immediately dangerous’, which means it was an immediate risk to life.
HSE inspector Simon Jones, speaking after the hearing, said: “Although no-one was hurt, this was an incredibly dangerous situation where gas appliances could have pumped poisonous and potentially fatal gasses into the loft space of a home instead of to outside the property.
“Whenever a chimney is removed or capped careful checks should be taken to ensure that the chimney is not being used and cannot be used in the future.
“Proper work instruction and control by Cornwall Housing and then proper on-site enquiries by Barry Shipton would have prevented this dangerous situation from arising and putting the lives of their tenants at risk.”