BS 5839-6 explained for landlords: smoke alarm rules for rented homes in England

Under the Smoke and Carbon Monoxide Alarm Regulations, as updated in October 2022, private and social landlords in England must make sure there's at least one smoke alarm on every storey with a room used as living accommodation. There must be a carbon monoxide alarm in any room with a fixed combustion appliance, such as a boiler or a wood burner. Gas cookers are excluded.

Alarms must be working on the first day of each new tenancy, and repaired or replaced once you're told they're faulty. Councils enforce this, and fines can reach 5,000 pounds.

But the law sets a minimum, not a design. It doesn't say which type of alarm to fit. The government's guidance for landlords points to BS 5839-6, and says alarms with sealed-for-life batteries are the better option.

For new homes, and some building work, Approved Document B goes further: mains-powered alarms with a backup supply, to at least Grade D2, Category LD3. So what do those grades and categories mean?

In BS 5839-6, the grade describes the type of system and how it's powered. Grade F alarms run on batteries alone. Grade D alarms run on mains power, with a backup battery built in.

The number matters too. A 1 means the battery is sealed in and can't be removed. A 2 means the user can replace it.

So D1 is mains powered with a sealed backup, and F2 is a battery alarm with a replaceable battery. Above these, Grades A and C use central control equipment, for larger or higher risk homes.

The category describes coverage: where the detectors go. LD3 covers the escape route, meaning the hallways and landings you'd use to get out. LD2 adds the rooms where a fire is most likely to start, or would be most dangerous, such as the kitchen and the main living room.

LD1 goes further still, covering nearly every room. In kitchens, a heat alarm is normally used, so cooking doesn't set off false alarms.

So what should a landlord aim for? Rented homes are treated as higher risk, partly because a tenant might remove a battery from an alarm that keeps going off. That's why mains-powered alarms with sealed backup batteries, Grade D1, are widely recommended for lets.

Where there's more than one alarm, they should be interlinked, so when one sounds, they all sound. And in houses in multiple occupation, councils often set higher standards through licensing, so always check with your local authority.

Then keep it working. Test every alarm on the first day of each tenancy, and keep a record, for example on an inventory the tenant signs. Show tenants how to test their alarms.

Fix faults as soon as you can once they're reported. And replace alarms by the date the manufacturer gives, because detectors don't last forever.