On this page
- What changes the cost of fitting a smoke alarm
- Battery, mains or interlinked: which alarm fits your home
- Landlords in England: one alarm per storey, and carbon monoxide where fuel burns
- New homes and some extensions and loft conversions need mains alarms
- When fitting a smoke alarm needs Building Regulations sign-off
- Booking smoke alarm installation in London
The short version
- DA Electrical London fits smoke and carbon monoxide alarms from £80, typically £80–£150 including VAT.
- A new circuit for alarms is notifiable in England; a supply from an existing lighting circuit away from bathrooms is not.
- Landlords need a smoke alarm on every storey with living space, and sealed battery alarms meet the rule.
- New homes, and loft conversions that add a habitable room, need mains-operated smoke alarms with a standby supply such as a battery.
Having a smoke or carbon monoxide alarm fitted by DA Electrical London costs from £80, typically £80–£150 including VAT. The wiring sets the price. A sealed battery alarm is quick to fit, a mains alarm needs a supply, and a new circuit brings notification and a certificate.
| Job | Guide price (incl. VAT) | What decides the final figure |
|---|---|---|
| Fitting a smoke alarm | from £80 | Battery or mains, and whether a supply already reaches the ceiling |
| Fitting a carbon monoxide alarm | from £80 | How the alarm is powered and where the fuel-burning appliance is |
| Interlinked alarms through the whole home | Quoted after a visit | How many alarms, and how cable gets to each one |
The guide price covers a standard fitting of about an hour. A job with several alarms, or new cable to run under floors and across ceilings, is quoted once we've seen the property.
What changes the cost of fitting a smoke alarm
The price follows the work needed to power the alarm. Most jobs are one of these four, from the simplest to the most involved:
- A sealed battery alarm fixed to the ceiling. There's no wiring, so it's the quickest job.
- Swapping an old mains alarm for a new one on the same supply. The cable is already there.
- A new mains alarm fed from a lighting circuit. Cable has to reach the ceiling, which can mean lifting a floorboard or cutting into plaster.
- A new circuit from the consumer unit for the alarms. In England that's notifiable building work, explained further down.
Two things add time to any of these: linking the alarms so they all sound together, and the kitchen, where government advice is to fit a heat alarm instead of a smoke alarm. If your alarms need replacing or adding, our electricians in London fit battery and mains alarms.
Battery, mains or interlinked: which alarm fits your home
Three kinds of alarm cover almost every home. The difference is how they're powered and what the rules say about each.
| Alarm | How it's powered | Upkeep | Where the rules point |
|---|---|---|---|
| Sealed ten-year battery | Built-in battery, no wiring | Replace the whole alarm after ten years | Allowed in rented homes |
| Mains-powered | Wired to the home's supply, with a back-up battery | Test it every month | Expected in new homes and some extensions |
| Interlinked | Mains or battery, joined by cable or radio | Test every month; one alarm sets off the rest | Your choice in an existing home |
Government fire safety advice is to test alarms at least once a month. A ten-year alarm is replaced whole when its time is up, and an alarm with a one-year battery needs a new battery every year.
Landlords in England: one alarm per storey, and carbon monoxide where fuel burns
What regulation 4 requires
Private landlords and registered providers of social housing must follow the Smoke and Carbon Monoxide Alarm (England) Regulations 2015. Regulation 4 sets three duties:
- a smoke alarm on each storey with a room used as living accommodation, where a bathroom or toilet counts as such a room
- a carbon monoxide alarm in any of those rooms with a fixed combustion appliance, such as a stove or an open fire. A cooker on a piped or bottled fuel supply is the one exception
- a check that each alarm works on the day a new tenancy begins
Since 1 October 2022, landlords must also repair or replace an alarm once they're told it's faulty and find that it is. Councils enforce the rules, and they can fine a landlord who ignores a remedial notice.
Licensed HMOs, owner-occupiers and decorative fireplaces
Licensed HMOs are exempt from Parts 1 to 5 of these regulations, but only because the same regulations add similar alarm conditions to HMO licences under the Housing Act 2004. A licensed HMO still needs alarms, and an unlicensed HMO falls under the regulations directly.
Owner-occupiers aren't covered at all. The government guidance also says a decorative fireplace that doesn't work isn't a fixed combustion appliance.
Alarms are separate from the wiring check. The five-yearly EICR comes from different regulations, and our landlord EICR service in East London covers that inspection and its report.
New homes and some extensions and loft conversions need mains alarms
Approved Document B sets the standard for building work. New homes need a fire detection and alarm system to at least Grade D2 Category LD3 under BS 5839-6. The smoke alarms should be mains operated, with a standby supply such as a battery.
Extensions and loft conversions
The same applies when a project adds a habitable room above or below the ground storey, or a ground-floor room with no final exit. A loft conversion with a new bedroom is one example. The smoke alarms then go in the home's circulation spaces, meaning its halls and landings.
Larger houses, and homes nobody is altering
Bigger houses need more. Under the same guidance, a house with more than one storey and a storey over 200 m² needs a Grade A system. If you own your home and aren't building or converting, neither set of rules applies, though government advice is at least one smoke alarm on every level.
When fitting a smoke alarm needs Building Regulations sign-off
In England, electrical work in a home is notifiable under regulation 12(6A) of the Building Regulations when it installs a new circuit, replaces a consumer unit, or adds to a circuit in a special location. The zone around a bath or shower is the usual one.
So a mains alarm fed from an existing lighting circuit, away from the bathroom, isn't notifiable, though it still has to meet the regulations. A dedicated alarm circuit is notifiable.
For notifiable work you either tell building control first or use a registered electrician, who notifies it for you. With a registered electrician you then receive an Electrical Installation Certificate or Minor Works Certificate, plus a Building Regulations compliance certificate. Our guide to the EIC certificate explains each one.
Booking smoke alarm installation in London
When you get in touch, tell us how many alarms you need, whether any are already wired to the mains, and whether the home is rented. Those three answers decide which of the jobs above it is.
To book, see our electrician service in London or call 07727 619854.
Frequently asked questions
A standard fitting takes about an hour. A whole-home interlinked system with new cable takes longer, and the cable routes decide how much.
No. The rule covers each room used as living accommodation that has a fixed combustion appliance, such as a stove or open fire. A cooker on a piped or bottled fuel supply doesn't count, and nor does a decorative fireplace that doesn't work.
Government guidance for landlords suggests head height, on a wall or a shelf, in the room with the appliance. Smoke alarms are different: they go on the ceiling of a hall or landing.