Your building is rarely domestic or commercial as a whole. Gas safety law tests each part of the premises, and then each appliance and its pipework. A flat above a shop, a house half converted to offices and a block with a shared plant room can all sit on both sides of the line at once. This guide sets out the two legal definitions, the appliance test that decides the flat above the shop, and the duties that take over when a part is not residential. It covers England, under the Gas Safety (Installation and Use) Regulations 1998 as amended.
Is a flat above a shop domestic or commercial for gas safety?
A flat above a shop is a mixed building, and the gas rules follow the use of each part. The Gas Safety (Installation and Use) Regulations 1998 as amended apply to relevant premises, meaning premises, or parts of them, occupied for residential purposes, whether exclusively or not.
HSE states that regulation 36, the landlord gas safety duty, does not apply to gas appliances or installation pipework used exclusively in a part of the premises that is not occupied for residential purposes. The flat is in scope on that reading. A gas heater serving only the shop floor is not.
Work the answer out part by part, then appliance by appliance. One address can be domestic for the boiler serving the flat and non-domestic for a heater that serves only the shop.
What counts as 'domestic premises', and why a shared stairwell does not
Domestic premises are defined in section 53 of the Health and Safety at Work etc. Act 1974 as premises occupied as a private dwelling. The definition takes in a garden, yard, garage, outhouse or other appurtenance of the dwelling. It then carves out anything used in common by the occupants of more than one such dwelling.
Shared stairs, corridors and the plant room in a block of flats are therefore not domestic premises. HSE points to the same section 53 wording when explaining where the domestic gas rules stop. A part of premises that is not domestic, and is made available to someone as a place of work, is a workplace under the Workplace (Health, Safety and Welfare) Regulations 1992. HSE notes that stairs, entrances, corridors and heating or boiler rooms can fall into that description.
Communal gas equipment still has an owner with duties. HSE states that building owners must make sure shared gas appliances, flues and pipework that tenants may use are properly maintained and checked for safety.
The boiler is in the shop but heats the flat — whose duty is it?
An appliance installed in a non-domestic part that also serves living accommodation is caught by the landlord duty. HSE treats such an appliance, and its own example is a central heating boiler, as a relevant gas fitting under regulation 36 of the Gas Safety (Installation and Use) Regulations 1998 as amended.
Where the boiler sits does not decide the answer. What the boiler serves decides it. A boiler in the shop's back room that heats the flat above falls under the same annual check as the flat's other gas appliances.
Regulation 36 already assumes buildings get split up. It disregards what a tenant does to gas fittings in parts of the premises occupied for non-residential purposes when judging whether the landlord met the duty. If the same boiler heats only the shop, it sits outside regulation 36. HSE states that a landlord's maintenance obligations under section 4 of the Health and Safety at Work etc. Act 1974 can still reach that equipment.
A house converted to offices: is a landlord gas safety record still needed?
Once no part of a converted house is occupied as a dwelling, the landlord duty in regulation 36 has nothing to attach to, because there are no relevant premises. The duties do not vanish, they change shape. Where the converted part is a workplace, regulation 35 of the Gas Safety (Installation and Use) Regulations 1998 as amended sets maintenance requirements. The Health and Safety at Work etc. Act 1974 and regulations made under it apply alongside, and HSE names the Provision and Use of Work Equipment Regulations 1998 among them.
Employers have their own instruction from HSE. Use a Gas Safe registered engineer or other competent person to install, maintain or repair gas fittings, and have pipework, appliances and flues maintained regularly.
One remaining flat changes the picture again. A caretaker's flat or an unconverted top floor makes the building mixed, and the test runs per part and per appliance once more. Our guide to landlord gas safety in England covers what the residential side asks for.
Who counts as a landlord under the gas rules, and what falls to you
HSE describes a landlord for gas purposes as someone who rents out a property they own under a lease of less than seven years, or under a licence. That takes in private landlords, local authorities, housing associations, housing co-operatives, hostels, rooms in bed-sit accommodation, B&Bs and hotels. Rented holiday accommodation is included too, such as chalets, cottages, flats, caravans and narrowboats. Where a lease runs for more than seven years or for life, HSE states the landlord is not responsible for the checks and maintenance.
- An annual gas safety check on each gas appliance and flue in the residential part
- The record kept for two years
- A copy to existing tenants within 28 days of the check, and to new tenants before they move in
A tenancy agreement cannot move these duties to the tenant. HSE and gov.uk are both clear that even a full repairing and insuring lease leaves them with the landlord. In England, gov.uk states a section 21 notice cannot be served without a valid gas safety record. Shared houses carry extra points, set out in our guide to gas safety in an HMO.
Alarms follow a separate rulebook in England. The Smoke and Carbon Monoxide Alarm (England) Regulations 2015, as amended in 2022, require a carbon monoxide alarm in every room used as living accommodation that contains a fixed combustion appliance, with gas cookers excepted. Local authorities enforce those regulations. The detail sits in our guide to CO alarm rules for rented homes in England.
Paying business rates does not make a building commercial for gas safety
Business rates and council tax answer a tax question, not a gas safety question. gov.uk describes a composite property as one that is part domestic and part non-domestic, a shop with a flat above being the standard example. Business rates apply to the non-domestic part and council tax to the home. The Valuation Office Agency sets council tax bands for domestic properties and rateable values for non-domestic ones.
None of that decides whether regulation 36 applies to your boiler. The gas test comes from the Gas Safety (Installation and Use) Regulations 1998 as amended and section 53 of the Health and Safety at Work etc. Act 1974. Two questions do the work. Is the part occupied for residential purposes, and what does the appliance actually serve? A home-based business may bring business rates on part of a house while the boiler still heats a dwelling.
Which engineer can do the work, and who enforces gas safety in a mixed building?
Check that the engineer's registration covers the specific job in front of you. HSE points out that the areas a Gas Safe registered engineer is competent in are shown on the back of the registration card. Manufacturers split their own ranges as well. Worcester Bosch describes a 50kW boiler as the point where domestic meets light commercial, and Baxi notes the ErP framework covers domestic and commercial products below 400kW output. The line between domestic and commercial moves depending on which rulebook you are reading.
Enforcement splits too. Schedule 1 of the Health and Safety (Enforcing Authority) Regulations 1998 sets out which activities in non-domestic premises the local authority enforces, with the remainder falling to HSE. Each separately occupied part of non-domestic premises is assigned by the main activity carried on there. Work on gas systems is assigned to HSE, unless it is done by someone who normally works in premises assigned to the local authority.
Anything involving gas, the flue or the inside of the boiler casing is work for a Gas Safe registered engineer, whichever side of the line the room sits on. When the boiler serving the living accommodation is due a check or has stopped, you can arrange a visit through our boiler service and repairs page.
Sources
- Health and Safety at Work etc. Act 1974, section 53 (definitions)
- HSE — Gas safety checks: who needs them?
- The Gas Safety (Installation and Use) Regulations 1998, regulation 36
- HSE — Summary of legislation interfacing with GSIUR 1998
- HSE — Who is a landlord?
- GOV.UK — Private renting: your landlord's safety responsibilities
- HSE — Health and Safety (Enforcing Authority) Regulations 1998 guidance
- GOV.UK — Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022: guidance for landlords and tenants